Cancer researchers around the world are excited about a virus-based treatment developed in Ottawa that blows up leukemia cells “like popcorn.”
Results of the treatment, which boasts a 60 per cent cure rate in mice, are so promising and safe that it could go to clinical trials in humans in as little as two years.
The treatment is an engineered virus micro-particle that attacks leukemia cells. Within a day of an injection, the membranes of the cancer cells are compromised. The cell membranes deteriorate and the cells blow up “like popcorn,” says hematologist Dr. David Conrad, the senior coauthor of the study.
Three doses cured 60 per cent of the mice, and 80 per cent of the experimental population had long-term survival.
This is a “paradigm shift” in the understanding of using virus-based therapies to treat acute leukemia, the researchers said in Blood Cancer Journal, which is associated with the prestigious science journal Nature.
The news generated a lot of buzz at a recent international cancer conference in Quebec City, says Conrad, who’s part of a research team with members from the Ottawa Hospital Research Institute, the Ottawa Hospital and the University of Ottawa.
“When the immune system sees these cells, it gets rid of the debris. It forms an immune response. If new cancer cells grow, the immune system recognizes them and kills them,” says Conrad.
“There’s a lot of interest because it’s not just potent, it’s safe.”
For about a decade, Ottawa Hospital Research Institute scientists including Dr. John Bell, who was the other senior
researcher in this study, have been investigating viruses as cancer therapeutics.
But there’s an added wrinkle to using viruses to attack leukemia. Blood is a liquid, not a solid as with most cancer tumours. Blood cancers are “liquid tumours” circulating throughout the body.
The second difficulty is leukemia patients themselves, says Conrad.
Leukemia is often quite advanced before it is recognized, and it has already compromised the patient’s immune system.
Patients, particularly those who are older, are therefore prone to infections. Leukemia treatment often has to be initiated quickly – and it is harsh. The majority of leukemia patients do not survive longterm – only about 40 per cent are still alive after five years. Survivors are usually young, otherwise healthy patients who can tolerate a stem-cell transplant.
Patients who don’t qualify must take harsh and repetitive chemotherapy and radiation.
“Uncontrolled infections could cause a significant problem,” says Conrad.
The research team used virus particles that are nonreplicating. It’s the first time this approach has been used successfully to treat a cancer that has spread throughout the body.