Roche's blood cancer antibody outperforms MabThera

Roche has said its investigational drug GA101 (obinutuzumab) outperformed MabThera/Rituxan in a head-to-head study in patients with non-Hodgkin's lymphoma (NHL).

Roche says it will now press on with phase III testing of GA101 as an alternative to MabThera (rituximab), which was originated by Biogen Idec and is sold by Roche outside the USA and Japan.

The first comparative study of GA101 and MabThera (rituximab) - called GAUSS - showed that Roche's drug increased the overall response rate in patients with relapsed CD20-positive NHL, a common type of blood cancer. The two drugs also had a similar safety profile, according to data presented at the American Society of Hematology meeting yesterday.

GA101, an anti-CD20 monoclonal antibody, achieved an overall response rate of 45 per cent in the 175-patient phase II study, compared to 33 per cent for MabThera. Meanwhile, an independent review of radiology data from a subgroup of 149 patients with follicular lymphoma suggested that GA101 was even more effective in achieving a clinical response than the older drug, boosting response rates by 18 per cent.

A second phase Ib study, called GAUDI, found that GA101 was effective in combination with chemotherapy in patients with relapsed/refractory follicular lymphoma, once again without any additional safety concerns.

"Our goal with the GA101 programme is to demonstrate superior efficacy and comparable tolerability to MabThera/Rituxan," commented Hal Barron Roche's chief medical officer and head of global product development.

If approved, GA101 will address an NHL market expected to more than double in size from its 2009 level of $4bn to $8.4bn in 2019, despite the anticipated launch of biosimilar versions of MabThera/Rituxan from 2013, according to market research firm Decision Resources.

Novartis' Sandoz unit began phase II testing a biosimilar of rituximab in January, while Teva and Spectrum Pharmaceuticals are also reported to be developing their own copycat versions of the drug.

Roche hopes GA101 and other pipeline products such as a subcutaneous formulation of rituximab will soften the blow when biosimilars reach the market.

MabThera/Rituxan is one of the top three biologic drugs on the market and added 4.42bn Swiss francs ($4.7bn) to Roche's coffers in the first nine months of the year, up 6 per cent on the same period of 2010. In addition to NHL it is also indicated for rheumatoid arthritis and chronic lymphocytic lymphoma.