SMA is a rare neuromuscular disorder caused by reduced levels of the SMN protein, leading to a loss of motor neurons and progressive muscle weakness. Type 1 is the most severe form of SMA and usually results in death before the age of two.
The trial is in its pivotal phase, examining the efficacy and safety of RG7916 administered at the dose level selected from a Phase I trial. The compound will be given over a period of two years.
Part two of the study will be carried out in around 40 infants with Type 1 SMA, followed by a long-term extension.
The primary objective of the trial is to analyse the proportion of infants sitting without support for five seconds, assessed by the Bayley Gross Motor Scale, after 12 months of treatment.
PTC Therapeutics CEO Stuart Peltz said: “It is especially encouraging that preliminary data from the first part of the FIREFISH study demonstrated that RG7916 was well tolerated at all doses, and that there have been no drug-related safety findings leading to withdrawal.
“A treatment that is delivered orally with systemic distribution has the potential to benefit the central nervous system, as well as other parts of the body that are affected by low SMN protein.”
RG7916 is an investigational splicing modifier designed to target the survival motor neuron 2 (SMN2) RNA, restoring a functional transcript.
The drug is taken orally to cross the blood-brain barrier and show systemic distribution to the organs that are affected by low levels of SMN protein.