MacroGenics looks to future with breast cancer drug margetuximab

A small biotech, MacroGenics, took the market by surprise earlier this year with some surprising data from its margetuximab essentially a tweaked version of Roche’s Herceptin (trastuzumab) where a few amino acid mutations are enough to produce a stronger cellular response to cancer.CEO Scott Koenig has been doing the rounds at the American Society of Clinical Oncology (ASCO) conference in Chicago following release of detailed data from the SOPHIA trial of margetuximab in breast cancer patients who have previously been treated with Herceptin and other similar medicines.In SOPHIA, the median progression-free survival (PFS) of patients treated with margetuximab and chemotherapy was 5.8 months compared to 4.9 months in patients treated with trastuzumab and chemotherapy.Among the approximately 85% of patients carrying the CD16A 158F allele, a pre-specified exploratory subpopulation in the study, PFS was prolonged by 1.8 months in the margetuximab arm compared to the trastuzumab arm (6.9 months versus 5.1 months).The objective response rate, a secondary outcome measure in the SOPHIA study, was 22% in the margetuximab arm compared to 16% in the trastuzumab arm at data cut-off in October.MacroGenics argues that margetuximab works by tweaking the “Fc” part of Herceptin the tail of the ‘Y’ shaped antibody so that it interacts more efficiently with the immune system and produces a stronger anti-cancer response.With Roche losing sales to biosimilars as Herceptin goes off patent, the obvious question to Koenig is whether he is looking to sell up to the Swiss pharma or one of its competitors on the basis of the margetuximab data.Not necessarily is the answer from Koenig, who pointed out that the company has eight other cancer drugs in various stages of clinical development in the pipeline and a share price that has been boosted by the data from SOPHIA.