A team of researchers lead by Dr. John Bell, professor at the University of Ottawa’s Faculty of Medicine, and senior scientist at the Ottawa Hospital Research Institute (OHRI), has helped carry out a cancer therapy trial, the first of its kind in the world, that reported very promising results.
The study shows that an intravenously-delivered viral therapy can consistently infect and spread within tumors without harming normal tissues in humans. It is also the first to show tumor-selective expression of a foreign gene after intravenous delivery.
The trial involved a total of 23 patients, 7 of which were in Ottawa, with advanced cancers that had spread to multiple organs and were unresponsive to standard treatments. The patients were administered one of five dose levels of a virus called JX-594 derived from a strain of vaccinia virus used extensively as a live vaccine against smallpox. It has a natural ability to replicate preferentially in cancer cells, but it has also been genetically engineered to enhance its anti-cancer properties.
Biopsies of the patients showed that 87% of patients in the two highest dose groups showed that the virus was replicated in their tumor but left normal tissues untouched. The trial also gave substance to promising anti-cancer capabilities reporting six out of eight patients (75%) in the two highest dose groups experienced a shrinking or stabilization of their tumor. Those in lower dose groups were less likely to experience this effect.
Additionally, the treatment proved to be extremely safe as the most common side effect was mild to moderate flu-like symptoms that lasted less than one day.
Illustration: This three-dimensional reconstruction of part of a human colorectal tumor shows widespread infection with oncolytic vaccinia virus (green). –Naomi De Silva/University of Ottawa.
University of Ottawa News Release (08/31/11)
Science Daily (08/31/11)
Abstract (Nature; 477, 99-102 (09/01/11))