Nearly all (96 per cent) people aged 65 or older diagnosed with acute myeloid leukemia (AML) die within five years, as do two-thirds of younger patients. Because it primarily affects older people, the incidence of this aggressive cancer is expected to rise in coming years as the population ages. Chemotherapy regimens for AML have remained essentially unchanged since the 1970s. With standard treatment, many patients can achieve remission, but most will relapse; following relapse two-thirds of patients will die within 3 years.
One of the reasons for the high rate of relapse in AML is that standard chemotherapy does not kill leukemia stem cells, leaving them to grow and mature into new leukemia cells. Leukemia stem cells express high levels of a protein called CD47. This protein sends a “do not eat” signal that stops white blood cells of the immune system called macrophages from surrounding and “eating” cancer cells.
With previous support from Genome Canada and Trillium Therapeutics Inc. (TTI), a publicly traded biotech company in Toronto, Canada, Dr. Jean Wang and team at the Princess Margaret Cancer Centre, University Health Network, and Dr. Jayne Danska and team at SickKids have developed SIRPαFc, a novel therapeutic that blocks the “do not eat” signal, freeing the immune system to attack leukemia stem cells. TTI is completing formal preclinical studies and will carry out clinical trials aimed at demonstrating SIRPαFc’s safety and efficacy. The collaboration between Drs. Wang and Danska and TTI will assist in realizing the commercial potential of this promising discovery.