title: Cyclophosphamide enhances the antitumor efficacy of adoptively transferred immune cells through the induction of cytokine expression, B-cell and T-cell homeostatic proliferation, and specific tumor infiltration.
abstract: OBJECTIVE
  Immunotherapy is a promising antitumor strategy, which can be successfully combined with current anticancer treatments, as suggested by recent studies showing the paradoxical chemotherapy-induced enhancement of the immune response. The purpose of the present work is to dissect the biological events induced by chemotherapy that cooperate with immunotherapy in the success of the combined treatment against cancer. In particular, we focused on the following: (a) cyclophosphamide-induced modulation of several cytokines, (b) homeostatic proliferation of adoptively transferred lymphocytes, and (c) homing of transferred lymphocytes to secondary lymphoid organs and tumor mass.
  
  
  METHODS
  Here, we used the adoptive transfer of tumor-immune cells after cyclophosphamide treatment of tumor-bearing mice as a model to elucidate the mechanisms by which cyclophosphamide can render the immune lymphocytes competent to induce tumor rejection.
  
  
  RESULTS
  The transfer of antitumor immunity was found to be dependent on CD4(+) T cells and on the cooperation of adoptively transferred cells with the host immune system. Of note, tumor-immune lymphocytes migrated specifically to the tumor only in mice pretreated with cyclophosphamide. Cyclophosphamide treatment also promoted homeostatic proliferation/activation of transferred B and T lymphocytes. Optimal therapeutic responses to the transfer of immune cells were associated with the cyclophosphamide-mediated induction of a "cytokine storm" [including granulocyte macrophage colony-stimulating factor, interleukin (IL)-1beta, IL-7, IL-15, IL-2, IL-21, and IFN-gamma], occurring during the "rebound phase" after drug-induced lymphodepletion.
  
  
  CONCLUSIONS
  The ensemble of these data provides a new rationale for combining immunotherapy and chemotherapy to induce an effective antitumor response in cancer patients.
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bracci
authors.forename: Federica
authors.initials: F
authors.lastname: Moschella
authors.forename: Paola
authors.initials: P
authors.lastname: Sestili
authors.forename: Valentina
authors.initials: V
authors.lastname: La Sorsa
authors.forename: Mara
authors.initials: M
authors.lastname: Valentini
authors.forename: Irene
authors.initials: I
authors.lastname: Canini
authors.forename: Sara
authors.initials: S
authors.lastname: Baccarini
authors.forename: Sonia
authors.initials: S
authors.lastname: Maccari
authors.forename: Carlo
authors.initials: C
authors.lastname: Ramoni
authors.forename: Filippo
authors.initials: F
authors.lastname: Belardelli
authors.forename: Enrico
authors.initials: E
authors.lastname: Proietti
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003520:Cyclophosphamide / Q000494:pharmacology*; D016207:Cytokines / Q000378:metabolism*; D007107:Immune System; D007167:Immunotherapy / Q000379:methods; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D016207:Cytokines; D007371:Interferon-gamma; D003520:Cyclophosphamide