What happened

Shares of MacroGenics (NASDAQ:MGNX) had jumped 5.3% as of 3:09 p.m. EST on Monday. The gain came after the company announced results from a late-stage study of Margenza as a third-line treatment for metastatic HER2-positive breast cancer. These results were published in the Journal of the American Medical Association Oncology

So what

MacroGenics stated that Margenza met the primary endpoint of the phase 3 study with a 24% progression-free survival relative risk reduction versus Roche's Herceptin. Both Margenza and Herceptin were administered along with chemotherapy.

Physician holding a pink ribbon symbolizing breast cancer awareness

Image source: Getty Images.

Investors reacted positively to the latest results, which bode well for Margenza's prospects in achieving commercial success. The drug won Food and Drug Administration approval as a third-line treatment for HER2-positive breast cancer in December.

CEO Scott Koenig said that Margenza is "the first HER2-targeted therapy to reduce the risk of disease progression in metastatic breast cancer patients over trastuzumab [Herceptin] in a head-to-head comparison involving a heavily pre-treated patient population." The potential market opportunity for Margenza should be significant. As many as 20% of breast cancers diagnosed are HER2-positive. Herceptin has long been a leading treatment for HER2-positive breast cancer. An even better therapy would be welcomed by physicians and patients.

Now what

What's the next likely catalyst for the biotech stock? MacroGenics expects to launch Margenza in the U.S. beginning in March. The company's first-quarter update could provide a hint as to how the rollout is going, but its second-quarter update will likely give a better picture.

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