Following hot on the heels of an identical European approval, Pfizer says it has secured a nod from the US Food and Drug Administration to market its new cancer therapy Sutent (sunitinib) for advanced kidney cancer patients who have not previously received treatment for the disease.

A first-line indication is an enormous boon for a product because it opens the door to a significantly larger market. Although relatively rare in comparison to other tumour types, kidney cancer – or renal cell carcincoma – has been increasing year on year, with an estimated 51,000 people expected to be diagnosed in the USA alone in 2007.

The thumbs up from the FDA stems from impressive results in a Phase III study showing a doubling of progression-free survival in 750 treatment-naïve patients with advanced disease who were given either Sutent or the current standard of care, interferon-alfa. Median progression free survival was 11 months in patients given the Pfizer therapy, versus five months amongst those in the comparator group. Furthermore, five times more patients responded to treatment (28% versus 5%) and Sutent was also better tolerated, with fewer discontinuations (9% versus 12%).

Sutent was first approved in January 2006 under the US drug regulator’s accelerated approvals process to treat both gastrointestinal stromal tumours in patients who have failed to respond to Novartis’ blockbuster agent Glivec (imatinib) and as a second-line therapy for kidney cancer that has spread to other parts of the body. With the new labeling, this accelerated approval – which was based on partial response rates and duration of response rather than the more concrete endpoints of objective response rate and progression-free survival – is now converted to regular approval.

Sutent (sunitinib) belongs to a new class of multiple receptor tyrosine kinase inhibitors - which work by preventing tumour growth while simultaneously restricting cancer cells' blood supply. It competes with Bayer’s new kidney cancer drug Nexavar (sorafenib), which is also cleared for treating advanced disease, but does not specify first-line use.