Trial Outcomes & Findings for Study to Evaluate Imetelstat in Patients With High-Risk MDS or AML Failing HMA-based Therapy (NCT NCT05583552)

Last Updated: 2026-05-12

Results Overview

The combined response assessment criteria for MDS and AML based on IWG (International Working Group) 2018 criteria (MDS) and the criteria of the European LeukemiaNet (AML) will be used to define responders. The response rate is calculated as number of responders divided by the number of all participants of the analysis set.

Recruitment status

ACTIVE_NOT_RECRUITING

Study phase

PHASE2

Target enrollment

46 participants

Primary outcome timeframe

Up to Week 17 (Visit 9; approximately 17 weeks after first dose).

Results posted on

2026-05-12

Participant Flow

Participant milestones

Participant milestones
Measure	Imetelstat Sodium (1 Treatment / Cycle) 2-hour intravenous (IV) infusion with Imetelstat one dose per cycle Treatment until any of the following: Disease progression Unacceptable toxicity Withdrawal of consent Lack of response Response-based continuation: Patients achieving a partial remission (PR) or better may continue Imetelstat Continued treatment is allowed until loss of response or disease progression.	Imetelstat Sodium (2 Treatments / Cycle) 2-hour intravenous (IV) infusion with Imetelstat two doses per cycle Treatment until any of the following: Disease progression Unacceptable toxicity Withdrawal of consent Lack of response Response-based continuation: Responders with ≥5% / \<5% bone marrow blasts continue Imetelstat until loss of response or disease progression Non-responders discontinue Imetelstat, complete End-of-Treatment procedures, and enter follow-up. In absence of alternative treatment options, non-responders with stable or controlled disease may continue in the extension phase provided disease remains controlled and no discontinuation criteria met
Overall Study STARTED	23	23
Overall Study COMPLETED	0	3
Overall Study NOT COMPLETED	23	20

Reasons for withdrawal

Reasons for withdrawal
Measure	Imetelstat Sodium (1 Treatment / Cycle) 2-hour intravenous (IV) infusion with Imetelstat one dose per cycle Treatment until any of the following: Disease progression Unacceptable toxicity Withdrawal of consent Lack of response Response-based continuation: Patients achieving a partial remission (PR) or better may continue Imetelstat Continued treatment is allowed until loss of response or disease progression.	Imetelstat Sodium (2 Treatments / Cycle) 2-hour intravenous (IV) infusion with Imetelstat two doses per cycle Treatment until any of the following: Disease progression Unacceptable toxicity Withdrawal of consent Lack of response Response-based continuation: Responders with ≥5% / \<5% bone marrow blasts continue Imetelstat until loss of response or disease progression Non-responders discontinue Imetelstat, complete End-of-Treatment procedures, and enter follow-up. In absence of alternative treatment options, non-responders with stable or controlled disease may continue in the extension phase provided disease remains controlled and no discontinuation criteria met
Overall Study Death	15	13
Overall Study Adverse Event	2	2
Overall Study Physician Decision	4	0
Overall Study Withdrawal by Subject	0	1
Overall Study Progressive disease	1	2
Overall Study Treatment inefficiency	0	1
Overall Study Per protocol decision	1	0
Overall Study Ongoing in the extension phase at data cutoff	0	1

Baseline Characteristics

Study to Evaluate Imetelstat in Patients With High-Risk MDS or AML Failing HMA-based Therapy

