(Reuters) – Sanofi said on Tuesday that the International Chamber of Commerce rejected rival drugmaker Boehringer Ingelheim’s (BI) claims to be indemnified by Sanofi (NASDAQ:SNY) in cancer lawsuits linked to heartburn drug Zantac in the United States.

Shares in France’s Sanofi, which added that the decision cannot be appealed, gained 2.4% shortly after the 0700 GMT market open, reaching a three-week high.

Germany’s family-owned Boehringer said it had taken note of the arbitral tribunal’s decision and would not comment further.

Thousands of U.S. lawsuits claiming Zantac causes cancer have been disputed by drugmakers that have sold either the branded or generic version of the drug since it was initially approved in 1983. It went on to become one of the first medicines to top $1 billion in sales.

Sanofi and Boehringer had sought arbitration to determine whether liability in lawsuits was transferred to the French group after it acquired the marketing rights from Boehringer in a 2017 deal.

Originally marketed by a forerunner of GSK, the medicine has been sold at different times by companies including Pfizer (NYSE:PFE), Boehringer and Sanofi as well as several generic drugmakers.

Sanofi reiterated that it regarded its defence of the underlying litigation as very strong.

“There is no reliable scientific evidence that Zantac causes the alleged injuries in the cases brought against GSK, Pfizer, BI, Sanofi, and others in the U.S. litigation,” the company said.