Fulcrum Therapeutics’ losmapimod for facioscapulohumeral muscular dystrophy (FSHD) had its Phase Transition Success Rate (PTSR) dive by 19 points to 9% after full Phase IIb trial data was revealed. Complete results from the 80-patient Phase IIb ReDUX4 trial (NCT04003974) were announced on 24 June, with its PTSR updated on 25 June. PTSR is the probability, given as a percentage, of a drug progressing successfully from one development stage to the next.

In August 2020, Fulcrum announced interim ReDUX4 data covering 29 patients. It showed losmapimod does not offer improvement over placebo in the primary endpoint of DUX4-gene driven gene expression reduction from baseline at 16 weeks. On 24 June, the company announced full ReDUX4 data showing losmapimod still did not meet ReDUX4’s primary endpoint. This is despite the asset offering improvements over placebo with regards to structural and functional FSHD disease progression and patient-reported outcomes at 48 weeks.

Fulcrum has said it will meet with regulatory authorities in 2H21 to discuss the regulatory path for losmapimod in FSHD. FSHD features muscle degeneration and fat infiltration, which initially affects movement in face and then eventually affects the arms, trunk, and legs. There are no approved FSHD therapies.

Losmapimod is a p38alpha and beta mitogen activated protein kinase inhibitor. Its Likelihood of Approval (LoA) also reduced by 1 point to 2%. LoA is calculated by GlobalData’s analysis, uses a combination of machine learning and a proprietary algorithm.

Fulcrum has a market cap of $293.8m.

Reynald Castaneda is an Associate Editor for Clinical Trials Arena parent company GlobalData’s investigative journalism team. A version of this article originally appeared on the Insights module of GlobalData’s Pharmaceutical Intelligence Center. To access more articles like this, visit GlobalData.