Nonclinical evaluation of the combination of mouse IL-21 and anti- mouse CTLA-4 or PD-1 blocking antibodies in mouse tumor models.

Abstract

3019 Background: Interleukin 21 (IL-21), a γc chain family cytokine, is produced primarily by CD4+ T cells and has many effects on immune cells, including enhancing CD8+ T cell and NK cell proliferation and cytotoxicity. Recombinant IL-21 (rIL-21) therapy resulted in objective responses in ~20% of melanoma and renal cell carcinoma patients. In mouse models, monoclonal antibody (mAb) blockade of CTLA-4 prolongs antigen-specific T cell responses, while blockade of programmed death 1 (PD-1) reverses tumor induced T cell suppression. Ipilimumab, a CTLA-4 blocking mAb, significantly improved overall survival in patients with metastatic melanoma in 2 phase III trials, and in phase I studies a PD-1 blocking mAb (nivolumab) has antitumor activity in various cancers. Side effect profiles for each mAb have been related to their mechanism and are generally manageable. It was hypothesized that combination of IL-21 plus CTLA-4 or PD-1 blockade may enhance antitumor responses, potentially leading to improved clinical activity. Methods: Preclinical studies were conducted to test the antitumor activity of mouse IL-21 (mIL-21) in combination with an anti-mouse PD-1 (mPD-1) mAb (4H2-IgG1) or with an anti-mCTLA-4 blocking mAb (9D9-IgG2b) in syngeneic mouse tumor models, including MC38, CT-26, EMT-6, and B16F10. mIL-21 was tested at doses ranging from 50-200 μg/dose, administered up to 3d/wk. mCTLA-4 mAb or mPD-1 mAb were administered 3-4x total at 200-300 μg/dose. Results: Combination treatments produced enhanced antitumor activity vs. monotherapy. In the MC38 model, mIL-21 treatment led to 30% median tumor growth inhibition (TGI) by d29, while mPD-1 mAb produced 60% median TGI and 1/10 tumor-free mice. Combination of both agents led to synergistic antitumor activity, with complete regressions (CR) in 7/10 mice and 99.9% median TGI (p=0.046). CTLA-4 mAb + mIL-21 also produced synergistic activity in the MC38 model. By d21, mIL-21 monotherapy induced 34% TGI while CTLA-4 mAb resulted in 28% TGI, with no CR in either group. Combination resulted in 6/8 mice with CR and 86% TGI (p<0.05). Conclusions: These results support the use of rIL-21+nivolumab and rIL-21+ipilimumab in recently initiated clinical trials.

OCT4&SOX2‐specific cytotoxic T lymphocytes plus programmed cell death protein 1 inhibitor presented with synergistic effect on killing lung cancer stem‐like cells in vitro and treating drug‐resistant lung cancer mice in vivo

“…For instance, combination of cytotoxic T‐lymphocyte‐associated antigen 4 inhibitor and PD‐1 inhibitor raises the antitumor activity compared with each regimen alone (Curran et al, ; Selby et al, ); and lymphocyte activation gene‐3 inhibitor plus PD‐1 inhibitor illustrate good efficacy in treating established tumors, which are resistant to each single inhibitor treatment (Woo et al, ). Similarly, PD‐1 inhibitor improves the antitumor activity of recombinant interleukin (IL)‐21 with strong tumor growth inhibition and complete regression in the majority of cancer mice (Jurekunkel et al, ).…”

“…Accumulating evidences have verified that the PD‐1 pathway is closely involved in tumor immune evasion, and tumor cells with upregulated PD‐1/PD‐L1 show increased resistance to T‐cell‐mediate lysis and exhibit elevated tumorigenesis as well as invasiveness compared to tumor cells with downregulated PD‐L1 expression, indicating blockade of the PD‐1 pathway would restore antitumor immune responses in cancers (Iwai et al, ; Iwai, Terawaki, & Honjo, ). Most importantly, blockade of PD‐1 pathway is widely discovered to enhance the antitumor effect of other immunotherapeutic approaches (Curran, Montalvo, Yagita, & Allison, ; Jurekunkel et al, ; Selby et al, ; Woo et al, ). For instance, combination of cytotoxic T‐lymphocyte‐associated antigen 4 inhibitor and PD‐1 inhibitor raises the antitumor activity compared with each regimen alone (Curran et al, ; Selby et al, ); and lymphocyte activation gene‐3 inhibitor plus PD‐1 inhibitor illustrate good efficacy in treating established tumors, which are resistant to each single inhibitor treatment (Woo et al, ).…”

OCT4 and SOX2 Specific Cytotoxic T Cells Exhibit Not Only Good Efficiency but Also Synergize PD-1 Inhibitor (Nivolumab) in Treating Breast Cancer Stem-Like Cells and Drug-Resistant Breast Cancer Mice

“…Furthermore, nivolumab reportedly promotes the antitumor effect of several other immunotherapeutics; for instance, a previous study revealed a synergistic effect between nivolumab and a cytotoxic T lymphocyte-associated antigen four blockade (9D9) (another representative first-generation four immune checkpoint inhibitor) in melanoma treatment ( 45 ). Another study illustrated that nivolumab enhances the antitumor effect of recombinant IL-21 in several cancer mouse models ( 46 ). Based on the data above, it was hypothesized that nivolumab could improve the cytotoxic activity of OCT4&SOX2 CTLs towards BCSCs.…”