Merck Sued Over Fatal Immune Reactions Linked to Cancer Meds

A Florida widow has filed a wrongful death lawsuit against Merck & Co. Inc., claiming that their cancer medication Keytruda contributed to her husband's fatal immune reaction. Penny Dombeck, on behalf of herself and her late husband Jeffrey Dombeck, alleges that Merck failed to warn about the risks of Keytruda's side effects, particularly for patients with pre-existing health conditions.

Jeffrey Dombeck was diagnosed with non-terminal melanoma in June 2024 and began taking Keytruda as part of his treatment. However, within weeks, he experienced severe health issues, including myocarditis, myositis, and myasthenia gravis, all of which doctors believed were caused by the drug.

The lawsuit notes that Merck had received thousands of reports of similar injuries over many years but only added an MMM warning to the Keytruda label in May 2026, months after Dombeck's death. The complaint seeks both compensatory and punitive damages, claiming that Merck prioritized profits over patient safety.

The FDA has issued warnings about Keytruda's risks, including a 2017 alert regarding an increased risk of death when used with certain medications to treat multiple myeloma. A study published in October 2024 warned that ICIs like Keytruda could increase the risk of life-threatening heart problems after only a year of use.