High complete remission rate and promising outcome by combination of imatinib and chemotherapy for newly diagnosed BCR-ABL-positive acute lymphoblastic leukemia: a phase II study by the Japan Adult Leukemia Study Group

Time to tune the treatment of Ph+ ALL

In this issue of Blood, Chalandon et al report the results of a prospective randomized study comparing standard vs less-intensive chemotherapy, both combined with imatinib, for patients with newly diagnosed Philadelphia chromosome–positive (Ph+) acute lymphoblastic leukemia (ALL). They show that the less-intensive therapy reduces early mortality without impairing efficacy, resulting in a significantly higher hematologic complete remission (CR) rate and an equivalent major molecular response (MMolR) rate.

Downregulated Poly-C binding protein-1 is a novel predictor associated with poor prognosis in Acute Myeloid Leukemia

Background

Depletion of Poly-C binding protein-1(PCBP1) is implicated in various human malignancies. However, the underlying biological effect of PCBP1 in cancers, including acute myeloid leukemia (AML), still remains elusive. The purpose of this study was to examine the expression and clinical outcome of PCBP1in acute myeloid leukemia.

Methods

Bone marrow fluids of 88 newly diagnosed AML patients were sampled, and the PCBP1 mRNA expression level was evaluated using quantitative RT-PCR. The association between PCBP1 expression and clinicopathological features or the survival status of the patients was assessed by Chi-square test and Kaplan-Meier method.

Results

Comparing newly diagnosed AML patients to normal healthy donors, PCBP1 expression was significantly decreased in AML patients (P < 0.001). Conversely, PCBP1 expression had accordingly recovered back to normal in patients with complete remission (P < 0.001). Clinical feature analyses showed that PCBP1 expression was negatively correlated with white blood cell count (P = 0.024). In addition, patients with low PCBP1 expression had poor disease-free survival (11.8 % vs. 45.3 %; P = 0.01) and overall survival (18.2 % vs. 42.4 %; P = 0.032), respectively.

Conclusions

Taken together, our results showed for the first time that expression of PCBP1 was down-regulated in newly diagnosed AML patients and might be an independent prognostic marker in AML and should to be further investigated.

Nilotinib combined with multiagent chemotherapy for newly diagnosed Philadelphia-positive acute lymphoblastic leukemia

We investigated the effects of nilotinib plus multiagent chemotherapy, followed by consolidation/maintenance or allogeneic hematopoietic cell transplantation (allo-HCT) for adult patients with newly diagnosed Philadelphia-positive (Ph-pos) acute lymphoblastic leukemia (ALL). Study subjects received induction treatment that comprised concurrent vincristine, daunorubicin, prednisolone, and nilotinib. After achieving complete hematologic remission (HCR), subjects received either 5 courses of consolidation, followed by 2-year maintenance with nilotinib, or allo-HCT. Minimal residual disease (MRD) was assessed at HCR, and every 3 months thereafter. The molecular responses (MRs) were defined as MR3 for BCR-ABL1/G6PDH ratios ≤10(-3) and MR5 for ratios <10(-5). Ninety evaluable subjects, ages 17 to 71 years, were enrolled in 17 centers. The HCR rate was 91%; 57 subjects received allo-HCT. The cumulative MR5 rate was 94%; the 2-year hematologic relapse-free survival (HRFS) rate was 72% for 82 subjects that achieved HCR, and the 2-year overall survival rate was 72%. Subjects that failed to achieve MR3 or MR5 were 9.1 times (P = .004) or 6.3 times (P = .001) more prone to hematologic relapse, respectively, than those that achieved MR3 or MR5. MRD statuses just before allo-HCT and at 3 months after allo-HCT were predictive of 2-year HRFS. Adverse events occurred mainly during induction, and most were reversible with dose reduction or transient interruption of nilotinib. The combination of nilotinib with high-dose cytotoxic drugs was feasible, and it effectively achieved high cumulative complete molecular remission and HRFS rates. The MRD status at early postremission time was predictive of the HRFS. This trial was registered at www.clinicaltrials.gov as #NCT00844298.

