LONDON — Shares of British pharmaceuticals giant GSK plunged 9% Monday, after a U.S. court ruled that scientific evidence could be presented as a stack of lawsuits relating to the discontinued heartburn drug Zantac move forward.
The Delaware State Court late on Friday ruled that plaintiffs’ expert witnesses could testify in the roughly 75,000 cases alleging the once-popular drug ranitidine — sold under the brand name Zantac in the U.S. — may cause cancer.
“This case has always been about getting the science in front of a jury,” Brent Wisner, lawyer at the firm Wisner Baum which is representing many of the plaintiffs, said in a statement.
The dispute has been rumbling for years and involves numerous pharmaceutical firms. Zantac was sold by GSK as a prescription drug in the 1980s before transitioning to an over-the-counter medicine, and following its patent expiry in the 1990s has been sold by companies including France’s Sanofi, U.S. firm Pfizer and Germany’s Boehringer Ingelheim.
The drug was withdrawn from European and U.S. markets in 2019 and 2020 after regulators conducted a safety review which raised concerns it contained a probable carcinogen called NDMA.
The companies involved deny there is a scientific consensus that the drug can be linked to any later development of cancers.
In a statement Friday, GSK said it disagreed with the latest Delaware ruling and would immediately seek an appeal.
It said the decision contradicted the federal court’s multi-district litigation ruling in December 2022, which dismissed all cases alleging five cancer types. It added that the court decision only related to whether the methodology used by the plaintiffs’ experts was sufficiently reliable to be presented as evidence at trial.
“Following the 16 epidemiological studies looking at human data regarding the use of ranitidine, the scientific consensus is that there is no consistent or reliable evidence that ranitidine increases the risk of any cancer,” GSK said.
While the majority are in Delaware, a smaller numbers of cases against various firms are being heard in California, Illinois and Pennsylvania.
Analysts at Jefferies had in late May flagged a possible tailwind for GSK after an Illinois jury found GSK and Boehringer Ingelheim were not liable for colorectal cancer in the first Zantac case to reach trial.
GSK, the company most exposed to the cases, could face settlement costs from $1 billion to more than $3 billion, according to a range of analyst notes cited by Reuters.
Sanofi, which is named in roughly 25,000 of the 75,000 cases, said in its own statement Friday it was disappointed with the decision not to exclude the plaintiffs’ experts from the cases and that it would also appeal. Sanofi shares were 1% lower on Monday.
Pfizer told CNBC Monday it was implicated in a “fraction” of the Delaware cases and had resolved a “substantial number” of cases in which it was named as a defendant.
“While we have great sympathy for plaintiffs in these cases, there is no reliable scientific evidence that Zantac, which was reviewed and approved by FDA, causes cancer. Pfizer has not sold a Zantac product in more than 15 years and did so only for a limited period of time, nor has Pfizer ever manufactured a Zantac product,” the company said in a statement.
The Financial Times last month reported that Pfizer agreed to pay between $200 million and $250 million to settle more than 10,000 Zantac lawsuits. CNBC has not independently confirmed the amount.
CNBC has contacted Boehringer Ingelheim for comment.