Abstract
<title>Abstract</title> <p> <bold>Backgrounds:</bold> The incidence of solid tumors in patients over 85 years will triple proportionally to the growth of this elderly population by 2050. Immune checkpoint inhibitors (ICI) have become a new standard of care for all cancer types in monotherapy or combine to other antineoplastic drugs. However, even geriatric studies predominantly include patients under 85 years, resulting in a lack of clinical data for this population. This results in limited evidence regarding safety and efficacy in this age group. Accordingly, this study aimed to evaluate the safety of ICI monotherapy in a real-world population aged 85 years and older <bold>Methods:</bold> We conducted a multicenter, retrospective study including patients who initiated ICI monotherapy after 85 years for a locally advanced or metastatic solid cancer between 2015 and 2023. The primary endpoint was safety, assessed through the incidence, type, and severity of immune-related adverse events (irAEs). Secondary endpoints were overall survival (OS), overall response rate (ORR), and the identification of prognostic factors. <bold>Results:</bold> A total of 114 patients were included (median age 88 years [85-101]); Primary tumor types were melanomas (40%), non-small-cell lung (NSCLC) cancers (27%), and other solid tumors (33%). IrAEs occurred 45 times in 35 patients (30%) — predominantly endocrine, hepatic, or cutaneous. Thirteen irAEs were grade 3; none were grade ≥4. ORR was 31% with substantial differences across tumor types (melanoma 17.8 months; NSCLC 3.3 months). In multivariate analysis, NSCLC and polypharmacy were associated with poorer OS. <bold>Conclusion:</bold> Considering all inherent limitations of retrospective analysis, ICIs monotherapy demonstrated an acceptable safety profile in patients over 85 years, without a signal for increased severe toxicity. These findings suggest that chronological age alone should not preclude ICI use in carefully selected oldest-old patients. Prospective studies focused on the oldest-old population are required to confirm these observations and refine patient selection. <bold>Funding:</bold> None </p>