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.
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.
Bracci
Laura
L
Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Moschella
Federica
F
Sestili
Paola
P
La Sorsa
Valentina
V
Valentini
Mara
M
Canini
Irene
I
Baccarini
Sara
S
Maccari
Sonia
S
Ramoni
Carlo
C
Belardelli
Filippo
F
Proietti
Enrico
E
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*
D000970:Antineoplastic Agents; D016207:Cytokines; D007371:Interferon-gamma; D003520:Cyclophosphamide