the long-term outcome and efficacy of pr1/bcr-abl multipeptides vaccination in chronic myeloid leukemia: results of a 7-year longitudinal investigation

Background: although imatinib has revolutionized the treatment of chronic myeloid leukemia (cml), not all patients reach complete remission and a considerable proportion of the patients develop resistance to imatinib. material and methods: in an attempt to increase the tail on the survival curve, we conducted a phase i/ii study of pr1/bcr-abl multipeptides vaccination trial in cml patients with at least 15 months of imatinib treatment and 5 months of persistent molecular residual disease. results: one month after the completion of the vaccinations, 4 patients nearly developed a 1-log fall in their bcr-abl transcript level, with 4 patients achieving a major molecular response (mmr). nine patients were followed for more than a period of 7 years. the vaccinations were associated with a mmr in five patients and a complete molecular response (cmr) in one patient. the removal of imatinib in two patients who achieved mmr after the vaccinations led to a resurgence of the leukemia population and relapse. conclusion: our study suggests that a combination of immunotherapy with imatinib targeted therapy keeps the leukemia population under control, improving the long-lasting clinical and molecular response of cml patients, for at least 7 years.