Sirtex Medical (ASX:SRX) saw shares tumble more than 25% today after a trial of its radioactive microspheres reported no effect in improving survival in patients with colorectal cancer.
Results from the Foxfire analysis study indicated that the use of SIR-Spheres Y-90 microspheres in combination with chemotherapy did not improve overall survival in patients with unresectable colorectal cancer compared to chemotherapy alone, the Woburn, Mass.-based company said.
While it wasn’t shown to improve overall survival, Sirtex said that data from the trial indicated that patients with cancer originating within the right side of the colon may gain more of a benefit from the spheres than chemotherapy alone.
“While these results are not what we expected, we believe that SIR-Spheres Y-90 resin microspheres will continue to play an important role in the treatment of patients with metastatic colorectal cancer. We are committed to helping people with advanced colorectal cancer and look forward to additional validation of this potentially significant finding to improve survival in patients with right-sided colon cancer in the first-line setting. Understanding why patients with right-sided colon cancer do not respond as well to certain drug regimens is currently one of the most actively investigated and controversial conundrums in the gastrointestinal oncology field. We have known for several years that patients with right-sided colon cancer that metastasizes generally have a poorer prognosis than those with left-sided disease. If our initial findings are confirmed, a five-month improvement in median survival in the first line setting could be seen as clinically meaningful in this difficult-to-treat population with liver metastases. This is an important time for the Sirtex Americas team. Every trial provides us with valuable information on how our product should be used and which patient populations may benefit the most. We are confident that our experienced customer-facing team can continue to educate on the recent NCCN Category 2A recommendation in the chemo-refractory population and use the emerging data from the Foxfire Combined Analysis to identify the most appropriate patients to benefit from our product in the earlier setting,” Sirtex Americas senior VP Gary Donofrio said in a press release.
Shares in Sirtex fell 28.3% today, down $4.25 to close at $10.75.