In situ tumor vaccination with adenovirus vectors encoding measles virus fusogenic membrane proteins and cytokines

AIM: To evaluate whether intratumoral expression of measles virus fusogenic membrane glycoproteins H and F (MV-FMG), encoded by an adenovirus vector Ad.MV-H/ F, alone or in combination with local coexpression of cytokines (IL-2, IL-12, IL-18, IL-21 or GM-CSF), can serve as a platform for inducing tumor-specifi c immune responses in colon cancer. METHODS: We used confocal laser scanning microscopy and flow cytometry to analyze cell-cell fusion after expression of MV-FMG by dye colocalization. In a syngeneic bilateral subcutaneous MC38 and Colon26 colon cancer model in C57BL/6 and BALB/c mice, we assessed the effect on both the directly vector-treated tumor as well as the contralateral, not directly vector- treated tumor. We assessed the induction of a tumor- specific cytotoxic T lymphocyte (CTL) response with a lactate dehydrogenase (LDH) release assay. RESULTS: We demonstrated in vitro that transduction of MC38 and Colon26 cells with Ad.MV-H/F resulted in dye colocalization, indicative of cell-cell fusion. In addition, in the syngeneic bilateral tumor model we demonstrated a signifi cant regression of the directly vector-inoculated tumor upon intratumoral expression of MV-FMG alone or in combination with the tested cytokines. We observed the highest anti-neoplastic efficacy with MV-FMG and IL-21 coexpression. The degree of tumor regression of the not directly vector-treated tumor correlated with the anti-neoplastic response of the directly vector-treated tumor. This regression was mediated by a tumor-specifi c CTL response. CONCLUSION: Our data indicate that intratumoral expression of measles virus fusogenic membraneglycoproteins is a promising tool both for direct tumor treatment as well as for tumor vaccination approaches that can be further enhanced by cytokine coexpression.

The two faces of vaccine-induced immune response:protection or increased risk of HIV infection?!

Since the first HIV vaccine trial in1986 a variety of vaccination strategies have been developed and tested for immunogenicity in clinical phase I safety trials.Nevertheless,only six vaccines have been approved for phaseⅡb/Ⅲefficacy trials with only one,the Thai RV144 trial。

Immune-mediated anti-neoplastic effect of intratumoral RSV envelope glycoprotein expression is related to apoptotic death of tumor cells but not to the size of syncytia

AIM: To promote the development of improved tumor vaccination strategies relying on the intratumoral expression of viral fusogenic membrane proteins, we elucidated whether the size of syncytia or the way tumor cells die has an effect on the therapeutic outcome. METHODS: In two syngeneic subcutaneous murine colon cancer models we assessed the anti-neoplastic effect on vector-treated and contralateral untreated tumors. RESULTS: Intratumoral injection of a replication-defective adenovirus encoding respiratory syncytial virus fusion protein (RSV-F) alone (Ad.RSV-F) or together with the attachment glycoprotein RSV-G (Ad.RSV-F/G) led to a significant growth reduction of the vector-treated and contralateral untreated tumors. The treatment response was associated with a strong tumor-specific CTL response and significantly improved survival with medians of 46 d and 44 d, respectively. Intratumoral injection of Ad.RSV-G or a soluble RSV-F encoding adenovirus (Ad.RSV-Fsol) had no significant anti-neoplastic effect. The median survival of these treatment groups and of Ad.Null-treated control animals was about 30 d. CONCLUSION: Although in vitro transduction of colon cancer cell lines with Ad.RSV-F/G resulted in about 8-fold larger syncytia than with Ad.RSV-F, the in vivo outcome was not significantly different. Transduction of murinecolon cancer cell lines with Ad.RSV-F or Ad.RSV-F/G caused apoptotic cell death, in contrast to transduction with Ad.RSV-G or Ad.RSV-Fsol, suggesting an importance of the mode of cell death. Overall, these findings provide insight into improved tumor vaccination strategies relying on the intratumoral expression of viral fusogenic membrane proteins.