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Total n=46 Participants Total of all reporting groups
Age, Continuous	77.5 years STANDARD_DEVIATION 4.8 • n=1512 Participants	77.7 years STANDARD_DEVIATION 6.2 • n=504 Participants	77.6 years STANDARD_DEVIATION 5.5 • n=2016 Participants
Sex/Gender, Customized Male	15 Participants n=1512 Participants	14 Participants n=504 Participants	29 Participants n=2016 Participants
Sex/Gender, Customized Female	8 Participants n=1512 Participants	9 Participants n=504 Participants	17 Participants n=2016 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=1512 Participants	0 Participants n=504 Participants	0 Participants n=2016 Participants
Race (NIH/OMB) Asian	0 Participants n=1512 Participants	1 Participants n=504 Participants	1 Participants n=2016 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=1512 Participants	0 Participants n=504 Participants	0 Participants n=2016 Participants
Race (NIH/OMB) Black or African American	0 Participants n=1512 Participants	0 Participants n=504 Participants	0 Participants n=2016 Participants
Race (NIH/OMB) White	9 Participants n=1512 Participants	6 Participants n=504 Participants	15 Participants n=2016 Participants
Race (NIH/OMB) More than one race	0 Participants n=1512 Participants	0 Participants n=504 Participants	0 Participants n=2016 Participants
Race (NIH/OMB) Unknown or Not Reported	14 Participants n=1512 Participants	16 Participants n=504 Participants	30 Participants n=2016 Participants
WHO (World Health Organization) 2016 Disease Classification (MDS vs AML) MDS (Myelodysplastic Syndromes)	6 Participants n=1512 Participants	5 Participants n=504 Participants	11 Participants n=2016 Participants
WHO (World Health Organization) 2016 Disease Classification (MDS vs AML) AML (Acute Myeloid Leukemia)	17 Participants n=1512 Participants	18 Participants n=504 Participants	35 Participants n=2016 Participants
IPSS-R Risk Category Intermediate Risk	0 Participants n=1512 Participants	2 Participants n=504 Participants	2 Participants n=2016 Participants
IPSS-R Risk Category High Risk	1 Participants n=1512 Participants	0 Participants n=504 Participants	1 Participants n=2016 Participants
IPSS-R Risk Category Very High Risk	4 Participants n=1512 Participants	4 Participants n=504 Participants	8 Participants n=2016 Participants
IPSS-R Risk Category Score not done for AML	18 Participants n=1512 Participants	17 Participants n=504 Participants	35 Participants n=2016 Participants
Cytogenetic Risk (Karyotype) Good	1 Participants n=1512 Participants	2 Participants n=504 Participants	3 Participants n=2016 Participants
Cytogenetic Risk (Karyotype) Intermediate	1 Participants n=1512 Participants	1 Participants n=504 Participants	2 Participants n=2016 Participants
Cytogenetic Risk (Karyotype) Poor	3 Participants n=1512 Participants	1 Participants n=504 Participants	4 Participants n=2016 Participants
Cytogenetic Risk (Karyotype) Very poor	0 Participants n=1512 Participants	2 Participants n=504 Participants	2 Participants n=2016 Participants
Cytogenetic Risk (Karyotype) Score not done for AML	18 Participants n=1512 Participants	17 Participants n=504 Participants	35 Participants n=2016 Participants
Prior Azacitidine (AZA) cycles 1-6 cycles	7 Participants n=1512 Participants	5 Participants n=504 Participants	12 Participants n=2016 Participants
Prior Azacitidine (AZA) cycles 7-12 cycles	8 Participants n=1512 Participants	8 Participants n=504 Participants	16 Participants n=2016 Participants
Prior Azacitidine (AZA) cycles 13-24 cycles	3 Participants n=1512 Participants	7 Participants n=504 Participants	10 Participants n=2016 Participants
Prior Azacitidine (AZA) cycles ≥25 cycles	5 Participants n=1512 Participants	6 Participants n=504 Participants	11 Participants n=2016 Participants
Prior Venetoclax (VEN) cycles 1-6 cycles	8 participants n=1512 Participants	5 participants n=504 Participants	13 participants n=2016 Participants
Prior Venetoclax (VEN) cycles 7-12 cycles	3 participants n=1512 Participants	2 participants n=504 Participants	5 participants n=2016 Participants
Prior Venetoclax (VEN) cycles 13-24 cycles	1 participants n=1512 Participants	1 participants n=504 Participants	2 participants n=2016 Participants
Prior Venetoclax (VEN) cycles ≥25 cycles	1 participants n=1512 Participants	1 participants n=504 Participants	2 participants n=2016 Participants
Hemoglobin (g/dl) at Screening	8.9 g/dl STANDARD_DEVIATION 1.4 • n=1512 Participants	9.3 g/dl STANDARD_DEVIATION 1.5 • n=504 Participants	9.1 g/dl STANDARD_DEVIATION 1.5 • n=2016 Participants
Bone Marrow Blasts (%) at Screening	36.6 Percent (%) STANDARD_DEVIATION 24 • n=1512 Participants	28.4 Percent (%) STANDARD_DEVIATION 19.2 • n=504 Participants	33.5 Percent (%) STANDARD_DEVIATION 22.1 • n=2016 Participants
Height	169.9 cm STANDARD_DEVIATION 8.2 • n=1512 Participants	168.3 cm STANDARD_DEVIATION 9.9 • n=504 Participants	169.1 cm STANDARD_DEVIATION 9.05 • n=2016 Participants
Weight	71.437 kg STANDARD_DEVIATION 11.761 • n=1512 Participants	66.839 kg STANDARD_DEVIATION 15.883 • n=504 Participants	69.138 kg STANDARD_DEVIATION 13.822 • n=2016 Participants

