Trial Outcomes & Findings for Sub-study of Belantamab Mafodotin (GSK2857916) in Combination With Isatuximab in Participants With RRMM (NCT NCT07217184)

This is a sub-study of the master study NCT04126200. The study was planned to include two phases - Dose Escalation (DE) and Cohort Expansion (CE) and no participants from this sub study were enrolled in CE phase as CE Phase was not initiated due to business strategic reason.

The results presented are based on the data cut-off date of 17 Apr 2025. Those participants still benefiting from study drug in the opinion of their treating physician continued to receive study drug in Post Analysis Continuation of Treatment (PACT) phase and their safety data will be provided within a year of study completion.

Sub-study of Belantamab Mafodotin (GSK2857916) in Combination With Isatuximab in Participants With RRMM

Criteria for dose-limiting toxicity (DLT) included hematologic indicators such as Grade 3-5 febrile neutropenia and thrombocytopenia with bleeding. Non-hematologic criteria, excluding corneal toxicity, comprise Grade 3-5 toxicities, with exceptions for manageable nausea, vomiting, or diarrhea, controlled Grade 3 hypertension, and events linked to disease progression. Tumor lysis syndrome (TLS) of Grade 3 or 4, successfully managed within 7 days without end-organ damage, is considered. Corneal toxicity, assessed by the GSK corneal grading scale at Grade 4, is a DLT. Other organ-specific toxicities, notably liver toxicity meeting GSK stopping criteria, also qualify as DLT severity was graded using National Cancer Institute (NCI) - Common Terminology Criteria for Adverse Events (CTCAE) Version (v) 5.0.

An AE is any untoward medical occurrence in a clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. AEs were coded using the Medical Dictionary for Regulatory Activities (MedDRA) coding system.

Blood samples were collected for the analysis of hematology parameters. The laboratory parameters were graded according to CTCAE v 5.0. Grade 1 (G1): mild; Grade 2 (G2): moderate; Grade 3 (G3): severe; Grade 4 (G4) life-threatening or disabling. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade. Any worst-case post baseline increase to G1, G2, G3, and G4 are presented. Baseline value was defined as the most recent, non-missing value from a local laboratory prior to the first dose of study treatment. WBC: White blood cells.

Blood samples were collected for the analysis of chemistry parameters. The laboratory parameters were graded according to CTCAE version 5. G1: mild; G2: moderate; G3: severe. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade. Any worst-case post baseline increase to G1, G2 and G3 are presented. Baseline value was defined as the most recent, non-missing value from a local laboratory prior to the first dose of study treatment. BLD : Blood lactate dehydrogenase, CPK: Creatine Kinase.

Overall Response Rate (ORR) was defined as the percentage of participants with a confirmed Partial Response (PR) or better as the best overall response (i.e., PR, Very Good Partial Response \[VGPR\], Complete Response \[CR\], and stringent Complete Response \[sCR\]), as assessed by the investigator per international myeloma working group (IMWG) (2016). PR is defined as ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to \<200 mg/24 h. VGPR is defined as serum and urine M-component detectable by immunofixation but not on electrophoresis OR ≥ 90% reduction in serum M-component plus urine M-component \<100 mg/24 h. CR is defined as negative immunofixation of serum and urine AND disappearance of any soft tissue plasmacytomas AND \<5% plasmacytomas in the bone marrow. sCR is defined as CR as above PLUS normal serum free light-chain (FLC) assay ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

Overall Response Rate (ORR) was defined as the percentage of participants with a confirmed Partial Response (PR) or better as the best overall response (i.e., PR, Very Good Partial Response \[VGPR\], Complete Response \[CR\], and stringent Complete Response \[sCR\]), as assessed by the investigator per international myeloma working group (IMWG) (2016). PR is defined as ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to \<200 mg/24 h. VGPR is defined as serum and urine M-component detectable by immunofixation but not on electrophoresis OR ≥ 90% reduction in serum M-component plus urine M-component \<100 mg/24 h. CR is defined as negative immunofixation of serum and urine AND disappearance of any soft tissue plasmacytomas AND \<5% plasmacytomas in the bone marrow. sCR is defined as CR as above PLUS normal serum free light-chain (FLC) assay ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

Clinical benefit rate was defined as the percentage of participants with a confirmed minimal response (MR) or better according to the IMWG Response Criteria. MR is \>= 25% but \< 49% reduction of serum M-protein and reduction in 24-hour urinary M-protein by 50-89%.

