Raptor to Cease Development of Liver Drug

Raptor Pharmaceuticals says it does not plan to develop its liver drug, RP103, after it missed the primary endpoint in a Phase 2b study for nonalcoholic steatohepatitis in children.

RP103 (cysteamine bitartrate) delayed-release capsules did not achieve its primary endpoint, a two-point decrease in the nonalcoholic fatty liver disease activity score or stop the worsening of fibrosis in patients at 52 weeks, the study showed.

The trial results replicated the serological improvements observed in a Phase 2a study, but did not translate into a measureable effect on histology, says Raptor CEO Julie Anne Smith.

The company will work with the study’s sponsor — the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases — to understand the data, but does not expect to advance the program, Smith says.

Raptor will continue developing RP103 in Huntington’s disease and mitochondrial diseases. It is approved for treatment of nephropathic cystinosis, she adds. — Jonathon Shacat