Single-center cohort study of symptomatic necrosis with dual immune checkpoint inhibition and radiosurgery for brain metastases

Radionecrosis, a delayed form of brain injury after radiosurgery for brain metastases (BMs) is a neuro-oncologic challenge with significant patient morbidity and mortality. A cohort study at Duke Cancer Institute (Durham, NC) investigated risk of radionecrosis with concurrent dual, single, or no immune checkpoint inhibition (ICI) for BMs of melanoma or NSCLC. The 24-month cumulative incidence of symptomatic radionecrosis was 21.8% among patients receiving radiosurgery with dual ICI, compared with 13.5% with single ICI and 13.7% with no ICI. After accounting for other patient and treatment-related factors, only dual ICI was associated with increased risk for symptomatic radionecrosis (HR 2.4; p=0.01). Survival was significantly reduced for patients with symptomatic radionecrosis within 1 year of radiosurgery compared with no radionecrosis (median 6.9 versus 46.0 months; p<0.001). The authors conclude that concurrent dual ICI and radiosurgery for BMs of melanoma or NSCLC was associated with increased risk of radionecrosis.