By Michael Dabaie

 

Shares of Rigel Pharmaceuticals Inc. fell sharply after the company said data from the Forward Phase 3 clinical trial of fostamatinib in warm autoimmune hemolytic anemia, or wAIHA, didn't demonstrate statistical significance in the primary efficacy objective.

Shares fell 60% to 70 cents premarket Wednesday.

The company said the study didn't demonstrate statistical significance in the primary efficacy endpoint of durable hemoglobin response in the overall study population.

In a post-hoc regional analysis of U.S., Canadian, Australian, and Western European trial sites, patients treated with fostamatinib had a favorable durable hemoglobin response compared with placebo, the company said. In the Eastern European trial sites, patients didn't.

Rigel said it plans to continue analyzing the data to understand the geographical differences in patient disease characteristics and outcomes and discuss these findings with the U.S. Food and Drug Administration.

The safety and tolerability profile in the Forward trial was consistent with the existing fostamatinib safety database, the company said.

Autoimmune hemolytic anemia is a rare, serious blood disorder in which the immune system produces antibodies that lead to the destruction of the body's own red blood cells. Warm antibody AIHA, the most common form, is characterized by the presence of antibodies that react with the red blood cell surface at body temperature.

"While we are disappointed in the overall results, which were impacted by a large placebo response rate from Eastern European clinical sites, we are encouraged by the top-line results from the U.S., Canada, Australia, and Western Europe. We continue to believe fostamatinib has the potential to benefit patients with wAIHA, a population with a serious unmet medical need," Chief Executive Raul Rodriguez said.

 

Write to Michael Dabaie at michael.dabaie@wsj.com

 

(END) Dow Jones Newswires

June 08, 2022 08:07 ET (12:07 GMT)

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