Pfizer's axitinib has shown promising activity in patients with advanced kidney cancer in a Phase II study.

A report in Lancet Oncology says the drug was able to stabilise some patients with cytokine-refractory, metastatic clear-cell renal cancer, a condition that usually responds poorly to treatment. Clear-cell renal cancer is the most common type of kidney cancer, which causes 13,000 deaths in the US alone each year. Current treatment options for this disease are limited and survival is poor; responses with use of chemotherapy, hormonal, biological treatment, and even with some of the new targeted drugs, seldom exceed 10%.

However, the new study of 52 patients carried out by Olivier Rixe of the University of Paris found that axitinib was able to stabilise the disease in a quarter of patients for six months of more. In addition, a total of 23 patients had complete or partial responses; 12 of these patients progressed during the study, with a duration of response ranging from around 4 months to 26 months. Additionally, 22 patients showed stable disease for longer than 8 weeks, including the 13 patients who demonstrated stable disease for 24 weeks or longer.

Prof Rixe said: "The objective response and time to progression in our study suggest that axitinib might be a promising drug in the treatment of patients with metastatic renal-cell cancer; although a randomised controlled trial is needed to confirm this finding." Four patients had early disease progression and 30 patients had hypertension related to the treatment, but side-effects in general were "manageable and controlled by dose modification or supportive care", the authors said.

Axitinib is a selective inhibitor of vascular endothelial growth factor receptors 1, 2 and 3, and works by restricting the growth of new blood vessels that the tumours need to spread. Recent Phase II studies have suggested that the drug also has potential to treat thyroid and pancreatic cancers. In addition, Prof Rixe speculated that by combining drugs that targeted different growth factor receptor pathways it might eventually be possible to lower doses, minimise toxicity and still achieve the optimum therapeutic benefit.

Commenting on the results, Dr Marston Linehan of the US National Cancer Institute, in Bethesda, said the findings suggested "that a drug such as axitinib has promise as a second-line treatment in cytokine-refractory metastatic renal-cell carcinoma, and might have potential as first-line treatment or in combination with other agents targeting the Von Hippel-Lindau pathway (or both)". By Michael Day

Pfizer to appeal Lipitor patent reversal in Germany

Meantime, Pfizer’s bid to protect its blockbuster Lipitor from generic competition has suffered a bit of a setback with the news that a German court has revoked the patent covering the firm’s cholesterol-lowerer.

The Federal Patent Court in Munich revoked the company’s patent covering Lipitor (atorvastatin) which expires in July 2010. The decision, which resulted from a challenge by Ranbaxy Laboratories and Germany’s Basics, “has no immediate commercial impact because neither company has regulatory approval to sell a generic atorvastatin product in Germany,” Pfizer said. The firm added that its basic patent covering atorvastatin remains in force and expires after the enantiomer patent (in November 2011).

Pfizer concluded by saying that it will appeal the decision, “a process expected to take two to three years”, noting that the ruling will have no effect on a pending challenge to the basic atorvastatin patent in Germany by the same two companies.