On March 9, 2021, a U.S. District Court judge in the Southern District of California granted the drug company defendants’ motion for summary judgment in a consolidated multidistrict litigation (MDL). The case involved plaintiff claims that the drug companies failed to warn about the risks of pancreatic cancer associated with their type-2 diabetes drugs. In Judge Anthony Battaglia’s decision for In re Incretin-Based Therapies Products Liability Litigation, the court found that federal law preempted the plaintiffs’ state failure-to-warn claims. Further, the ruling excluded the plaintiffs’ experts, denied as moot the exclusion of defendants’ experts, and did not find general causation.
The Diabetes Drugs in Question
The MDL involved five type-2 diabetes drugs marketed and/or manufactured by a number of household-name drug giants. The defendants were AstraZeneca PLC’s Amylin Pharmaceuticals, Eli Lilly and Co, Merck & Co Inc, and Novo Nordisk Inc. The FDA generally classifies the diabetes medications in question as incretin mimetics or incretin-based therapies.
The Journey to the Recent Summary Judgement
Starting in 2013, 1,500 eventual MDL class members began to file cases with similar claims concerning pancreatic cancer risks and these type-2 diabetes drugs. The volume of cases eventually led to consolidation and the MDL ran its course, with a litany of additions, motions, filings, and discovery issues.
On November 9, 2015, Judge Battaglia issued a summary judgment based on preemption in favor of the defendants. On appeal, the case was remanded to allow certain plaintiffs additional discovery, and to order the judge to consider “the materiality of Plaintiffs’ asserted new safety information, and reinstate the opinion of Plaintiffs’ expert, Dr. Fleming” in 2017. The appellate court did not rule on the preemption question.
After completion of the additional discovery, the defendants again asked the court for summary judgment saying, “it is impossible to comply with both the FDA’s regulatory scheme and state law failure-to-warn requirements, and because there is no genuine dispute of material fact as to general causation.” The plaintiffs asserted that preemption had not been established and that their experts could show a path to causation.
March 2021 Summary Judgment Ruling
The court recently ruled on these motions. In the ruling’s introduction, the court notes that the U.S. Food and Drug Agency (FDA) oversees new drug introductions, regulates the content of labeling, and enforces compliance with post-marketing compliance. The court also explains that product labeling responsibility lies in the hands of the manufacturers who have a duty to provide warnings of risks based on reasonable evidence.
Judge Battaglia disagreed with the plaintiffs that a Canada Health publication provided such reasonable evidence. The judge went on to granularly review FDA studies, publications, and a citizen petition to remove one of the drugs at issue from the market. Judge Battaglia found that there was no sound evidence of pancreatic cancer risks in incretin-based therapies. Because the defendant drug companies could not unilaterally change their labels without reasonable evidence, Judge Battaglia found that there was a conflict between state warning laws and federal law. Thus, federal law preempts, resulting in the summary judgment for defendants.
Though saying it was unnecessary, the Court also found that the defendants had established “clear evidence that the FDA would not approve a label change.” The FDA was fully informed by both its own monitoring of incretin mimetics for pancreatic safety for decades and the defendants’ material reports to the FDA. Therefore, the court reasoned, the FDA had essentially said it would not approve a pancreatic cancer warning on the label.
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Plaintiff’s Experts Excluded
In this case, both sides sought to have the other’s experts excluded under Daubert. The judge analyzed the Daubert motions (central to general causation) to deny the plaintiffs’ expert exclusion motions as moot after granting the defendant’s motion to exclude plaintiffs’ experts.
Plaintiff offered two biostatistician experts. Judge Battaglia found the first expert’s analysis to be dated and based on a selective data review. This testimony would be “unreliable and not helpful to the jury.” The second expert’s opinion that there is “strong evidence of a causal association between GLP-1 exposure and pancreatic cancer” was based on favorable, cherry-picked data—not good science, according to the court.
The plaintiffs also proffered a biological plausibility expert. This expert theorized “that incretin-based therapies promote the development of pancreatic cancer because they activate GLP-1 signaling in certain pancreatic cells, causing those cells to proliferate, which in turn, causes cancer.” The expert also admitted that he “just didn’t have time” to compare the animal and human dosages. The court saw this and other gaps as indicators that he did not use the level of intellectual rigor expected of an expert in his field and his testimony was excluded.
The plaintiff’s oncology expert analyzed whether incretin-based therapies cause or contribute to pancreatic cancer. The expert’s latency opinion lacked foundation, said the court. “… [t]he literature from which he extrapolates his conclusion does not concern incretins, and he has not explained why such an extrapolation is scientifically sound.” The court also did not like that he failed to independently review the statisticians’ evidence and did not weigh all available evidence.
The plaintiff’s chemical toxicology expert analyzed the existence of a viable mechanism “whereby incretin-based therapies could contribute to the development of pancreatic cancer.” The court booted this testimony because he did not “consider all available clinical trial data, observational studies, and other epidemiological literature on incretin-based therapies.”
Next, a gastroenterology expert reviewed literature to opine on “whether incretin mimetics more likely than not increase the risk of pancreatic cancer.” This testimony was excluded in large measure because he admitted that the plaintiffs’ counsel “first taught him about the alleged relationship between incretins and pancreatic cancer.”
Finally, the plaintiffs’ pathology expert examined non-human primate slides from two toxicology studies involving exenatide. Judge Battaglia said the record showed that this “methodology of applying the human PanIN classification system to non-human primates is not a reliable scientific method.” The testimony was thus ruled inadmissible.
Future MDL Impacts
Plaintiffs planning to bring class actions relating to cancer risk warnings on drug labels should take note that years of FDA monitoring of the safety of drugs will not easily be overcome by a “new study.” The plaintiff’s evidence demonstrating new information on risks must be based on rigorous science that goes beyond what the FDA already has established. This Ninth District Court, at least, is more than willing to painstakingly assess the FDA change in labeling process under legal precedent to find that with a conflict, federal law will preempt state drug warning laws.
Further, the importance of the quality of experts and their methodologies in these types of cases where general causation is not easily understood by laypeople can’t be overstated. The gaps in the experts’ evaluations in this case ultimately crushed any chance of proving general causation.
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