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SABCS 2019: Margetuximab Versus Trastuzumab in HER2-Positive Metastatic Breast Cancer

By: Hillary Ojeda
Posted: Wednesday, December 18, 2019

Based on the findings of the phase III SOPHIA trial, conducted by Hope S. Rugo, MD, FASCO, of the University of California San Francisco, and colleagues, adding the monoclonal antibody margetuximab to chemotherapy improved progression-free survival compared with trastuzumab plus chemotherapy in patients with HER2-positive metastatic breast cancer. In the first prospective analysis of the effect of CD16A genotype on the efficacy of anti-HER2 antibodies, presented at the 2019 San Antonio Breast Cancer Symposium (Abstract GS1-02), the investigators suggested a greater benefit was noted in patients with a 158F allele.

“Maturing data comparing the overall survival of patients treated with margetuximab vs trastuzumab with chemotherapy will provide important new insights in characterizing clinical activity of this regimen in patients with metastatic breast cancer,” the authors commented.

A total of 536 patients were enrolled in the study. The patients were randomly assigned to chemotherapy plus either margetuximab (15 mg/kg intravenously every 3 weeks) or trastuzumab. A total of 266 patients were in the margetuximab group and 270 patients were in the trastuzumab group. At the time of the study, patients had disease progression and had received at least two lines of anti-HER2 therapy.

The margetuximab group experienced improved progression-free survival—5.8 months vs 4.9 months for the trastuzumab group. For patients with the CD16A genotype with a 158F allele, the progression-free survival results were more dramatic: 6.9 months vs 5.1 months. “Overall survival at the first interim analysis demonstrated a hazard ratio of 0.95 (95% confidence interval [CI] = 0.69–1.31) for the intent-to-treat population (n = 536) and a hazard ratio of 0.82 (95% CI = 0.58–1.17) for the CD16A/FF or FV genotype population (n = 457),” the investigators concluded.

Disclosure: The study authors’ disclosure information can be found at https://www.abstractsonline.com.



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