Fulcrum Therapeutics tanks, as losmapimod misses in FSHD study

Shares of US biotech Fulcrum Therapeutics (Nasdaq: FULC) crashed more than 48% to $8.90 by close of trading Tuesday, after it announced mixed results from a pre-specified interim analysis of the primary endpoint of the Phase II ReDUX4 trial in subjects with facioscapulohumeral muscular dystrophy (FSHD) treated with losmapimod.

The primary endpoint is the reduction from baseline of DUX4-driven gene expression in affected skeletal muscle after subjects have been treated with losmapimod or placebo. Secondary and exploratory endpoints were not assessed as part of this analysis.

Results from the interim analysis in the first 29 randomized subjects indicate that DUX4-driven gene expression did not show a separation from placebo at 16 weeks. However, in a pre-specified sensitivity analysis, those with the highest pre-treatment DUX4-driven gene expression in their muscle biopsy sample showed a 38-fold reduction in DUX4-driven gene expression following treatment with losmapimod compared to a 5.4-fold reduction with placebo.