Zavareh RB, Spangenberg SH, Woods A, Martínez-Peña F, Lairson LL. HSP90 Inhibition Enhances Cancer Immunotherapy by Modulating the Surface Expression of Multiple Immune Checkpoint Proteins.
Cell Chem Biol 2020;
28:158-168.e5. [PMID:
33113406 DOI:
10.1016/j.chembiol.2020.10.005]
[Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 08/31/2020] [Accepted: 10/07/2020] [Indexed: 12/19/2022]
Abstract
Cancer immunotherapies, including immune checkpoint blockade, have the potential to significantly impact treatments for diverse tumor types. At present, response failures and immune-related adverse events remain significant issues, which could be addressed using optimized combination therapies. Through a cell-based chemical screen of ∼200,000 compounds, we identified that HSP90 inhibitors robustly decrease PD-L1 surface expression, through a mechanism that appears to involve the regulation of master transcriptional regulators (i.e., STAT-3 and c-Myc). Interestingly, HSP90 inhibitors were found to also modulate the surface expression of additional checkpoint proteins (i.e., PD-L2). In the MC-38 syngeneic mouse tumor model, HSP90 inhibition was found to dramatically reduce PD-L1 surface expression on isolated live tumor cells and, consistent with recent findings, was found to increase the number of activated CD8+ T cells within the tumor microenvironment. These findings provide further rationale to explore HSP90 inhibitors as part of combination immunotherapies for the treatment of cancer.
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