Dasatinib preferentially induces apoptosis by inhibiting Lyn kinase in nilotinib-resistant chronic myeloid leukemia cell line

Nilotinib is approved for treatment of newly diagnosed chronic myeloid leukemia (CML) and it is shown superiority over imatinib in first-line treatment for patients of CML. In this study, we established a nilotinib-resistant cell line, K562NR, and evaluated the resistance to nilotinib and efficacy of dasatinib. We found activation of Lyn plays a dominant role in survival of the nilotinib-resistant cell line. We found dasatinib induces the apoptosis of nilotinib-resistant cells and inhibits Lyn kinase activity. This novel nilotinib-resistant CML cell line may help to explore novel therapy for CML

Management of imatinib-resistant CML patients

Imatinib has had marked impact on outcomes in chronic myelogenous leukemia (CML) patients for all stages of the disease and is endorsed by international treatment guidelines as the first line option. Although imatinib is highly effective and well tolerated, the development of resistance represents a clinical challenge. Since the most frequently identified mechanism of acquired imatinib resistance is bcr-abl kinase domain point mutations, periodic hematologic, cytogenetic, and molecular monitoring is critical throughout imatinib therapy. Once cytogenetic remission is achieved, residual disease can be monitored by bcr-abl transcript levels as assayed by reverse transcription polymerase chain reaction (RT-PCR). Detection of bcr-abl mutants prior to and during imatinib therapy can aid in risk stratification as well as in determining therapeutic strategies. Thus, mutation screening is indicated in patients lacking or losing hematologic response. Moreover, search for mutations should also be performed when a 3-log reduction of bcr-abl transcripts is not achieved or there is a reproducible increase of transcript levels. In patients harboring mutations which confer imatinib resistance, novel second line tyrosine kinase inhibitors have demonstrated encouraging efficacy with low toxicity. Only the T315I bcr-abl mutant has proved totally resistant to all clinically available bcr-abl inhibitors. Strategies to further increase the rates of complete molecular remissions represent the next frontier in the targeted therapy of CML patients

Blinatumomab compared with standard of care for the treatment of adult patients with relapsed/refractory Philadelphia chromosome–positive B-precursor acute lymphoblastic leukemia

Background: A single-arm, phase 2 trial demonstrated the efficacy and safety of blinatumomab, a bispecific T-cell\u2013engaging antibody construct, in patients with relapsed/refractory (r/r) Philadelphia chromosome\u2013positive (Ph+) acute lymphoblastic leukemia (ALL), a rare hematologic malignancy with limited treatment options. This study compared outcomes with blinatumomab with those of a historical control treated with the standard of care (SOC). Methods: The blinatumomab trial enrolled adult patients with Ph+ ALL who were r/r to at least 1 second-generation tyrosine kinase inhibitor (n = 45). Propensity score analysis (PSA) was used to compare outcomes with blinatumomab with those of an external cohort of similar patients receiving SOC chemotherapy (n = 55). The PSA mitigated confounding variables between studies by adjusting for imbalances in the age at diagnosis and start of treatment, sex, duration from diagnosis to most recent treatment, prior allogeneic hematopoietic stem cell transplantation, prior salvage therapy, and number of salvage therapies. Bayesian data augmentation was applied to improve power to 80% with data from a phase 3 blinatumomab study in r/r Philadelphia chromosome\u2013negative ALL. Results: In the PSA, the rate of complete remission or complete remission with partial hematologic recovery was 36% for blinatumomab and 25% for SOC, and this resulted in an odds ratio of 1.54 (95% confidence interval [CI], 0.61-3.89) or 1.70 (95% credible interval [CrI], 0.94-2.94) with Bayesian data augmentation. Overall survival favored blinatumomab over SOC, with a hazard ratio of 0.81 (95% CI, 0.57-1.14) or 0.77 (95% CrI, 0.61-0.96) with Bayesian data augmentation. Conclusions: These results further support blinatumomab as a treatment option for patients with r/r Ph+ ALL

Molecular measurement of BCR-ABL transcript variations in chronic myeloid leukemia patients in cytogenetic remission

<p>Abstract</p> <p>Background</p> <p>The monitoring of <it>BCR-ABL </it>transcript levels by real-time quantitative polymerase chain reaction (RT-qPCR) has become important to assess minimal residual disease (MRD) and standard of care in the treatment of chronic myeloid leukemia (CML). In this study, we performed a prospective, sequential analysis using RT-qPCR monitoring of <it>BCR-ABL </it>gene rearrangements in blood samples from 91 CML patients in chronic phase (CP) who achieved complete cytogenetic remission (CCyR) and major molecular remission (MMR) throughout imatinib treatment.</p> <p>Methods</p> <p>The absolute level of <it>BCR-ABL </it>transcript from peripheral blood was serially measured every 4 to 12 weeks by RT-qPCR. Only level variations > 0.5%, according to the international scale, was considered positive. Sequential cytogenetic analysis was also performed in bone marrow samples from all patients using standard protocols.</p> <p>Results</p> <p>Based on sequential analysis of <it>BCR-ABL </it>transcripts, the 91 patients were divided into three categories: (A) 57 (62.6%) had no variation on sequential analysis; (B) 30 (32.9%) had a single positive variation result obtained in a single sample; and (C) 4 (4.39%) had variations of <it>BCR-ABL </it>transcripts in at least two consecutive samples. Of the 34 patients who had elevated levels of transcripts (group B and C), 19 (55.8%) had a < 1% of <it>BCR-ABL/BCR </it>ratio, 13 (38.2%) patients had a 1% to 10% increase and 2 patients had a >10% increase of RT-qPCR. The last two patients had lost a CCyR, and none of them showed mutations in the <it>ABL </it>gene. Transient cytogenetic alterations in Ph-negative cells were observed in five (5.5%) patients, and none of whom lost CCyR.</p> <p>Conclusions</p> <p>Despite an increase levels of <it>BCR-ABL/BCR </it>ratio variations by RT-qPCR, the majority of CML patients with MMR remained in CCyR. Thus, such single variations should neither be considered predictive of subsequent failure and nor an indication for altering imatinib dose or switching to second generation therapy. Changing of imatinib on the basis of <it>BCR-ABL/BCR</it>% sustained increase and mutational studies is a prudent approach for preserving other therapeutic options in imatinib-resistant patients.</p