Immune checkpoint inhibitor toxicity and associated outcomes in older patients with cancer.

INTRODUCTION

Increased immune checkpoint inhibitor (ICI) use in various advanced cancer types has led to a parallel rise in immune-related adverse events (irAEs). Despite widespread use, ICI data in older patients remains limited. We investigate irAE prevalence in older patients receiving ICI and whether irAEs and survival are associated.

MATERIALS AND METHODS

Our retrospective study included patients aged ≥65 years with advanced malignancies who had ≥1 dose of ICI from January 2011 through September 2019. We evaluated irAE cases and their respective grades and assessed oncological response by progression-free survival (PFS) and overall survival (OS).

RESULTS

Mean age of 210 patients was 75.0 ± 7.2 years, 58.1% were men, and most were white. IrAE prevalence was 41.4% (n = 87); 9.5% (n = 20) developed multisystem irAE. Most irAEs were grades 1 and 2 (27.6% and 49.4%, respectively), while grades 3 and 4 accounted for 17.2% and 5.8%, respectively. No grade 5 irAE occurred. Compared with patients with no irAEs, those with irAEs had improved OS (HR [hazard ratio], 0.41; 95% CI [confidence interval], 0.282-0.597; p < 0.0001) and PFS (HR, 0.311; 95% CI: 0.213-0.453; p < 0.0001). Improved OS was seen with irAE grades 1 and 2 versus grades 3 and 4 (HR, 0.344; 95% CI: 0.171-0.694; p = 0.0029). Similarly, improved PFS was seen with lower grade irAE (HR, 0.489; 95% CI: 0.247-0.965; p = 0.0391).

DISCUSSION

The irAE prevalence in older patients was similar to that in younger patients. To our knowledge, this is one of few studies that confirms a positive association of irAE on both OS and PFS in older patients with cancer, and improved OS and PFS with lower versus higher grade irAE.