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MacroGenics' Margenza Garners FDA Approval in HER2-Positive Metastatic Breast Cancer

NEW YORK – The US Food and Drug Administration on Wednesday approved MacroGenics' monoclonal antibody margetuximab (Margenza) in combination with chemotherapy for HER2-postive, metastatic breast cancer patients who have received two prior anti-HER2 regimens.

The FDA approved the drug based on results from the Phase III SOPHIA trial, which randomized 536 advanced HER2-positive breast cancer patients to margetuximab plus chemo or trastuzumab (Genentech's Herceptin) plus chemo. Margetuximab-based treatment reduced the risk of disease progression or death by 24 percent. Median progression-free survival was 5.8 months in the margetuximab arm versus 4.9 months in the trastuzumab arm. In the study, 22 percent of patients receiving margetuximab saw their tumors shrink compared to 16 percent on trastuzumab.

The company is expecting final overall survival data to read out in the second half of 2021. Common adverse events seen in patients due to margetuximab were fatigue, nausea, diarrhea, and vomiting. The FDA-approved label for the drug contains a boxed warning for left ventricular dysfunction and embryo-fetal toxicity.

Margetuximab is the first drug approved in MacroGenics' pipeline. According to the Rockville, Maryland-based firm, margetuximab is also the first HER2-targeted drug to improve progression-free survival in a head-to-head Phase III comparison with trastuzumab, a first-generation anti-HER2 drug. The company will launch margetuximab on the market in March 2021.