PTC Therapeutics’ PTC518 achieves primary endpoint in Phase 2 Huntington’s study

PTC Therapeutics (PTCT) announced results from the Phase 2 PIVOT-HD study of PTC518 – votoplam – in Stage 2 and Stage 3 Huntington’s disease, or HD, patients. The study met its primary endpoint of reduction in blood Huntingtin protein levels at Week 12 and favorable safety and tolerability. In addition, the 12-month data from the Stage 2 patients are consistent with the previously reported dose-dependent lowering of HTT protein and dose-dependent trends across clinical scales. Results from the 12-month cohort demonstrate dose-dependent lowering in blood HTT levels, with 23% at the 5mg dose level for both Stage 2 and 3 patients and 39% and 36% at the 10mg dose level for Stage 2 and 3 patients, respectively. For Stage 2 patients, there were dose-dependent trends of benefit on clinical scales. For Stage 3 patients, there were trends favoring the 5mg dose group relative to placebo, but not the 10mg dose group, suggesting that treatment effect may differ in Stage 3 patients relative to Stage 2 patients. For all dose levels and disease stages, PTC518 showed a favorable safety and tolerability profile with no treatment-related serious adverse events or neurofilament light chain protein spikes. In addition, 24-month treatment data from the patients on whom data were shared last year demonstrate signals of dose-dependent trends on the cUHDRS, Total Function Capacity and Symbol Digit Modalities Test subscales. At Month 24, there was also dose-dependent lowering of plasma NfL from baseline of -8.9% for the 5mg dose level and -14% for 10mg dose level.