MacroGenics Announces Lancet Oncology Publication of Margetuximab Data in Gastric Cancer

Rockville, MD, July 09, 2020 (GLOBE NEWSWIRE) --

MacroGenics, Inc. (NASDAQ: MGNX), a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer, today announced that Lancet Oncology has published results from a Phase 2 study of margetuximab plus pembrolizumab as a chemotherapy-free regimen for patients with advanced HER2-positive gastroesophageal adenocarcinoma (GEA) who have previously been treated with chemotherapy and trastuzumab. Margetuximab is an investigational, Fc-engineered, monoclonal antibody targeting HER2. Pembrolizumab is an anti-PD-1 monoclonal antibody.

“Current standard of care treatment for patients with metastatic gastroesophageal adenocarcinoma is heavily dependent on the use of cytotoxic chemotherapy,” said Stephen Eck, M.D., Ph.D., Senior Vice President, Clinical Development & Chief Medical Officer. “The published data suggest that a chemotherapy-free regimen combining the immune-enhancing properties of margetuximab with checkpoint blockade may improve upon clinical outcomes for certain first-line patients with metastatic HER2-positive gastroesophageal adenocarcinoma and provide a strong rationale for the ongoing Phase 2/3 MAHOGANY study.”

The Phase 2 study enrolled patients with gastric cancer (GC) or gastroesophageal junction (GEJ) cancer whose tumors were IHC3-positive or IHC2-positive/FISH-positive at diagnosis. Enrollment was regardless of PD-L1 expression status, which was subsequently determined from available archived tumor tissue.

Tolerability of margetuximab and pembrolizumab was acceptable in patients treated in this study. Grade 3 or higher treatment-related adverse events (TRAEs) were reported in 20% of patients, with anemia (4%) and infusion-related reactions (3%) being the most common. No treatment-related deaths were reported.

Patients who had received margetuximab at the recommended Phase 2 dose of 15 mg/kg every three weeks were evaluable for response. In this overall population, the objective response rate (ORR) was 18% (17/92 patients), including complete responses (CR) and partial responses (PR). The disease control rate (DCR), which includes CR, PR, and stable disease (SD), was 53% (49/92 patients). Median progression-free survival (PFS) was 2.7 months (95% CI 1.6–4.3) and median overall survival (OS) was 12.5 months (95% CI 9.1–14.1).