title: Polyfunctional CD4⁺ T cells are essential for eradicating advanced B-cell lymphoma after chemotherapy.
abstract: The finding that many chemotherapeutic agents have immunostimulatory effects has provided the impetus to combine chemotherapy and immunotherapy for synergistic antitumor effects. However, the critical determinants of effective antitumor immunity after chemotherapy have not been defined. Here we report that adoptive transfer of tumor-specific CD4⁺ T cells after chemotherapy with cyclophosphamide gave rise to polyfunctional CD4⁺ effector cells, which in turn intensified the inflammatory milieu and enhanced the activation of CD8⁺ T cells in the tumor microenvironment. Although this combined chemoimmunotherapy initially resulted in progressive regression of advanced B-cell lymphoma, its therapeutic efficacy was not durable and most mice succumbed to late relapse. Notably, relapse was associated with acquisition of a tolerized phenotype in tumor-specific CD4⁺ T cells, characterized by overexpression of program death-1 (PD-1). Remarkably, effective antitumor immunity was maintained and cure became prevalent when polyfunctional CD4⁺ effector cells were prevented from undergoing PD-1-mediated tolerization, either by antibody blockade of the PD-1-PD-L1 pathway, or targeted ablation of PD-1 in tumor-specific CD4⁺ T cells. Our study suggests that tumor-reactive CD4⁺ T cells act as the "gatekeepers" of the host antitumor immunity in the postchemotherapy setting, thereby their functional status governs the choice between eradication versus regrowth of residual tumors.
authors.affiliation: Cancer Immunology, Inflammation and Tolerance Program, Georgia Health Sciences University (GHSU) Cancer Center, Augusta, GA 30912, USA.
authors.forename: Zhi-Chun
authors.initials: ZC
authors.lastname: Ding
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Blazar
authors.forename: Hideo
authors.initials: H
authors.lastname: Yagita
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Mellor
authors.forename: David H
authors.initials: DH
authors.lastname: Munn
authors.forename: Gang
authors.initials: G
authors.lastname: Zhou
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking; D000970:Antineoplastic Agents / Q000627:therapeutic use; D015704:CD4 Antigens / Q000378:metabolism; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000627:therapeutic use; D003602:Cytotoxicity, Immunologic; D005260:Female; D016219:Immunotherapy, Adoptive; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000276:immunology* / Q000517:prevention & control / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009368:Neoplasm Transplantation; D061026:Programmed Cell Death 1 Receptor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D055502:Secondary Prevention; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation*; D015854:Up-Regulation
chemical_list: D019138:Antibodies, Blocking; D000970:Antineoplastic Agents; D015704:CD4 Antigens; C491383:Pdcd1 protein, mouse; D061026:Programmed Cell Death 1 Receptor; D003520:Cyclophosphamide