PD-1 Blockade and OX40 Triggering Synergistically Protects against Tumor Growth in a Murine Model of Ovarian Cancer

PLOS ONE, Dec 2019

The co-inhibitory receptor Programmed Death-1 (PD-1) curtails immune responses and prevent autoimmunity, however, tumors exploit this pathway to escape from immune destruction. The co-stimulatory receptor OX40 is upregulated on T cells following activation and increases their clonal expansion, survival and cytokine production when engaged. Although antagonistic anti-PD-1 or agonistic anti-OX40 antibodies can promote the rejection of several murine tumors, some poorly immunogenic tumors were refractory to this treatment. In the present study, we evaluated the antitumor effects and mechanisms of combinatorial PD-1 blockade and OX40 triggering in a murine ID8 ovarian cancer model. Although individual anti-PD-1 or OX40 mAb treatment was ineffective in tumor protection against 10-day established ID8 tumor, combined anti-PD-1/OX40 mAb treatment markedly inhibited tumor outgrowth with 60% of mice tumor free 90 days after tumor inoculation. Tumor protection was associated with a systemic immune response with memory and antigen specificity and required CD4+ cells and CD8+ T cells. The anti-PD-1/OX40 mAb treatment increased CD4+ and CD8+ cells and decreased immunosuppressive CD4+FoxP3+ regulatory T (Treg) cells and CD11b+Gr-1+ myeloid suppressor cells (MDSC), giving rise to significantly higher ratios of both effector CD4+ and CD8+ cells to Treg and MDSC in peritoneal cavity; Quantitative RT-PCR data further demonstrated the induction of a local immunostimulatory milieu by anti-PD-1/OX40 mAb treatment. The splenic CD8+ T cells from combined mAb treated mice produced high levels of IFN-γ upon tumor antigen stimulation and exhibited antigen-specific cytolytic activity. To our knowledge, this is the first study testing the antitumor effects of combined anti-PD-1/OX40 mAb in a murine ovarian cancer model, and our results provide a rationale for clinical trials evaluating ovarian cancer immunotherapy using this combination of mAb.

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PD-1 Blockade and OX40 Triggering Synergistically Protects against Tumor Growth in a Murine Model of Ovarian Cancer

et al. (2014) PD-1 Blockade and OX40 Triggering Synergistically Protects against Tumor Growth in a Murine Model of Ovarian Cancer. PLoS ONE 9(2): e89350. doi:10.1371/journal.pone.0089350 PD-1 Blockade and OX40 Triggering Synergistically Protects against Tumor Growth in a Murine Model of Ovarian Cancer Zhiqiang Guo 0 Xin Wang 0 Dali Cheng 0 Zhijun Xia 0 Meng Luan 0 Shulan Zhang 0 Hiroshi Shiku, Mie University Graduate School of Medicine, Japan 0 1 Department of Gynecology and Obstetrics, Shengjing Hospital, China Medical University , ShenYang , China , 2 Department of Gynecology and Obstetrics, No. 306 Hospital of PLA , Beijing , China , 3 Department of Gynecology and Obstetrics, The First Affiliated Hospital, China Medical University , Shen Yang , China The co-inhibitory receptor Programmed Death-1 (PD-1) curtails immune responses and prevent autoimmunity, however, tumors exploit this pathway to escape from immune destruction. The co-stimulatory receptor OX40 is upregulated on T cells following activation and increases their clonal expansion, survival and cytokine production when engaged. Although antagonistic anti-PD-1 or agonistic anti-OX40 antibodies can promote the rejection of several murine tumors, some poorly immunogenic tumors were refractory to this treatment. In the present study, we evaluated the antitumor effects and mechanisms of combinatorial PD-1 blockade and OX40 triggering in a murine ID8 ovarian cancer model. Although individual anti-PD-1 or OX40 mAb treatment was ineffective in tumor protection against 10-day established ID8 tumor, combined anti-PD-1/OX40 mAb treatment markedly inhibited tumor outgrowth with 60% of mice tumor free 90 days after tumor inoculation. Tumor protection was associated with a systemic immune response with memory and antigen specificity and required CD4+ cells and CD8+ T cells. The anti-PD-1/OX40 mAb treatment increased CD4+ and CD8+ cells and decreased immunosuppressive CD4+FoxP3+ regulatory T (Treg) cells and CD11b+Gr-1+ myeloid suppressor cells (MDSC), giving rise to significantly higher ratios of both effector CD4+ and CD8+ cells to Treg and MDSC in peritoneal cavity; Quantitative RT-PCR data further demonstrated the induction of a local immunostimulatory milieu by anti-PD-1/OX40 mAb treatment. The splenic CD8+ T cells from combined mAb treated mice produced high levels of IFN-c upon tumor antigen stimulation and exhibited antigen-specific cytolytic activity. To our knowledge, this is the first study testing the antitumor effects of combined anti-PD-1/OX40 mAb in a murine ovarian cancer model, and our results provide a rationale for clinical trials evaluating ovarian cancer immunotherapy using this combination of mAb. - Funding: This work was supported by the Free Researcher Project of Shengjing Hospital (No.200806). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Ovarian carcinoma (OC) is the most lethal malignancy in women, with 22,280 new cases and 15,460 deaths estimated in the United States for 2012 [1]. The high rate of lethality from OC is primarily due to the advanced stage of disease at diagnosis. Early stage cancers can be cured in up to 90% of patients with current therapies [2], but this rate drops substantially for advanced disease with approximately 30% of patients with advanced stage OC survive 5 years after initial diagnosis [3]. The standard treatment for ovarian cancer is surgical debulking followed by platinumtaxane based chemotherapy [4]. Although most patients are responsive to chemotherapy at first, the majority of them will eventually have a relapse and die of the disease. Therefore, novel strategies are urgently needed to improve the outcomes of ovarian cancer. Accumulating evidence suggests that immunotherapy should be effective for OC treatment [5]. Firstly, OC cells express many tumor-associated antigens against which specific immune responses have been detected [610]. Secondly, the studies pioneered by Coukos and colleagues indicate tumor immune response is a critical determinant of clinical outcomes of patients with OC supported by the close correlation between survival of these patients and tumor infiltration with CD3+ T cells in the large annotated clinical samples [11]. Thirdly, although OC is a devastating disease, metastases are frequently restricted to the peritoneal cavity where the tumor microenvironment is directly accessible, which obviates the need for systemic delivery of immunostimulatory treatments [12]. Despite the abundant evidence supporting OC immunotherapy, clinical success with immune-based therapies for OC has generally been modest [13]. Programmed Death 1 (PD-1) protein is a key coinhibitory receptor on T cells with a structure similar to that of CTLA-4 but with a distinct biologic function and ligand specificity [14]. PD-1 functions primarily i (...truncated)


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Zhiqiang Guo, Xin Wang, Dali Cheng, Zhijun Xia, Meng Luan, Shulan Zhang. PD-1 Blockade and OX40 Triggering Synergistically Protects against Tumor Growth in a Murine Model of Ovarian Cancer, PLOS ONE, 2014, 2, DOI: 10.1371/journal.pone.0089350