Cytos Biotechnology and partner Novartis have suffered a setback following disappointing data from a mid-stage trial of their investigational nicotine vaccine.

An interim analysis of a Phase II study of the vaccine, NIC002, has revealed showed that the primary endpoint of the trial, a statistically significant difference in continuous abstinence from smoking determined from weeks 8 to 12 after start of treatment compared to placebo, was not achieved. The study, which involved 200 ‘motivated to quit’ smokers, demonstrated that NIC002 was safe and well tolerated “but failed to induce sufficiently high antibody titers, which may have led to the negative outcome”.

Cytos said that Novartis is continuing the study in order to collect more long-term data on NIC002 “and will decide on the next steps once the scheduled 12-month duration of the clinical trial is completed and when all data have been analysed”. The company added that in a previous Phase II trial, the vaccine has promoted and sustained long-term abstinence from smoking in the subgroup of smokers that achieved high antibody levels upon vaccination.

Nevertheless, this latest data is a major blow to Cytos and its shares collapsed 32%. Novartis signed a deal in August 2007 which gave it global rights to NIC002.