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Patients allege that heartburn drug caused their cancer

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Court says expert opinions not backed by reliable science

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FDA asked in 2020 that Zantac be pulled from market

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Lawyer for patients had no immediate comment

(Adds details from decision, attempts to obtain comment, case

citation, byline)

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

, Pfizer ( PFE ), Sanofi 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.

A lawyer for the patients had no immediate comment. Lawyers

who argued the drugmakers' appeal did not immediately respond to

requests for comment.

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

they pull the drug off the market. All manufacturers complied

with the voluntary recall.

That reflected the agency's concern that ranitidine, which

was marketed as Zantac, could degrade into the carcinogen NDMA

over time and when exposed to heat.

'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.