FDA Approves Margetuximab-cmkb Plus Chemo in Metastatic HER2+ Breast Cancer

The FDA has approved margetuximab-cmkb (Margenza) plus chemotherapy for use in adult patients with metastatic HER2-positive breast cancer who have previously received 2 or more anti-HER2 regimens, at least one of which was for metastatic disease.

“The approval of [margetuximab-cmkb] is an exciting milestone for MacroGenics and, more importantly, it brings a new treatment option to metastatic breast cancer patients. We are grateful for the patients who participated in this study, as well as their families, and everyone who played a role in helping MacroGenics reach this milestone,” Scott Koenig, MD, PhD, president and CEO of MacroGenics, stated in a press release. “As we prepare for our first commercial launch and look forward to being able to deliver [margetuximab-cmkb] to patients, we continue to focus on developing and commercializing innovative antibody-based therapeutics for the treatment of cancer with eight product candidates currently in clinical development.”

The regulatory decision was based on findings from the phase 3 SOPHIA trial, in which the agent plus chemotherapy demonstrated a statistically significant reduction of 24% in the risk of disease progression or death compared with trastuzumab (Herceptin) plus chemotherapy (HR, 0.76; 95% CI, 0.59-0.98; P =.033), with a median PFS of 5.8 months vs 4.9 months, respectively. The objective response rate for the margetuximab-cmkb plus chemotherapy was 22% and for trastuzumab plus chemotherapy was 16%. The final overall survival (OS) analysis is expected in the second half of 2021.

Adverse reactions occurring in more than 20% of patients who received margetuximab-cmkb plus chemotherapy included fatigue/asthenia (57%), nausea (33%), diarrhea (25%), and vomiting (21%).

Notably, the US Prescribing information has a Boxed Warning for left ventricular dysfunction and embryo-fetal toxicity. Moreover, margetuximab-cmkb is known to cause infusion-related reactions (IRRs) These reactions were reported by 13% of patients treated with the agent; however, most of the cases reported were grade 2 or less in severity. Grade 3 IRRs were experienced by 1.5% of patients.

This article was originally published on OncLive as, "FDA Approves Margetuximab-cmkb Plus Chemo in Pretreated Metastatic HER2+ Breast Cancer."