Dr. Ribas on Combination Immunotherapy and Radiation in Melanoma

Antoni Ribas, MD, PhD, professor of medicine, University of California, Los Angeles, director, Tumor Immunology Program, Jonsson Comprehensive Cancer Center, discusses the potential for combination immunotherapy and radiation in the treatment of patients with melanoma.

The goal of this combination, Ribas says, is to achieve the abscopal effect, which is when radiation is directed toward 1 lesion and there is a systemic effect throughout the body. Based on recent data published in the New England Journal of Medicine, researchers believe this is effect is boosted when added to immune checkpoint blockade.

However, Ribas notes that this is not something that is commonly seen in the clinic. When you radiate a progressive tumor that is also being treated with PD-1 or CTLA-4 checkpoint inhibitors, most of the time you will see synergy, but not the abscopal effect, he says. Preclinical data with mouse models initially suggested the potential for this, but in the last 50 years researchers have not quite been able to reach that end goal. Ribas concludes that physicians need to better understand the immune effects of radiation therapy, as there are benefits and limitations to its use.