CD122-directed interleukin-2 treatment mechanisms in bladder cancer differ from αPD-L1 and include tissue-selective γδ T cell activation

Abstract

BackgroundAnti-programmed death-ligand 1 (αPD-L1) immunotherapy is approved to treat bladder cancer (BC) but is effective in <30% of patients. Interleukin (IL)-2/αIL-2 complexes (IL-2c) that preferentially target IL-2 receptor β (CD122) augment CD8+ antitumor T cells known to improve αPD-L1 efficacy. We hypothesized that the tumor microenvironment, including local immune cells in primary versus metastatic BC, differentially affects immunotherapy responses and that IL-2c effects could differ from, and thus complement αPD-L1.MethodsWe studied mechanisms of IL-2c and αPD-L1 efficacy using PD-L1+ mouse BC cell lines MB49 and MBT-2 in orthotopic (bladder) and metastatic (lung) sites.ResultsIL-2c reduced orthotopic tumor burden and extended survival in MB49 and MBT-2 BC models, similar to αPD-L1. Using antibody-mediated cell depletions and genetically T cell-deficient mice, we unexpectedly found that CD8+ T cells were not necessary for IL-2c efficacy against tumors in bladder, whereas γδ T cells, not reported to contribute to αPD-L1 efficacy, were indispensable for IL-2c efficacy there. αPD-L1 responsiveness in bladder required conventional T cells as expected, but not γδ T cells, altogether defining distinct mechanisms for IL-2c and αPD-L1 efficacy. γδ T cells did not improve IL-2c treatment of subcutaneously challenged BC or orthotopic (peritoneal) ovarian cancer, consistent with tissue-specific and/or tumor-specific γδ T cell contributions to IL-2c efficacy. IL-2c significantly altered bladder intratumoral γδ T cell content, activation status, and specific γδ T cell subsets with antitumor or protumor effector functions. Neither IL-2c nor αPD-L1 alone treated lung metastatic MB49 or MBT-2 BC, but their combination improved survival in both models. Combination treatment efficacy in lungs required CD8+ T cells but not γδ T cells.ConclusionsMechanistic insights into differential IL-2c and αPD-L1 treatment and tissue-dependent effects could help develop rational combination treatment strategies to improve treatment efficacy in distinct cancers. These studies also provide insights into γδ T cell contributions to immunotherapy in bladder and engagement of adaptive immunity by IL-2c plus αPD-L1 to treat refractory lung metastases.

CD122-targeted interleukin-2 and αPD-L1 treat bladder cancer and melanoma via distinct mechanisms, including CD122-driven natural killer cell maturation

“…We previously reported that CD122-targeting IL-2c activated γδ T cells but not CD8 + T cells to treat orthotopic MB49 BC. 20 However, effects on other CD122 + immune cell populations in bladder are unreported. Like MB49, we observed reduced tumor growth and tumor weight in IL-2c treated mice bearing orthotopic MBT-2 (Fig.…”

“…Note: We previously reported data showing survival of isotype-treated mice bearing orthotopic MB49. 20 Eomes, Eomesodermin. IL-2c, interleukin-2 complex.…”

“…Lung BC tumors were generated via intravenous tail vein injection of 7 × 10 5 MB49 or 2.5 × 10 5 MBT-2 cells in 200 μL DPBS into male mice. 20 Lung B16 tumors were generated via similar methods using 3 × 10 5 B16 cells. Bladder tumor and peritoneal B16 tumor growth was assessed by tumor weight at sacrifice.…”

“…Bladder tumor dissection was as previously described. 20 Subcutaneous and peritoneal B16 tumors were dissected and placed in a 6-well plate filled with serum-free RPMI-1640 and manually dissociated with the back of a syringe. Cells were incubated for 45–60 min in 3 mL serum-free RPMI-1640 with 0.25 mg/mL DNAse I and 1.65 mg/mL collagenase Type IV (both Sigma Aldrich; St. Louis, MO) and passed through a 70 µm filter to generate single-cell suspensions.…”

“…However, specific effector populations activated by IL-2c are highly dependent on tumor type and the tumor immune microenvironment, which also differentially affects αPD-L1 efficacy despite potentially targeting similar immune populations. 20 Here, we studied IL-2c and αPD-L1 immunotherapy treatment mechanisms in orthotopic mouse models of BC (MB49 and MBT-2) and melanoma (B16-F10) versus mechanisms in peritoneal and lung metastatic sites. We show that IL-2c promotes NK cell maturation and effector function in distinct primary (orthotopic bladder) and metastatic (peritoneum and lung) sites in a T cell-independent manner.…”