To generate tumor-reactive lymphocytes, Kirkin et al. used genome demethylation to induce the expression of cancer/testis (CT) antigens on autologous CD4+ Th cells, which acted as APCs when incubated with patient’s peripheral blood lymphocytes, resulting in CD8+ T cells and NK cells exhibiting early differentiation state markers. In a phase I clinical trial of 25 patients with late-stage glioblastoma, injection of these cytotoxic lymphocytes was safe, demonstrated homing to tumor, and led to tumor regression in multiple patients.

In cancer cells, cancer/testis (CT) antigens become epigenetically derepressed through DNA demethylation and constitute attractive targets for cancer immunotherapy. Here we report that activated CD4(+) T helper cells treated with a DNA-demethylating agent express a broad repertoire of endogenous CT antigens and can be used as antigen-presenting cells to generate autologous cytotoxic T lymphocytes (CTLs) and natural killer cells. In vitro, activated CTLs induce HLA-restricted lysis of tumor cells of different histological types, as well as cells expressing single CT antigens. In a phase 1 trial of 25 patients with recurrent glioblastoma multiforme, cytotoxic lymphocytes homed to the tumor, with tumor regression ongoing in three patients for 14, 22, and 27 months, respectively. No treatment-related adverse effects were observed. This proof-of-principle study shows that tumor-reactive effector cells can be generated ex vivo by exposure to antigens induced by DNA demethylation, providing a novel, minimally invasive therapeutic strategy for treating cancer.

Author Info: (1) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. aki@cytovac.dk. CytoVac A/S, 2970, Horsholm, Denmark. aki@cytovac.dk. (2) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark

Author Info: (1) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. aki@cytovac.dk. CytoVac A/S, 2970, Horsholm, Denmark. aki@cytovac.dk. (2) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. CytoVac A/S, 2970, Horsholm, Denmark. (3) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. (4) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. CytoVac A/S, 2970, Horsholm, Denmark. (5) Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, 5000, Odense, Denmark. (6) Danish Cancer Society Research Center, 2100, Copenhagen, Denmark. (7) Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark. (8) Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark. (9) Department of Neuroradiology, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark. (10) Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark. (11) Department of Neuropathology, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark. (12) Department of Pathology, Aarhus University Hospital, 8000, Aarhus, Denmark. (13) CytoVac A/S, 2970, Horsholm, Denmark. (14) Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, 5000, Odense, Denmark. (15) Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, 5000, Odense, Denmark. Department of Oncology, Odense University Hospital, 5000, Odense, Denmark. (16) CytoVac A/S, 2970, Horsholm, Denmark. (17) CytoVac A/S, 2970, Horsholm, Denmark. Department of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, 2100, Copenhagen, Denmark.

Less