Catalyst Pharma reports vamorolone Phase 1 data on immune activity

Catalyst Pharmaceuticals, Inc. (Nasdaq: CPRX) announced topline results from a two-part Phase 1 clinical study of vamorolone in healthy adult volunteers, according to a press release issued June 30, 2026.

The study evaluated cortisol suppression, anti-inflammatory activity, and immunosuppressive effects across clinical and supratherapeutic doses. Results showed expected cortisol suppression and no evidence of significant immunosuppressive activity at clinical doses.

Part A of the study enrolled 24 healthy adults in a randomized, single-center, crossover design. Participants received single doses of vamorolone (300 mg) and deflazacort (0.9 mg/kg). Both agents showed cortisol suppression and leukocyte redistribution, with a similar time to onset of approximately two to four hours post-dose. Vamorolone showed less pronounced immunosuppressive biomarker effects compared with deflazacort.

"By demonstrating similar cortisol suppression at label-based clinical doses of vamorolone and deflazacort, these data support the currently labeled dosing of vamorolone in the treatment of DMD and do not suggest the need for other dosing considerations when switching patients from deflazacort to vamorolone," said William Andrews, MD, Chief Medical Officer of Catalyst Pharmaceuticals.

Part B enrolled 36 healthy volunteers who received vamorolone at doses of 9, 27, or 40 mg/kg once daily for seven days. Clinically relevant immunosuppressive effects were observed only at the highest dose of 40 mg/kg per day. No relevant immunosuppressive effects were observed at the 9 or 27 mg/kg per day dose levels. Immunosuppressive effects at the 40 mg/kg dose increased with repeated dosing and persisted after treatment cessation.

"As the 40 mg/kg/day dose is above currently approved vamorolone dosing and higher than doses previously studied in clinical trials, these findings suggest that clinically meaningful immunosuppression with vamorolone is unlikely at clinically relevant doses," Dr. Andrews said.

Catalyst Pharmaceuticals is headquartered in Coral Gables, Florida, and focuses on rare and difficult-to-treat diseases.

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