Predictive and dynamic signature for anti-angiogenics in combination with PD-1 inhibitor in soft-tissue sarcoma: correlative studies linked to the IMMUNOSARC trial

Purpose: IMMUNOSARC trial combined an anti-angiogenic agent (sunitinib) with a PD-1 inhibitor (nivolumab) in advanced sarcomas. Here we present the first correlative studies of the STS cohort enrolled in this trial. Experimental design: Formalin-fixed paraffin-embedded (FFPE) and peripheral blood samples were collected at baseline and week 13. FFPE were used for transcriptomics and multiplex immunofluorescence, while peripheral blood samples were used for multiplexed immunoassays. Flow cytometry and Luminex assays were performed to validate translational findings in tumor-isolated cells and peripheral blood mononuclear cells derived from patients. Results: The density of intratumoral CD8+ T cells, measured by multiplexed immuno-phenotyping, was significantly increased after treatment. This augment was accompanied by the dynamic significant increase in gene expression of CD86, CHI3L1, CXCL10, CXCL9, LAG3, and VCAM1, and the decrease in the expression levels of NR4A1. In peripheral blood, 12 proteins were significantly modulated by treatment at W13. A score integrating the dynamic expression of the 7 genes and the 12 soluble factors separated two groups with distinct progression-free survival (PFS): 4.1 months (95% CI 3.5-NR) vs 17 months (95% CI 12.0 - NR), p=0.014. This molecular score was predictive of PFS when applied to the normalized data determined in the baseline samples. Conclusions: Treatment with sunitinib and nivolumab inflamed the sarcoma microenvironment, increasing CD8+ T cell density and the expression of several genes/ proteins with relevance in the response to PD-1 inhibitors. A molecular signature identified two groups of patients with distinct PFS for the combination of anti-angiogenics plus PD-1 inhibitor.