Partial Response \[PR\], Very Good Partial Response \[VGPR\], Complete Response \[CR\], and stringent Complete Response \[sCR\] were assessed by the investigator per IMWG (2016). PR defined as ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to \<200 mg/24 h. VGPR defined as serum and urine M-component detectable by immunofixation but not on electrophoresis OR ≥ 90% reduction in serum M-component plus urine M-component \<100 mg/24 h. CR defined as negative immunofixation of serum and urine AND disappearance of any soft tissue plasmacytomas AND \<5% plasmacytomas in the bone marrow. sCR defined as CR as above PLUS normal serum free light-chain (FLC) assay ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

Partial Response \[PR\], Very Good Partial Response \[VGPR\], Complete Response \[CR\], and stringent Complete Response \[sCR\] was assessed by the investigator per IMWG (2016). PR defined as ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to \<200 mg/24 h. VGPR defined as serum and urine M-component detectable by immunofixation but not on electrophoresis OR ≥ 90% reduction in serum M-component plus urine M-component \<100 mg/24 h. CR defined as negative immunofixation of serum and urine AND disappearance of any soft tissue plasmacytomas AND \<5% plasmacytomas in the bone marrow. sCR defined as CR as above PLUS normal serum free light-chain (FLC) assay ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

Blood samples were collected for PK analysis of belantamab mafodotin Antibody-Drug Conjugate (ADC). Only those participants who were measured and analyzed (i.e., contributed data reported in the table) were included in the Overall Number of Participants Analyzed field. 'Number Analyzed' signifies participants evaluable for the specified timepoints.

Blood samples were to be collected for PK analysis of Belantamab Mafodotin Antibody-Drug Conjugate (ADC).

Blood samples were collected for PK analysis of Belantamab mafodotin total antibody.

Blood samples were to be collected for PK analysis of Belantamab mafodotin plasma total antibody.

Blood samples were collected for PK analysis of belantamab mafodotin cys- monomethyl auristatin-F (cys-mcMMAF).

Blood samples were to be collected for PK analysis of Belantamab Mafodotin Cys- Monomethyl Auristatin-F (Cys-mcMMAF)

Blood samples were collected for PK analysis of Isatuximab when administered intravenously in combination with belantamab mafodotin.

Blood samples were planned to be collected for PK analysis of isatuximab when administered intravenously in combination with belantamab mafodotin.

Serum samples were collected for the analysis of the presence of ADAs using validated immunoassays. All samples were tested in screening assay, and positive samples were further characterized for antibody titers.

Serum samples were to be collected for the analysis of the presence of ADAs using validated immunoassays. All samples were to be further tested in screening assay, and positive samples were further to be characterized for antibody titers.

Serum samples were collected for the analysis of the presence of ADAs using validated immunoassays. All samples were tested in screening assay, and positive samples were further characterized for antibody titers.

Serum samples were to be collected for the analysis of the presence of ADAs using validated immunoassays. All samples were to be further tested in screening assay, and positive samples were further to be characterized for antibody titers.

An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. AESI, whether serious or non serious were collected.

An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. AESI, whether serious or non serious, were to be collected.

The corneal events were graded according to CTCAE version 5. Grade 1: mild; Grade 2: moderate; Grade 3: severe or medically significant. Grade 4: Life-threatening consequences; Grade 5: Death related to AE. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade. Results are presented for number of participants with any corneal events by maximum grade as per CTCAE grade v 5.0.

The corneal events were planned to be graded according to CTCAE version 5. Grade 1: mild; Grade 2: moderate; Grade 3: severe or medically significant. Grade 4: Life-threatening consequences; Grade 5: Death related to AE. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade. Results were to be presented for number of participants with any corneal events by maximum grade as per CTCAE grade v5.0.

PFS is defined as the time from randomization until the earliest date of confirmed progressive disease (PD) per IMWG, or death due to any cause.

DoR is defined as the time from first documented evidence or PR or better until progressive disease per IMWG or death due to progressive disease among participants who achieve confirmed partial response or better.

TTR is defined as the time between the date of randomization and the first documented evidence of response (PR or better), among participants who achieve a response (confirmed PR or better).

OS is defined as the time from randomization until death due to any cause.

An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. SAE is defined as any untoward medical occurrence that; results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, is a congenital anomaly/birth defect, other situations judged by physician, is associated with liver injury and impaired liver function. AEs and SAEs were to be coded using the Medical Dictionary for Regulatory Activities (MedDRA) coding system.

An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. Number of participants with AEs leading to discontinuation were to be evaluated.

Number of participants with dose reduction or delay were to be evaluated.

Blood samples were to be collected for the analysis of hematology parameters. The laboratory parameters were to be graded according to CTCAE version 5.0. Grade 1 (G1): mild; Grade 2 (G2): moderate; Grade 3 (G3: severe or medically significant; Grade 4 (G4): Life-threatening consequences; Grade 5 (G5): Death related to AE. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade.

Blood samples were to be collected for the analysis of chemistry parameters. The laboratory parameters were to be graded according to CTCAE version 5.0. G1: mild; G2: moderate; G3: severe or medically significant; Grade 4: Life-threatening consequences; Grade 5: Death related to AE. Higher grade indicates greater severity and an increase in CTCAE grade was defined relative to the Baseline grade.