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Eradication of metastatic mouse cancers resistant to immune checkpoint blockade by suppression of myeloid-derived cells.

ABSTRACT: Impressive responses have been observed in patients treated with checkpoint inhibitory anti-programmed cell death-1 (PD-1) or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibodies. However, immunotherapy against poorly immunogenic cancers remains a challenge. Here we report that treatment with both anti-PD-1 and anti-CTLA-4 antibodies was unable to eradicate large, modestly immunogenic CT26 tumors or metastatic 4T1 tumors. Cotreatment with epigenetic-modulating drugs and checkpoint inhibitors markedly improved treatment outcomes, curing more than 80% of the tumor-bearing mice. Functional studies revealed that the primary targets of the epigenetic modulators were myeloid-derived suppressor cells (MDSCs). A PI3K inhibitor that reduced circulating MDSCs also eradicated 4T1 tumors in 80% of the mice when combined with immune checkpoint inhibitors. Thus, cancers resistant to immune checkpoint blockade can be cured by eliminating MDSCs.

SUBMITTER: Kim K

PROVIDER: S-EPMC4136565 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Eradication of metastatic mouse cancers resistant to immune checkpoint blockade by suppression of myeloid-derived cells.

Kim KiBem K Skora Andrew D AD Li Zhaobo Z Liu Qiang Q Tam Ada J AJ Blosser Richard L RL Diaz Luis A LA Papadopoulos Nickolas N Kinzler Kenneth W KW Vogelstein Bert B Zhou Shibin S

Proceedings of the National Academy of Sciences of the United States of America 20140728 32

Impressive responses have been observed in patients treated with checkpoint inhibitory anti-programmed cell death-1 (PD-1) or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibodies. However, immunotherapy against poorly immunogenic cancers remains a challenge. Here we report that treatment with both anti-PD-1 and anti-CTLA-4 antibodies was unable to eradicate large, modestly immunogenic CT26 tumors or metastatic 4T1 tumors. Cotreatment with epigenetic-modulating drugs and checkpoin ...[more]

PMID: 25071169

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Project description:OBJECTIVE:Myeloid-derived suppressor cells (MDSCs) contribute to tumour immunosuppressive microenvironment and immune-checkpoint blockade resistance. Emerging evidence highlights the pivotal functions of cyclin-dependent kinases (CDKs) in tumour immunity. Here we elucidated the role of tumour-intrinsic CDK20, or cell cycle-related kinase (CCRK) on immunosuppression in hepatocellular carcinoma (HCC). DESIGN:Immunosuppression of MDSCs derived from patients with HCC and relationship with CCRK were determined by flow cytometry, expression analyses and co-culture systems. Mechanistic studies were also conducted in liver-specific CCRK-inducible transgenic (TG) mice and Hepa1-6 orthotopic HCC models using CRISPR/Cas9-mediated Ccrk depletion and liver-targeted nanoparticles for interleukin (IL) 6 trapping. Tumorigenicity and immunophenotype were assessed on single or combined antiprogrammed death-1-ligand 1 (PD-L1) therapy. RESULTS:Tumour-infiltrating CD11b+CD33+HLA-DR- MDSCs from patients with HCC potently inhibited autologous CD8+T cell proliferation. Concordant overexpression of CCRK and MDSC markers (CD11b/CD33) positively correlated with poorer survival rates. Hepatocellular CCRK stimulated immunosuppressive CD11b+CD33+HLA-DR- MDSC expansion from human peripheral blood mononuclear cells through upregulating IL-6. Mechanistically, CCRK activated nuclear factor-?B (NF-?B) via enhancer of zeste homolog 2 (EZH2) and facilitated NF-?B-EZH2 co-binding to IL-6 promoter. Hepatic CCRK induction in TG mice activated the EZH2/NF-?B/IL-6 cascade, leading to accumulation of polymorphonuclear (PMN) MDSCs with potent T cell suppressive activity. In contrast, inhibiting tumorous Ccrk or hepatic IL-6 increased interferon ?+tumour necrosis factor-?+CD8+ T cell infiltration and impaired tumorigenicity, which was rescued by restoring PMN-MDSCs. Notably, tumorous Ccrk depletion upregulated PD-L1 expression and increased intratumorous CD8+ T cells, thus enhancing PD-L1 blockade efficacy to eradicate HCC. CONCLUSION:Our results delineate an immunosuppressive mechanism of the hepatoma-intrinsic CCRK signalling and highlight an overexpressed kinase target whose inhibition might empower HCC immunotherapy.

Dataset Information

Eradication of metastatic mouse cancers resistant to immune checkpoint blockade by suppression of myeloid-derived cells.

Publications

Eradication of metastatic mouse cancers resistant to immune checkpoint blockade by suppression of myeloid-derived cells.

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