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  • Manganese is critical for antitumor immune responses via cGAS-STING and improves the efficacy of clinical immunotherapy.

Manganese is critical for antitumor immune responses via cGAS-STING and improves the efficacy of clinical immunotherapy.

Cell research (2020-08-26)
Mengze Lv, Meixia Chen, Rui Zhang, Wen Zhang, Chenguang Wang, Yan Zhang, Xiaoming Wei, Yukun Guan, Jiejie Liu, Kaichao Feng, Miao Jing, Xurui Wang, Yun-Cai Liu, Qian Mei, Weidong Han, Zhengfan Jiang
ABSTRACT

CD8+ T cell-mediated cancer clearance is often suppressed by the interaction between inhibitory molecules like PD-1 and PD-L1, an interaction acts like brakes to prevent T cell overreaction under normal conditions but is exploited by tumor cells to escape the immune surveillance. Immune checkpoint inhibitors have revolutionized cancer therapeutics by removing such brakes. Unfortunately, only a minority of cancer patients respond to immunotherapies presumably due to inadequate immunity. Antitumor immunity depends on the activation of the cGAS-STING pathway, as STING-deficient mice fail to stimulate tumor-infiltrating dendritic cells (DCs) to activate CD8+ T cells. STING agonists also enhance natural killer (NK) cells to mediate the clearance of CD8+ T cell-resistant tumors. Therefore STING agonists have been intensively sought after. We previously discovered that manganese (Mn) is indispensable for the host defense against cytosolic dsDNA by activating cGAS-STING. Here we report that Mn is also essential in innate immune sensing of tumors and enhances adaptive immune responses against tumors. Mn-insufficient mice had significantly enhanced tumor growth and metastasis, with greatly reduced tumor-infiltrating CD8+ T cells. Mechanically, Mn2+ promoted DC and macrophage maturation and tumor-specific antigen presentation, augmented CD8+ T cell differentiation, activation and NK cell activation, and increased memory CD8+ T cells. Combining Mn2+ with immune checkpoint inhibition synergistically boosted antitumor efficacies and reduced the anti-PD-1 antibody dosage required in mice. Importantly, a completed phase 1 clinical trial with the combined regimen of Mn2+ and anti-PD-1 antibody showed promising efficacy, exhibiting type I IFN induction, manageable safety and revived responses to immunotherapy in most patients with advanced metastatic solid tumors. We propose that this combination strategy warrants further clinical translation.

MATERIALS
Product Number
Brand
Product Description

Roche
DNase I, grade II, from bovine pancreas
Sigma-Aldrich
Anti-MB21D1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution
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Lipopolysaccharides from Escherichia coli O111:B4, purified by trichloroacetic acid extraction
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Histopaque®-1077, sterile-filtered, density: 1.077 g/mL