IPI-549 is an oral, selective phosphoinositide-3-kinase gamma (PI3K-gamma) inhibitor, and the partners believe the combination will help overcome resistance to PD-1s seen in these patients.

Drugs from the PI3K-gamma class aim to reduce function of white blood cells known as macrophages, which normally locate and “eat” foreign particles that it deems to be a threat. But macrophage ...