Predictive biomarkers identify those patients suffering from immunoglobulin positive (Ig+) B lineage malignancies that are responsive to active immunotherapy, where the active immunotherapy comprises vaccination with a tumor-specific idiotype-immunogen. It is shown herein that patient responsiveness to the idiotype-immunogen is dependent upon the sequence of the immunogen, where an immunogen having a low number of tyrosine residues in the CDR1 (herein termed CDR1-Y10) regions of one or both of the immunogen heavy and light chains is predictive of a positive anti-tumor response, while a high number of CDR1 tyrosine residues (herein termed CDR1-Yhi) is predictive of a low anti tumor response.