If you took Byetta or Bydureon and developed pancreatic cancer, thyroid cancer, or pancreatitis, filing an exenatide lawsuit in Michigan is now legally possible after a 2024 change in state law, but the practical odds are poor. The federal multidistrict litigation that handled thousands of exenatide claims nationwide ended in a defense victory in 2022, and Michigan plaintiffs face additional state-specific hurdles on top of the same causation problem that sank the federal cases.
Why Michigan Blocked These Claims Until 2024
From 1995 until early 2024, Michigan was the only state in the country that gave drug manufacturers what amounted to absolute immunity from product liability claims, as long as the drug was FDA-approved and carried FDA-compliant labeling. The statute, MCL 600.2946(5), was part of the 1995 Michigan Product Liability Act, and it ended cases that elsewhere went forward, including the state attorney general’s $20 million Vioxx case against Merck and opioid claims brought by the attorney general and Monroe County.1Michigan Legislature. Senate Fiscal Agency Analysis of Senate Bill 410 Michigan residents were also shut out of national Risperdal settlements because their claims were barred at home.
Byetta and Bydureon were FDA-approved with FDA-compliant labels, so the statute would have ended almost any Michigan exenatide suit before it started.
That changed on December 7, 2023, when the governor signed Senate Bill 410 repealing the immunity. The repeal took effect February 13, 2024.2Michigan Attorney General. AG Nessel Celebrates Bill Signing for Drug Immunity Repeal
The repeal is not retroactive. Michigan courts apply the law in effect on the date of injury, not the date a lawsuit is filed, so injuries that happened while the immunity was in force cannot support a new claim. Senator Jeff Irwin, who sponsored the repeal, acknowledged there is no mechanism for retroactive payouts on previously barred claims.3Tucker Ellis LLP. But Is It Retroactive? Michigan Repeal of Drugmaker Immunity Statute In practical terms: if your exenatide injury occurred before February 13, 2024, the old immunity still blocks you.
What the Federal MDL Decided
More than 7,000 plaintiffs filed suits alleging that exenatide and other incretin-based diabetes drugs caused pancreatic cancer, thyroid cancer, and pancreatitis. The cases were consolidated in August 2013 as In re: Incretin-Based Therapies Products Liability Litigation, MDL No. 2452, in the Southern District of California before Judge Anthony J. Battaglia.4Judicial Panel on Multidistrict Litigation. MDL-2452 Initial Transfer Order Defendants included AstraZeneca, Amylin, Eli Lilly, Merck, and Novo Nordisk. The plaintiffs’ core theory was failure to warn.
On March 9, 2021, after a trip to the Ninth Circuit and back, the court granted summary judgment for all defendants on two independent grounds: federal preemption and lack of general causation.5U.S. District Court, Southern District of California. Omnibus Order, Case No. 13-md-2452-AJB-MDD On preemption, the court found “clear evidence” that the FDA would have rejected a pancreatic cancer warning, since the agency had consistently described the causal link as “indeterminate.” On causation, the court excluded the plaintiffs’ expert witnesses across the board, finding their methods unreliable — biostatisticians were faulted for “cherry-picked” data, a gastroenterology expert admitted counsel had taught him the alleged drug-cancer relationship, and a pathology expert used unreliable methodology on non-human primates.6Expert Institute. Judge Grants Defendants Motion for Summary Judgment in Diabetes Drug MDL, Excludes Plaintiffs Experts
The Ninth Circuit affirmed in March 2022, the plaintiffs’ steering committee declined further appeals, and the MDL formally closed on November 9, 2022.7U.S. District Court, Southern District of California. MDL 2452 Closure Order
For a Michigan plaintiff, that history matters in two ways. First, any new case would have to clear the same general-causation hurdle with better expert testimony than the MDL plaintiffs mustered. Second, the federal preemption ruling — grounded in the FDA’s position that the causal link is indeterminate — would likely be cited against any new failure-to-warn theory on the same facts.
What the Science Shows
The published evidence has largely not supported a causal link between exenatide and pancreatic cancer, which is why the litigation collapsed. A 2012 retrospective cohort analysis of more than 268,000 privately insured diabetes patients found no statistically significant association between exenatide use and either acute pancreatitis hospitalization or pancreatic cancer.8National Library of Medicine. Exenatide Therapy and the Risk of Pancreatitis and Pancreatic Cancer in a Privately Insured Population A 2019 meta-analysis in Scientific Reports covering 12 randomized trials and over 36,000 patients reached the same conclusion for GLP-1 receptor agonists as a class, though the authors noted mean follow-up of only about 1.7 years and said longer studies would be needed to rule out very small risks.9Nature. GLP-1 Receptor Agonists and Pancreatic Cancer Risk Meta-Analysis
The warning picture is more mixed. The FDA added a pancreatitis warning to the Byetta label in 2007 and strengthened it to reflect fatal cases.8National Library of Medicine. Exenatide Therapy and the Risk of Pancreatitis and Pancreatic Cancer in a Privately Insured Population Bydureon carries a boxed warning about thyroid C-cell tumors seen in rats, with the caveat that human relevance is unknown.10U.S. Food and Drug Administration. BYDUREON Prescribing Information A pancreatitis claim with contemporaneous medical documentation is on firmer scientific footing than a cancer claim, though neither escapes the legal hurdles below.
Michigan Hurdles That Survive the Repeal
Even without the old immunity, Michigan law still gives pharmaceutical defendants meaningful protection.
A rebuttable presumption of non-liability applies when the aspect of the product that caused injury complied with federal or state safety standards at the time of sale.11Michigan Legislature. MCL 600.2946 The presumption can be overcome, but the burden sits with the plaintiff.
Michigan does not recognize strict liability for product defect claims. You would have to proceed on negligence, breach of warranty, or misrepresentation. The learned intermediary doctrine also applies, meaning the manufacturer’s duty to warn runs to your prescribing doctor, not to you directly.12Drug and Device Law Blog. Possible Learned Intermediary Showdown in Michigan
The statute of limitations is three years from the date of injury, and Michigan does not apply a discovery rule to product liability claims. The clock starts when the injury happens, not when you learn the drug may have caused it.13Drug and Device Law Blog. Michigan Product Liability Law: Retroactivity of New Law and Primer That is a particularly harsh rule for latent conditions like cancer.
Noneconomic damages in product liability cases are capped. The limits are adjusted annually and stood at $569,000 or $1,016,000, depending on severity, as of 2024.
The Narrow Window for New Michigan Cases
Put the dates together and the opening is small. The immunity repeal reaches only injuries on or after February 13, 2024. AstraZeneca discontinued both Byetta and Bydureon BCise in October 2024, citing business reasons.14UnitedHealthcare. Discontinuation of Bydureon BCise and Byetta That leaves a roughly eight-month window of post-repeal exposure to these specific drugs, plus any ongoing injury traceable to use during that period, all subject to the three-year filing clock running from the date of injury.
If you believe you have a claim, the first conversation to have is with a Michigan product liability attorney who can pin down your injury date against the February 13, 2024 cutoff, assess whether the three-year clock has started or run, and evaluate whether current medical evidence can support causation in a way the MDL plaintiffs could not.