CancerVax partnered with Serono and released Canvaxin in 2004; a therapeutic polyvalent cancer vaccine. It was an antigen-rich, allogeneic whole-cell vaccine developed in 1984 from three melanoma cell lines and is the most extensively studied melanoma vaccine to date. However, on October 3, 2005, CancerVax announced the discontinuation of its Phase 3 clinical trial of Canvaxin in patients with Stage III melanoma. The decision followed the recommendation of the independent Data and Safety Monitoring Board (DSMB) with oversight responsibility for the clinical trial. The DSMB decided, based upon the data reviewed at the third interim analysis, that it was unlikely that the trial would provide significant evidence of a survival benefit for Canvaxin-treated patients versus those receiving placebo. In addition, in April 2005, the companies announced the discontinuation of their other Phase 3 clinical trial of Canvaxin in patients with Stage IV melanoma based upon a similar recommendation of the independent DSMB following its review of data from the second interim analysis of this clinical trial.
The unsuccessful results of these clinical trials prompted CancerVax to say it would cut payroll by more than half to roughly 80 employees from 183. Immediately following this announcement, CancerVax's stock plunged $1.30, or 44.5%, to $1.62 and well below its 52-week low of $2.70. In less than 30 minutes after the opening bell, nearly 850,000 CancerVax shares had been traded, or more than 17 times the average daily trade for the previous three months. Shares of Serono were off 15 cents, or 0.9%, to $16.35.