Medical oncologist Alexander Lesokhin discusses a phase I clinical trial assessing anti-PD-1 immunotherapy in patients with relapsed or refractory hematologic cancers. These drugs are designed to boost the body's immune system against cancer by targeting the PD-1 protein on white blood cells. PD-1 normally maintains the balance of the immune system by shutting it down at appropriate times. Some cancers take advantage of this shut-down mechanism by activating PD-1, enabling the cancer cells to escape attack from white blood cells. In the trial, researchers are assessing the safety, pharmacokinetics, immunoregulatory activity, and antitumor activity of an anti-PD-1 therapy called BMS-936558 in patients with relapsed or refractory multiple myeloma, non-Hodgkin lymphoma, Hodgkin lymphoma, or chronic myelogenous leukemia.