Dr. Nghiem on Response to Immunotherapy in Merkel Cell Carcinoma

Paul Nghiem, MD, PhD, Michael Piepkorn Endowed Chair in Dermatology Research, professor of Dermatology/Medicine at Fred Hutchinson Cancer Research Center, University of Washington Medicine, discusses response to immunotherapy in Merkel cell carcinoma (MCC).

More than two-thirds of patients with MCC have disease caused by the Merkel cell polyomavirus. These patients have a very low tumor mutational burden (TMB), Nghiem says. The remaining third, which have disease caused by ultraviolet light, have an extremely high TMB. Nghiem says this is interesting because the efficacy of immunotherapy appears to be very similar between the 2 groups.

The dichotomy of causes does not yet seem to signal a difference in response to immunotherapy, Nghiem explains, and patients with both virally-mediated MCC and MCC as a result of sun exposure, can be very immunogenic. There is still a lot to learn, Nghiem adds, as about 50% of all patients with MCC do not respond to immunotherapy.