Intratumoural injection of complete Freund’s adjuvant (CFA), an emulsion of heat-killed Mycobacterium butyricum, is a novel and effective cancer immunotherapy currently in clinical trial at The Canberra Hospital. This PhD project focused on correlating the efficacy of CFA immunotherapy and immune cell infiltration in murine tumours, utilising the novel method of Fine-needle aspiration. By identifying the essential immune infiltrates for effective treatment, I aimed to improve the efficacy of intratumoural CFA by manipulating the anti-cancer immune response. Increased toll-like receptor stimulation, through combination with ‘Coley’s toxins’, was capable of initiating an improved anti-cancer response, increasing the efficacy of CFA treatment. It is generally assumed that T lymphocytes are key in the induction of anti-cancer responses, however, the results of this project propose a more important role of the innate immune system, specifically neutrophils (stimulated by our treatment), in the generation of an anti-cancer immune response. This project provides a novel, and broad approach to induce anti-tumour responses against various tumour types without the need for personalised therapies and with minimal adverse effects.