Biotech giant Sirtex has suffered a massive share price plunge amid disappointing results from its key cancer treatment study.
More than $1 billion has been wiped from the market value of biotech Sirtex Medical after a treatment under development for colorectal cancer produced mixed results.
The company's share price more than halved, reducing its total value to $991 million, from $2.2 billion at the start of the day's trade.
Sirtex has been evaluating a new treatment option for patients with colorectal cancer that has spread to the liver.
It considered whether a type of chemotherapy in combination with internal radiation implants, known as SIR-Spheres, was more effective than chemotherapy alone.
"Based on the preliminary analysis just completed, the primary endpoint of the SIRFLOX study was not achieved," Sirtex said.
Sirtex shares dropped by 62 per cent to $14.80 in early trade, before recovering some ground to close at $17.53, down $21.47, or 55 per cent.
The study did not show a statistically significant improvement in overall progression-free survival in the first line treatment of non-resectable metastatic colorectal cancer (mCRC).
Overall progression-free survival measures progression of existing tumours and/or the development of new tumours in any organ or body.
But the study did show a statistically significant improvement in progression-free survival in the liver.
Sirtex said this was important because liver tumours were commonly the only or dominant site of disease in patients with mCRC and were the major site of disease influencing survival.
Up to 90 per cent of mCRC patients die of liver failure as a result of the effects of liver tumours.