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Genentech/Roche: Trial Delay Won't Choke Avastin's Growth

Posted on: Monday, 13 February 2006, 15:00 CST

Following a higher rate of death in an experimental treatment arm, Roche and Genentech have temporarily suspended patient enrollment in a phase III study evaluating Avastin in colorectal cancer. Although Roche's shares slipped following the news, Avastin's blockbuster status is unlikely to be affected given its overall utility in colorectal cancer.

The phase III trial, named AVANT, aims to evaluate 3,450 stage II and III colorectal cancer patients, who will be given adjuvant treatment following surgery as one of three regimens: the FOLFOX regimen (oxaliplatin, leucovorin and 5-fluorouracil), FOLFOX plus Avastin (bevacizumab), or XELOX (capecitabine and oxaliplatin) plus Avastin.

Excluding deaths due to recurrence of colorectal cancer, mortality rates in the three treatments arms were 0.6% for FOLFOX, 0.4% for FOLFOX plus Avastin and 1% for XELOX plus Avastin.

Suspension of enrollment was based on the incidence of two fatalities in the Avastin/XELOX arm due to cardiac events and three because of unknown causes, some of which occurred in younger patients.

While some industry analysts have shown concern over the effect the suspension will have on Avastin's potential sales in the adjuvant setting, these worries may be unfounded. Another large-scale phase III trial, named C-08, is continuing enrollment as planned. This trial will randomize 2,714 early-stage colorectal cancer patients to receive adjuvant therapy of FOLFOX with or without Avastin. It does not include a XELOX plus Avastin arm and the data safety monitoring board (DSMB) has recommended that no changes be made to the study.

It is therefore likely that, even if the AVANT DSMB concludes with an outcome that negatively affects the trial, Avastin's potential in the adjuvant setting for colorectal cancer will remain largely unaffected.

In addition, worldwide sales of Avastin in 2005 were $1.3 billion and it is unlikely that the AVANT announcement will deter physicians from continuing to prescribe the drug. Furthermore. if results from the C-08 trial are positive, Avastin could build on this by making its mark in the adjuvant treatment of colorectal cancer, particularly in the US.

Conversely, Avastin's later approval in Europe and the more cautious nature of European physicians means the news could slow uptake of the drug in the first-line setting in this market. The use of Avastin is nevertheless expected to eventually reach the same levels in Europe as those seen in the US.

Source: Datamonitor

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