LONDON - An experimental cancer pill from GlaxoSmithKline reduced the risk of tumour progression or death by 54 percent in advanced kidney cancer patients compared to placebo, trial results showed on Monday.

In spite of this, however, some 4 percent of patients taking the drug died during the course of the study against 3 percent of those on placebo.

Pazopanib belongs to a growing class of anti-cancer drugs that prevent the growth of new blood vessels which feed tumours.

Data presented at the annual American Society for Clinical Oncology meeting in Orlando showed the median progression free survival (PFS) -- the time without tumour growth or death -- for patients on pazopanib was 9.2 months compared with 4.2 months for those on placebo.

The study shows that pazopanib significantly improved PFS for patients regardless of whether or not they had prior therapy, said Dr. Cora Sternberg of the Department of Medical Oncology, San Camillo and Forlanini Hospitals, Rome.

While there have been many treatment advances for patients with advanced kidney cancer, there is still a need for medicines that are effective and well-tolerated.

The pivotal Phase III trial involved 435 patients with advanced kidney cancer, or renal cell carcinoma, who had either received no prior drug therapy or had been given cytokine-based treatment.

Side effects associated with the new drug included diarrhoea, hypertension, hair colour change, nausea, anorexia, vomiting and raised liver enzymes, which can signal liver toxicity, as well as rarer cases of thrombosis and haemorrhage.

Investigators attributed death due to the drug in 1.4 percent of patients in the treatment arm.

Glaxo is looking to pazopanib to help boost its position in cancer medicine. The drug was filed for approved with regulators in the United States in December 2008 and was submitted in Europe early this year.

The British-based drugmaker is also currently conducting a head-to-head study comparing pazopanib with Pfizer's (PFE.N) rival kidney cancer treatment, Sutent. (Reporting by Ben Hirschler; editing by Simon Jessop)

Medicine Pfizer Glaxosmithkline Cancer