The FDA approved Torisel (temsirolimus) from Wyeth for treating a type of advanced kidney cancer, but analysts say its potential may be limited.
The drug is an enzyme inhibitor, a protein regulating cell production, cell growth and cell survival. Approval was based on data showing it lengthened survival for some.
The approval marks the third new drug for the same tumor type, called renal cell carcinoma (RCC), in the past 18 months. Preceding Torisel in December 2005 was Bayer/Onyx’ Nexavar (sorafenib), which gained approval based on a delay in disease progression. In January 2006 Pfizer’s Sutent (sunitinib) gained accelerated approval for its ability to shrink tumor size.
This year, data showing Sutent delayed tumor progression led regulators to expand Sutent's label to include first-line treatment for RCC. Sutent appears to have been warmly received by oncologists. The drug posted $219 million in sales last year and $102 million in global revenues in the first quarter of 2007. Nexavar had $165 million in global revenue last year.
Torisel's use may be relegated to those patients who have issues with the other two products. Considering that RCC is a relatively rare disease affecting only about 51,000 people in the US annually, analysts say growth may be limited. But they estimate sales potential at around $392 million a year by 2010, a projection that figures in future indications.
Wyeth is studying Torisel in a Phase III trial of patients with mantle cell lymphoma, and the company is pursuing several additional studies in RCC. Pfizer and Bayer/Onyx also continue to study their drugs for other indications. A Phase III trial of Nexavar in patients with liver cancer was recently stopped early due to favorable results. Sutent is being tested in liver cancer and non-small cell lung cancer.