One-year data from the FIREFISH Part 2 study, a global study evaluating Roche's risdiplam in infants aged one - seven months old with symptomatic Type 1 spinal muscular atrophy (SMA), has shown a significant increase in motor milestones after 12 months' treatment with the drug.

The study met its primary endpoint with 29% of infants sitting without support for five seconds by month 12, as assessed by the Gross Motor Scale of the Bayley Scales of Infant and Toddler Development Third Edition (BSID-III). No infants achieve this milestone in the natural history of Type 1 SMA.

In addition, 43.9% infants were able to hold their head upright, 31.7% were able to roll to the side and 4.9% infants were able to stand with support, as measured by the Hammersmith Infant Neurological Examination 2 (HINE-2).

Additionally, in an exploratory endpoint, 95% of infants who were alive at 12 months (36/38) maintained the ability to swallow and 89% (34/38) were able to feed orally. In contrast, in a natural history cohort, all infants with Type 1 SMA older than 12 months required feeding support.

"These results are particularly encouraging given the median age at enrolment was 5.3 months, so these infants already had progressed disease," said Professor Laurent Servais, FIREFISH investigator and Professor of Paediatric Neuromuscular Diseases at the MDUK Oxford Neuromuscular Centre. “Maintaining the ability to swallow is particularly important as it helps infants to feed and suggests risdiplam has a major effect on bulbar function.”

Also of note, safety for risdiplam in the FIREFISH study was consistent with its known safety profile, the most common adverse events being upper respiratory tract infection (46.3%), pneumonia (39%), pyrexia (39%), constipation (19.5%) nasopharyngitis (12.2%), rhinitis (12.2%) and diarrhoea (9.8%). The most common serious adverse events were pneumonia (31.7%), bronchiolitis (4.9%), respiratory failure (4.9%) and hypotonia (4.9%).

Risdiplam is being studied in a broad clinical trial programme in SMA, with patients ranging from birth to 60 years old, and includes pre-symptomatic patients and those previously treated with other SMA therapies.