Risk factors for outcomes after unrelated cord blood transplantation for adults with acute lymphoblastic leukemia: a report on behalf of Eurocord and the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation

We performed a retrospective analysis on 421 adult patients who underwent unrelated cord blood transplantation (UCBT) for ALL. Median age was 32 years; 46% were in first CR (CR1), 32% in CR2 and 22% had advanced disease. Double UCBT was performed in 173 patients (41%). Myeloablative conditioning (MAC) was given to 314 patients (75%). Cumulative incidence (CI) of 60-day neutrophil recovery was 78%. CI of acute and chronic GVHD was 33 and 26%, respectively. Non-relapse mortality (NRM) at 2 years was 42%. Age⩾35 years (P<0.0001), advanced disease at UCBT (P<0.0001) and use of MAC (P<0.0001) were associated with increased NRM. Relapse incidence (RI) at 2 years was 28%; use of reduced intensity conditioning (RIC) (P=0.0002) was associated with increased RI. Two-year leukemia-free survival (LFS) was 39% for patients in CR1, 31% for CR2 and 8% for advanced disease. In multivariate analysis, factors associated with decreased LFS rate were: age ⩾35 years (P=0.034), use of MAC (P=0.032) and advanced disease (P<0.0001). These results show that UCBT is a valuable option to treat high-risk adult ALL when in remission. Strategies to decrease toxicity and relapse are needed to improve final outcomes.

The role of ponatinib in Philadelphia chromosome-positive acute lymphoblastic leukemia

The introduction of tyrosine kinase inhibitors has improved outcomes in Philadelphia chromosome-positive acute lymphoblastic leukemia, yet relapse due to the development of resistance mutations remains a major obstacle. Ponatinib is a novel tyrosine kinase inhibitor designed to overcome single-resistance mutations in the ABL kinase. Three clinical trials confirmed the efficacy of ponatinib in the relapsed and front-line setting in Philadelphia positive acute lymphoblastic leukemia, even in the presence of the T315I mutation, which confers resistance to other tyrosine kinase inhibitors. The rate of relapse appears to be very low when used in combination with chemotherapy, suggesting a role for ponatinib in newly diagnosed patients. A major concern with the use of ponatinib is the associated high risk of life-threatening vascular thrombotic events. Potential strategies to reduce this risk include minimizing the use of ponatinib in patients with significant baseline cardiovascular risk, careful surveillance and treatment of cardiovascular risk-factors and dose reduction of ponatinib.

Impact of Additional Cytogenetic Abnormalities in Adults with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

The occurrence of additional cytogenetic abnormalities (ACAs) is common in Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) but is of unknown significance in the tyrosine kinase inhibitor (TKI) era. We retrospectively analyzed data from a consecutive case series of adults with Ph+ ALL who had undergone allogeneic hematopoietic cell transplantation (alloHCT) at City of Hope between 2003 and 2014. Among 130 adults with Ph+ ALL who had TKI therapy before alloHCT, 78 patients had available data on conventional cytogenetics at diagnosis and were eligible for outcomes analysis. ACAs were observed in 41 patients (53%). There were no statistically significant differences in median age, median initial WBC count, post-HCT TKI maintenance, or disease status at the time of transplant between the Ph-only and ACA cohorts; however, the Ph-only cohort had a higher rate of minimal residual disease positivity at the time of HCT. Three-year leukemia-free survival (79.8% versus 39.5%, P = .01) and 3-year overall survival (83% versus 45.6%, P = .02) were superior in the Ph-only cohort compared with the ACA cohort, respectively. Monosomy 7 was the most common additional aberration observed in our ACA cohort (n = 12). Thus, when TKI therapy and alloHCT are used as part of adult Ph+ ALL therapy, the presence of ACAs appears to have a significant deleterious effect on outcomes post-HCT.

Allogeneic hematopoietic stem cell transplantation for adult patients with mixed phenotype acute leukemia: results of a matched-pair analysis

Adult patients with mixed phenotype acute leukemia (MPAL) have a poor prognosis, and the therapeutic role of allogeneic stem cell transplantation (allo-SCT) for MPAL remains to be elucidated. Thus, we retrospectively assessed the efficacy of allo-SCT for MPAL. Eighteen patients with MPAL were identified from the transplant outcome database of Kanto Study Group for Cell Therapy (KSGCT). We also selected 215 patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) as control cohorts using an optimal matching method. The 5-yr overall survival (OS) rate of patients with MPAL was 48.1%, and patients in remission at the time of transplant showed significantly better survival than those not in remission (5-yr OS: 71.8% vs. 0%, P = 0.001). No significant differences were seen in OS when stratifying patients according to immunophenotype, cytogenetic abnormalities, or the type of induction therapy. The 5-yr OS rate of patients with MPAL was not significantly different compared with AML control patients (48.1% vs. 48.1%; P = 0.855) or ALL control patients (48.1% vs. 37.8%; P = 0.426). These results suggested that allo-SCT is an effective treatment for MPAL, especially early in the disease course, and innovative transplant approaches are warranted to improve the transplant outcome of patients with MPAL who are not in remission.

Haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for the treatment of philadelphia chromosome-positive acute lymphoblastic leukemia

The role of haploidentical related allogeneic hematopoietic stem cell transplantation (allo-HSCT) in Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) is not clear. We aimed to investigate the long-term survival of Ph(+) ALL patients who underwent haploidentical donor (HID)-HSCT and to analyze the factors influencing relapse and survival after allo-HSCT. The study population included Ph(+) ALL patients who underwent haploidentical related allo-HSCT. Additionally, Ph(+) ALL patients who underwent HLA-matched related donor (MRD) transplants during the same period were included to compare outcomes. BCR-ABL transcript levels were analyzed by using real-time quantitative reverse transcription PCR. Clinical data from 139 Ph(+) ALL patients who received allo-HSCT in our center were analyzed. Of these patients, 101 received HID transplants and 38 received MRD transplants. At a median follow-up of 36 months, 5-year disease-free survival (DFS) and overall survival (OS) rates in the HID transplant group were 65.8% and 74.0%, respectively. The 5-year cumulative incidence of relapse (CIR) and nonrelapse mortality (NRM) rates for the HID transplant group were 20.3% and 15.6%, respectively. In addition, there were no differences in OS, DFS, CIR, and NRM between the HID and MRD groups. Multivariate analysis showed that imatinib resistance was a significant factor influencing DFS and CIR in HID transplant patients. Haploidentical HSCT for the treatment of Ph(+) ALL achieves promising long-term survival, which is comparable with that of HLA-MRD HSCT. Imatinib resistance is a negative predictor of relapse and DFS after allo-HSCT.

Final report of a phase II study of imatinib mesylate with hyper-CVAD for the front-line treatment of adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

We have previously reported on the efficacy and tolerability of hyper-CVAD regimen (cyclophosphamide, vincristine, Adriamycin, and dexamethasone) and imatinib followed by imatinib-based consolidation/maintenance therapy in 20 patients with newly diagnosed Philadelphia-positive acute lymphoblastic leukemia. Here, we present the 13-year follow up of our study. Fifty-four patients with newly diagnosed Philadelphia-positive acute lymphoblastic leukemia were enrolled: 39 (72%) with de novo disease, 6 (11%) whose disease was primary refractory after induction (without a tyrosine kinase inhibitor), and 9 (17%) in complete remission after one course of induction therapy (without tyrosine kinase inhibitor). Forty-two (93%) of the 45 patients treated for active disease achieved complete remission, one achieved complete remission with incomplete recovery of platelets, one achieved partial remission and one died during induction. Nineteen (35%) patients are alive and 18 are in complete remission. The 5-year overall survival rate for all patients was 43%. Significant negative predictors of overall survival were age over 60 years, p190 molecular transcript, and active disease at enrollment. Sixteen (30%) patients underwent allogeneic stem cell transplantation. Median overall survival was not significantly greater for patients who underwent transplant. Patients with residual molecular disease at three months had improved complete remission duration with transplant. The median time to hematologic recovery and severe toxicities with combination were not significantly different from those observed with conventional chemotherapy. Only one patient discontinued therapy due to toxicity. HyperCVAD chemotherapy and imatinib is an effective regimen for Philadelphia-positive acute lymphoblastic leukemia. Transplant may not be indicated in all patients with Philadelphia-positive acute lymphoblastic leukemia. (clinicaltrials.gov identifier: NCT00038610).

Identification of heat shock protein 32 (Hsp32) as a novel target in acute lymphoblastic leukemia

