Catalyst Pharmaceuticals’ (CPRX) Firdapse (amifampridine phosphate) hit both co-primary endpoints successfully in a phase 3 trial in Lamberton-Eaton myasthenic syndroms (LEMS), announced on Monday afternoon. The stock climbed 20% in after-hours trading.
Both endpoints – quantitative myasthenia gravis score (QMG) and subject global impression (SGI) – demonstrated that Firdapse was significantly superior to placebo, although QMG squeaked by from a statistical perspective (p=0.0452). Improvements on a secondary endpoint, the physician’s clinical global impression of improvement (CGI-I), also reached statistical significance.
The study, a “withdrawal trial”, included a 91 day run-in period in which patients received Firdapse, followed by treatment with either Firdapse or placebo during a 2-week randomization period. 38 patients completed the entire trial. Firdapse was well tolerated, and all subjects elected to continue with Firdapse in the safety follow-up phase of the study.
Firdapse is approved and marketed by Biomarin (BMRN) in Europe, but has been met with cold reception due to its steap price and the existence of a cheap alternative from Jacobus Pharmaceuticals. New Jersey-based Jacobus offers 3,4-diaminopyridine free to patients under a compassionate use program, and is running its own mid-stage study to support approval. Most important for CPRX, perhaps, is whether the company can get to the FDA – for approval and the exclusivity that would accompany – before Jacobus.
