Keytruda Wrongful Death Lawsuit Alleges Merck Failed to Warn About Fatal Immune Reactions

Drugmaker only put warnings on the label after plaintiff’s death, despite receiving thousands of reports of similar injuries over many years.

A wrongful death lawsuit filed by a Florida widow claims the side effects of Keytruda attacked her husband’s heart, muscles, nerves and kidney.

The complaint (PDF) was brought by Penny Dombeck, on behalf of herself and her late husband, Jeffrey Dombeck, who died in September 2024, after receiving Keytruda as part of his melanoma cancer treatment. It names Keytruda’s manufacturer, Merck & Co. Inc., as the defendant.

Dombeck claims Merck failed to adequately warn about the risks of Keytruda auto-immune side effects, particularly on individuals who already suffered from health problems that could be exacerbated by a reaction. She indicates her husband’s slow and deteriorating death could have been avoided had the company placed patients before profits.

Keytruda Side Effects

Keytruda (pembrolizumab) was originally approved by the U.S. Food and Drug Administration (FDA) in 2014 for the treatment of advanced melanoma. The drug’s label has significantly expanded since then as a treatment for numerous types of cancer.

It belongs to a class of cancer drugs known as immune checkpoint inhibitors (ICIs), which also includes medications like Opdivo and Libtayo. These drugs are used to block key proteins that regulate the immune system, preventing it from over-responding to cancer cells and damaging healthy ones.

For years there have been growing concerns as to whether Keytruda health risks are greater than the cancer drug’s benefits. The same month Dombeck died, a panel of FDA scientific advisors urged the agency to restrict drugs like Keytruda, particularly for patients with certain types of cancer. The panel determined that Keytruda only moderately lowered the risk of death from cancer compared to chemotherapy.

Another study, published a month later in October 2024, warned that Keytruda and other ICIs could increase the risk of life-threatening heart problems, like pulmonary embolism, deep vein thrombosis and heart attack after only a year of use.

In addition, the FDA issued a Keytruda safety alert in August 2017, after analyzing three studies that found an increased risk of death when the drug is used in combination with some other medications to treat multiple myeloma.

Keytruda Wrongful Death Allegations

In June 2024, Jeffrey Dombeck, 77, was diagnosed with non-terminal melanoma, a form of skin cancer. His doctor prescribed surgery and a year of taking Keytruda. He was known to have coronary artery disease, including two heart stents, as well as an autoimmune/rheumatological disorder known as Meniere’s disease.

Dombeck’s first dose of Keytruda was given on August 6, 2024. By August 24, 2024, he was in the hospital and was diagnosed with myocarditis, myositis and myasthenia gravis, all of which doctors believed were caused by the drug. 

The condition, known as MMM or triple-M overlap syndrome, causes inflammation of the heart, the skeletal muscles and nerve muscles. In addition, doctors found a complete heart block, stage 3 acute kidney injury (AKI), acute rhabdomyolysis, respiratory failure and dysphagia.

“Mr. Dombeck died on September 20, 2024, after his family watched him deteriorate and suffer for weeks before they made the painful decision at the recommendation of treating physicians to transition him to comfort care. The cause of death on Mr. Dombeck’s death certificate listed Keytruda-immune therapy induced MMM.”

— Penny Dombeck v. Merck & Co. Inc.

According to Dombeck’s wife, Merck either knew, or should have known, about the risks of MMM. The lawsuit notes that Merck had reports of MMM and kidney injury dating back to long before Dombeck was prescribed the drug.

The complaint indicates that by 2023, Merck had received a total of 52,032 Keytruda adverse event reports, 11,000 of which involved patient deaths, with many linked to the same conditions as Dombeck suffered. It was not until May 2026 that Merck added an MMM warning to the Keytruda label.

Penny Dombeck presents claims of failure to warn and negligence. She seeks both compensatory and punitive damages.

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