Mutations of the BCR-ABL kinase domain are a common mechanism of resistance to imatinib in chronic myeloid leukemia. We screened for mutations 171 patients failing imatinib therapy. Sixty-six mutations in 23 amino acids were identified in 62 (36%) patients not responding to imatinib. Phosphate-binding loop (P-loop) mutations were the most frequent (n ¼ 24; 36%). By multivariate analysis, factors associated with development of mutations were older age (P ¼ 0.026) prior interferon therapy (P ¼ 0.026), and accelerated phase or blast phase at time of imatinib failure (P ¼ 0.001). After a median follow-up of 38 months (range, 4-68 months) from the start of imatinib therapy, seven patients with non-P-loop and two with P-loop mutation died. By multivariate analysis, development of clonal evolution and higher percentage of peripheral blood basophils were associated with worse survival from the time of imatinib failure. Mutation status had no impact on survival. When survival was measured from the time therapy started, non-P-loop mutations together with duration of response and transformation at the time of failure to imatinib were associated with shorter survival. In conclusion, P-loop mutations were not associated with poor outcome, suggesting that the prognosis of patients who fail imatinib is multifactorial.

We examined whether combining alltrans retinoic acid (ATRA) and arsenic trioxide (ATO) might be an alternative to ATRA plus chemotherapy in untreated acute promyelocytic leukemia (APL). Twenty-five low-risk patients (

A B S T R A C T PurposeWe examined the outcome of patients with newly diagnosed acute promyelocytic leukemia (APL) treated with all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) with or without gemtuzumab ozogamicin (GO) but without traditional cytotoxic chemotherapy. From February 2002 to March 2008 patients with APL were treated with a combination of ATRA plus ATO. The first cohort of 65 patients received ATRA and ATO (beginning on day 10 of ATRA). High-risk patients (WBCs Ն 10 ϫ 10 9 /L) received GO on the first day. From July 2007, the second cohort of 17 patients received ATRA and ATO concomitantly on day 1. They also received GO on day 1, if high risk, and if their WBC increased to more than 30 ϫ 10 9 /L during induction. Monitoring for PML-RARA fusion gene was conducted after induction and throughout consolidation and follow-up. Patients and Methods ResultsOverall, 74 patients achieved complete remission (CR) and one achieved CR without full platelet recovery after the induction, for a response rate of 92%. Seven patients died at a median of 4 days (range, 1 to 24 days) after inclusion in the study from disease-related complications. The median follow-up is 99 weeks (range, 2 to 282 weeks). Among the responding patients, three experienced relapse at 39, 52, and 53 weeks. Three patients died after being in CR for 14, 21, and 71 weeks, all from a second malignancy. The estimated 3-year survival rate is 85%. ConclusionThe combination of ATRA and ATO (with or without GO) as initial therapy for APL was effective and safe and can substitute chemotherapy-containing regimens.

The combination of cytotoxic chemotherapy and imatinib has improved the outcome for patients with Philadelphia chromosome-positive (Ph ؉ ) acute lymphoblastic leukemia (ALL). Dasatinib has significant clinical activity in patients with imatinib resistance. We examined the efficacy and safety of combining chemotherapy with dasatinib for patients with Ph ؉ ALL. Newly diagnosed patients received dasatinib 50 mg by mouth twice per day (or 100 mg daily) for the first 14 days of each of 8 cycles of alternating hyper-CVAD, and high-dose cytarabine and methotrexate. Patients in complete remission received maintenance daily dasatinib and monthly vincristine and prednisone for 2 years, followed by dasatinib indefinitely. Thirty-five patients with untreated Ph ؉ ALL with a median age of 53 years (range, 21-79 years) were treated; 33 patients (94%) achieved complete remission. Two patients died of infections before response assessment. Grade 3 and 4 adverse events included hemorrhage and pleural and pericardial effusions. With a median follow-up of 14 months (range, 4-37 months), the median disease-free survival and median overall survival have not been reached, with an estimated 2-year survival of 64%. The combination of chemotherapy with dasatinib is effective in achieving long-term remissions in patients with newly diagnosed Ph ؉ ALL. This study was registered at www.ClinicalTrials.gov as

Dasatinib and nilotinib are potent tyrosine kinase inhibitors (TKIs) with activity against many imatinib-resistant chronic myeloid leukemia (CML) clones with BCR-ABL kinase domain (KD) mutations, except T315I. We assessed for changes in the BCR-ABL KD mutation status in 112 patients with persistent CML who received a second-generation TKI after imatinib failure. Sixty-seven different KD mutations were detected before the start of therapy with a second TKI, with T315I seen in 15%. Equal numbers of patients received nilotinib or dasatinib following imatinib, and 18 received 3 TKIs. Response rates were similar for patients with and without mutations, regardless of mutation site except for T315I. Overall, 29 patients (26%) developed new KD mutations after therapy with a second (n ‫؍‬ 24) or third (n ‫؍‬ 5) TKI, but only 4 (4%) developed T315I. In 73% of cases, the KD mutations that persisted or developed following switch to new TKI were at sites also found in prior in vitro TKI mutagenesis assays. Although there is only a mild increase in mutation frequency with sequential TKI treatment, novel mutations do occur and mutation regression/acquisition/persistence generally reflects the in vitro differential sensitivity predicted for each TKI. In this study, there was no marked increase in development of T315I. (Blood. 2007;110: [4005][4006][4007][4008][4009][4010][4011]