ABSTRACT
CCR8 is a chemokine receptor expressed principally on regulatory T cells (Treg) and is known to be critical for CCR8+ Treg-mediated immunosuppression. Recent studies have demonstrated that CCR8 is uniquely upregulated in human tumor-resident Tregs of patients with breast, colon, and lung cancer when compared with normal tissue-resident Tregs. Therefore, CCR8+ tumor-resident Tregs are rational targets for cancer immunotherapy. Here, we demonstrate that mAb therapy targeting CCR8 significantly suppresses tumor growth and improves long-term survival in colorectal tumor mouse models. This antitumor activity correlated with increased tumor-specific T cells, enhanced infiltration of CD4+ and CD8+ T cells, and a significant decrease in the frequency of tumor-resident CD4+CCR8+ Tregs. Tumor-specific CD8+ T cells displayed lower expression of exhaustion markers as well as increased functionality upon restimulation. Treatment with anti-CCR8 mAb prevented de novo induction and suppressive function of Tregs without affecting CD8+ T cells. Initial studies explored a combinatorial regimen using anti-CCR8 mAb therapy and a Listeria monocytogenes-based immunotherapy. Anti-CCR8 mAb therapy synergized with L. monocytogenes-based immunotherapy to significantly delay growth of established tumors and to prolong survival. Collectively, these findings identify CCR8 as a promising new target for tumor immunotherapy and provide a strong rationale for further development of this approach, either as a monotherapy or in combination with other immunotherapies.Significance: Inhibition of CCR8 represents a promising new cancer immunotherapy strategy that modulates tumor-resident regulatory T cells to enhance antitumor immunity and prolong patient survival. Cancer Res; 78(18); 5340-8. ©2018 AACR.
Subject(s)
Cancer Vaccines/immunology , Colonic Neoplasms/immunology , Colonic Neoplasms/therapy , Receptors, CCR8/antagonists & inhibitors , Animals , Antibodies, Monoclonal/immunology , CD8-Positive T-Lymphocytes/immunology , Cell Line, Tumor , Humans , Immune Tolerance , Immunosuppression Therapy , Immunotherapy , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Receptors, CCR8/immunology , T-Lymphocytes, Regulatory/immunology , Treatment Outcome , Tumor Microenvironment/immunology , Up-RegulationABSTRACT
BACKGROUND: Oral mucositis (OM) is a frequent complication of mucotoxic cancer therapy, causing significant oral pain, increased infection risk, and impaired functioning. The efficacy and safety of Saforis (glutamine) powder in UpTec for oral suspension was evaluated for the prevention and treatment of OM. METHODS: Three hundred twenty-six patients developing World Health Organization (WHO) grade >or=2 OM during a chemotherapy screening cycle were randomized to Saforis (n = 163) or placebo (n = 163) 3 times/day during their next chemotherapy cycle (Treatment Cycle 1). Patients were crossed over to the alternate treatment during Treatment Cycle 2. As prespecified in the statistical plan, because of a carryover effect in Treatment Cycle 2 the primary efficacy analysis was based on Treatment Cycle 1 only. RESULTS: Compared with placebo, Saforis significantly reduced the incidence of clinically significant WHO grade >or=2 OM (38.7% vs. 49.7%; P = .026) and severe WHO grade >or=3 OM (1.2% vs. 6.7%; P = .005) in Treatment Cycle 1. Saforis also significantly reduced the worst Oral Mucositis Assessment Scale ulceration score in Treatment Cycle 1 compared with placebo (mean, 0.23 +/- 0.39 vs. 0.32 +/- 0.45; P = .013). Patients receiving Saforis in Treatment Cycle 1 had a lower-than-expected OM incidence when crossed over to placebo in Treatment Cycle 2, indicating a significant carryover effect (P = .027). The incidence of treatment-emergent adverse events was similar between groups. CONCLUSIONS: Saforis is safe and effective for preventing and treating OM in patients receiving mucotoxic cancer chemotherapy.
