Immune System-Boosting "Immune Checkpoint Inhibitors" Show Promise for Treating Many Kinds of Cancer

The gist: Drugs called “immune checkpoint inhibitors” have shown promise for patients with multiple types of cancer. Immune checkpoint inhibitors are a type of immunotherapy, meaning they boost a patient’s own immune system to fight cancer. Two particularly promising immune checkpoint inhibitor drugs are MPDL3280A and pembrolizumab.

“Treatment with an immune checkpoint inhibitor led to consistent responses across multiple types of cancer, particularly in patients with suppressed immune systems that appeared to be ‘reinvigorated’ by the therapy, investigators reported.

“Response rates of 20% to 25% were seen in patients with advanced cancers, including lung, kidney, and head and neck cancers, as well as melanoma. The overall response to the engineered antibody MPDL3280A increased to 46% in patients whose tumors exhibited overexpression of programmed death-ligand 1 (PD-L1), a protein associated with immune suppression in multiple types of cancer, as reported a research letter in Nature.

“The antitumor activity was encouraging, but the identification of markers predictive of response could prove to be equally important if not more so, according to Roy S. Herbst, MD, PhD, of the Yale Cancer Center.

” ‘The most compelling thing about the study is the fact that we worked to develop predictive markers for who responds and who doesn’t,’ Herbst told MedPage Today. ‘We can measure PD-L1 immunostaining in the immune infiltrate — not on the tumor cells but on the macrophages and the lymphocytes in the immune microenvironment.’ “