(Updated - December 16, 2020 5:23 PM EST)

MacroGenics, Inc. (Nasdaq: MGNX), a biopharmaceutical company focused on developing and commercializing innovative monoclonal antibody-based therapeutics for the treatment of cancer, today announced that the U.S. Food and Drug Administration (FDA) has approved MARGENZA, in combination with chemotherapy, for the treatment of adult patients with metastatic HER2-positive breast cancer who have received two or more prior anti-HER2 regimens, at least one of which was for metastatic disease. MARGENZA is the first product approved from MacroGenics’ promising pipeline. The approval was based on safety and efficacy results from the pivotal Phase 3 SOPHIA trial.

“The approval of MARGENZA 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,” said Scott Koenig, M.D., Ph.D., President and CEO of MacroGenics. “As we prepare for our first commercial launch and look forward to being able to deliver MARGENZA 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 approval for MARGENZA was based on data from SOPHIA, a randomized Phase 3 clinical trial. The study, which included 536 patients, showed a statistically significant 24% reduction in the risk of disease progression or death with MARGENZA plus chemotherapy compared with trastuzumab plus chemotherapy (hazard ratio [HR]=0.76; 95% CI, 0.59-0.98; P=0.033; median PFS 5.8 vs 4.9 months). The objective response rate for MARGENZA 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 greater than twenty percent of patients with MARGENZA in combination with chemotherapy were fatigue/asthenia (57%), nausea (33%), diarrhea (25%), and vomiting (21%). The MARGENZA U.S. Prescribing Information has a BOXED WARNING for left ventricular dysfunction and embryo-fetal toxicity. In addition, MARGENZA can cause infusion related reactions (IRRs). IRRs occurred in 13% of patients treated with MARGENZA, with the majority reported as Grade 2 or less. Grade 3 IRRs occurred in 1.5% of patients. See below for Important Safety Information.

“Early detection and treatment have had a positive impact on the survival of patients with breast cancer, but the prognosis for people diagnosed with metastatic breast cancer remains poor, and additional treatments are needed,” said Hope S. Rugo, M.D., Professor of Medicine and Director of Breast Oncology and Clinical Trials Education, University of California San Francisco Helen Diller Family Comprehensive Cancer Center. “As the only HER2-targeted agent to have shown a PFS improvement versus trastuzumab in a head-to-head Phase 3 clinical trial, MARGENZA with chemotherapy represents the newest treatment option for patients who have progressed on available HER2-directed therapies.”

"Women with metastatic HER2-positive breast cancer are benefitting from ongoing scientific advances," said Christine Benjamin, LMSW, Chair, Metastatic Breast Cancer Alliance. "We are always excited to learn of additional treatment options that are available to healthcare professionals and those living with metastatic breast cancer."

MacroGenics anticipates that MARGENZA will be available in March of 2021.

Conference Call

MacroGenics will host a conference call for analysts and investors on Thursday, December 17, 2020, at 8:00 a.m. ET. To participate in the conference call, please dial (877) 303-6253 (domestic) or (973) 409-9610 (international) ten minutes prior to the start of the call and provide the Conference ID: 8657888.

The listen-only webcast of the conference call, including presentation slides, can be accessed under "Events & Presentations" in the Investor Relations section of the Company's website at https://ir.macrogenics.com/events.cfm. A replay of the webcast will be available shortly after the conclusion of the call and archived on the Company's website for 30 days following the call.