Neoadjuvant Chemotherapy of Ovarian Cancer Results in Three Patterns of Tumor-Infiltrating Lymphocyte Response with Distinct Implications for Immunotherapy

Purpose: Some forms of chemotherapy can enhance antitumor immunity through immunogenic cell death, resulting in increased T-cell activation and tumor infiltration. Such effects could potentially sensitize tumors to immunotherapies, including checkpoint blockade. We investigated whether platinum-and taxane-based chemotherapy for ovarian cancer induces immunologic changes consistent with this possibility. Experimental Design: Matched pre- and post-neoadjuvant chemotherapy tumor samples from 26 high-grade serous carcinoma (HGSC) patients were analyzed by immunohistochemistry (IHC) for a large panel of immune cells and associated factors. The prognostic significance of post-chemotherapy TIL patterns was assessed in an expanded cohort (n = 90). Results: Neoadjuvant chemotherapy was associated with increased densities of CD3(+), CD8(+), CD8(+) TIA-1(+), PD-1(+) and CD20(+) TIL. Other immune subsets and factors were unchanged, including CD79a(+) CD138(+) plasma cells, CD68(+) macrophages, and MHC class I on tumor cells. Immunosuppressive cell types were also unchanged, including FoxP3(+) PD-1(+) cells (putative regulatory T cells), IDO-1(+) cells, and PD-L1(+) cells (both macrophages and tumor cells). Hierarchical clustering revealed three response patterns: (i) TILhigh tumors showed increases in multiple immune markers after chemotherapy; (ii) TILlow tumors underwent similar increases, achieving patterns indistinguishable from the first group; and (iii) TILnegative cases generally remained negative. Despite the dramatic increases seen in the first two patterns, post-chemotherapy TIL showed limited prognostic significance. Conclusions: Chemotherapy augments pre-existing TIL responses but fails to relieve major immune-suppressive mechanisms or confer significant prognostic benefit. Our findings provide rationale for multipronged approaches to immunotherapy tailored to the baseline features of the tumor microenvironment. (C)2016 AACR.