Our results show that, irrespective of the hematologic response, monitoring for emerging mutations in the first months of therapy may play a role in detecting patients with worse prognosis, for whom a revision of the therapeutic strategy should be considered.

Key Points• UDS demonstrated that BCR-ABL KD mutations detectable with conventional methods may just be the tip of the iceberg.• The information provided by conventional Sanger sequencing may not always be sufficient to predict responsiveness to a given TKI.In chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, tyrosine kinase inhibitor (TKI) therapy may select for drug-resistant BCR-ABL mutants. We used an ultra-deep sequencing (UDS) approach to resolve qualitatively and quantitatively the complexity of mutated populations surviving TKIs and to investigate their clonal structure and evolution over time in relation to therapeutic intervention. To this purpose, we performed a longitudinal analysis of 106 samples from 33 patients who had received sequential treatment with multiple TKIs and had experienced sequential relapses accompanied by selection of 1 or more TKI-resistant mutations. We found that conventional Sanger sequencing had misclassified or underestimated BCR-ABL mutation status in 55% of the samples, where mutations with 1% to 15% abundance were detected. A complex clonal texture was uncovered by clonal analysis of samples harboring multiple mutations and up to 13 different mutated populations were identified. The landscape of these mutated populations was found to be highly dynamic. The high degree of complexity uncovered by UDS indicates that conventional Sanger sequencing might be an inadequate tool to assess BCR-ABL kinase domain mutation status, which currently represents an important component of the therapeutic decision algorithms. Further evaluation of the clinical usefulness of UDS-based approaches is warranted. (Blood. 2013;122(9):1634-1648

We used a sensitive real-time reverse transcription-polymerase chain reaction assay to quantify cyclin D1 mRNA levels in bone marrow samples collected at diagnosis from 74 newly diagnosed multiple myeloma (MM) patients who were randomized to undergo either single or double autologous peripheral blood stem cell transplantation as part of first-line therapy for their malignancy. In 46 cases, fluorescence in situ hybridization (FISH) analysis and/or conventional cytogenetics were performed to detect chromosome 11 abnormalities. Patients with the t(11;14) or trisomy 11 significantly overexpressed cyclin D1 (P < .0001) in comparison with patients without 11q abnormalities, who had cyclin D1 mRNA levels similar to healthy donors. Overall, 32 (43%) of 74 patients showed cyclin D1 overexpression. No difference was found between cyclin D1-positive (group A) and cyclin D1-negative (group B) patients with respect to presenting clinical and laboratory characteristics, including chromosome 13 abnormalities, as well as to response to therapy and overall survival, both of which were calculated on an intent-to-treat basis. Patients who overexpressed cyclin D1 had significantly longer duration of remission in comparison with patients who did not (41 vs 26 months, respectively; P ‫؍‬ .02). As a result, median event-free survival (EFS) was longer in group A than in group B (33 vs 24 months, respectively; P ‫؍‬ .055). We concluded that cyclin D1 overexpression is closely associated with 11q abnormalities and identifies a subset of MM patients who are more likely to have prolonged duration of remission and EFS following autologous transplantation. (Blood. 2003;102:1588-1594)