Shares in KalVista Pharmaceuticals shed more than half their value in Tuesday morning trading, after the company revealed it halted a mid-stage clinical trial of an experimental rare disease drug due to safety concerns.
The study had enrolled 33 people with a genetic condition called hereditary angioedema, which causes painful and unpredictable swelling attacks. Seven experienced elevations in liver enzymes that, while asymptomatic, were judged to be serious enough to stop testing.
The seven affected patients were in all three of the study groups that received the experimental drug, known as KVD824, KalVista said.
“We made the difficult decision to terminate [the trial] because we concluded that the emerging safety profile of the current formulation will not meet our requirements for a best-in-class oral prophylactic therapy,” said company CEO Andrew Crockett in the statement.
KalVista is working to finalize and assess data from the trial to determine whether there is any path forward for further development of the drug.
News of the side effect and KalVista’s decision to end the study sent shares in the biotechnology company down by 55% by mid-morning Tuesday. Shares in BioCryst Pharmaceuticals and Intellia Therapeutics, two other companies developing drugs for hereditary angioedema, or HAE, rose by nearly 9% and 5%, respectively.
Several drugs from Takeda, CSL and BioCryst are approved to treat or prevent the swelling attacks caused by HAE. But they have limitations, spurring KalVista, BioCryst and Intellia to try to improve on existing treatments in one way or another. The bar for success is high, however.
“Even in a scenario where [Kalvista’s] drug worked, HAE is a competitive space with multiple good options, and the tolerance for safety risk is low,” wrote Paul Matteis, an analyst at Stifel, in a note to clients.
Another company, Pharvaris, recently disclosed that the Food and Drug Administration had put testing of an HAE drug it’s developing on hold due to safety concerns it had after reviewing nonclinical data.