A vaccine that could work in tandem with Novartis’ Glivec/Gleevec in the treatment of patients with chronic myeloid leukaemia has shown preliminary efficacy in a Phase II clinical trial.

The vaccine, developed by US biotechnology firm Breakthrough Therapeutics and called VAX100, was tested in 21 patients with CML whose disease had stabilized but not gone into remission after two years of Glivec (imatinib mesylate) therapy.

VAX100 induced an immunological response in 94% of those treated, and out of 10 patients with cytogenetic markers for the disease at enrollment, six showed a complete response. In addition, three were found to have no sign of a hybrid gene product – the kinase BCR-ABL – which is thought to lie at the root of CML.

Breakthrough said the results were encouraging because although Glivec has transformed the treatment of CML patients – and turned itself into a blockbuster drug as a result - not all patients achieve a complete cytogenetic remission and most patients maintain detectable CML at the molecular level.

Additional studies will look at a different dosing regimen of the vaccine, with booster doses that are closer together, according to the researchers who conducted the study.

The research was presented at the American Society of Hematology annual meeting in Atlanta last month.