Bocchia M et al. (2005) Effect of a p210 multipeptide vaccine associated with imatinib or interferon in patients with chronic myeloid leukaemia and persistent residual disease: a multicentre observational trial. Lancet 365: 657–662

Early results from an observational trial in Italy suggest that a new vaccine might improve outcomes in patients with chronic myeloid leukemia.

The multipeptide vaccine, named CMLVAX100, was designed to target the b3a2 splice-region variant of the BCR-ABL-derived fusion protein p210, expression of which is specific to chronic myeloid leukemia. Sixteen patients with persistent, stable, b3a2-related chronic myeloid leukemia each received six subcutaneous vaccinations every 2 weeks. All patients continued to receive conventional treatment with imatinib or interferon-alpha (IFN-α).

The vaccine was well tolerated and appeared to generate an antitumor effect in the majority of patients. After 3 months, improved cytogenetic responses were observed in all nine imatinib-treated patients who had cytogenetic disease at baseline, and in five of the six patients receiving IFN-α. A total of seven patients achieved complete cytogenetic remission. Furthermore, a molecular response—indicated by a failure to detect BCR-ABL transcripts—was observed in four of these patients. The one imatinib-treated patient who began the study in complete cytogenetic remission also showed a reduction in residual molecular disease after receiving the vaccine.

The investigators conclude that vaccination with CMLVAX100 might help to reduce residual disease in patients with b3a2-related chronic myeloid leukemia, and might also improve molecular response rates. The results of larger studies are awaited.