Swiss drug giant Roche has called a temporary halt to enrollment in a Phase III trial of its cancer drug Avastin (bevacizumab) on concerns over safety, causing its shares to drop up to 5% in early morning trading across Europe.

Recruitment in the AVANT study, which is assessing the drug’s efficacy in preventing colon cancer recurrence following surgery, was stopped as it emerged that more deaths had occurred in patients taking a combination of Avastin and Xelox (Roche’s Xeloda [capecitabine] plus Sanofi-Aventis’ cancer drug Eloxatin [oxaliplatin]) compared to those receiving a regimen of Avastin and the standard chemotherapy combination Folfox (oxaliplatin, 5-fluorouracil, leucovorin), or Folfox alone.

However, Roche does not seem overly-concerned with the temporary suspension, and people already taking part in the evaluation will continue with treatment while an independent monitoring board completes a 60-day safety review, the group said in a statement.

“We concur with the Data Safety Monitoring Board’s recommendation,” stated Ed Holdener, Head of Global Development at Roche. “Patient safety is of utmost importance to us. Speed of recruitment in the AVANT trial is exceeding expectations and safety should be carefully monitored, especially in the adjuvant setting where the risk/benefit profile is different from that of the metastatic setting. As such, we are committed to continuous monitoring and evaluation of all safety data reported from the AVANT trial,” he added.

And Professor Aimery de Gramont, Principal Investigator for AVANT, commented: “We look forward to exciting findings that will hopefully confirm the efficacy benefits that we have already observed in the metastatic setting. This will open the avenue for new options for patients suffering from colon cancer.”

Avastin, one of the fastest growing of Roche’s top-five sellers, was the first drug to be approved in a new class of cancer agents that work by inhibiting the formation of blood vessels to the tumour. Referred to by many as "a pipeline in a product," due to its potential application across a spectrum of tumour types, Avastin, which is marketed in the USA by Genentech, pulled in sales of 1.7 billion Swiss francs ($1.3 billion) for Roche in 2005 - its first full year on the market.

Meanwhile, Roche and Genentech’s flagship product, the non-Hodgkin's lymphoma treatment MabThera/Rituxan (rituximab), which is also marketed in the US with Biogen Idec, has received extended approval from US regulators.

The US Food and Drug Administration has given the green light for the product, which raked in a whopping $4 billion for Roche in 2005, to be used in combination with standard chemotherapy as a first-line treatment for patients with diffuse large B-cell lymphoma, a fast-growing form of the condition.

"Diffuse large B-cell lymphoma can be fatal within as little as six months to two years without aggressive treatment," remarked Sandra J Horning, Chair of the lymphoma group for the Eastern Cooperative Oncology Group. "With this approval, Rituxan in combination with chemotherapy becomes the first FDA-approved treatment to improve survival for patients with this type of non-Hodgkin's lymphoma since the introduction of the CHOP chemotherapeutic regimen more than 25 years ago,” she added.