Heat shock proteins (Hsp) are increasingly employed as therapeutic targets in oncology. We have shown that Hsp32, also known as heme oxygenase-1 (HO-1), serves as survival factor and potential target in Ph⁺ chronic myeloid leukemia. We here report that primary cells and cell lines derived from patients with acute lymphoblastic leukemia (ALL) express Hsp32 mRNA and the Hsp32 protein in a constitutive manner. Highly enriched CD34⁺/CD38⁻ ALL stem cells also expressed Hsp32. Two Hsp32-targeting drugs, pegylated zinc protoporphyrine (PEG-ZnPP) and styrene maleic acid-micelle-encapsulated ZnPP (SMA-ZnPP), induced apoptosis and growth arrest in the BCR/ABL1⁺ cell lines, in Ph⁻ lymphoblastic cell lines and in primary Ph⁺ and Ph⁻ ALL cells. The effects of PEG-ZnPP and SMA-ZnPP on growth of leukemic cells were dose-dependent. In Ph⁺ ALL, major growth-inhibitory effects of the Hsp32-targeting drugs were observed in imatinib-sensitive and imatinib-resistant cells. Hsp32-targeting drugs were found to synergize with imatinib, nilotinib, and bendamustine in producing growth inhibition and apoptosis in Ph⁺ ALL cells. A siRNA against Hsp32 was found to inhibit growth and survival of ALL cells and to synergize with imatinib in suppressing the growth of ALL cells. In conclusion, Hsp32 is an essential survival factor and potential new target in ALL.

Tyrosine kinase inhibitors improve long-term outcome of allogeneic hematopoietic stem cell transplantation for adult patients with Philadelphia chromosome positive acute lymphoblastic leukemia

This study aimed to determine the impact of tyrosine kinase inhibitors given pre- and post-allogeneic stem cell transplantation on long-term outcome of patients allografted for Philadelphia chromosome-positive acute lymphoblastic leukemia. This retrospective analysis from the EBMT Acute Leukemia Working Party included 473 de novo Philadelphia chromosome-positive acute lymphoblastic leukemia patients in first complete remission who underwent an allogeneic stem cell transplantation using a human leukocyte antigen-identical sibling or human leukocyte antigen-matched unrelated donor between 2000 and 2010. Three hundred and ninety patients received tyrosine kinase inhibitors before transplant, 329 at induction and 274 at consolidation. Kaplan-Meier estimates of leukemia-free survival, overall survival, cumulative incidences of relapse incidence, and non-relapse mortality at five years were 38%, 46%, 36% and 26%, respectively. In multivariate analysis, tyrosine-kinase inhibitors given before allogeneic stem cell transplantation was associated with a better overall survival (HR=0.68; P=0.04) and was associated with lower relapse incidence (HR=0.5; P=0.01). In the post-transplant period, multivariate analysis identified prophylactic tyrosine-kinase inhibitor administration to be a significant factor for improved leukemia-free survival (HR=0.44; P=0.002) and overall survival (HR=0.42; P=0.004), and a lower relapse incidence (HR=0.40; P=0.01). Over the past decade, administration of tyrosine kinase inhibitors before allogeneic stem cell transplantation has significantly improved the long-term allogeneic stem cell transplantation outcome of adult Philadelphia chromosome-positive acute lymphoblastic leukemia. Prospective studies will be of great interest to further confirm the potential benefit of the prophylactic use of tyrosine kinase inhibitors in the post-transplant setting.

Successful use of extracorporeal membrane oxygenation for respiratory failure caused by mediastinal precursor T lymphoblastic lymphoma

Precursor T lymphoblastic lymphoma (T-LBL) often manifests as a mediastinal mass sometimes compressing vital structures like vessels or large airways. This case was a 40-year-old male who developed T-LBL presenting as respiratory failure caused by mediastinal T-LBL. He presented with persistent life threatening hypoxia despite tracheal intubation. We successfully managed this respiratory failure using venovenous (VV) ECMO. Induction chemotherapy was started after stabilizing oxygenation and the mediastinal lesion shrank rapidly. Respiratory failure caused by compression of the central airway by tumor is an oncologic emergency. VV ECMO may be an effective way to manage this type of respiratory failure as a bridge to chemotherapy.

ETV6/ARG oncoprotein confers autonomous cell growth by enhancing c-Myc expression via signal transducer and activator of transcription 5 activation in the acute promyelocytic leukemia cell line HT93A

We investigated the role of ETV6/ARG fusion gene by exposing the HT93A cell line to nilotinib. HT93A cells were cultured with or without nilotinib±50 ng/mL of granulocyte colony-stimulating factor (G-CSF). Nilotinib treatment inhibited cell growth by increasing the percentage of cells in G0/G1 phase through the decrease of phosphorylated signal transducer and activator of transcription 3 (STAT3) (Y705), STAT5 (Y694) and c-Myc expression. After stimulation with G-CSF, STAT5 but not STAT3 was significantly phosphorylated in both nilotinib-treated and untreated cells. Moreover, combination therapy with nilotinib and G-CSF returned the expression level of c-Myc, cell growth and cell cycle distribution to the control level. These findings suggest that the ETV6/ARG oncoprotein contributes to autonomous cell growth by compensating for the requirement of growth factor through activating STAT5 signaling, which leads to the up-regulation of c-Myc. Our data suggest that ETV6/ARG oncoprotein is a potential target in the treatment of leukemia.

