title: Reversal of gastrointestinal carcinoma-induced immunosuppression and induction of antitumoural immunity by a combination of cyclophosphamide and gene transfer of IL-12.
abstract: Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic doses of an adenovirus expressing IL-12 genes (AdIL-12) mediated a potent antitumour effect against subcutaneous (s.c.) colorectal carcinomas (CRC) in mice pre-treated with low doses of cyclophosphamide (Cy). In our study we used this combination to assess its impact on the immunosuppressive microenvironment. In s.c. CRC model we demonstrated that non-responder mice failed to decrease Tregs in tumour, spleen and peripheral blood. Reconstitution of Tregs into tumour-bearing mice treated with combined therapy abolished the antitumoural effect. In addition, Cy + AdIL-12 modified Tregs functionality by inhibiting the in vitro secretion of IL-10 and TGF-β and their ability to inhibit dendritic cells activation. Combined treatment decreased the number of myeloid-derived suppressor cells (MDSCs) in comparison to non-treated mice and, interestingly, administration of Tregs restored splenic MDSCs population. Furthermore, combined therapy potently generated specific cytotoxic IFN-γ-secreting CD4+ T cells able to eradicate established CRC tumours after adoptive transfer. Finally, we evaluated the combination on disseminated CRC and pancreatic carcinoma (PC). Cy + AdIL-12 were able to eradicate liver metastatic CRC (47%) and PC tumour nodules (40%) and to prolong animal survival. The results of this study support the hypothesis that Cy + AdIL-12 might be a valid immunotherapeutic strategy for advanced GIC.
authors.affiliation: Gene Therapy Laboratory, Liver Unit, School of Medicine, Austral University, Derqui-Pilar, Buenos Aires, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Malvicini
authors.forename: Mariana
authors.initials: M
authors.lastname: Ingolotti
authors.forename: Flavia
authors.initials: F
authors.lastname: Piccioni
authors.forename: Mariana
authors.initials: M
authors.lastname: Garcia
authors.forename: Juan
authors.initials: J
authors.lastname: Bayo
authors.forename: Catalina
authors.initials: C
authors.lastname: Atorrasagasti
authors.forename: Laura
authors.initials: L
authors.lastname: Alaniz
authors.forename: Jorge B
authors.initials: JB
authors.lastname: Aquino
authors.forename: Jaime A
authors.initials: JA
authors.lastname: Espinoza
authors.forename: Manuel
authors.initials: M
authors.lastname: Gidekel
authors.forename: O Graciela
authors.initials: OG
authors.lastname: Scharovsky
authors.forename: Pablo
authors.initials: P
authors.lastname: Matar
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mazzolini
mesh_terms: D000256:Adenoviridae / Q000187:drug effects / Q000235:genetics; D019264:Adoptive Transfer; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000494:pharmacology / Q000627:therapeutic use*; D003713:Dendritic Cells / Q000276:immunology; D004195:Disease Models, Animal; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy* / Q000276:immunology*; D018014:Gene Transfer Techniques; D006801:Humans; D007109:Immunity / Q000187:drug effects / Q000276:immunology*; D007165:Immunosuppression Therapy; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000235:genetics* / Q000627:therapeutic use; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
chemical_list: D000970:Antineoplastic Agents; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma; D003520:Cyclophosphamide