GlaxoSmithKline's experimental drug pazopanib appears to be effective in fighting ovarian cancer, based on measurements of a biological marker used to predict tumour recurrence.

Given the promising results, the world's second largest drugmaker said it planned to push ahead with a final-stage Phase III clinical trial of the once-daily pill in ovarian cancer.

Pazopanib, like Genentech ‘s blockbuster injection Avastin, works by inhibiting the formation of new blood vessels that feed tumours.

Results of a small Phase II study, involving 35 patients, showed that 31 percent of ovarian cancer patients had a greater than 50 percent decrease in blood levels of a protein called CA-125 when given the drug.

Because CA-125 levels rise when tumours are growing, the protein is used to predict the risk of tumours recurring and to test patients' response to chemotherapy.

The results were presented at the annual meeting of the European Society of Medical Oncology (ESMO) in Stockholm. "Many patients with ovarian cancer will have a recurrence of cancer following initial chemotherapy," said Michael Friedlander of the Prince of Wales Cancer Centre in Sydney.

"This study clearly demonstrates that pazopanib is an active, well-tolerated drug for women with recurrent ovarian cancer."