Roche’s cancer immunotherapy drug Tecentriq (atezolizumab), a PD-L1 inhibitor, was approved for another treatment by the Food and Drug Administration (FDA) for triple-negative breast cancer. This is the first immunotherapy approved for breast cancer. It is a narrow approval—for locally advanced or metastatic triple-negative breast cancer expressing PD-L1 (molecule that locks with PD-1 receptors on the surface of T cells). Triple-negative means the tumor cells do not have estrogen receptors, progesterone receptors, or HER2, all of which fuel uncontrolled cell proliferation but can be blocked with drugs such as Herceptin. The “handshake between the PD-L1 and PD-1 stops the T cells from attacking the tumor. Bristol-Myers Squibb’s nivolumab and Merck’s pembrolizumab act as blockers between this handshake. Tencentriq does the same.