Biogen (NASDAQ:BIIB) and Ionis Pharmaceuticals' (NASDAQ:IONS) Phase III trial of nusinersen in later-onset spinal muscular atrophy (SMA Type 2) should hit its primary endpoint based on past data in Type 2 and Type 1 SMA, said experts. However, they cautioned the natural presentation of SMA Type 2 means the benefit will be less dramatic than in Type 1.
Also, the planned introduction of newborn SMA screening may eliminate the need for distinctions between SMA Type 1 and 2, and have all infants who test positive treated before symptoms appear, added a doctor.
Analysts report peak sales of up to USD 1.7bn for nusinersen. One analyst report noted that positive data from the open-label Phase I/II in Type 2 (NCT01703988) had at least driven some optimism, though it was cautious in predicting success in the Phase III trial.
The Phase III Type 2 trial (NCT02292537) is randomised, double-blind and sham-procedure controlled with a primary endpoint of change from baseline in Hammersmith Functional Motor Scale, according to ClinicalTrials.gov. The trial has an estimated study completion date of June 2017. The trial has completed enrolment, but no data have yet been analysed, said a neurologist.
SMA is a rare neuromuscular disorder characterised by the loss of motor neurons and progressive muscle wasting. The disorder is caused by a genetic defect in the SMN1 gene which encodes SMN, a protein crucial to the survival of motor neurons.