Thyroid dysfunction and immune checkpoint inhibitors: Effect on survival in elderly patients

e24020 Background: Aging inevitably leads to an accumulation of senescent cells, and immune system cells aren't an exception. They can contribute to a pro-inflammatory state and be involved in the immune escape of cancer cells through a boosted PD-L1 expression. Immunocheckpoint inhibitors (ICIs) represent the standard of care in several cancer histotypes, and immune-related adverse events (irAEs) seem to be associated with better outcomes. ICIs represent a valid therapeutic agent in elderly patients too. However, there is a lack of data on irAEs and outcomes correlation in this subgroup of patients. This retrospective-prospective study aims to evaluate the relationship between thyroid dysfunction and progression-free survival (PFS) and overall survival (OS) in elderly patients undergoing ICIs. Methods: From January 2019 to January 2023, we retrospectively collected data from 65 elderly patients under treatment with ICIs at the Medical Oncology Unit of the University Hospital and University of Cagliari, Italy. All patients were affected by stage IV disease. The primary endpoint was PFS and the secondary endpoint was overall survival OS. Statistical analyses were performed using the MedCalc Statistical Software Version 20.216. Results: The median age was 76 (± 5,5); 15.38% were female, whereas 84.62% were male. The histologies were: melanoma (26.9%), lung cancer (48.0%), kidney cancer (15.3%), and colorectal cancer (9.8%). Compared to those without thyroid dysfunction during immunotherapy treatment, individuals with thyroid irAE had, at univariate analysis, longer median PFS (68 versus 26 months, p = 0.02, CI 95% 18.0-68.0, HR 0.29 0.10-0.83) and longer median OS (59 versus 39 months, p = 0.04, CI 95% 25.0-90.0 HR 0.50 0.25-0.99). Conclusions: In an era where biomarkers for immunotherapeutic agents are lacking, thyroid dysfunction irAE could be a predictive factor of better PFS and OS in elderly patients affected by cancer of various histology.