Sunfish, a clinical trial seeking to assess the efficacy and safety of risdiplam in patients with spinal muscular atrophy (SMA) in a 4-year period, is underway, according to an abstract presented at the 2023 Muscular Dystrophy Association Clinical & Scientific Conference. 

Risdiplan is an orally administered survival of motor neuron 2 (SMN2) premRNA splicing modifier distributed both centrally and peripherally, approved for the treatment of SMA in over 85 countries, the researchers noted.

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Previous clinical trials, such as the FIREFISH study and its open-label extension phase, as well as the JEWELFISH and SUNFISH studies, have already demonstrated the safety and efficacy of risdiplam in 5 and 24 months periods, they added.

The SUNFISH study was divided into 2 parts, part 1 aimed to assess the tolerability as well as pharmacokinetics of different dosing schemes in patients with type 2 and 3 SMA. Part 2 studied the safety and efficacy of the dosing schemes selected in the first part of the study. Patients were given the option of entering the open-label extension of the trial at month 24.

The open-label extension of the SUNFISH study aims to investigate the efficacy and safety of risdiplam over a 4-year period. The trial is designed as a placebo-controlled, double-blind, multicenter study including patients with SMA ranging between 2 and 25 years of age.

In the 2nd and 3rd year following  risdiplam therapy, increased motor function was maintained as noted by the Hammersmith Functional Motor Scale – Expanded, and Revised Upper Limb Module and the Motor Function Measure total score.

Upper Limb Modules were used to determine the efficacy of the selected dose. Researchers observed a significant increase in motor function during the first 36 months of treatment. No safety concerns led to the withdrawal of treatment in the first 3 years.

“SUNFISH is ongoing and will provide further long-term efficacy and safety data of risdiplam, in a broad population of children, teenagers and adults with SMA,” the authors wrote.


Oskoui M, Day J, Deconinck N, et al. SUNFISH Parts 1 and 2: 4-year efficacy and safety data of risdiplam in Types 2 and 3 SMA. Poster presentation at: 2023 Muscular Dystrophy Association Clinical & Scientific Conference; March 19-22, 2023; Dallas, TX.