Survival outcomes following immune checkpoint inhibitor therapy of advanced cutaneous melanoma by age and tumor infiltrating lymphocytes in the primary cutaneous site.

Abstract

e21514 Background: Tumor infiltrating lymphocytes (TILs) in the tumor microenvironment generate anti-tumor immunity and are associated with response to immune checkpoint inhibitor (ICI) therapy of melanoma. However, likelihood of response to ICI therapy depends upon intensity of TILs, proportion of effector and regulatory T cells and age. Methods: In a research study approved by the Institutional Review Board of University of Connecticut, we retrospectively analyzed outcome of patients diagnosed with cutaneous melanoma between 2009 and 2019 and developed unresectable stage III or stage IV disease requiring ICI treatment. Patients were stratified by age (< 75 and > 75 years old) and TILs at the primary cutaneous melanoma site categorized as brisk (present throughout vertical phase), non-brisk (present in one of more foci of vertical phase) or absent. Patient’s age at the time of metastases, as well as 12-month and 24-month overall survival (OS) following ICI treatment was recorded. Results: A total of 93 patients were screened, and 68 were included for analysis of survival outcome. Patients had to receive at least one dose of ICI treatment at UConn Health and had available data on TILs of primary cutaneous melanoma. In patients over 75 years of age, those with brisk TILs had an increased 24-month survival compared to those with non-brisk or absent TILs (100% vs. 45%, p = 0.04). In patients < 75 years of age, the 24 month survival was similar in those with brisk and non-brisk or absent TILs (67% vs. 69%, p = .91). There was no significant difference in overall survival between patients < 75 or > 75 years with brisk TILs (67% vs. 100%, p = .19). Additionally, in patients with non-brisk or absent TILs, there was a not quite significant difference in survival between those > 75 vs < 75 years (45% vs. 69%, p = .09). Conclusions: Our findings suggest that intensity of TILs in primary cutaneous melanoma is predictive of outcome following ICI treatment of advanced melanoma in patients over 75 years of age. These findings support possible interaction between qualitative differences of TILs and patient age. Our findings may help identify older melanoma patients who may benefit from ICI treatment.