Safety of Checkpoint Inhibitors Plus Radiotherapy for Metastatic Lung Cancer
For patients with metastatic lung cancer who are treated with checkpoint inhibitors as well as thoracic radiotherapy, the combination of therapies does not seem to significantly increase the risk of symptomatic immune-related adverse events compared with checkpoint inhibitors alone. William L. Hwang, MD, PhD, of the Harvard Medical School, Boston, and colleagues reported these findings, which appear to be comparable to the rates of such toxicity in randomized trials of checkpoint inhibitors in this patient population, in JAMA Oncology.
The study looked at 164 patients with metastatic lung cancer being treated with programmed cell death protein 1/programmed cell death ligand 1 inhibitors. The rates of grade 2 or higher immune-related adverse events, all-grade pneumonitis, and grade 2 or higher pneumonitis did not significantly differ between those who had or had not received thoracic radiotherapy.
Furthermore, the development of grade 2 or higher immune-related adverse events seemed to be associated with better survival. The investigators noted this finding may suggest patients who respond to checkpoint inhibitors are likely to receive more cycles of therapy, possibly predisposing them to the toxic effects.
Dr. Hwang and colleagues acknowledge the limitations of their analysis: It is a single-center series and the median time between radiotherapy and checkpoint inhibition was 8.6 months. Ongoing studies are investigating both consolidative checkpoint inhibition after definitive chemoradiotherapy and concurrent radiotherapy with checkpoint inhibition.