Role of immunohistochemical prognostic factors in various types of immunotherapy for metastatic melanoma: A retro-prospective study

Background. Anti-PD-1 immunotherapy (IT) is the standard of care for patients with metastatic melanoma. However, in the real world, IT is effective only in a fraction of patients. The lack of valid prognostic factors for various immunotherapy agents warrants a comprehensive and advanced study of this topic.

Aim. To improve the outcomes of the first-line therapy for disseminated melanoma based on identifying immunohistochemical predictors of IT efficacy.

Materials and methods. Data from 130 patients who were treated with immune checkpoint inhibitors nivolumab or prolgolimab in the first-line therapy for disseminated melanoma between 2017 and 2024 were analyzed.

Results. The expression of PD-L1>10 on tumor cells was found to be a predictor of effective therapy: in the nivolumab group, the 2-year disease-free survival (DFS) with PD-L1 level >10% was high at 79% (95% confidence interval – CI 61–100); the 1-year DFS was 89% (95% CI 78–100) compared to 17% (95% CI 3.2–88) with a lower level of PD-L1 expression (p<0.0001). In the prolgolimab group, the 2-year DFS with PD-L1>10% was also high at 78% (p<0.0001; CI 54–100), the 1-year DFS was 94% (95% CI 84–100) compared to 35% (95% CI 17–73) with a lower level of PD-L1 expression (p<0.0001). A less severe course of the disease was observed in patients with both peritumoral and intratumoral locations versus those with only peritumoral locations of the immune infiltrate. The study of the presence and form of lymphoid infiltration of the tumor showed the following direct relationship: in the nivolumab group, the 2-year DFS was 94% (95% CI 83–100) compared to 8.3% (95% CI 1.3–54), in the prolgolimab group, the 1-year DFS was 82% (95% CI 68–100) compared to 15% (95% CI 2.6–86); p<0.0001. It was found that the predominance of CD8+ over CD4+ is associated with better results of IT: in the nivolumab group, the 2-year DFS was 87% (95% CI 74–100) compared to 19% (95% CI 4–91) in the absence of CD8+ predominance over CD4+; in the prolgolimab group, the 2-year DFS was 73% (95% CI 51–100) in patients with CD8+ predominance over CD4+ (p=0.0001). In patients without CD8 predominance over CD4, 2-year DFS was not achieved. The one-year DFS was 85% (95% CI 70–100) and 25% (95% CI 8.4–76), respectively; p=0.0001.

Conclusion. The results of the study suggest that immunohistochemical characteristics such as a PD-L1 expression level >10%, the simultaneous presence of peri- and intratumoral lymphoid infiltration of the tumor, the ratio of the intensity of lymphoid infiltration with tumor-infiltrating lymphocytes (TILs), and the predominance of CD8+ over CD4+ can be considered predictors of IT efficacy with nivolumab and prolgolimab.