Introduction: The field of cancer immunotherapy aims to modulate immune responses to enhance tumour destruction. The aim of this project is to investigate the efficacy of an immunotherapeutic cancer vaccine. The hypothesis is that injecting a strong immunostimulant intratumourally could induce an anti-tumour immune response (Fahrer, 2012).
Methods: Mice were injected subcutaneously with tumour cells and treated when tumours reached 5 mm in diameter. Mice received either a single intratumoural injection of CFA emulsified in PBS, or just PBS for control mice. Mice were euthanized when tumours reached 15 mm in diameter or animals showed signs of illness. Intratumoural infiltrates were collected by fine-needle aspiration, and analyzed by flow cytometry.
Results: We observed that intratumoural CFA treatment of P815 mastocytomas and 4T1 mammary adenocarcinomas resulted in a statistically significant survival increases (p-value <0.0001, p-value 0.0229, respectively), and fewer CFA-treated mice (P815 model) developed metastasis to the liver than PBS-controls (p-value 0.0088). In the P815 model, Flow cytometry of fine-needle aspirations of tumours revealed CFA mice had increased levels of intratumoural Neutrophils, NK cells, Macrophages on day 3 post-treatment, and Dendritic cells on day 8 post-treatment. By correlating infiltrates with survival, we were able to show that the CFA-treated mice with the longest survival had higher levels of intratumoural Neutrophils and NK cells at three days post-treatment and CD4 and CD8 T cells one day post-treatment.
CFA treatment was found to be a promising candidate for use as a simple and inexpensive cancer vaccine.