Janumet Lawsuit: Pancreatic Cancer Claims and Dismissals

The Janumet lawsuit story is largely closed. Nearly 1,000 patients sued Merck alleging that Janumet and its sister drug Januvia caused pancreatic cancer or pancreatitis, but a federal judge dismissed the consolidated litigation in March 2021, no settlements were paid, and most law firms have stopped taking new cases.¹²

What the Lawsuits Claimed

Janumet combines sitagliptin with metformin and belongs to a class of Type 2 diabetes drugs called DPP-4 inhibitors. Beginning around 2013, patients filed individual product liability suits against Merck alleging the drug caused pancreatic cancer, pancreatitis, and in some cases death. Similar suits targeted Byetta (Amylin and Eli Lilly) and Victoza (Novo Nordisk).

Plaintiffs advanced three theories. They said Merck failed to warn doctors and patients that the drug could cause pancreatic cancer, a risk not mentioned on the label. They said the drug was defectively designed because its risks outweighed its benefits. And they alleged negligence, arguing Merck knew or should have known about the cancer risk and kept marketing the drug as safe.³

The scientific spark for the litigation was a 2011 UCLA study by Elashoff and colleagues in Gastroenterology. It analyzed FDA adverse event reports and found that patients on sitagliptin or exenatide had roughly six times the reported pancreatitis rate and nearly three times the reported pancreatic cancer rate of patients on older diabetes drugs.⁴ The authors acknowledged that voluntary adverse event reports are not controlled data, but the finding drew regulator and plaintiff attention.

Was It a Class Action?

No. The cases were individual lawsuits, and no class was ever certified. On August 26, 2013, the Judicial Panel on Multidistrict Litigation consolidated 53 federal actions into MDL No. 2452, In re Incretin-Based Therapies Products Liability Litigation, before Judge Anthony J. Battaglia in the U.S. District Court for the Southern District of California.⁵ The MDL eventually grew to about 970 cases involving close to 1,000 plaintiffs.¹ More than 300 additional cases proceeded in a coordinated state court action before Judge William F. Highberger in Los Angeles County Superior Court.⁶

The MDL structure meant each plaintiff had a separate case, but they shared discovery and coordinated expert proceedings.³

Why the Cases Were Dismissed

On March 9, 2021, Judge Battaglia issued an omnibus order granting summary judgment to Merck, Amylin, Lilly, and Novo Nordisk on two independent grounds: federal preemption and lack of causation.⁷

On preemption, the court applied the Supreme Court’s decisions in Wyeth v. Levine and Merck Sharp & Dohme Corp. v. Albrecht and concluded that state-law failure-to-warn requirements irreconcilably conflicted with FDA labeling requirements. In practical terms, the court accepted that the FDA would have rejected any pancreatic cancer warning during the relevant time period, so Merck could not have added the warning plaintiffs said was missing.¹

On causation, the court excluded all seven of the plaintiffs’ general causation experts — Drs. Madigan, Wells, Brown, Gale, Landolph, Woolf, and Taylor — finding their methodologies insufficient to show that incretin-based drugs cause pancreatic cancer.⁷ Without admissible expert testimony on general causation, the claims could not survive.

Plaintiffs appealed. In March 2022, the Ninth Circuit affirmed the summary judgment as to Novo Nordisk.⁸ The California state court coordinated proceeding (JCCP 4272) was formally terminated in October 2022.⁹

Were Any Settlements Paid?

No. Because the litigation was dismissed at summary judgment, the cases never reached trial and no bellwether verdicts prompted a mass settlement. Law firms that had been accepting Janumet and Januvia clients stopped, and at least one major firm ceased handling the cases entirely by 2023.² As of early 2026, ClassAction.org lists its investigation as complete, with no new developments reported.³

The FDA and Scientific Record

The FDA’s own review did not support the plaintiffs’ theory. In March 2013 the agency announced it was investigating whether incretin drugs raised the risk of pancreatitis and pancreatic cancer, describing the associations as “not yet conclusive” and telling patients to keep taking their medication.¹⁰ The FDA later concluded that its review of clinical and animal data did not establish a causal link and considered the existing pancreatitis warning on the label adequate.¹¹ An earlier 2009 label change had already added a warning about acute pancreatitis reports in patients taking sitagliptin.

Large studies pointed the same way. The TECOS trial, which specifically studied sitagliptin, found fewer pancreatic cancer cases in the sitagliptin group than in the placebo group. A 2023 Korean study following more than 100,000 patients for a median of nearly eight years found no significant association between DPP-4 inhibitor use and pancreatic cancer risk.¹²

The Separate Nitrosamine Issue

A different Januvia safety question emerged in August 2022, and it is worth separating from the pancreatic cancer suits because searchers sometimes conflate them. The FDA reported that a nitrosamine impurity called Nitroso-STG-19 (NTTP) — nitrosamines are potential carcinogens of the same family that triggered Zantac and valsartan recalls — had been detected in certain Januvia samples.¹³

Rather than ordering a recall, the FDA allowed Januvia to remain on the market to prevent shortages, temporarily permitting NTTP levels up to 246.7 nanograms per day against a standard limit of 37 nanograms per day. Merck said it added quality controls and did not expect supply disruptions.¹³ By August 2023, the FDA formally re-established the 37 nanograms per day limit. In October 2023, generic drugmaker Zydus Pharmaceuticals filed a citizen petition asking the FDA for mandatory recalls of non-compliant sitagliptin products and a black-box warning about nitrosamine cancer risk.¹⁴

No major litigation over the nitrosamine contamination has materialized. Legal commentators have said the situation is unlikely to produce lawsuits on the scale of Zantac or valsartan.²

1
Drugwatch. Januvia Lawsuits
2
Miller & Zois. Januvia
3
ClassAction.org. Januvia
4
National Library of Medicine. Pancreatitis, Pancreatic, and Thyroid Cancer With Glucagon-Like Peptide-1–Based Therapies
5
Judicial Panel on Multidistrict Litigation. MDL-2452 Initial Transfer Order
6
RxInjuryHelp. Byetta Pancreatic Cancer Lawsuit Decision California
7
vLex. In Re Incretin-Based Therapies Products Liability Litigation, 524 F.Supp.3d 1007
8
GovInfo. In Re Incretin-Based Therapies Products Liability Litigation
9
Mealey’s Litigation Report. California Judge Closes Coordinated Docket for Incretin Mimetic Drugs
10
Regulatory Affairs Professionals Society. Class of Diabetes Drugs Associated With Pancreatitis
11
National Library of Medicine. Risk of Pancreatic Cancer and Use of Dipeptidyl Peptidase 4 Inhibitors
12
Endocrinology and Metabolism. Risk of Pancreatic Cancer and Use of Dipeptidyl Peptidase 4 Inhibitors in Patients With Type 2 Diabetes
13
Fierce Pharma. FDA Angles to Avert Shortage of Merck’s Diabetes Med Januvia After Testing Flags Possible Impurity
14
Regulations.gov. Citizen Petition Regarding Sitagliptin Nitrosamine Impurity