Pfizer's bid to cement the position of its mTOR inhibitor Torisel in the kidney cancer market suffered a setback when the drug failed to show a benefit in a phase III combination study.
Torisel (temsirolimus) was being tested alongside Roche's Avastin (bevacizumab) to see if it was more effective than Avastin plus interferon alfa-2b in treating patients with advanced renal cell carcinoma (RCC).
Pfizer's drug failed to achieve the primary endpoint of extending progression-free survival (PFS) in the INTORACT study, which sought to expand Torisel's indications from its current approval as a first-line monotherapy in advanced RCC patients with poor prognostic risk.
The news is another setback in Pfizer's bid to extend the indications for the mTOR inhibitor. In May a late-stage trial of the drug in the second-line treatment of RCC found that Torisel was not as effective as rival drug Nexavar (sorafenib) from Bayer in improving survival.
"This trial advances our knowledge about the role and limitations of combining targeted therapies in the treatment of advanced RCC," commented Dr Mace Rothenberg, Pfizer's senior vice president of clinical development and medical affairs, oncology.
"Additional analyses will be performed to help us understand this result," he added.
RCC has been a fertile development ground for pharma companies in recent years, and Pfizer has built up its own portfolio of treatments for the cancer, which occurs in around 270,000 people around the world each year.
In addition to Torisel, the pharma company won approval for kinase inhibitor Inlyta (axitinib) as a second-line treatment for RCC earlier this year, joining its Sutent (sunitinib) product for the cancer which debuted in 2006.
The failure of its latest study closes the door on a potentially lucrative line extension for Torisel, as Avastin plus interferon alfa-2b is a widely used first-line therapy in advanced RCC patients.