Trial Outcomes & Findings for Extension of Study HGT-SAN-055 Evaluating Administration of rhHNS in Patients With Sanfilippo Syndrome Type A (MPS IIIA) (NCT NCT01299727)

The study was conducted at 2 study centers in the Netherlands and United Kingdom between 01 March 2011 (first participant first visit) and 12 April 2019 (last participant last visit).

A total of 12 participants were enrolled in this extension study (HGT-SAN-067 \[NCT01299727\]), with 4 participants included in each of the 3 dose groups. Out of them, 10 participants completed the treatment period of the study.

Extension of Study HGT-SAN-055 Evaluating Administration of rhHNS in Patients With Sanfilippo Syndrome Type A (MPS IIIA)

An adverse event (AE) was any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in any phase of a clinical study, whether or not considered study drug related. Treatment-emergent Adverse events (TEAEs) were defined as all adverse events (AEs) from the time of the surgery for first IDDD implantation or first dose of HGT-1410 in study HGT-SAN-055 (NCT01155778) to the data cutoff date, or 30 days after the date of the last dose or 2 weeks after the date of device explant if early termination occurred. TEAEs included participants with any AE, any drug-related AE, any surgery-related AE, any IDDD-related AE, and any IT administration process-related AE, any SAE, any serious drug-related AE.

An adverse event (AE) was any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in any phase of a clinical study, whether or not considered study drug related. TEAEs were defined as all AEs from the time of the surgery for first IDDD implantation or first dose of HGT-1410 in study HGT-SAN-055 (NCT01155778) to the data cutoff date, or 30 days after the date of the last dose or 2 weeks after the date of device explant if early termination occurred. Severity of an AE is determined by following definitions: Mild: No limitation of usual activities; Moderate: Some limitation of usual activities; Severe: Inability to carry out usual activities.

Clinical laboratory assessments include hematology, serum chemistry including liver function tests, coagulation urinalysis and cerebrospinal fluid (CSF) were reported.

Any change in ECG assessments which were deemed to be clinically significant findings and abnormalities were recorded as TEAEs.

Antibody titers were determined for the samples that tested positive for anti-rhHNS antibodies. Participants with positive Anti-rhHNS antibody status in serum were reported.

Antibody titers were determined for the samples that tested positive for anti-rhHNS antibodies. Participants with positive anti-rhHNS antibody in CSF were reported

BSID-III was used to assess the motor (fine and gross), language (receptive and expressive), and cognitive development of infants and toddlers aged 0-42 months and consisted of a series of developmental play tasks. Score ranges: Cognitive scale 0-91, Receptive communication 0-49, Expressive communication 0-48, Fine motor 0-66 and Gross motor 0-72. Higher values denote stronger skills and abilities in the domain, indicating better outcomes.

BSID-III was used to assess the motor (fine and gross), language (receptive and expressive), and cognitive development of infants and toddlers aged 0-42 months and consisted of a series of developmental play tasks. KABC-II was an individually administered measure of the processing and reasoning abilities of children and adolescents between the ages of 3 and 18 years and an alternative to BSID-III. Raw scores were converted to age--equivalent scores to measure ability, skill, and knowledge, expressed as the age at which most individuals reach the same level (age norm; range: 0, unbound ). A positive value indicates improvement. The BSID--III and KABC--II age--equivalent scores were based on the cognitive domain and average non-verbal age-equivalent score, respectively.

BSID-III was used to assess the motor (fine and gross), language (receptive and expressive), and cognitive development of infants and toddlers aged 0-42 months and consisted of a series of developmental play tasks. KABC-II was an individually administered measure of the processing and reasoning abilities of children and adolescents between the ages of 3 and 18 years and an alternative to BSID-III. Raw scores of successfully completed items are converted to scale scores and to composite scores. The mean composite score is 100 and the standard deviation (SD) is 15. The DQ was a means to express a neurodevelopmental/cognitive delay which was computed as a ratio and expressed as a percentage using the age equivalent score divided by the age at testing (\[age-equivalent score/chronological age\] × 100; range: 0-100). A positive value indicates improvement in health and cognition.

VABS-II measured adaptive behaviors, including the ability to cope with environmental changes, to learn new everyday skills, and to demonstrate independence. It was an instrument that supports the diagnosis of intellectual and developmental disabilities in participants. This test measured 5 key domains: communication, daily living skills, socialization, motor skills, and the adaptive behavior composite (a composite of the other four domains). Scoring is 'Usually' = 2, 'Sometimes'/Partially' = 1 or 'Never' = 0. The standard scores represent a score (mean = 100 and standard deviation of 15) on which higher scores indicate a higher level of cognitive ability. A positive change value indicates improvement in adaptive functioning, communication, daily living skills, socialization and motor skills domains were reported here. The range for individual standard scores is 20-160.

Change from baseline in CSF total heparan sulfate at month 103 was recorded.

Change from baseline in Urine GAG at month 103 was recorded.

Brain MRI parameters include grey matter volume (GMV), white matter volume (WMV) and Intracranial cerebrospinal fluid Volume (ICSFV). Change from baseline in brain MRI at Month 103 was reported.