Susceptibility of Ph-positive all to TKI therapy associated with Bcr-Abl rearrangement patterns: a retrospective analysis

Background

Tyrosine kinase inhibitors (TKIs) have demonstrated success in the treatment of acute lymphoblastic leukemia (ALL) in patients that express BCR-ABL rearrangements (Philadelphia chromosome [Ph]). The current study aimed to assess the efficacy of TKIs and prognostic factors in the treatment of adults with Ph+-ALL.

Methods

In this multicenter retrospective study, the relationship between Ph+-ALL and treatment outcomes among Chinese patients receiving TKI-containing induction/consolidation chemotherapy was examined. A total of 86 Ph+-ALL patients were included and followed for 3.85 (0.43–9.30) years. Overall survival (OS) and event-free survival (EFS) were analyzed.

Results

A total of 86 Ph+-ALL patients (40 females and 46 males; median age: 34.0 years) were enrolled, including those with BCR/ABL transcripts 190 (n = 52), 210 (n = 25), and 230 (n = 2); BCR/ABL isoform determination was not available for 7 patients. Mortality was influenced by variable BCR/ABL transcripts and TKI administration, and BCR/ABL transcripts, hematopoietic stem cell transplantation (HSCT), and TKI administration were associated with the occurrence of events. The OS rate in the TKI administration group during steady state was significantly higher compared with those patients who did not receive TKI administration (P = 0.008), the EFS rate in the TKI administration group during steady state was significantly higher compared with those patients who did not receive TKIs (P = 0.012), and also higher than those with TKI salvage administration (P = 0.004). BCR/ABL transcripts 210 showed preferable OS and EFS compared with BCR/ABL transcripts 190 and 230 (P<0.05 for each).

Conclusions

The susceptibility of Ph+-ALL to TKI associated with the patterns of BCR-ABL rearrangement is demonstrated for the first time, thus adding another risk-stratifying molecular prognostic tool for the management of patients with Ph+-ALL.

Role of allogeneic hematopoietic stem cell transplantation in adult patients with acute lymphoblastic leukemia

Adult acute lymphoblastic leukemia (ALL) is a heterogeneous disease, due to the expression of different biological and clinical risk factors, for which allogeneic stem cell transplantation (alloHSCT) is an effective consolidation therapy. The non-relapse mortality of alloHSCT remains significantly higher compared with that of conventional chemotherapy. Therefore, one of the main challenges in the care of ALL is to establish a more precise prognostic definition to select patients who could take advantage from an alloHSCT. Currently, the use of minimal residual disease following induction and early consolidation therapy has improved the prognostic accuracy in defining ALL risk class. In Philadelphia-positive ALL, the introduction of tyrosine kinase inhibitors pre and post alloHSCT appears to improve outcomes significantly and, in the absence of specially designed clinical trials, alloHSCT remains the most effective post-remission therapy. Nowadays, alloHSCT can be performed according to various modalities encompassing the use of different conditioning regimens, as well as distinct donors and stem cell source, with a significant accessibility to transplant.

Inhibition of calcineurin combined with dasatinib has direct and indirect anti-leukemia effects against BCR-ABL1(+) leukemia

Treatment of BCR-ABL1(+) leukemia has been revolutionized with the development of tyrosine kinase inhibitors. However, patients with BCR-ABL1(+) acute lymphoblastic leukemia and subsets of patients with chronic myeloid leukemia are at high risk of relapse despite kinase inhibition therapy, necessitating novel treatment strategies. We previously reported synthetic lethality in BCR-ABL1(+) leukemia cells by blocking both calcineurin/NFAT signaling and BCR-ABL1, independent of drug efflux inhibition by cyclosporine. Here, using RNA-interference we confirm that calcineurin inhibition sensitizes BCR-ABL1(+) cells to tyrosine kinase inhibition in vitro. However, when we performed pharmacokinetic and pharmacodynamic studies of dasatinib and cyclosporine in mice, we found that co-administration of cyclosporine increases peak concentrations and the area under the curve of dasatinib, which contributes to the enhanced disease control. We also report the clinical experience of two subjects in whom we observed more hematopoietic toxicity than expected while enrolled in a Phase Ib trial designed to assess the safety and tolerability of adding cyclosporine to dasatinib in humans. Thus, the anti-leukemia benefit of co-administration of cyclosporine and dasatinib is mechanistically pleiotropic, but may not be tolerable, at least as administered in this trial. These data highlight some of the challenges associated with combining targeted agents to treat leukemia.

