Tumor-associated Macrophage-derived Interleukin-23 Interlinks Kidney Cancer Glutamine Addiction with Immune Evasion.

BACKGROUND

Glutamine addiction is a hallmark of clear cell renal cell carcinoma (ccRCC); yet whether glutamine metabolism impacts local immune surveillance is unclear. This knowledge may yield novel immunotherapeutic opportunities.

OBJECTIVE

To seek a potential therapeutic target in glutamine-addicted ccRCC.

DESIGN, SETTING, AND PARTICIPANTS: Tumors from ccRCC patients from a Shanghai cohort and ccRCC tumor data from The Cancer Genome Atlas (TCGA) cohort were analyzed. In vivo and in vitro studies were conducted with fresh human ccRCC tumors and murine tumor cells.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Immune cell numbers and functions were analyzed by flow cytometry. Glutamine and cytokine concentrations were determined. Survival was compared between different subpopulations of patients using Kaplan-Meier and Cox regression analyses.

RESULTS AND LIMITATIONS

We found that in ccRCC, high interleukin (IL)-23 expression was significantly associated with poor survival in both TCGA (overall survival [OS] hazard ratio [HR]=2.04, cancer-specific survival [CSS] HR=2.95; all p<0.001) and Shanghai (OS HR=2.07, CSS HR=3.92; all p<0.001) cohorts. IL-23 blockade prolongs the survival of tumor-bearing mice, promotes T-cell cytotoxicity in in vitro cultures of human ccRCC tumors, and augments the therapeutic benefits of anti-PD-1 antibodies. Mechanistically, glutamine consumption by ccRCC tumor cells results in the local deprivation of extracellular glutamine, which induces IL-23 secretion by tumor-infiltrating macrophages via the activation of hypoxia-inducible factor 1α (HIF1α). IL-23 activates regulatory T-cell proliferation and promotes IL-10 and transforming growth factor β expression, thereby suppressing tumor cell killing by cytotoxic lymphocytes. The positive correlations between glutamine metabolism, IL-23 levels, and Treg responses are confirmed in both TCGA cohort and tumors from Shanghai ccRCC patients. Study limitations include the unclear impacts of glutamine deprivation and IL-23 on other immune cells.

CONCLUSIONS

Macrophage-secreted IL-23 enhanced Treg functions in glutamine-addicted tumors; thus, IL-23 is a promising target for immunotherapy in ccRCC.

PATIENT SUMMARY

In this study, we analyzed the immune components in glutamine-addicted clear cell renal cell carcinoma (ccRCC) tumors from two patient cohorts and conducted both in vitro and in vivo studies. We found that ccRCC tumor cell-intrinsic glutamine metabolism orchestrates immune evasion via interleukin (IL)-23, and IL-23-high patients had significantly poorer survival than IL-23-low patients. IL-23 should thus be considered a therapeutic target in ccRCC, either alone or in combination with immune checkpoint inhibitors.