http://www.investorideas.com/news/2015/biotech/04161.asp May be...

http://www.investorideas.com/news/2015/biotech/04161.asp

May be of interest.

Shane Storey, head of research at Australia-based Wilson HTM Investment Group,


SS : Sirtex Medical Ltd. (SRX:ASX) has a product that has been on the American market for more than a decade. It sells a selective internal radiation therapy (SIRT) product called SIR-Spheres, which is similar to the brachytherapy that some men receive for prostate cancer treatment. Microspheres of resin are impregnated with an isotope, yttrium-90, and the indication is metastatic colorectal cancer. The metastases are in the liver, and so the company is also going for primary hepatocellular carcinoma (HCC).
The therapy has been used in a salvage setting, in the sense that folks who have been diagnosed with metastatic colorectal cancer have gone through first-line chemotherapy, and perhaps treatment with some biological agents. SIR-Spheres has been a "third- or beyond-line" therapy, and has been an extraordinarily successful application. It has made great inroads penetrating the market, and it's been seen as pretty safe and effective in this clinical setting.
TLSR : Why do you think the company's first Phase 3 trial, SIRFLOX, did not meet its primary endpoint?
SS : Sirtex was going for progression-free survival. It did the trial very bravely, on an all-comers basis. If you look at the 530-odd patients enrolled, I think 40% of them had extrahepatic metastasis. Whether in the lung or lymph nodes or wherever, the metastes were also outside the liver. Keep in mind that this is a liver-directed therapy, administered almost directly into the tumor in the liver. The microparticle resins get trapped inside the tumor vasculature and effectively irradiate the tumor from inside out. The therapy did achieve progression-free survival in the liver cancer patients, so it worked in the manner it was intended. I'm looking forward to seeing the full data at the American Society for Clinical Oncology (ASCO) meeting this year, but I think the inclusion of those folks with extrahepatic tumors may have complicated the picture.
TLSR : The FDA won't allow a retrospective analysis for a subpopulation of patients--in this case to eliminate the extrahepatic liver cancer patients, will it? Will the company have to design another trial to eliminate those extrahepatic patients?
SS : The FDA won't allow a retrospective study, so yes, more trials are planned. The Phase 3 that failed the primary endpoint was the first of three trials designed to be prospectively combined to measure the more significant endpoint of overall survival. The first Phase 3 failed on the primary endpoint of progression-free survival, but the data on overall survival are still ongoing. Ultimately, we have another two trials reading into overall survival in 2017, and so all hope is not lost.
TLSR : You have a target price of AU$50/share on Sirtex. The last price I saw was more than AU$25/share. I'm thinking this has to be very speculative, doesn't it?
SS : Sirtex's current market price discounts any chance that SIR-Spheres will progress into first-line therapy, either in metastatic colorectal cancer or in primary liver cancer, not metastatic liver cancer. That has another set of safety and efficacy trials, from which we won't learn the data until the end of 2016. The current market price in the AU$20s is absolutely wiping out all of that upside, and only valuing the salvage business. I think it's too early to write Sirtex off.
TLSR : It's been a pleasure, Shane. Thank you.