Dual blockade of PD-1 and CTLA-4 combined with tumor vaccine effectively restores T-cell rejection function in tumors.

Tumor progression is facilitated by regulatory T cells (Treg) and restricted by effector T cells. In this study, we document parallel regulation of CD8(+) T cells and Foxp3(+) Tregs by programmed death-1 (PD-1, PDCD1). In addition, we identify an additional role of CTL antigen-4 (CTLA-4) inhibitory receptor in further promoting dysfunction of CD8(+) T effector cells in tumor models (CT26 colon carcinoma and ID8-VEGF ovarian carcinoma). Two thirds of CD8(+) tumor-infiltrating lymphocytes (TIL) expressed PD-1, whereas one third to half of CD8(+) TIL coexpressed PD-1 and CTLA-4. Double-positive (PD-1(+)CTLA-4(+)) CD8(+) TIL had characteristics of more severe dysfunction than single-positive (PD-1(+) or CTLA-4(+)) TIL, including an inability to proliferate and secrete effector cytokines. Blockade of both PD-1 and CTLA-4 resulted in reversal of CD8(+) TIL dysfunction and led to tumor rejection in two thirds of mice. Double blockade was associated with increased proliferation of antigen-specific effector CD8(+) and CD4(+) T cells, antigen-specific cytokine release, inhibition of suppressive functions of Tregs, and upregulation of key signaling molecules critical for T-cell function. When used in combination with GVAX vaccination (consisting of granulocyte macrophage colony-stimulating factor-expressing irradiated tumor cells), inhibitory pathway blockade induced rejection of CT26 tumors in 100% of mice and ID8-VEGF tumors in 75% of mice. Our study indicates that PD-1 signaling in tumors is required for both suppressing effector T cells and maintaining tumor Tregs, and that PD-1/PD-L1 pathway (CD274) blockade augments tumor inhibition by increasing effector T-cell activity, thereby attenuating Treg suppression.

Duraiswamy J ，Kaluza KM ，Freeman GJ ，Coukos G ... -  《-》

Simultaneous inhibition of two regulatory T-cell subsets enhanced Interleukin-15 efficacy in a prostate tumor model.

Yu P ，Steel JC ，Zhang M ，Morris JC ，Waitz R ，Fasso M ，Allison JP ，Waldmann TA ... -  《-》

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 ... -  《-》

Therapeutic PD-1 pathway blockade augments with other modalities of immunotherapy T-cell function to prevent immune decline in ovarian cancer.

Duraiswamy J ，Freeman GJ ，Coukos G 《-》

CD27 Agonism Plus PD-1 Blockade Recapitulates CD4+ T-cell Help in Therapeutic Anticancer Vaccination.

While showing promise, vaccination strategies to treat cancer require further optimization. Likely barriers to efficacy involve cancer-associated immunosuppression and peripheral tolerance, which limit the generation of effective vaccine-specific cytotoxic T lymphocytes (CTL). Because CD4(+) T cells improve CTL responsiveness, next-generation vaccines include helper epitopes. Here, we demonstrate in mice how CD4(+) T-cell help optimizes the CTL response to a clinically relevant DNA vaccine engineered to combat human papillomavirus-expressing tumors. Inclusion of tumor-unrelated helper epitopes greatly increased CTL priming, effector, and memory T-cell programming. CD4(+) T-cell help optimized the CTL response in all these aspects via CD27/CD70 costimulation. Notably, administration of an agonistic CD27 antibody could largely replace helper epitopes in promoting primary and memory CTL responses, acting directly on CD8(+) T cells. CD27 agonism improved efficacy of the vaccine without helper epitopes, more so than combined PD-1 and CTLA-4 blockade. Combining CD27 agonism with CTLA-4 blockade improved vaccine-induced CTL priming and tumor infiltration, but only combination with PD-1 blockade was effective at eradicating tumors, thereby fully recapitulating the effect of CD4(+) T-cell help on vaccine efficacy. PD-1 blockade alone did not affect CTL priming or tumor infiltration, so these results implied that it cooperated with CD4(+) T-cell help by alleviating immune suppression against CTL in the tumor. Helper epitope inclusion or CD27 agonism did not stimulate regulatory T cells, and vaccine efficacy was also improved by CD27 agonism in the presence of CD4(+) T-cell help. Our findings provide a preclinical rationale to apply CD27 agonist antibodies, either alone or combined with PD-1 blockade, to improve the therapeutic efficacy of cancer vaccines and immunotherapy generally. Cancer Res; 76(10); 2921-31. ©2016 AACR.

Ahrends T ，Bąbała N ，Xiao Y ，Yagita H ，van Eenennaam H ，Borst J ... -  《-》