A prospective cohort study on the safety of checkpoint inhibitors in older cancer patients - the ELDERS study.

Objective: Older cancer patients are underrepresented in the pivotal trials of checkpoint inhibitors (CPIs). This study aimed to investigate the impact of an ageing immune system on CPI-related toxicity and provide evidence for the role of geriatric assessments with CPI.

Methods: The ELDERS study is a prospective observational study with two cohorts: older (70+ years of age) and younger (<70 years of age). Patients with advanced/metastatic non-small-cell lung cancer or melanoma starting single-agent CPI were eligible. The older cohort was assessed for frailty with Geriatric-8 (G8) screening, which when positive (<15 points) was followed by a holistic set of geriatric assessments. Primary endpoint was the incidence of grade 3-5 immune-related adverse events (irAEs).

Results: One hundred and forty patients were enrolled with 43% being pretreated and pembrolizumab represented 92% of treatments on study. The older cohort had a significantly higher comorbidity burden (P < 0.001) and polypharmacy (P = 0.004). While 50% of older patients had a positive G8 screening, 60% on this frail subgroup had a performance status score of 0 or 1. There was no significant difference in the incidence of irAEs grade 3-5 between older and younger cohorts (18.6% versus 12.9%; odds ratio 1.55, confidence interval 95% 0.61-3.89; P = 0.353). Exposure to systemic steroids due to irAEs was numerically longer for older patients (22 versus 8 weeks; P = 0.208). A positive G8 screening predicted hospital admissions (P = 0.031) and risk of death (P = 0.01).

Conclusions: The use of CPI in older patients was not associated with more high-grade toxicity. The G8 screening identified a subgroup with higher risk of AEs and its implementation should be considered in the context of CPI.