Immunotherapy, hailed as one of the most promising methods for tackling cancerous tumours, has recently taken a decisive new step in its development – a new study recently published in the journal Proceedings of the National Academy of Science introduces a melanoma vaccine shown to be highly effective in mice.
The team behind the discovery, including co-lead researcher Professor Dale Boger, PhD, and Nobel laureate Bruce Beutler, MD, had infused the vaccine with a molecule called Diprovocim which draws cancer-fighting cells to tumour sites, thereby giving patients who did not see any benefit from drug therapy a fighting chance.
Diprovocim, an “adjuvant” molecule which ramps ups immune activity when combined with a vaccine, is inexpensive and easy to synthesise and modify, which makes it an excellent candidate for large-scale deployment.
“This co-therapy produced a complete response – a curative response – in the treatment of melanoma,” said Boger.
Calling the outcome a “complete response” is no exaggeration either – mice with a form of notoriously aggressive type of melanoma who were given the anti-cancer therapy anti-PD-L1 in combination with Diprovocim had a 100 percent survival rate over 54 days of observation.
In contrast, none of the mice given only the vaccine survived over the same period, while mice given the vaccine with alum (a different adjuvant) had a 25 percent survival rate.
Furthermore, just like with regular vaccines, the new therapy not only attacks the existing lesions, but also trains the body to go after them in case they return.
Thanks to the adjuvant molecule, shown to stimulate the production of tumour-specific CTLs (cytotoxic T lymphocytes), the researchers have been unable to re-establish the cancerous lesions in the mice treated with the vaccine-adjuvant combo.
According to Boger, the vaccine does not need to be injected directly into the tumour – the therapy was effective with two doses delivered seven days apart from each other by intramuscular injection.
Prior to applying for studies in humans, the team plans to resume pre-clinical testing to see how the vaccine works in combination with other cancer treatment modalities.