GlaxoSmithKline's Votrient is comparable to Pfizer's market leader Sutent in terms of progression free survival (PFS) in patients with kidney cancer, data from a head-to-head study show.

The eagerly awaited results of the open-label, Phase III COMPARZ trial showed that Votrient was non-inferior to Sutent (sunitinib) with a hazard ratio for PFS of 1.047.

Median PFS was found to be 8.4 months for GSK's drug compared to 9.5 months for Pfizer's rival, while the overall response rates (a secondary endpoint) were 31% and 25%, respectively.

The drugs' safety profiles also seem broadly comparable, with 42% in the Votrient arm and 41% in Sutent arm experiencing serious adverse events.

Looking more closely, there are some differences within the most common side effects, with 29% of patients taking Votrient and 50% of patients taking Sutent experiencing hypertension, and 10% and 34% experiencing thrombocytopenia, respectively. 

On the other hand, forty-six percent of patients taking Votrient experienced hypertension compared to 41% on Sutent, while 31% versus 18% showed increased levels of alanine transaminase, a marker of liver function.

GSK pleased

GSK said it is pleased with the results, but while it is undoubtedly good news for the firm that its drug is on par with the market leader on the PFS side, it is unlikely that this alone will help it make significant inroads into Sutent's lion's share of the market, experts believe.

Sutent was approved in the US for renal cell carcinoma in 2006, and currently generates sales of almost $1.2 billion (including for refractory gastrointestinal stromal tumors (GIST) and advanced pancreatic neuroendocrine tumors) a year, and has a 50% hold of the RCC market. 

Votrient appeared on the market three years later, but made annual sales of just $100 million in 2011. The drug was approved for the treatment of soft tissue sarcoma on both sides of the Atlantic earlier this year.