Positive trial results for Sirtex

Sydney-based company Sirtex Medical has completed Phase II/III clinical trials that showed over 90 per cent of liver cancer patients successfully responded to its radioactive SIR-Spheres treatment.

In the same study, no patients responded to chemotherapy alone.

The results of the trial were presented at the annual meeting of the American Society of Clinical Oncology in Orlando, Florida this week.

Sirtex's chief financial officer, Peter Manley, said the trials were the first in which systemic (whole body) chemotherapy was used in combination with SIR-Spheres. "In our initial studies we looked at SIR-Sphere therapy, which is always directed at the liver, combined with regional chemotherapy," he said.

He said that from these first studies, it was revealed that liver cancer patients could still develop cancer at other sites that were not being treated with regional chemotherapy.

"To overcome the problem of the cancer spreading to other organs, systemic (whole body) chemotherapy was used instead of regional chemotherapy, in combination with the SIR-Spheres" said Manley.

Dr Colin Sutton, Sirtex's CEO, said the results were far better than the company could have anticipated and the company would now launch confirmatory studies in the northern hemisphere.

The small clinical trial involved 21 patients, and was designed to compare the response to treating patients with either chemotherapy alone using fluorouracil and leucovorin, or the same chemotherapy but with the addition of a single administration of SIR-Spheres. No patient receiving chemotherapy alone responded, compared with 91 per cent of patients who also received the SIR-Spheres.

Dr Guy Van Hazel, a senior medical oncologist at Perth Oncology and the trial's principal investigator, said that although the study was small, the response rate was much higher than had ever been achieved with chemotherapy alone, even with the newer second-generation drugs.

Van Hazel said the trial showed that the SIR-Spheres responses result in prolonged cancer remission of up to 15 months compared to chemotherapy's five months. If the results are translated into improved survival as seems likely, this will be a major advance.

"Further studies are planned combining SIR-Spheres with the second generation chemotherapy drugs, which may result in further improvements," said Van Hazel.

Severe bowel cancer is one of the most common forms of cancer in the western world with 11,000 new cases each year in Australia alone, the company said. The disease is usually fatal once it spreads to the liver and currently there is no treatment.

Sirtex estimated the potential US market for liver cancer treatment was worth $1 billion ($US522 million).