Combined vaccine+axitinib therapy yields superior antitumor efficacy in a murine melanoma model

Axitinib, a tyrosine kinase inhibitor of vascular endothelial growth factor receptors, has demonstrated modest efficacy when applied as a single agent in the setting of advanced-stage melanoma. On the basis of the reported ability of axitinib to 'normalize' the tumor vasculature, we hypothesize that combination therapy using axitinib plus specific peptide-based vaccination would promote superior activation and recruitment of protective T cells into the melanoma microenvironment, leading to enhanced treatment benefit. Using a subcutaneous M05 (B16.OVA) melanoma model, we observed that a treatment regimen consisting of a 7-day course of axitinib (0.5 mg/day provided orally) combined with a subcutaneous vaccine ovalbumin (OVA) peptide-pulsed syngenic dendritic cells adenovirally engineered to produce IL-12p70 yielded superior protection against melanoma growth and extended overall survival when compared with animals receiving either single modality therapy. Treatment benefits were associated with: (a) a reduction in suppressor cell (myeloid-derived suppressor cells and Treg) populations in the tumor, (b) activation of tumor vascular endothelial cells, and (c) activation and recruitment of type-1, vaccine-induced CD8 T cells into tumors. These results support the therapeutic superiority of combined vaccine+axitinib immunotherapy and the translation of such approaches into the clinic for the treatment of patients with advanced-stage melanoma.