Most patients who take cancer drugs today get them through an intravenous infusion. Scientists have never been quite been able to consistently get this delivery route to work for genetically engineered cancer-fighting viruses, but San Francisco-based Jennerex Biotherapeutics is reporting today that it has found a way, in a move that could help its oncolytic viruses break out of a narrow market niche.
Instead of relying on a direct injection into a single bulky tumor, the usual way oncolytic viruses are delivered, Jennerex and its collaborators were able create an IV formulation that migrated from the bloodstream into tumors, according to research published this week in the journal Nature. The study looked at 23 patients with a variety of tumor types, and found that the drug made its way into tumors in greater amounts when given in an escalating series of doses. Side effects were mostly mild to moderate flu-like symptoms that lasted a few days, consistent with prior studies of the other formulation.
“The idea has been around for decades, but nobody has been able to show you could deliver [an oncolytic virus] through an IV. If you can achieve IV delivery, it opens up the possibility of treating 10-fold more tumors,” says David Kirn, the CEO of Jennerex, and the lead author on the scientific publication.
No one has yet come up with an FDA-approved therapy from this field of oncolytic viruses, although plenty have tried. Jennerex is one of a handful of companies, along with Calgary, AB-based Oncolytics Biotech (NASDAQ: ONCY) and Woburn, MA-based Biovex (recently acquired by Amgen), pursuing the method.
The basic idea here is to genetically modify viruses to selectively infect tumors, replicate like crazy in there, and cause the cancer cells to burst. Most of the treatments, Jennerex’s included, are also designed to provoke an immune reaction to mop up residual cancer cells. Jennerex reported some encouraging, albeit preliminary, results last May from a clinical trial of its experimental oncolytic virus, when it was directly injected into the tumors of 30 patients with liver cancer.
But the new intravenous study, which started about 18 months ago, gives Jennerex a potentially more attractive delivery route for liver cancer patients, and opens the door to treating other malignancies, beyond just helping people with inoperable liver tumors.
Here’s how the study worked. Researchers gave just a single IV infusion of Jennerex’s JX-594, and then followed up one week later to take a biopsy from each patient, Kirn says. Scientists looked at those biopsies a couple of different ways, through traditional pathology staining, and through quantitative PCR measurement, to see if the drug infected the tumor, and if so, to what extent. Patients were given an escalating series of five doses. While the drug didn’t appear to have any effect at the lowest dose, it infected tumors in increasing concentrations as the doses got higher, Kirn says.
“We were worried at the start that we were looking for a needle in haystack, that we could miss seeing a replicating virus if it was spotty in the tumor. What surprised us was the extent of replication in tumors,” Kirn says.
This work is still at a very early stage, so all the usual caveats apply. Researchers will need to show the IV method can work with the repeated dosing required in real-world cancer treatment, and that the drug can help people live longer with acceptable side effects. Doctors will want to know which specific forms of cancer are most vulnerable to this treatment method (so far, it looks like liver and colon cancer, Kirn says).
But the early findings are encouraging enough that Jennerex is incorporating the IV dose into the design of an ongoing a 120-patient Phase II liver cancer study, and plans to use it in a Phase III study to come later, Kirn says. Jennerex recently raised $8.5 million to finance the Phase II liver cancer study, which should be enough to run the company through the first quarter of 2013, when it expects to find out whether its drug offers longer survival times than today’s best supportive care, Kirn says.
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