PRIMARY outcome

Timeframe: Up to Week 17 (Visit 9; approximately 17 weeks after first dose).

Population: The Full Analysis Set (FAS) includes all participants who received at least one dose of imetelstat and fulfilled the study inclusion criteria. The FAS was used for the primary endpoint (overall hematological response rate).

Outcome measures

Outcome measures
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat
Overall Hematological Response Rate of Participants After Treatment With Imetelstat	0 Participants	1 Participants

SECONDARY outcome

Timeframe: From first dose of imetelstat through the last dose received, including follow-up to 28 ± 5 days after the last dose (duration varies by subject).

Population: Safety endpoints: Number of Participants With at Least One Treatment-Emergent Adverse Event (TEAE). Analyzed using Safety Evaluation Set (SES). SES includes all participants who received at least one dose of study drug, regardless of protocol adherence or follow-up completeness.

Toxicity was assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5.0. A treatment-emergent adverse event (TEAE) was defined as any adverse event arising or worsening after the first dose of study drug. The number of participants experiencing at least one TEAE was summarized in the Safety Evaluation Set.

Outcome measures

Outcome measures
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat
Toxicity Measured by NCI CTCAE v5.0 (National Cancer Institute - Common Terminology Criteria for Adverse Events Version 5.0)	23 participants	23 participants

OTHER_PRE_SPECIFIED outcome

Timeframe: From Treatment Start (Cycle 1 Day 1) to End of Treatment (EOT). Duration varies by subject.

The number of days between the first and last doses of study treatment. Subjects who discontinued early have duration calculated to their final dose date.

Outcome measures

Outcome measures
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat
Treatment Duration (Days)	53.8 days Standard Deviation 27.6	76.8 days Standard Deviation 71.7

OTHER_PRE_SPECIFIED outcome

Timeframe: From first dose of imetelstat through the last dose received, including follow-up to 28 ± 5 days after the last dose (duration varies by subject).

Percentage of study-drug doses received relative to the number of doses planned per protocol. Computed as: Compliance (%) = (Actual doses received ÷ Planned doses) × 100. Missed or undocumented doses are counted as not received unless justified per protocol or Statistical Analysis Plan (SAP). Dose holds and reductions are included in compliance assessment.

Outcome measures

Outcome measures
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat
Treatment Compliance	70 percentage Standard Deviation 20	60 percentage Standard Deviation 30

OTHER_PRE_SPECIFIED outcome

Timeframe: From first dose of imetelstat through the last dose received, including follow-up to 28 ± 5 days after the last dose (duration varies by subject)

Total amount of imetelstat (mg) received across all treatment administrations. Calculated as the sum of all administered doses documented in the dose-administration eCRF (electronic Case Report Form). Notes: Dose reductions, missed doses, and dose delays are captured in the calculation. Missing dose records default to "not administered" unless clarified.

