A Conatus Pharmaceuticals drug developed as a treatment for chronic liver disease has failed to beat a placebo in a mid-stage study, the first of four underway for the drug.
Conatus (NASDAQ: CNAT) tested its drug, emricasan, in liver transplant patients whose hepatitis C virus has cleared, but who still have fibrosis or cirrhosis in the transplanted organ. The drug is meant to reduce the activity of enzymes that play a role in inflammation and cell death. The goal of the Phase 2b study was to assess whether the Conatus drug was better than a placebo at stopping or reversing damage to the new liver caused by hepatitis C.
San Diego-based Conatus said late Wednesday that the response rate in the patient group given the test drug was 77.4 percent. But that measure did not place enough distance from the placebo group, where the response rate was 75 percent.
Following the news of the clinical trial failure, shares of Conatus fell more than 28 percent to $4.30 each in early trading Thursday.
Despite the clinical trial failure, Conatus’s executives chose to focus on a subgroup of patients who had advanced fibrosis and early cirrhosis. In those patients, the response rate was 95 percent, CEO Steven Mento said in a prepared statement. He also emphasized that the study in liver transplant patients is separate from the company’s evaluation of the drug in partnership with Novartis (NYSE: NVS), which is focused on developing the drug as a treatment for nonalcoholic steatohepatitis (NASH), a fatty liver disease whose incidence has grown with the prevalence of obesity.
Last year, Novartis paid Conatus $50 million up front for worldwide rights to emricasan. If the Conatus drug hits development, regulatory, and commercialization milestones, Novartis could be on the hook to pay up to $650 million more. The partners are sharing the costs of four Phase 2b studies testing emricasan, including the study in liver transplant patients.
Emricasan was initially developed by Pfizer (NYSE: PFE), which hoped to develop the compound into a treatment that prevents fibrosis and inflammation in patients who have chronic liver disease. But Pfizer stopped work on emricasan after preclinical studies raised concerns that the drug might contribute to the formation of tumors. Conatus acquired the drug from Pfizer in 2010.
Here’s more on the history of Conatus and emricasan.