Roche's new leukaemia drug superior to Rituxan in study ZURICH (Reuters) - Roche's experimental leukaemia drug known as GA101 delayed disease progression in people with one of the most common forms of blood cancer longer than its top-seller Rituxan, the Swiss drugmaker said on Wednesday. Roche is hoping GA101 will help fend off cheaper competition for Rituxan, which loses patent protection in Europe later this year, threatening a blockbuster product with nearly $7 billion in annual sales. A late stage study showed GA101, or obinutuzumab, used in combination with chemotherapy, helped people with a particular form of leukaemia live longer without their disease worsening when compared with Rituxan which is also known as MabThera. The drugs were given in conjunction with the commonly used chemotherapy chlorambucil to previously untreated patients with chronic lymphocytic leukemia (CLL) who also had other health problems, such as heart disease. Roche said specific sugar molecules in GA101 were modified to change its interaction with the body's immune cells, creating a unique antibody designed to engage the patient's own immune system to help attack the cancerous cells. Roche said final data from the study would be submitted to the American Society of Hematology's annual meeting in December. Reporting by Martin de Sa'Pinto; Editing by David Cowell