Delaware Supreme Court sides with Zantac drugmakers over cancer evidence

By Jonathan Stempel

July 10 (Reuters) - Delaware's highest court ruled on Thursday that nearly 75,000 patients suing four large drugmakers cannot introduce reports from several experts to support their claim that the heartburn drug Zantac caused them to develop cancer.

The Delaware Supreme Court unanimously sided with GSK GSK.L, Pfizer PFE.N, Sanofi SASY.PA and Boehringer Ingelheim in excluding testimony from 10 doctors and scientists, eight of whom opined that the active ingredient in Zantac causes 10 types of cancer.

Justice Abigail LeGrow said the trial judge wrongly employed a lenient legal standard that presumed expert testimony was admissible, and failed to require the patients' experts to use "reliable scientific methodology" to reach their conclusions.

The case has been closely watched by business groups including the U.S. Chamber of Commerce, which have expressed fear that an adverse outcome could erode Delaware's reputation as a business safe haven by encouraging mass tort litigation.

Zantac was approved by U.S. regulators in 1983, and within five years was the world's best-selling medicine. Various companies manufactured the drug at different times.

Lawsuits against Zantac manufacturers began piling up after the U.S. Food and Drug Administration asked in April 2020 that the companies pull the drug off the market.

The request reflected the agency's concern that ranitidine, the active ingredient in Zantac, could degrade into the carcinogen NDMA over time and when exposed to heat. All manufacturers complied with the voluntary recall.

Brent Wisner, a lawyer for the patients, said in an email that his clients will press forward to a possible trial, "given the robust scientific record we now have that NDMA in ranitidine causes cancer."

Lawyers who argued the drugmakers' appeal did not immediately respond to requests for comment. Patheon, a unit of Thermo Fisher TMO.N, is also a defendant.

'GATEKEEPER'

In allowing testimony from the 10 doctors and scientists, Delaware Superior Court Judge Vivian Medinilla ruled in May 2024 it was up to juries to weigh both sides' scientific arguments.

But the Supreme Court said the judge abrogated her role as the "gatekeeper" of expert testimony, and should not have dismissed the experts' "significant methodological flaws" in the plaintiffs' expert reports.

These flaws had been identified in December 2022, when a federal judge in West Palm Beach, Florida said another 50,000 Zantac cases could not go forward because reliable science did not support the plaintiffs' expert testimony there.

"An expert who cannot explain to the court's satisfaction why her method is reliably applied should not be permitted to opine for a jury," LeGrow wrote for a five-judge panel.

LeGrow also said the trial judge did not discuss why experts could opine that ranitidine causes cancer, based on research that did not examine NDMA exposure from ranitidine or established a scientific link.

Drugmakers have long maintained that Zantac does not cause cancer, and no reliable evidence shows it exposes patients to harmful NDMA levels.

Most U.S. litigation over the drug has been resolved.

A drug now sold Zantac 360 contains no ranitidine and uses a different active ingredient.

The case is In re Zantac (Ranitidine) Litigation, Delaware Supreme Court, No. 255, 2024.