Scientists have developed a new safer gene therapy that may reduce the risk of cancer and can be used for many blood diseases. Researchers at Washington State University in the US identified a way to reduce the development of cancer cells that are an infrequent but dangerous byproduct of gene therapy. They altered the way a virus carries a beneficial gene to its target cell.
The modified viral vectors reduce the risk of cancer and can be used for many blood diseases. Grant Trobridge, associate professor at Washington State University and his team is translating their findings into a stem cell gene therapy to target a life-threatening immunodeficiency in newborns called SCID-X1, also known as “Boy in the Bubble Syndrome.” Gene therapy holds potential for treating genetic diseases by replacing defective genes with repaired ones.
It has shown promise in clinical trials but has also been set back by difficulties delivering genes, getting them to work for a long time and safety issues. A joint French and English trial, for example, successfully treated 17 out of 20 patients with SCID-X1 only to see five of them develop leukemia. Trobridge and his colleagues are using a vector developed from a foamy retrovirus, so named because it appears to foam in certain situations.
Unlike other retroviruses, they do not normally infect humans. They also are less prone to activate nearby genes, including genes that might cause cancer. Retroviruses are a natural choice for gene therapy because they work by inserting their genes into a host’s genome.
With an eye towards making the vector safer, the team altered it to change how it interacts with a target stem cell so it would insert itself into safer parts of the genome. They found that it integrated less often near potential cancer-causing genes.
“Our goal is to develop a safe and effective therapy for SCID-X patients and their families. We have started to translate this in collaboration with other scientists and medical doctors into the clinic,” said Trobridge. He predicted that the therapy could be ready for clinical trials within five years.
The study appears in the journal Scientific Reports.