The Delaware Supreme Court has overturned a lower court’s decision that allowed expert testimony supporting plaintiffs’ claims in a high-profile case alleging that Zantac, or its generic ranitidine, can cause cancer.
The justices concluded that the trial court applied an incorrect legal standard when it ruled that the reliability of expert opinions should be determined by a jury rather than by the judge.
Initially marketed by a forerunner of GSK plc (NYSE:GSK), Zantac, once a blockbuster heartburn drug, has been sold at different times by companies, including Pfizer Inc. (NYSE:PFE), Boehringer Ingelheim, Sanofi SA (NASDAQ:SNY), and several generic drugmakers.
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The case centers on nearly 75,000 plaintiffs who claim their cancer diagnoses were caused by exposure to ranitidine, the active ingredient in Zantac, which may degrade into the probable human carcinogen NDMA.
Plaintiffs submitted expert reports linking the drug to ten types of cancer, but the defendants challenged the validity of those reports, questioning the scientific methods used.
The Superior Court denied motions to exclude the expert opinions, citing Delaware’s “liberal thrust” toward admitting expert testimony. It found that any methodological disputes were issues for the jury.
The court also allowed the experts to base their causation claims on studies involving NDMA, rather than requiring a direct link to Zantac itself.
However, the Supreme Court found this reasoning flawed. In its opinion, the court emphasized that Delaware’s rules on expert evidence align with federal standards, which burden the proponent to prove that testimony is based on sufficient and reliable scientific methods.
The court also faulted the trial judge for improperly framing the central question of general causation. Rather than asking whether Zantac specifically could cause cancer, the lower court allowed experts to rely on data involving NDMA without demonstrating that Zantac exposure levels were comparable to those in the referenced studies.
The Supreme Court ruled that this failed to establish a scientifically valid connection between the product and the alleged harm.
In June, a federal judge ruled that key claims brought by plaintiffs against Patheon Manufacturing Services in the Zantac litigation may move forward, while one claim related to misrepresentation was dismissed.
In its motion to dismiss, Patheon argued that the plaintiffs’ claims failed on multiple fronts. The company said the plaintiffs did not identify a specific manufacturing defect, asserted that the design defect claim was preempted by federal law, and claimed that negligence was not pled with adequate specificity.
Additionally, Patheon contended that no valid misrepresentation claim had been made. However, the court found that plaintiffs had adequately stated distinct claims for manufacturing and design defects.
The judge noted that plaintiffs alleged a flawed manufacturing process that caused ranitidine to form NDMA, a probable carcinogen, or that the manufacturing method contributed to the contamination. The court ruled that, at this stage of litigation, those allegations were sufficient to proceed.
On the negligence claim, the judge concluded that plaintiffs had met the specificity requirements under Rule 9(b), citing detailed allegations that Patheon exposed ranitidine to heat and humidity, leading to its degradation into NDMA.
The court emphasized that the claims were grounded in either violations of federal law or state law duties not solely governed by the FDA, meaning federal preemption did not apply at this stage.
Although the court, in June, agreed with Patheon that the plaintiffs had not asserted a misrepresentation claim, it allowed the remaining claims to proceed.
In May 2024, Pfizer settled 10,000 lawsuits alleging it concealed the cancer risks associated with its Zantac heartburn medication, marking the largest resolution in the litigation.
In October 2024, GSK reached agreements with ten plaintiff firms representing approximately 80,000 Zantac product liability cases in the U.S. state courts.
Price Action: PFE stock is down 0.43% at $25.67, and SNY stock is down 1.01% at $48.84 during the premarket session at last check Friday.
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