Inflammation and cell proliferation signatures: Implications for response to immune checkpoint inhibition therapies.

Abstract

67 Background: Progress in unraveling the complex tumor immune microenvironment (TIME) has aided our understanding of the host immune response to ICI therapies. To gain further insight, we associate a 160-gene tumor inflammation signature (TIS) with cell proliferation status and response to ICI. Methods: 242 FFPE tumor samples from lung, RCC and melanoma were evaluated by RNA-seq to measure expression levels of 394 immune related genes. TIS (weak, moderate, strong) and cell proliferation status (poor, moderate, high) were determined by algorithmic analysis of selected gene pathways. All cases were evaluated for association with ORR to ICIs using RECIST criterion. Furthermore, 13 pre-post ICI treated biopsy pairs were studied to understand the dynamics of these signatures following treatment. Results: In both weakly and moderately inflamed tumors, ORR was highest in moderately proliferative tumors 32.6% (15/46) and 37.8% (14/37), respectively (Table). Surprisingly, in strongly inflamed tumors, both highly and moderately proliferative tumors had a high response rate of 55% (11/20) and 43.2% (16/37), whereas poorly proliferative tumors have a significantly lower response rate of 12.5% (3/24; p= 0.03). 6 of 13 pre-post ICI treated cases demonstrated increased inflammation post treatment, with 83% (5/6) demonstrating concurrent decrease in cell proliferation. Conclusions: Together, TIS and cell proliferation predict response to ICI in NSCLC, RCC and melanoma. The data suggests that in strongly inflamed and highly proliferative tumors, the cell proliferation signal could be attributed to antigen stimulated T-cell proliferation, whereas in other categories of inflammation, moderately proliferative tumors contain signal from both immune cells and tumor cells. Further studies are required to determine the relationship between these signatures in hot and cold tumors. [Table: see text]