Already in clinical trials, Reolysin, a reovirus-based therapy from Oncolytics Biotech, will soon be administered to patients with metastatic tumors in a company-sponsored phase I trial.
Reoviruses are only able to replicate in cancer cells with an activated Ras pathway, and do not harm healthy cells. The Ras pathway is instrumental in transferring growth signals to the nucleus of a cell, telling the cell when and how to grow – much like an ‘on-off’ switch. A cell with an activated Ras pathway, which has lost its ability to ‘turn off’, leads to uncontrolled cell growth. These mutations are found in approximately two-thirds of all human cancers.
The virus in Reolysin will invade Ras-activated cancer cells, where the virus is able to replicate until it kills the host tumor cell. When the cancer cell dies, thousands of progeny virus particles are released, which then proceed to infect and kill adjacent cancer cells.
Oncolytics is, unsurprisingly, confident about the therapy’s potential and has stated that the use of a common virus to kill cancer cells offers hope for a revolutionary approach to treating cancer.
Indeed, the new approach could prove a promising alternative to currently used therapies if, as the company believes, the process can infect and kill all of the infected cancer cells with activated Ras pathways without causing the side-effects such as nausea and hair loss that are associated with radiation and chemotherapy.
According to Oncolytics, patients have not suffered any serious adverse effects with Reolysin in completed clinical trials to date. If this encouraging safety profile is sustained, and if efficacy endpoints are achieved in future trials, Reolysin could well join the growing number of novel therapies with the potential to expand treatment options for a patient population that is also on the increase.