The present invention relates to a method of treating a B-cell malignancy in a subject using a vaccine composition comprising a population of malignant B cells from said subject transformed with a nucleic acid molecule encoding for a CD70 polypeptide.rnEpstein-Barr virus (EBV) infection in humans is a major trigger of malignant and non-malignant B cell proliferations. The inventors showed that EBV-specific T lymphocytes cannot expand properly when stimulated with CD70-deficient EBV-infected cells, while expression of CD70 restores expansion. In particular, the present invention relates to a method of treating a B-cell malignancy in a subject in need thereof comprising i) providing a sample of malignant B cells obtained from the subject ii) isolating and culturing a population of malignant B cells from the sample of step i), iii) introducing in the population malignant B cells of step ii) a nucleic acid molecule encoding for a CD70 polypeptide and iv) administering to the subject a therapeutically effective amount of the population of malignant B cells of step iii).