Anti-metabolite chemotherapy increases LAG-3 expressing tumor-infiltrating lymphocytes which can be targeted by combination immune checkpoint blockade.

Antibodies that target immune checkpoints such as cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death protein/ligand 1 (PD-1/PD-L1) are approved for treatment of multiple cancer types. Chemotherapy is often administered with immune checkpoint blockade (ICB) therapies that target CTLA-4 and/or PD-(L)1. ICB targeting other immune checkpoints such as lymphocyte activating gene-3 (LAG-3) has the potential to improve antitumor responses when combined with chemotherapy. Response to anti-PD-1 ICB is dependent on progenitor exhausted CD8+ T cells (TPEX) in the tumor, but it is unclear how chemotherapy alters TPEX proportions and phenotype. Here we investigated whether sequential chemotherapy altered TPEX frequency and immune checkpoint expression in multiple murine tumor models. Two doses of two different anti-metabolite chemotherapies increased tumor infiltrating CD4+, and CD8+ TPEX expressing LAG-3 in multiple mouse models, which was not restricted to tumor antigen specific CD8+ T cells. To determine if LAG-3+tumor infiltrating lymphocytes (TILs) could be targeted to improve tumor control, we administered anti-LAG-3 and anti-PD-1 ICB after two doses of chemotherapy and found combination therapy generated robust antitumor responses compared with each agent alone. Both anti-LAG-3 and anti-PD-1 ICB with chemotherapy were required for the complete tumor regression observed. Changes in immune checkpoint expression on TILs during chemotherapy administration informs selection of ICB therapies to combine with.

Principe N ，Phung AL ，Stevens KLP ，Elaskalani O ，Wylie B ，Tilsed CM ，Sheikh F ，Orozco Morales ML ，Kidman J ，Marcq E ，Fisher SA ，Nowak AK ，McDonnell AM ，Lesterhuis WJ ，Chee J ... -  《Journal for ImmunoTherapy of Cancer》

CDK4/6 inhibition promotes immune infiltration in ovarian cancer and synergizes with PD-1 blockade in a B cell-dependent manner.

Great progress has been made in the field of tumor immunotherapy in the past decade. However, the therapeutic effects of immune checkpoint blockade (ICB) against ovarian cancer are still limited. Recently, an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6i) has been reported to enhance antitumor immunity in preclinical models. The combined use of CDK4/6i and ICB may be beneficial, but the effects of CDK4/6is on the tumor immune microenvironment and whether they can synergize with ICB in treating ovarian cancer remain unknown. Methods: In this study, we first assessed the antitumor efficacy of abemaciclib, an FDA-approved CDK4/6i, in a syngeneic murine ovarian cancer model. Then, immunohistochemistry, immunofluorescence and flow cytometry were performed to evaluate the number, proportion, and activity of tumor-infiltrating lymphocytes. Cytokine and chemokine production was detected both in vivo and in vitro by PCR array analysis and cytokine antibody arrays. The treatment efficacy of combined abemaciclib and anti-PD-1 therapy was evaluated in vivo, and CD8+ and CD4+ T cell activities were analyzed using flow cytometry. Lastly, the requirement for both CD8+ T cells and B cells in combination treatment was evaluated in vivo, and potential cellular mechanisms were further analyzed by flow cytometry. Results: We observed that abemaciclib monotherapy could enhance immune infiltration, especially CD8+ T cell and B cell infiltration, in the ID8 murine ovarian cancer model. Immunophenotyping analysis showed that abemaciclib induced a proinflammatory immune response in the tumor microenvironment. PCR array analysis suggested the presence of a Th1-polarized cytokine profile in abemaciclib-treated ID8 tumors. In vitro studies showed that abemaciclib-treated ID8 cells secreted more CXCL10 and CXCL13, thus recruiting more lymphocytes than control groups. Combination treatment achieved better tumor control than monotherapy, and the activities of CD8+ and CD4+ T cells were further enhanced when compared with monotherapy. The synergistic antitumor effects of combined abemaciclib and anti-PD-1 therapy depended on both CD8+ T cells and B cells. Conclusion: These findings suggest that combined treatment with CDK4/6i and anti-PD-1 antibody could improve the efficacy of anti-PD-1 therapy and hold great promise for the treatment of poorly immune-infiltrated ovarian cancer.

Zhang QF ，Li J ，Jiang K ，Wang R ，Ge JL ，Yang H ，Liu SJ ，Jia LT ，Wang L ，Chen BL ... -  《Theranostics》

TOX-expressing terminally exhausted tumor-infiltrating CD8(+) T cells are reinvigorated by co-blockade of PD-1 and TIGIT in bladder cancer.

