This might be a good time to register for Theralase Technologies Inc.’s (“Theralase”) (TSXV: TLT) news alert. Theralase has demonstrated that it can induce resistance to cancer in mice using its proprietary Photo Dynamic Therapy (PDT) TLDOsH2IP molecule.

In medical research the half-life of knowledge is two years: every two years, half the knowledge of medical research becomes obsolete because new findings change the way we think. Theralase’s findings announced on May 29, 2014 may be the kind of knowledge that changes our thinking. This new press release from Theralase shows that mice previously injected with cancer cells and treated with phototherapy were permanently immune to new cancer cells. This is huge!

The demonstration has been made with colon cancer cells in mice, a suitable system at the pre-clinical stage to tweak new treatment protocols. The research is conducted at a highly credible laboratory: the Princess Margaret Cancer Centre, University Health Network (“UHN”). What is most important to understand here is that the work was conducted by a world-class arm’s length organization.

The University Health Network (UHN) is made up of Princess Margaret Cancer Centre, Toronto General Hospital, Toronto Rehabilitation Institute and Toronto Western Hospital. Each hospital retains its identity and name within the Network. Primary funding for University Health Network comes from the Ontario Ministry of Health and Long-Term Care. Other funding sources include patient services, grants and donations from individuals and corporations. The University Health Network is one of Canada’s largest teaching hospitals.

In previous research conducted at UHN by Theralase, mice were injected with 350,000 colon cancer cells to produce tumours that were allowed to grow to approximately five millimeters in size. They were treated with an intra-tumoural injection of Theralase’s most promising PDC (3 mg/kg TLDOsH2IP) and then illuminated by Near Infrared (NIR) light (808 nm, 600 J cm-2) to activate the PDC. The vast majority of tumours were completely destroyed, with the PDC treatment demonstrating prolonged tumour regression.

In this latest research, the same mice who received the initial and successful Photo Dynamic Therapy (PDT) were re-injected with the same number of colon cancer cells, 13 to 23 days later. Without additional treatments, mice in these experiments demonstrated either a small tumour regrowth, which quickly regressed, or in the majority of animals, no tumour regrowth at all, suggesting a short-term immune-mediated (immune “memory response”) tumour rejection.

And then ten months after the initial treatment these same animals were injected a third time with an additional 350,000 colon cancer cells. Three months later, none of these animals showed any sign of tumour regrowth, even at 3 months post follow up, suggesting the presence of a long-term anti-tumour immunity, responsible for complete tumour rejection.

To strengthen the data, control experiments were conducted where age matched mice without prior tumour exposure or PDT treatment were injected with the same number of colon cancer cells, where the majority of these mice proceeded to develop tumours and did not survive more than 1 month following the injection. In short, mice of the same age that received cancer cells without PDT died.

From a scientific perspective these experiments are beautifully conceived. Theralase’s next challenge is to see how well the results extend to other cancer cells and how we can extrapolate