Digital Immunophenotyping Predicts Disease Free and Overall Survival in Early Stage Melanoma Patients.

Background: the prognostic significance of tumor infiltrating lymphocytes (TILs) in intermediate/thick primary cutaneous melanoma (PCM) remains controversial, partially because conventional evaluation is not reliable, due to inter-observer variability and diverse scoring methods. We aimed to assess the prognostic impact of the density and spatial distribution of immune cells in early stage intermediate/thick PCM.

Materials And Methods: digital image acquisition and quantitative analysis of tissue immune biomarkers (CD3, CD4, CD8, CD68, PD-L1, CD163, FOX-P3, and PD-1) was carried out in a training cohort, which included patients with primary PCM ≥ 2 mm diagnosed, treated, and followed-up prospectively in three Italian centers. Results were validated in an independent Italian cohort.

Results: in the training cohort, 100 Stage II-III melanoma patients were valuable. At multivariable analysis, a longer disease free survival (DFS) was statistically associated with higher levels of CD4 intratumoral T-cells (aHR [100 cell/mm increase] 0.98, 95%CI 0.95-1.00, = 0.041) and CD163 inner peritumoral (aHR [high vs. low] 0.56, 95%CI 0.32-0.99, = 0.047). A statistically significant longer DFS (aHR [high-high vs. low-low] 0.52, 95%CI 0.28-0.99, = 0.047) and overall survival (OS) (aHR [high-high vs. low-low] 0.39, 95%CI 0.18-0.85, = 0.018) was found in patients with a high density of both intratumoral CD8 T-cells and CD68 macrophages as compared to those with low density of both intratumoral CD8 T-cells and CD68 macrophages. Consistently, in the validation cohort, patients with high density of both intratumoral CD8 and CD3 T-cells were associated to a statistically better DFS (aHR[high-high vs. low-low] 0.24, 95%CI 0.10-0.56, < 0.001) and those with high density of both intratumoral CD8 and CD68 were associated to a statistically longer OS (aHR[high-high vs. low-low] 0.28, 95%CI 0.09-0.86, = 0.025).

Conclusion: our findings suggest that a specific preexisting profile of T cells and macrophages distribution in melanomas may predict the risk of recurrence and death with potential implications for the stratification of stage II-III melanoma patients.