MacroGenics Soars on Phase III Breast Cancer Study

animation of Breast cancer

Shares of Rockville, Md.-based MacroGenics, Inc. have skyrocketed nearly 160 percent in premarket trading after the company announced its Phase III HER2-positive metastatic breast cancer study hit the mark.

Investors snapping up shares of MacroGenics drove the stock up more than $17 per share. MacroGenics closed at $11.11 per share on Tuesday, but this morning, the stock has jumped to $28.88 per share in premarket trading.

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MacroGenics said its clinical asset margetuximab met the primary endpoints of prolongation of progression-free survival (PFS) in patients who have HER2-positive metastatic breast cancer. In the Phase III SOPHIA trial, patients were treated with a combination of margetuximab plus chemotherapy. Their data were compared to those patients who were treated with Genentech’s Herceptin (trastuzumab) plus chemotherapy. Trial data showed that patients on the margetuximab arm experienced a 24 percent risk reduction in PFS compared to patients in the trastuzumab arm. MacroGenics pointed out that approximately 85 percent of the patients in the Phase III trial were carriers of the CD16A (FcγRIIIa) 158F allele, which has been previously associated with diminished clinical response to Herceptin and other antibodies. In this particular group of patients, MacroGenics said patients who took its treatment exhibited a 32 percent risk reduction in PFS compared to patients in the trastuzumab arm.

Margetuximab is an investigational monoclonal antibody that targets the human epidermal growth factor receptor 2, or HER2 oncoprotein. HER2 is expressed by tumor cells in breast, gastroesophageal and other solid tumors. Margetuximab was designed to provide HER2 blockade and has been engineered with an Fc domain to enhance the engagement of the immune system, the company said.

MacroGenics said a follow up of patients will continue in order to assess overall survival, which is part of the trial’s protocol. MacroGenics anticipates submitting a Biologics License Application (BLA) to the U.S. Food and Drug Administration in the second half of 2019.

Scott Koenig, president and chief executive officer of MacroGenics said the company is pleased with the results of the Phase III SOPHIA trial.

Our Fc-engineered, immune-enhanced molecule has demonstrated a superior outcome in a head-to-head study against Herceptin. We look forward to additional opportunities to develop margetuximab in other HER2-positive breast and gastric cancer populations,” Koenig said in a statement.

Hope S. Rugo, director of Breast Oncology and Clinical Trials Education at the University of California San Francisco Comprehensive Cancer Center, said there are no approved treatments for patients metastatic HER2+ breast cancer who have previously received trastuzumab, pertuzumab and ado-trastuzumab emtansine. If MacroGenics’ margetuximab is approved off of the SOPHIA data, Rugo said she believes it will become a “valuable treatment option.”

In addition to studying margetuximab in breast cancer, MacroGenics is also studying the asset as a potential treatment of patients with gastroesophageal cancer.

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