Sirtex Medical Slumps as Radiation Treatment Fails in Study

Sirtex Medical Ltd. slumped the most on record after its radiation treatment failed to meet a primary goal in a clinical trial.

The Sydney-based medical-product company fell 55 percent to A$17.53, an eight-month low, after saying that a combination of its radioactive beads, called SIR-Spheres, and chemotherapy didn’t meet the main target in a preliminary analysis of a study in bowel cancer patients. The so-called Sirflox study did, however, meet a secondary target for liver tumors.

The early results don’t support widening the use of SIR-Spheres, currently a treatment of last resort for patients with colorectal cancer that’s spread to the liver, said Derek Jellinek, a health-care analyst with Morgans Financial Ltd. in Sydney. Using SIR-Spheres in combination with chemotherapy as a frontline treatment could have quintupled its potential market.

“The treatment right now is relegated more to a salvage setting,” said Jellinek, who has had a reduce rating on Sirtex for more than a year. Today’s plunge puts “a more realistic” valuation on the stock, he said.

Final results of the Sirflox study will be submitted to the American Society of Clinical Oncology annual meeting, to be held May 29 to June 2 in Chicago, the company said.

The news wiped A$1.2 billion ($916 million) from Sirtex’s market value, the biggest one-day slide since they began trading in August 2000. The stock more than doubled in 2014, spurred by optimism for SIR-Spheres, which are injected into the liver’s blood supply.

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