ABSTRACT
OX40 ligand (OX40L), a member of TNF superfamily, is a co-stimulatory molecule involved in T cell activation. Systemic administration of mOX40L fusion protein significantly inhibited the growth of experimental lung metastasis and subcutaneous (s.c.) established colon (CT26) and breast (4T1) carcinomas. Vaccination with OX40L was significantly enhanced by combination treatment with intra-tumour injection of a disabled infectious single cycle-herpes simplex virus (DISC-HSV) vector encoding murine granulocyte macrophage-colony stimulating factor (mGM-CSF). Tumour rejection in response to OX40L therapy required functional CD4+ and CD8+ T cells and correlated with splenocyte cytotoxic T lymphocytes (CTLs) activity against the AH-1 gp70 peptide of the tumour associated antigen expressed by CT26 cells. These results demonstrate the potential role of the OX40L in cancer immunotherapy.
Subject(s)
Antineoplastic Agents/therapeutic use , Cancer Vaccines/therapeutic use , Membrane Glycoproteins/therapeutic use , Neoplasms, Experimental/immunology , Neoplasms, Experimental/therapy , Animals , Antineoplastic Agents/administration & dosage , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Cell Division/drug effects , Cell Line , Cell Line, Tumor , Female , Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Injections, Intraperitoneal , Membrane Glycoproteins/administration & dosage , Mice , Mice, Inbred BALB C , Neoplasm Transplantation , OX40 Ligand , Simplexvirus/genetics , Simplexvirus/immunology , Spleen/cytology , Spleen/immunology , T-Lymphocytes, Cytotoxic/immunology , Tumor Necrosis FactorsABSTRACT
BACKGROUND: DISC-hGMCSF is a gH-deleted HSV-2 based vector expressing human GM-CSF that has entered clinical trials for the therapy of metastatic melanoma. To determine whether this product also has potential to treat breast carcinoma, a series of in vitro and in vivo studies were made. METHODS: Breast carcinoma cell lines and primary cultures of breast carcinoma cells were infected with DISC-GFP or DISC-human-GMCSF (DISC-hGMCSF) and the number of GFP-positive cells and GM-CSF yields were determined. In vivo efficacy of DISC-murine-GMCSF (DISC-mGMCSF) in combination with systemic chemotherapy was assessed in the murine 4T1 breast carcinoma model by direct injection into subcutaneous tumours. RESULTS: DISC-hGMCSF was able to infect all breast carcinoma cell lines and the majority of primary breast carcinoma cultures with high efficiency, although culture-to-culture variability in infectability was noted in the latter. In the MCF-7 breast carcinoma cell line, expression of hGMCSF was found to peak over the first 24 h post-infection and drop to background levels by 7 to 14 days. In the 4T1 murine breast tumour model, injection of subcutaneous tumours led to a delay in tumour growth and, in rare cases, complete regression of visible tumour. DISC-mGMCSF and DISC-LacZ showed similar levels of efficacy. When mice were given simultaneous 5FU chemotherapy the effectiveness of DISC-mGMCSF treatment was undiminished, and up to three out of ten mice showed complete absence of visible tumour. CONCLUSIONS: DISC-hGMCSF is able to infect human breast carcinoma cells at high efficiency and express GM-CSF. DISC-mGMCSF demonstrated efficacy in the murine 4T1 model, even during concomitant chemotherapy. Taken together these results indicate that DISC-hGMCSF may have potential for the treatment of breast carcinoma.
Subject(s)
Breast Neoplasms/therapy , Genetic Therapy/methods , Granulocyte-Macrophage Colony-Stimulating Factor/genetics , Herpesvirus 2, Human/genetics , Mammary Neoplasms, Animal/therapy , Animals , Antimetabolites, Antineoplastic/pharmacology , Breast Neoplasms/genetics , Cell Line, Tumor , Cell Separation , Centrifugation , Female , Flow Cytometry , Fluorouracil/pharmacology , Genetic Vectors , Green Fluorescent Proteins , Humans , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Mammary Neoplasms, Animal/genetics , Mice , Mice, Inbred BALB C , Phenotype , Time FactorsABSTRACT
Direct intratumor injection of a disabled infectious single cycle HSV-2 virus encoding the murine GM-CSF gene (DISC/mGM-CSF) into established murine colon carcinoma CT26 tumors induced a significant delay in tumor growth and complete tumor regression in up to 70% of animals. Pre-existing immunity to HSV did not reduce the therapeutic efficacy of DISC/mGM-CSF, and, when administered in combination with syngeneic dendritic cells, further decreased tumor growth and increased the incidence of complete tumor regression. Direct intratumor injection of DISC/mGM-CSF also inhibited the growth of CT26 tumor cells implanted on the contralateral flank or seeded into the lungs following i.v. injection of tumor cells (experimental lung metastasis). Proliferation of splenocytes in response to Con A was impaired in progressor and tumor-bearer, but not regressor, mice. A potent tumor-specific CTL response was generated from splenocytes of all mice with regressing, but not progressing tumors following in vitro peptide stimulation; this response was specific for the gp70 AH-1 peptide SPSYVYHQF and correlated with IFN-gamma, but not IL-4 cytokine production. Depletion of CD8(+) T cells from regressor splenocytes before in vitro stimulation with the relevant peptide abolished their cytolytic activity, while depletion of CD4(+) T cells only partially inhibited CTL generation. Tumor regression induced by DISC/mGM-CSF virus immunotherapy provides a unique model for evaluating the immune mechanism(s) involved in tumor rejection, upon which tumor immunotherapy regimes may be based.