Combined PD-1 blockade and GITR triggering induce a potent antitumor immunity in murine cancer models and synergizes with chemotherapeutic drugs

Abstract

BackgroundThe coinhibitory receptor Programmed Death-1 (PD-1) inhibits effector functions of activated T cells and prevents autoimmunity, however, cancer hijack this pathway to escape from immune attack. The costimulatory receptor glucocorticoid-induced TNFR related protein (GITR) is up-regulated on activated T cells and increases their proliferation, activation and cytokine production. We hypothesize that concomitant PD-1 blockade and GITR triggering would synergistically improve the effector functions of tumor-infiltrating T cells and increase the antitumor immunity. In present study, we evaluated the antitumor effects and mechanisms of combined PD-1 blockade and GITR triggering in a clinically highly relevant murine ID8 ovarian cancer model.MethodsMice with 7 days-established peritoneal ID8 ovarian cancer were treated intraperitoneally (i.p.) with either control, anti-PD-1, anti-GITR or anti-PD-1/GITR monoclonal antibody (mAb) and their survival was evaluated; the phenotype and function of tumor-associated immune cells in peritoneal cavity of treated mice was analyzed by flow cytometry, and systemic antigen-specific immune response was evaluated by ELISA and cytotoxicity assay.ResultsCombined anti-PD-1/GITR mAb treatment remarkably inhibited peritoneal ID8 tumor growth with 20% of mice tumor free 90 days after tumor challenge while treatment with either anti-PD-1 or anti-GITR mAb alone exhibited little antitumor effect. The durable antitumor effect was associated with a memory immune response and conferred by CD4+ cells and CD8+ T cells. The treatment of anti-PD-1/GITR mAb increased the frequencies of interferon-γ-producing effector T cells and decreased immunosuppressive regulatory T cells and myeloid-derived suppressor cells, shifting an immunosuppressive tumor milieu to an immunostimulatory state in peritoneal cavity. In addition, combined treatment of anti-PD-1/GITR mAb mounted an antigen-specific immune response as evidenced by antigen-specific IFN-γ production and cytolytic activity of spleen cells from treated mice. More importantly, combined treatment of anti-PD-1/GITR mAb and chemotherapeutic drugs (cisplatin or paclitaxel) further increased the antitumor efficacy with 80% of mice obtaining tumor-free long-term survival in murine ID8 ovarian cancer and 4 T1 breast cancer models.ConclusionsCombined anti-PD-1/GITR mAb treatment induces a potent antitumor immunity, which can be further promoted by chemotherapeutic drugs. A combined strategy of anti-PD-1/GITR mAb plus cisplatin or paclitaxel should be considered translation into clinic.

Engineering high-affinity PD-1 variants for optimized immunotherapy and immuno-PET imaging

“…This is a key consideration in light of the impressive efficacy of combined checkpoint blockade with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA4) in melanoma patients (24) as well as numerous preclinical studies that have demonstrated synergy between antibodies targeting PD-1:PD-L1 and additional immunomodulatory pathways, such as TIM-3 (25), LAG-3 (26), GITR (27), OX-40 (28), and 4-1BB (29). In the case of HAC-PD-1, multispecific agents targeting synergistic immunomodulatory pathways can readily be elaborated by simply fusing multiple small protein modules, including other engineered receptor decoys or single-domain antibodies.…”

Nanoparticle design to induce tumor immunity and challenge the suppressive tumor microenvironment

“…For years cytostatic drugs were considered to be detrimental for immunity, as toxic effects on lymphocytes are a commonly observed side-effect. Still, studies point towards the synergy between TIL reactivation by blocking PD-1 (which suppresses CTL activation) and glucocorticoid-induced TNFR related protein (GITR) (which additionally stimulates T cells) and chemotherapeutics (paclitaxel or cisplatin) [139][140][141]. These and other stories of enemies becoming allies were recently picked up by material scientists, who packaged these synergistic components into single NPs.…”

Emerging Targets in Cancer Immunotherapy: Beyond CTLA-4 and PD-1

“…Combined anti-PD-1 blockage and GITR costimulation has potent antitumor activity in murine ID8 ovarian cancer model and is synergistic with chemotherapeutic agents. This combination promotes accumulation of CD4, CD8 T cells with decreased Treg and myeloid derived suppressive cells [111]. TRX518, an anti-GITR mAb, is being studied in a Phase I study in patients with stage III or stage IV melanoma or other solid tumor malignancies (NCT01239134 [86]).…”