FDA Halts MacroGenics Cancer Trial After Severe Patient Reactions

MacroGenics has paused enrollment in its Phase 2 study of lorigerlimab after the U.S. Food and Drug Administration (FDA) placed a clinical hold on the trial due to severe safety concerns. The Rockville, Maryland-based biopharmaceutical company halted the study, which targets gynecological cancers, after reporting serious adverse events in four participants.

February 24, 2026, 03:01 AM 0 0

FDA Halts MacroGenics Cancer Trial After Severe Patient Reactions

MacroGenics voluntarily notified the FDA of its decision to stop recruitment after four patients experienced life-threatening medical complications. According to the company, these safety events included Grade 4 thrombocytopenia, myocarditis, and a combination of neutropenia and septic shock.

Before the pause, 41 participants had received doses of the experimental drug every three weeks. While the FDA's hold prevents new patients from entering the study, the company confirmed that those already enrolled are permitted to continue treatment under the current protocol.

Market Reaction and Regulatory Outlook

News of the regulatory setback triggered an immediate sell-off in the biotech sector. Shares of MacroGenics dropped 8.6% to $1.60 during after-hours trading on Monday. The company is now expected to analyze the safety data in conjunction with federal regulators to determine if the development of lorigerlimab can safely proceed.

MacroGenics specializes in developing antibody-based therapeutics for cancer, and this trial was a key component of its oncology pipeline. The duration of the FDA hold remains uncertain as the company investigates the root cause of the patient complications.

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