THE INTERIM results of a small, ongoing Phase II trial have shown that the drug nusinersen is a well-tolerated treatment for infantile-onset spinal muscular atrophy that results in the improvement of motor functions for the majority of participants.
The results of the trial have informed the design of a larger, ongoing Phase III clinical study investigating the use of nusinersen for the treatment of the progressive motor neuron disorder in infants. The researchers note however that while their findings are promising, the drug does not represent a cure and failed to restore normal levels of muscle function in participants.
Led by Dr Richard Finkel, Nemours Children’s Hospital, Orlando, Florida, USA, the researchers tested the drug in 20 babies aged between 1 and 7 months old and diagnosed with infantile-onset spinal muscular atrophy. Four participants received three 6 mg equivalent doses of nusinersen on Day 1, 15, and 85. The dosage was then increased to 12 mg and given at Day 253 and every 4 months thereafter. The remaining 16 participants were given the 12 mg dose on the same schedule.
The interim results were reported at a time when the 6–12 mg group had received 4–9 doses of nusinersen and the 12 mg group had received 2–8 doses. One patient died at a stage too early in the study to be included in the analysis. Motor function was assessed using the 64-point CHOP-INTEND scale and showed a mean increase of 11.5 points from baseline to the last visit with 14 out of 18 patients experiencing improvement. In their paper the researchers noted: ‘Some of these infants developed the ability to sit independently and roll over independently and improved in head control, kicking, hand function, and standing and walking, changes that are beyond the motor repertoire expected for infants with Type I spinal muscular atrophy according to natural history reports.’
Intrathecal injections were used to administer the drug which resulted in no safety concerns. All patients experienced serious adverse events, with the most common being respiratory distress or failure, or respiratory infections. The study investigators determined that these were not drug-related.
Jack Redden, Reporter