Outcome measures

Outcome measures
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 Participants 2-hour intravenous (IV) infusion with Imetelstat
Cumulative Dose (mg)	1502.32 Milligrams Standard Deviation 511.08	2564.65 Milligrams Standard Deviation 1290.84

Adverse Events

Imetelstat Sodium (1 Treatment / Cycle)

Serious events: 18 serious events

Other events: 23 other events

Deaths: 15 deaths

Imetelstat Sodium (2 Treatments / Cycle)

Serious events: 19 serious events

Other events: 23 other events

Deaths: 13 deaths

Serious adverse events

Other adverse events

Additional Information

Dr. Andreas Beust, Sponsor Representative

GCP-Service International West GmbH

Phone: +49 (0) 421 89 67 66 11

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place

Restriction type: GT60

Serious adverse events
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 participants at risk 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 participants at risk 2-hour intravenous (IV) infusion with Imetelstat
Blood and lymphatic system disorders Anaemia	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Febrile neutropenia	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	17.4% 4/23 • Number of events 6 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Thrombocytopenia	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Cardiac arrest	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Cardio-respiratory arrest	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Dental caries	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Ileus	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
General disorders Death	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
General disorders Disease progression	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
General disorders General physical health deterioration	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
General disorders Pyrexia	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Immune system disorders Drug hypersensitivity	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Bronchopulmonary aspergillosis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Escherichia infection	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Fungal infection	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Haematoma infection	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Lung abscess	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Neutropenic sepsis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Osteomyelitis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Pneumonia	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Pseudomonas infection	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Pulmonary mucormycosis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Sepsis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Tooth infection	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Infections and infestations Urinary tract infection	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Injury, poisoning and procedural complications Fractured coccyx	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Acute myeloid leukaemia	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Blast cell crisis	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Transformation to acute myeloid leukaemia	21.7% 5/23 • Number of events 5 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Respiratory, thoracic and mediastinal disorders Chronic obstructive pulmonary disease	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Respiratory, thoracic and mediastinal disorders Lung disorder	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Vascular disorders Haemorrhage	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.

Other adverse events
Measure	Imetelstat Sodium (1 Treatment / Cycle) n=23 participants at risk 2-hour intravenous (IV) infusion with Imetelstat	Imetelstat Sodium (2 Treatments / Cycle) n=23 participants at risk 2-hour intravenous (IV) infusion with Imetelstat
Blood and lymphatic system disorders Anaemia	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	13.0% 3/23 • Number of events 8 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Febrile bone marrow aplasia	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Febrile neutropenia	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Leukocytosis	17.4% 4/23 • Number of events 4 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Leukopenia	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Lymphadenopathy	4.3% 1/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Neutropenia	17.4% 4/23 • Number of events 4 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Splenic infarction	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Splenomegaly	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Blood and lymphatic system disorders Thrombocytopenia	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	17.4% 4/23 • Number of events 5 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Angina pectoris	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Atrial fibrillation	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Bradycardia	4.3% 1/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Cardiac disorders Tachycardia	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Ear and labyrinth disorders Deafness	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Eye disorders Blindness unilateral	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Eye disorders Conjunctival haemorrhage	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Eye disorders Retinal haemorrhage	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Abdominal discomfort	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Abdominal pain	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Abdominal pain upper	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Anal fistula	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Angina bullosa haemorrhagica	8.7% 2/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Aphthous ulcer	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Constipation	8.7% 2/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	21.7% 5/23 • Number of events 9 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Diarrhoea	21.7% 5/23 • Number of events 7 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	26.1% 6/23 • Number of events 9 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Dysphagia	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Faecaloma	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Gingival bleeding	13.0% 3/23 • Number of events 3 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Gingival hypertrophy	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Gingival pain	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Haemorrhoids	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Melaena	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Mouth haemorrhage	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 4 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Mouth ulceration	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Nausea	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	21.7% 5/23 • Number of events 5 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Oral blood blister	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Oral mucosal blistering	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Rectal haemorrhage	4.3% 1/23 • Number of events 1 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.
Gastrointestinal disorders Vomiting	0.00% 0/23 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.	8.7% 2/23 • Number of events 2 • Adverse events were collected from informed consent until 28 (±5) days, up tp 1 month, after the last dose. Serious Adverse Events (SAEs) suspected to be related to imetelstat were collected at any time after discontinuation and documented without time limit. AEs were any medical events starting or worsening after informed consent; TEAEs were those beginning or worsening after first imetelstat dose. AEs were assessed at each scheduled visit in treatment and follow-up. Severity was graded per CTCAE v5.0, evaluating seriousness, severity, drug-relation, and expectedness. SAEs included death, life-threatening events, hospitalization, disability, congenital anomaly, or other medically significant events.