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Combined HDAC and BET inhibition to enhance cancer vaccine-elicited T-cell responses. J Clin Oncol 2017. [DOI: 10.1200/jco.2017.35.15_suppl.e14632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
e14632 Background: The combined inhibition of histone deacetylases (HDAC) and the proteins of the bromo and extra terminal (BET) family have recently shown therapeutic efficacy against pancreatic ductal adenocarcinoma, melanoma and lymphoma cancers in murine studies. However, in these studies the role of the immune system in therapeutically controlling these cancers was not explored. Methods: We sought to investigate the effect of the HDAC inhibitor romidepsin (RMD) and the BET inhibitor I-BET151, both singly and in combination, on vaccine elicited immune responses. C57Bl/6 mice were immunized with differing vaccines (Adenoviral, protein) in prime-boost regimens, under treatment with RMD, I-BET151, or RMD+I-BET151. Results: The combination RMD+I-BET151, administered during Adenoviral prime-boost vaccination, resulted in the significant increase in the frequency and number of antigen-specific CD8 T cells. RMD+I-BET151 treatment affected vaccine-elicited secondary T cell responses, significantly increasing the frequency of IFN-γ+ splenic CD8 T cells and maintaining their dual IFN-γ+TNFa+ polyfunctionality. These CD8 T cells maintained their protective ability against Listeria monocytogenes, and protected against B16-OVA challenge. The significant augmentation of vaccine elicited CD8 T cell responses under RMD+I-BET151 treatment was additionally observed following protein (OVA+CpG) prime-boost vaccination, resulting in greater protection against B16-OVA challenge and enhanced survival. T-regulatory cell (FoxP3+CD4+) frequency and total CD4 and CD8 cell numbers remained unaltered following RMD+I-BET151 treatment. Conclusions: Combined HDAC and BET inhibition resulted in greater vaccine-elicited CD8 T cell responses following immunization by multiple vaccine platforms, and enhanced protection against B16-OVA challenges. We are currently assessing immunological mechanisms of action for this combined HDAC and BET inhibition.
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Abstract A52: Eradication of large established tumors with combination immunotherapy engaging innate and adaptive immunity. Cancer Immunol Res 2017. [DOI: 10.1158/2326-6074.tumimm16-a52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Checkpoint blockade against CTLA-4 or PD-1 has demonstrated that an endogenous immune response can be stimulated to elicit durable regressions in advanced cancer, but these dramatic responses are currently confined to a minority of patients. This outcome is probably due in part to the complex network of immunosuppressive pathways present in advanced tumors, which are unlikely to be overcome by intervention at a single signaling checkpoint, requiring a counter-directed network of pro-immunity signals. Here we demonstrate a combination immunotherapy that recruits a diverse set of innate and adaptive immune effectors, enabling robust elimination of tumor burdens that to our knowledge have not previously been curable by treatments relying on endogenous immunity. Maximal anti-tumor efficacy required four components: a tumor antigen targeting antibody, an extended half-life IL-2, anti-PD-1, and a powerful T-cell vaccine. This combination elicited durable cures in a majority of animals, formed immunological memory in multiple transplanted tumor models, and induced sustained tumor regression in an autochthonous BRrafV600E/Pten-/- melanoma model. Multiple innate immune cell subsets, CD8+ T-cells, and cross-presenting dendritic cells were critical to successful therapy. Treatment induced high levels of intratumoral inflammatory cytokines and immune cell infiltration, enhanced antibody-mediated tumor antigen uptake, and promoted antigen spreading. These results demonstrate the capacity of an elicited endogenous immune response to destroy large, established tumors and elucidate essential characteristics of combination immunotherapies capable of curing a majority of tumors in experimental settings typically viewed as intractable.
Citation Format: Kelly Dare Moynihan, Cary Opel, Gregory Szeto, Alice Tzeng, Zhu Eric, Jesse Engreitz, Williams Robert, Kavya Rakhra, Michael Zhang, Adrienne Rothschilds, Sudha Kumari, Ryan L. Kelly, Byron Kwan, Wuhbet Abraham, Kevin Hu, Naveen Mehta, Monique Kauke, Heikyung Suh, Douglas A. Lauffenburger, K. Dane Wittrup, Darrell J. Irvine. Eradication of large established tumors with combination immunotherapy engaging innate and adaptive immunity. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A52.
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