Combination docetaxel plus vitamin D(3) as an immune therapy in animals bearing squamous cell carcinomas.

Abstract

OBJECTIVE: Background tumor growth results in the mobilization of immune inhibitory CD34(+) progenitor cells. However, vitamin D(3) can differentiate the CD34(+) cells into immune stimulatory dendritic cells. This study determined if docetaxel treatment could increase the impact of the vitamin D(3) to generate dendritic cells. METHODS: The murine squamous cell carcinoma model, SCC VII/SF, which is often used as a head and neck cancer model, was used to determine the immunological effects of two cycles of docetaxel plus vitamin D(3). RESULTS: Vitamin D(3) with or without docetaxel was similarly effective in reducing CD34(+) cell levels within the spleen, lymph nodes, and tumor. Dendritic cell levels were similarly enhanced in the lymph nodes by vitamin D(3) alone or combined with docetaxel. However, the combination treatment caused a prominent increase in intratumoral levels of active T cells, which was not observed by the individual treatments. CONCLUSION: Incorporating docetaxel treatment with vitamin D(3) differentiation-inducing treatment enhances intratumoral immune responsiveness.