Single-center phase 2 trial of pembrolizumab plus low-dose, single-fraction radiotherapy for relapsed or refractory multiple myeloma

A phase 2 trial at Emory University (Atlanta, GA) evaluated the combination of pembrolizumab with single-fraction, low-dose (8 Gy) radiotherapy for patients with relapsed or refractory multiple myeloma (RRMM). Among 25 patients, there was no grade 3 or higher radiation-related toxicity within irradiated volumes, whereas only one patient (4%) had a grade 3 pembrolizumab-related adverse event. At 3 months, two patients had complete response, two had very good partial response, three had partial response, and one had stable disease, for a clinical benefit rate of 32%. The authors conclude that combination of pembrolizumab with single-fraction, low-dose radiotherapy for RRMM was safe, with early promise of response activity.