Ovarian cancer immunogenicity is governed by a narrow subset of progenitor tissue-resident memory T-cells

Despite repeated associations between T-cell infiltration and patient outcome, human ovarian cancer remains poorly responsive to immunotherapy. We report that hallmarks of tumor recognition in ovarian cancer-infiltrating T-cells are primarily restricted to tissue-resident memory (TRM) cells. In mouse models we found that TRM T-cells were better than the re-circulating counterpart at controlling tumor growth. Single-cell RNA/TCR/ATAC sequencing of 83,454 CD3+CD8+CD103+CD69+ TRM cells and 24,175 CD3+CD8+CD103− re-circulating TILs showed that progenitor (TCF1low) tissue-resident memory T-cells (TRMstem cells) arise from transitional recirculating T-cells, which depends on antigen affinity/persistence, resulting in oligoclonal, trogocytic, effector lymphocytes. This effector population develops into proliferative lymphocytes that eventually become exhausted TRMs. Immunohistochemistry of 122 high-grade serous ovarian cancer tissues showed that only TRMstem cells, but not re-circulating TCF1+ T-cells, predict ovarian cancer outcome. Therefore, ovarian cancer is indeed an immunogenic disease that depends on ~13% of CD8+ tumor-infiltrating T-cells (~3% of CD8+ clonotypes), which are primed against high-affinity antigens and maintain waves of effector TRM cells.

Support for Shared Resources was provided by Cancer Center Support Grant (CCSG) CA076292 to H. Lee Moffitt Cancer Center and by CCSG CA010815 to The Wistar Institute. This study was supported by grants from NIH (R01CA157664, R01CA124515, R01CA178687, R01CA211913 and U01CA232758 to JRCG; R01CA184185 and RO1CA262121 to PCR.)

TGF-β-mediated silencing of genomic organizer SATB1 promotes Tfh cell differentiation and formation of intra-tumoral tertiary lymphoid structures

The immune checkpoint receptor PD-1 on T follicular helper (Tfh) cells promotes Tfh:B cell interactions and appropriate positioning within tissues. Here, we examined the impact of regulation of PD-1 expression by the genomic organizer SATB1 on Tfh cell differentiation. Vaccination of CD4^CreSatb1^f/f mice enriched for antigen-specific Tfh cells, and TGF-β-mediated repression of SATB1 enhanced Tfh differentiation of human T cells. Mechanistically, high Icos expression in Satb1^-/- CD4⁺ T cells promoted Tfh cell differentiation by preventing T follicular regulatory cell skewing and resulted in increased isotype-switched B cell responses in vivo. Ovarian tumors in CD4^CreSatb1^f/f mice accumulated tumor antigen-specific, LIGHT⁺CXCL13⁺IL-21⁺ Tfh cells and tertiary lymphoid structures (TLS). TLS formation decreased tumor growth in a CD4⁺ T cell and CXCL13-dependent manner. The transfer of Tfh cells, but not naive CD4⁺ T cells, induced TLS at tumor beds and decreased tumor growth. Thus, TGF-β-mediated silencing of Satb1 licenses Tfh cell differentiation, providing insight into the genesis of TLS within tumors.

Expansion of tumor infiltrating lymphocytes (TIL) from bladder cancer

Advanced bladder cancer patients have limited therapeutic options resulting in a median overall survival (OS) between 12 and 15 months. Adoptive cell therapy (ACT) using tumor infiltrating lymphocytes (TIL) has been used successfully in treating patients with metastatic melanoma, resulting in a median OS of 52 months. In this study, we investigated the feasibility of expanding TIL from the tumors of bladder cancer patients. Primary bladder tumors and lymph node (LN) metastases were collected. Tumor specimens were minced into fragments, placed in individual wells of a 24-well plate, and propagated in high dose IL-2 for four weeks. Expanded TIL were phenotyped by flow cytometry and anti-tumor reactivity was assessed after co-culture with autologous tumor digest and IFN-gamma ELISA. Of the 28 transitional cell bladder or LN tumors collected, 14/20 (70%) primary tumors and all of the LN metastases demonstrated TIL expansion. Expanded TIL were predominantly CD3⁺ (median 63%, range 10-87%) with a median of 30% CD8 + T cells (range 5-70%). TIL secreted IFN-gamma in response to autologous tumor. Addition of agonisitic 4-1BB antibody improved TIL expansion from primary bladder tumors regardless of pre-treatment with chemotherapy. This study establishes the practical first step towards an autologous TIL therapy process for therapeutic testing in patients with bladder cancer.

Abstract 1622: The role of the CCL-2 on lymphopenia-induced myeloid derived suppressor cells

The induction of lymphopenia prompts the expansion of CD11b+Ly6ChiLy6G- monocytic MDSCs (M-MDSCs) and CD11b+Ly6C+Ly6G+ polymorphonuclear MDSCs (PMN-MDSCs). Patients receiving adoptive cell therapy (ACT) require nonmyeloablative chemotherapy to induce lymphopenia and support anti-tumor immunity. However, the role of MDSCs in the setting of ACT is not fully understood. As high levels of CCL-2 can be measured in lymphopenic mice, in this study we investigate the role of CCL-2 in the expansion and function of lymphopenia-induced MDSCs using CCR2KO mouse models. Lymphopenia was induced in melanoma-bearing C57BL/6 (WT) and CCR2KO mice by 600rad of total body irradiation or combination therapy with cyclophosphamide and fludarabine. We first evaluated the percentages of splenic MDSCs in WT and CCR2KO mice after the induction of lymphopenia. At day 14, the expansion of total MDSCs were similar in WT (279% of normal) and CCR2KO (241% of normal). However, the mean percentages of M-MDSCs (3.5%) and PMN-MDSCs (30.3%) in CCR2KO mice were altered compared to M-MDSCs (22.2%) and PMN-MDSCs (21.7%) in WT mice. In addition, M-MDSCs in B16 tumors grown in CCR2KO mice were decreased compared to intratumoral M-MDSCs in WT mice (p<0.001). In contrast, the percentages of M-MDSCs and PMN-MDSCs were unchanged in the bone marrow (BM). To investigate the suppressive capacity of lymphopenia-induced MDSCs, OVA antigen-specific CD8+ T cells were co-cultured with OVA peptide in the presence of MDSCs purified from the spleens of CCR2KO and WT mice. Both CCR2KO and WT MDSCs potently suppressed T cell proliferation as measured by 3H thymidine incorporation. CCR2KO and WT MDSCs had significant arginase activity and production of nitrites. To investigate the efficacy of ACT, B16 tumor-bearing CCR2KO and WT mice were lymphodepleted and gp100 antigen-specific Thy1.2+CD8+ T cells were adoptively transferred followed by 3 days of IL-2 treatment. We found that donor T cell tumor infiltration was similar and no difference in tumor growth was observed between CCR2KO and WT mice. Collectively, these results suggest that the role of CCL-2 is important for the egress of lymphopenia-induced M-MDSCs from the BM, but has no effect on the expansion or function of PMN-MDSCs in the setting of lymphopenia. These data suggest that factors besides CCL-2 play an important role in the expansion and function of MDSCs after the induction of lymphopenia.

Citation Format: Pasquale P. Innamarato, Amy Weber, Shari Pilon-Thomas. The role of the CCL-2 on lymphopenia-induced myeloid derived suppressor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1622. doi:10.1158/1538-7445.AM2017-1622