Sirtex study to pave way for wider use of SIR-Spheres

The results of a trial of Sirtex Medical's (ASX:SRX) SIR-Spheres microspheres, currently in its final stages, could help lay the foundation for increased clinical adoption of the liver cancer treatment, investors have heard.

At an investor technical briefing held by Sirtex yesterday, a consultant medical oncologist said a perceived lack of available clinical trial data has historically impediment to take-up of Sir-Spheres in clinical practice.

Oncologists often require level one evidence from randomised controlled trials to have confidence in a treatment, according to professor Peter Gibbs, a consultant medical oncologist at Royal Melbourne Hospital.

The clinical data available for the SIRT treatment, involving the use of the Sir-Spheres, is smaller-scale than the evidence available for chemotherapy regimes. Previous data also compares to old regimes no longer in popular use.

But the results from the multi-year SIRFLOX study, which involves 450 participants, may provide the evidence needed to stimulate adoption.

The SIRFLOX trial commenced in 2006. It is due to reach its primary completion date this month and wrap up at the end of the year.

The randomised, controlled study is comparing the use of SIR-Spheres in conjunction with chemotherapy drug Folflox against the use of Folflox alone, in patients with nonresectable liver metastases from primary colorectal carcinoma.

The primary endpoint is progression-free survival, while the secondary endpoints are overall survival time, tumour response and recurrence rates, quality of life and surgical resection rate.

According to Gibbs, if SIRFLOX can demonstrate an increased rate of hepatic resection and an overall survival advantage, it could be the evidence required to see major use of SIRT therapy in first-line treatment.

SIR-Spheres microspheres are designed to deliver targeted radiation therapy directly to cancer cells. They are placed into a tumour's blood supply.

The products have CE Mark approval in Europe, TGA approval in Australia, and FDA approval in the US.

While dose sales across the markets have been strong, they still represent less than 1% of the addressable market for liver cancer treatments. Increased first-line adoption would help drive sales further.