CD122-Selective IL2 Complexes Reduce Immunosuppression, Promote Treg Fragility, and Sensitize Tumor Response to PD-L1 Blockade

Abstract

The IL2 receptor (IL2R) is an attractive cancer immunotherapy target that controls immunosuppressive T regulatory cells (Treg) and antitumor T cells. Here we used IL2Rb-selective IL2/anti-IL2 complexes (IL2c) to stimulate effector T cells preferentially in the orthotopic mouse ID8agg ovarian cancer model. Despite strong tumor rejection, IL2c unexpectedly lowered the tumor microenvironmental CD8 þ /Treg ratio. IL2c reduced tumor microenvironmental Treg suppression and induced a fragile Treg phenotype, helping explain improved efficacy despite numerically increased Tregs without affecting Treg in draining lymph nodes. IL2c also reduced Treg-mediated, high-affinity IL2R signaling needed for optimal Treg functions, a likely mechanism for reduced Treg suppression. Effector T-cell IL2R signaling was simultaneously improved, suggesting that IL2c inhibits Treg functions without hindering effector T cells, a limitation of most Treg depletion agents. Anti-PD-L1 antibody did not treat ID8agg, but adding IL2c generated complete tumor regressions and protective immune memory not achieved by either monotherapy. Similar anti-PD-L1 augmentation of IL2c and degradation of Treg functions were seen in subcutaneous B16 melanoma. Thus, IL2c is a multifunctional immunotherapy agent that stimulates immunity, reduces immunosuppression in a site-specific manner, and combines with other immunotherapies to treat distinct tumors in distinct anatomic compartments.Significance: These findings present CD122-targeted IL2 complexes as an advancement in cancer immunotherapy, as they reduce Treg immunosuppression, improve anticancer immunity, and boost PD-L1 immune checkpoint blockade efficacy in distinct tumors and anatomic locations.

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

“…To test an alternative orthotopic tumor and anatomic compartment, we challenged TCRδ KO mice intraperitoneally with ID8agg mouse ovarian carcinoma cells. ID8agg tumors in TCRδ KO mice were also sensitive to IL-2c ( figure 4E ), as we previously reported in wild-type mice, 9 consistent with tissue- and/or tumor-specific γδ T cell effects of IL-2c.…”

“…Because the tumor microenvironment is an important determinant of BC immunotherapy success, 29–31 we used orthotopic mouse BC models to assess immune responses to immune checkpoint blockade with αPD-L1 and showed effective immune checkpoint blockade treatment in two orthotopic BC models as a baseline for comparison versus IL-2 complexes made by incubating recombinant IL-2 with the CD122-directing αIL-2 antibody clone JES5H4 16 (IL-2c). We previously described distinct IL-2c treatment mechanisms in mouse melanoma and ovarian cancer models 9 and here we found IL-2c to be efficacious for orthotopic BC via mechanisms distinct from those tumors and strikingly distinct from αPD-L1 immune checkpoint blockade, including previously unreported γδ T cell requirements.…”

“…Of great interest was the lack of conventional T cell activation and participation in IL-2c efficacy in orthotopic BC, despite αPD-L1 activation of these cells and their requirement for αPD-L1 treatment efficacy, as well as contributions to other cancers as described. 25 Potential explanations include specific attributes of CD8 + T cells in bladder, contributions from specific immunosuppressive factors such as Tregs and MDSCs, and specialized dendritic cell effects as have been noted with IL-2c in subcutaneous tumors, 9 areas requiring further study. Identification of such factors could be exploited to improve IL-2c, αPD-L1, and other immunotherapies.…”

“…Selective IL-2 receptor stimulation with CD122-directed IL-2/αIL-2 complexes (IL-2c) improves antitumor immunity in many cancer models by augmenting CD8 + T cell effector cell functions while largely avoiding Treg expansion and/or reducing Treg activation and function. 9 10 CD122-directed IL-2 therapy using distinct molecules is also promising in human BC trials, including when combined with αPD-1. 11 Effects on other CD25 + and CD122 + cells including γδ T cells using targeted IL-2 therapies are unreported to our knowledge and recent reports suggest IL-2c can also act through non-IL-2 receptor expressing cells such as dendritic cells, 12 necessitating improved understanding of specific treatment mechanisms in distinct tumor microenvironments.…”

Estrogen receptor beta signaling in CD8+ T cells boosts T cell receptor activation and antitumor immunity through a phosphotyrosine switch

“…ID8agg-Luc ovarian tumor cells were generated by Dr. Tyler Curiel’s lab. 10 All cell lines were free of Mycoplasma and cultured in high glucose DMEM (Thermo Fisher Scientific; Cat: #11965) supplemented with 10% heat-inactivated fetal bovine serum, 1% L-glutamine, 100 µg/mL penicillin and 100 µg/mL streptomycin (P/S, Thermo Fisher Scientific, Cat: #15140122).…”