Development and Characterization of a Novel Immunotherapy for Treatment of Breast Cancer by Combining Particulate Cancer Vaccines with Immune-Modulators

Abstract

In the last half of the century, advances in the field of cancer therapy including chemotherapy, hormonal therapy and targeted therapy have been responsible for improvements in breast cancer related mortality. Although such advances have benefited all cancer types, there are considerable challenges faced by researchers striving to realize the goal of complete tumor remission. Immunotherapy is a great alternative as it has minimum side effects and several advantages over traditional cancer therapies. The aim of this project is to develop a novel immunotherapy for treatment of cancer by combining cancer vaccines with various immune-modulators. We take advantage of micron-sized particles to deliver vaccine along with other immune modifiers to target immune cells and to initiate immune response against breast cancer antigens. These particles were evaluated for their size, charge, surface morphology, release profiles, cyto-toxicity and particle uptake by various in vitro studies. The efficacy of breast cancer vaccine microparticles was tested in a murine breast cancer model. The immunized animals showed significantly lower tumor growth compared to the naive animals that did not receive any treatment. The delay in tumor growth in vaccinated animals was due to a strong immune response generated against tumor- associated antigens encapsulated within the microparticles. We observed a significant increase in the CD4+ T cell population.

The suppression mechanism employed by regulatory T cells are thought to contribute significantly to the failure of current therapies that rely on potentiation of anti-tumor responses. We evaluated the therapeutic efficacy of vaccine microparticles after depleting the immunosuppressive regulatory T cells. We observed a significant improvement in the efficacy of vaccine microparticles by depleting regulatory T cells. The tumor inhibitory effect of vaccine microparticles was due to depletion of regulatory T cells by cyclophosphamide. We observed a significant increase in the CD8+ T cell population.

The final aim of my research project was to enhance the immunogenicity of cancer vaccines using adjuvants. Based on our findings we conclude that Alum, Addavax (like MF59) R848 and CpG significantly enhanced the immunogenicity of breast cancer associated antigens.