molecules of the month

An early heme-binding inhibitor of the once red-hot immunotherapy target, IDO1. Indoleamine 2,3-dioxygenase 1 (IDO1) is an extrahepatic tryptophan-metabolizing enzyme which is believed to contribute to the evasion of the immune system by tumors, making it an attractive target for cancer immunotherapy, especially in combination with immune checkpoint inhibitors like Merck’s pembrolizumab or BMS’s nivolumab. The potential for an IDO1 inhibitor led to a frothy M&A environment for such molecules a few years ago, catalyzed by Incyte’s initially exciting Ph. I data in melanoma and capped by the acquisition of Flexus and its preclinical IDO molecule, linrodostat, by BMS for $1.25B, including $800M in upfront cash. Unfortunately disappointing Ph. III data from epacadostat + pembrolizumab in the ECHO-301 trial led…