Connecting the Dots: Therapy-Induced Senescence and a Tumor-Suppressive Immune Microenvironment.

Tumor cell senescence is a common outcome of anticancer therapy. Here we investigated how therapy-induced senescence (TIS) affects tumor-infiltrating leukocytes (TILs) and the efficacy of immunotherapy in melanoma. Tumor senescence was induced by AURKA or CDK4/6 inhibitors (AURKAi, CDK4/6i). Transcriptomes of six mouse tumors with differential response to AURKAi were analyzed by RNA sequencing, and TILs were characterized by flow cytometry. Chemokine RNA and protein expression were determined by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Therapeutic response was queried in immunodeficient mice, in mice with CCL5-deficient tumors, and in mice cotreated with CD137 agonist to activate TILs. CCL5 expression in reference to TIS and markers of TILs was studied in human melanoma tumors using patient-derived xenografts (n = 3 patients, n = 3 mice each), in AURKAi clinical trial samples (n = 3 patients, before/after therapy), and in The Cancer Genome Atlas (n = 278). All statistical tests were two-sided. AURKAi response was associated with induction of the immune transcriptome (P = 3.5 x 10-29) while resistance inversely correlated with TIL numbers (Spearman r = -0.87, P < .001). AURKAi and CDK4/6i promoted the recruitment of TILs by inducing CCL5 secretion in melanoma cells (P ≤ .005) in an NF-κB-dependent manner. Therapeutic response to AURKAi was impaired in immunodeficient compared with immunocompetent mice (0% vs 67% tumors regressed, P = .01) and in mice bearing CCL5-deficient vs control tumors (P = .61 vs P = .02); however, AURKAi response was greatly enhanced in mice also receiving T-cell-activating immunotherapy (P < .001). In human tumors, CCL5 expression was also induced by AURKAi (P ≤ .02) and CDK4/6i (P = .01) and was associated with increased immune marker expression (P = 1.40 x 10-93). Senescent melanoma cells secret CCL5, which promotes recruitment of TILs. Combining TIS with immunotherapy that enhances tumor cell killing by TILs is a promising novel approach to improve melanoma outcomes.

Vilgelm AE ，Johnson CA ，Prasad N ，Yang J ，Chen SC ，Ayers GD ，Pawlikowski JS ，Raman D ，Sosman JA ，Kelley M ，Ecsedy JA ，Shyr Y ，Levy SE ，Richmond A ... -  《-》

Aurora kinase inhibition sensitizes melanoma cells to T-cell-mediated cytotoxicity.

Punt S ，Malu S ，McKenzie JA ，Manrique SZ ，Doorduijn EM ，Mbofung RM ，Williams L ，Silverman DA ，Ashkin EL ，Dominguez AL ，Wang Z ，Chen JQ ，Maiti SN ，Tieu TN ，Liu C ，Xu C ，Forget MA ，Haymaker C ，Khalili JS ，Satani N ，Muller F ，Cooper LJN ，Overwijk WW ，Amaria RN ，Bernatchez C ，Heffernan TP ，Peng W ，Roszik J ，Hwu P ... -  《-》

Association of Germline Variants in Natural Killer Cells With Tumor Immune Microenvironment Subtypes, Tumor-Infiltrating Lymphocytes, Immunotherapy Response, Clinical Outcomes, and Cancer Risk.

Xu X ，Li J ，Zou J ，Feng X ，Zhang C ，Zheng R ，Duanmu W ，Saha-Mandal A ，Ming Z ，Wang E ... -  《JAMA Network Open》

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》

Stromal Senescence By Prolonged CDK4/6 Inhibition Potentiates Tumor Growth.

Senescent cells within the tumor microenvironment (TME) adopt a proinflammatory, senescence-associated secretory phenotype (SASP) that promotes cancer initiation, progression, and therapeutic resistance. Here, exposure to palbociclib (PD-0332991), a CDK4/6 inhibitor, induces senescence and a robust SASP in normal fibroblasts. Senescence caused by prolonged CDK4/6 inhibition is DNA damage-independent and associated with Mdm2 downregulation, whereas the SASP elicited by these cells is largely reliant upon NF-κB activation. Based upon these observations, it was hypothesized that the exposure of nontransformed stromal cells to PD-0332991 would promote tumor growth. Ongoing clinical trials of CDK4/6 inhibitors in melanoma prompted a validation of this hypothesis using a suite of genetically defined melanoma cells (i.e., Ras mutant, Braf mutant, and Ras/Braf wild-type). When cultured in the presence of CDK4/6i-induced senescent fibroblasts, melanoma cell lines exhibited genotype-dependent proliferative responses. However, in vivo, PD-0332991-treated fibroblasts enhanced the growth of all melanoma lines tested and promoted the recruitment of Gr-1-positive immune cells. These data indicate that prolonged CDK4/6 inhibitor treatment causes normal fibroblasts to enter senescence and adopt a robust SASP. Such senescent cells suppress the antitumor immune response and promote melanoma growth in immunocompetent, in vivo models.Implications: The ability of prolonged CDK4/6 inhibitor treatment to induce cellular senescence and a robust SASP in primary cells may hinder therapeutic efficacy and promote long-term, gerontogenic consequences that should be considered in clinical trials aiming to treat melanoma and other cancer types. Mol Cancer Res; 15(3); 237-49. ©2016 AACR.

Guan X ，LaPak KM ，Hennessey RC ，Yu CY ，Shakya R ，Zhang J ，Burd CE ... -  《-》