Our novel cancer immunotherapy involves an intratumoural injection of complete Freund’s adjuvant (CFA); an emulsion of heat-killed mycobacteria, water and oil. Since beginning a Phase I Clinical Trial of CFA at the Canberra Hospital assessing treatment in multiple solid tumours, the current focus of our research is improving the potency of our novel anticancer immunotherapy and elucidating its precise mechanism of action using murine cancer models.

In the P815 model of Mastocytoma, we have investigated the efficacy of combining CFA with additional bacterial components (Coley’s Toxins). Using our novel technique of ‘fine-needle aspiration’ (Carroll, et al. 2015), we can directly correlate early tumour infiltrating leukocytes with survival benefit.

Our CFA treatment can achieve cancer regression in 5% and achieve longer survival in 20% of treated animals. We have previously identified unexpected leukocytes associated with successful remission, showing a correlation between increased neutrophil infiltration and high survival rates.

The addition of Coley’s Toxins to CFA has increased regression rates and increased survival of treated mice, however, this did not hold in treatments lacking mycobacteria, which attracted neutrophils, but did not increase survival.

This finding allows for investigation into the plasticity of neutrophils in cancer, providing a means of potentially identifying markers for N1 and N2 neutrophil phenotypes and allowing for opportunities to increase the efficacy of our simple anti-cancer immunotherapy.