3539 Background: dMMR/MSI-H metastatic colorectal cancer (mCRC) is more common among the elderly. However, insufficient data about their treatment with immune checkpoint inhibitors (ICIs) are available from interventional and observational trials. Methods: ELDER CRC is an observational, multicenter Italian trial enrolling elderly (≥70 years yrs) patients (pts) treated with first-line ICI(s) for dMMR/MSI-H mCRC in the real world. Results from the retrospective cohort are presented. Results: 132 pts aged 77 yrs as median (IQR 74-82, range 70-93; 14 was related with better PFS (HR=0.79, p =0.06) and OS (HR=0.89, p =0.09). At multivariable model only neutrophils/lymphocytes ratio ≥3 was significantly associated with worse PFS (HR=1.91, p =0.03), while no variables with OS. Conclusions: Our results confirm the benefit of first-line immunotherapy for dMMR/MSI-H mCRC even among elderly pts treated in the real world, despite the substantial rate of right-sided and/or BRAF mut CRC pts and regardless of age group. The manageable safety profile of ICI(s) was also confirmed. G8 might be predictive of outcome but needs implementation in daily practice.
Cassaniti et al. (Wed,) studied this question.