Exhausted T cells in the tumor microenvironment are major targets of immunotherapies. However, the exhaustion status of CD8+ tumor-infiltrating lymphocytes (TILs) in bladder cancer has not been comprehensively evaluated. Herein, we examined distinct exhaustion status of CD8+ TILs based on the level of programmed cell death-1 (PD-1) and thymocyte selection-associated high mobility group box protein (TOX) expression in urothelial bladder cancer. We also evaluated the reinvigoration of exhausted CD8+ TILs upon ex vivo treatment with inhibitory checkpoint blockers. TOX-expressing PD-1highCD8+ TILs had the highest expression of immune checkpoint receptors (ICRs), the most terminally exhausted features, and the highest tumor antigen reactivity among PD-1+CD8+ TILs. Bladder cancer patients with a high percentage of PD-1highTOX+CD8+ TILs had more progressed T-cell exhaustion features and higher programmed death-ligand 1 expression in tumor tissues. TIGIT was the most frequent co-expressed ICR on PD-1+CD8+ TILs, and TIGIT blockade enhanced the PD-1 blockade-mediated cytokine production by CD8+ TILs from bladder cancer patients. Our findings provide an improved understanding of the heterogeneous exhaustion status of CD8+ TILs and additional immunotherapy strategies to improve outcomes of bladder cancer patients.

Han HS ，Jeong S ，Kim H ，Kim HD ，Kim AR ，Kwon M ，Park SH ，Woo CG ，Kim HK ，Lee KH ，Seo SP ，Kang HW ，Kim WT ，Kim WJ ，Yun SJ ，Shin EC ... -  《-》

Squamous cell carcinomas escape immune surveillance via inducing chronic activation and exhaustion of CD8+ T Cells co-expressing PD-1 and LAG-3 inhibitory receptors.

Mishra AK ，Kadoishi T ，Wang X ，Driver E ，Chen Z ，Wang XJ ，Wang JH ... -  《Oncotarget》

Antibodies Against Immune Checkpoint Molecules Restore Functions of Tumor-Infiltrating T Cells in Hepatocellular Carcinomas.

Ligand binding to inhibitory receptors on immune cells, such as programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte associated protein 4 (CTLA4), down-regulates the T-cell-mediated immune response (called immune checkpoints). Antibodies that block these receptors increase antitumor immunity in patients with melanoma, non-small-cell lung cancer, and renal cell cancer. Tumor-infiltrating CD4+ and CD8+ T cells in patients with hepatocellular carcinoma (HCC) have been found to be functionally compromised. We analyzed HCC samples from patients to determine if these inhibitory pathways prevent T-cell responses in HCCs and to find ways to restore their antitumor functions. We collected HCC samples from 59 patients who underwent surgical resection from November 2013 through May 2017, along with tumor-free liver tissues (control tissues) and peripheral blood samples. We isolated tumor-infiltrating lymphocytes (TIL) and intra-hepatic lymphocytes. We used flow cytometry to quantify expression of the inhibitory receptors PD-1, hepatitis A virus cellular receptor 2 (TIM3), lymphocyte activating 3 (LAG3), and CTLA4 on CD8+ and CD4+ T cells from tumor, control tissue, and blood; we studied the effects of antibodies that block these pathways in T-cell activation assays. Expression of PD-1, TIM3, LAG3, and CTLA4 was significantly higher on CD8+ and CD4+ T cells isolated from HCC tissue than control tissue or blood. Dendritic cells, monocytes, and B cells in HCC tumors expressed ligands for these receptors. Expression of PD-1, TIM3, and LAG3 was higher on tumor-associated antigen (TAA)-specific CD8+ TIL, compared with other CD8+ TIL. Compared with TIL that did not express these inhibitory receptors, CD8+ and CD4+ TIL that did express these receptors had higher levels of markers of activation, but similar or decreased levels of granzyme B and effector cytokines. Antibodies against CD274 (PD-ligand1 [PD-L1]), TIM3, or LAG3 increased proliferation of CD8+ and CD4+ TIL and cytokine production in response to stimulation with polyclonal antigens or TAA. Importantly, combining antibody against PD-L1 with antibodies against TIM3, LAG3, or CTLA4 further increased TIL functions. The immune checkpoint inhibitory molecules PD-1, TIM3, and LAG3 are up-regulated on TAA-specific T cells isolated from human HCC tissues, compared with T cells from tumor-free liver tissues or blood. Antibodies against PD-L1, TIM3, or LAG3 restore responses of HCC-derived T cells to tumor antigens, and combinations of the antibodies have additive effects. Strategies to block PD-L1, TIM3, and LAG3 might be developed for treatment of primary liver cancer.

Zhou G ，Sprengers D ，Boor PPC ，Doukas M ，Schutz H ，Mancham S ，Pedroza-Gonzalez A ，Polak WG ，de Jonge J ，Gaspersz M ，Dong H ，Thielemans K ，Pan Q ，IJzermans JNM ，Bruno MJ ，Kwekkeboom J ... -  《-》