Astellas and partner Aveo Pharmaceuticals are breathing easier now they have reported overall survival (OS) data with their kidney cancer drug tivozanib which show it matches a key rival.

Two-year data from the TIVO-1 study indicate there is no statistically significant difference in OS between tivozanib and Bayer/Onyx' Nexavar (sorafenib), with both drugs providing a benefit of around 29 months.

Prospects for tivozanib have been under scrutiny since one-year OS data from the trial suggested it may not be as effective as Nexavar, a leading first-line therapy for advanced renal cell carcinoma (RCC) with sales approaching $1 billion a year worldwide in 2012.

For the primary measure in the study - progression-free survival (PFS) - tivozanib was superior to Nexavar with a significantly better PFS of 8.4 months and a response rate of 13 per cent, and the trial is something of a milestone in advanced RCC because it is the first to directly compare two of the newer first-line therapies.

Aveo and Astellas have always maintained that patient crossover in the study skewed the efficacy results in Nexavar's favour, while tivozanib has a better safety and tolerability profile than Bayer and Onyx's drug. In TIVO-1 the rate of patients requiring dose reductions because of side effects 14% for tivozanib compared with 44% for Nexavar.

The FDA is due to deliver its verdict on the product by July 28 and has said it intends to convene an advisory committee meeting to review the drug, which will probably take place sometime after April.

Astellas licensed worldwide rights outside Asia to tivozanib in February 2011 for an upfront payment of $125 million and up to $1.3 billion in clinical, regulatory and commercial milestones, Kyowa Hakko Kirin owning rights in Asia.

The drug is an oral drug in the vascular endothelial growth factor(VEGF) receptor inhibitor class, which includes Nexavar, GlaxoSmithKline's Votrient/Patorma (pazopanib) and Pfizer's Sutent(sunitinib) and Inlyta (axitinib).

The price paid by Astellas has been seen as fairly steep in some quarters; Decision Resources indicated last year that the drug would achieve sales of between $100m and $250m a year given its late entry into the RCC market, but with upside if it can also win approval in other indications such as colorectal and breast cancer.