Vertex Pharmaceuticals Inc. said U.S. regulators placed a partial clinical hold on its trial of a drug for hepatitis C after three patients receiving a high dose of the medicine showed signs of potential liver toxicity. The shares sank the most in eight months.
The Food and Drug Administration hold is on a study in the U.S. using a dose of 200 milligrams of the drug VX-135, the Cambridge, Massachusetts-based company said yesterday in a statement. The trial, in the second of three phases generally required for approval, is continuing in the 100-milligram dose.
Vertex is competing with drugmakers including Gilead Sciences Inc., AbbVie Inc. and Bristol-Myers Squibb Co. to develop an oral hepatitis C treatment that doesn’t involve injections of interferon, which can cause flu-like symptoms. The hepatitis C virus, which attacks the liver and can lead to liver cancer, affects about 150 million people worldwide.
“Developing safe and effective medicines for patients is our goal,” Robert Kauffman, Vertex chief medical officer, said in the statement. “We are committed to continuing to work closely with the FDA to provide the data needed to support evaluation of a 200 mg dose of VX-135 in the U.S.”
Vertex dropped 7.9 percent to $80.71 at 4 p.m. New York time for its biggest decline since November. The shares are up 93 percent this year.
Three patients taking 400 milligrams of the drug in combination with ribavirin in a separate European trial had elevated liver enzymes, and their levels returned to normal after they stopped treatment, Zach Barber, a spokesman for Vertex, said in an e-mail. The company said it finished dosing a 12-week study in Europe that included a 200-milligram arm and no serious adverse events or liver or heart safety issues arose.
The clinical hold may widen the edge Gilead has over Vertex in developing its hepatitis C products, Mark Schoenebaum, an analyst with ISI Group, said in a note to clients.
“Clearly, the FDA’s risk tolerance in hepatitis C is now extremely low, which puts a large moat around Gilead’s franchise,” Schoenebaum said.
Gilead’s shares gained 2.8 percent to $62.57. The company released second-quarter results yesterday that included revenue higher than analysts had estimated.
U.S. regulators are expected to decide by Dec. 8 on marketing approval for a hepatitis C combination therapy including sofosbuvir, Gilead’s leading experimental medicine for the disease. Sofosbuvir and Vertex’s VX-135 belong to a class of drugs called nucleotide polymerase inhibitors, which have been part of combination pill therapies being tested for hepatitis C.
The FDA previously put clinical holds on experimental hepatitis C compounds from Idenix Pharmaceuticals Inc., Achillion Pharmaceuticals Inc. and Bristol-Myers Squibb Co. because of potential adverse effects on the liver and heart.
No similar concerns have been raised during the development of its hepatitis C drugs, Norbert Bischofberger, Gilead’s executive vice president for research and development, said on a conference call after the earnings were released.
“There’s no evidence right now we’re seeing any, anything that’s related to either sofosbuvir or the sofosbuvir-ledipasvir fixed-dose combination that could be ascribed to either an adverse event or a laboratory anomaly,” he said in response to a question.