Judge to weigh key evidence ahead of first Zantac cancer trial

Feb 16 (Reuters) - GSK Plc is expected to urge a California judge on Thursday to limit what expert testimony jurors can hear in the first trial over claims that the company's heartburn drug Zantac caused cancer.

The trial, scheduled to begin Feb. 27 before Alameda County Superior Court Judge Evelio Grillo, will offer the first test of how Zantac cancer claims may fare in state courts.

A federal judge in December threw out all of the Zantac cases in federal court, some 50,000, after finding the opinions of the experts put forth by plaintiffs to establish their cancer was caused by the drug were not backed by sound science.

Tens of thousands of cases still remain in state courts, many consolidated before Grillo in California.

The plaintiff in the upcoming trial, James Goetz, says he developed bladder cancer from taking Zantac sold by British drugmaker GSK. Thursday's hearing will decide what his expert witnesses can say to support that claim.

Goetz's lawyers are also expected to seek to limit the expert testimony that GSK can use. Grillo will consider whether both sides' proposed testimony has scientific support, using a legal standard created by California's Supreme Court.

Representatives for GSK and for plaintiffs' lawyers did not immediately comment on the upcoming hearing.

Zantac, first approved in 1983, became the world's best selling medicine in 1988 and one of the first drugs to top $1 billion in annual sales.

Originally marketed by a forerunner of GSK, it was later sold successively to Pfizer Inc, Boehringer Ingelheim and finally Sanofi SA. All four drugmakers are facing Zantac lawsuits and have denied that the pill causes cancer.

In 2019, some manufacturers and pharmacies halted sales of the drug over concerns that its active ingredient, ranitidine, degraded over time to form a chemical called NDMA. While NDMA is found in low levels in food and water, it is known to cause cancer in larger amounts.

The U.S. Food and Drug Administration in 2020 pulled all remaining brand name Zantac and generic versions off the market, citing research showing the amount of NDMA in the products increases the longer the drug is stored and could potentially become unsafe.

Lawsuits began piling up soon after the recalls began from people who said they developed cancer after taking Zantac. Plaintiffs said the companies knew, or should have known, that ranitidine posed a cancer risk and that they failed to warn consumers.

Cases have been filed linking Zantac to at least 10 types of cancer. The federal litigation was limited to bladder, stomach, esophageal, liver and pancreatic cancers, but cases over other cancers remain in state courts. (Reporting By Brendan Pierson in New York, Editing by Alexia Garamfalvi and Bill Berkrot)