Impact of minimal residual disease on outcomes after umbilical cord blood transplantation for adults with Philadelphia-positive acute lymphoblastic leukaemia: an analysis on behalf of Eurocord, Cord Blood Committee and the Acute Leukaemia working party of the European group for Blood and Marrow Transplantation

The status of umbilical cord blood transplantation (UCBT) in adults with Philadelphia-positive acute lymphoblastic leukaemia (Ph+ALL) and the impact of minimal residual disease (MRD) before transplant are not well established. We analysed 98 patients receiving UCBT for Ph+ALL in first (CR1) or second (CR2) complete remission (CR1, n = 79; CR2, n = 19) with MRD available before UCBT (92% analysed by reverse transcription polymerase chain reaction). Median age was 38 years and median follow-up was 36 months; 63% of patients received myeloablative conditioning and 42% received double-unit UCBT. Eighty-three patients were treated with at least one tyrosine kinase inhibitor before UCBT. MRD was negative (-) in 39 and positive (+) in 59 patients. Three-year cumulative incidence of relapse was 34%; 45% in MRD+ and 16% in MRD- patients (P =0·013). Three-year cumulative incidence of non-relapse mortality was 31%; it was increased in patients older than 35 years (P = 0·02). Leukaemia-free survival (LFS) at 3 years was 36%; 27% in MRD+ and 49% in MRD- patients (P = 0·05), and 41% for CR1 and 14% for CR2 (P = 0·008). Multivariate analysis identified only CR1 as being associated with improved LFS. In conclusion, MRD+ before UCBT is associated with increased relapse. Strategies to decrease relapse in UCBT recipients with Ph+ALL and MRD+ are needed.

An imatinib-only window followed by imatinib and chemotherapy for Philadelphia chromosome-positive acute leukemia: long-term results of the CMLALL1 trial

We report long-term results in 40 patients with Philadlephia chromosome-positive (Ph+) acute leukemia who received an imatinib monotherapy window to evaluate in vivo effects on BCR-ABL signaling prior to induction chemotherapy. The first 25 patients (cohort 1) received the LALA-94 protocol without further imatinib (newly diagnosed Ph+ acute lymphoblastic leukemia [ALL]) or induction chemotherapy followed by single-agent imatinib. Subsequent patients (cohort 2) continued imatinib concurrently with either LALA-94 (newly diagnosed Ph + ALL) or other intensive chemotherapy regimens. Cohort 2 had a complete response (CR) rate of 93% and 5-year survival of 69%. For newly diagnosed Ph+ ALL, survival was superior in cohort 2 compared with cohort 1. Toxicity was similar to that expected for chemotherapy alone. Among 10 evaluable patients, rapid loss of phospho-CRKL occurred during the imatinib window in seven patients (all achieved CR) and incomplete inhibition in three patients (none with CR). In summary, a pharmacodynamic window design permitted biomarker assessment of BCR-ABL targeting without compromising clinical outcomes.

Philadelphia chromosome-positive mixed phenotype acute leukemia in the imatinib era

Although the introduction of imatinib dramatically improved the outcomes for patients with Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia (Ph + BCP-ALL), the survival benefit of imatinib has not been assessed in the context of Ph + mixed phenotype acute leukemia (Ph + MPAL). To clarify this important issue, we studied 42 Ph+ acute leukemia (Ph + AL) patients who received intensive chemotherapy and concurrent administration of imatinib. Of the 42 Ph + AL patients, 13 (31%) patients were categorized as Ph + MPAL (positive for both myeloid and B-cell lineage), 27 (64%) were categorized as Ph + BCP-ALL, and two (5%) were categorized as Ph + acute myeloid leukemia. The complete remission rates after the initial induction therapy were not significantly different when comparing Ph + MPAL and Ph + BCP-ALL patients (100% vs. 85%, respectively, P = 0.14). Likewise, there were no significant differences in the 5-yr overall survival (OS) or disease-free survival (DFS) rates when comparing the MPAL and BCP-ALL groups (OS: 55% vs. 53%, respectively, P = 0.87, DFS: 46% vs. 42%, respectively, P = 0.94). These findings suggest that concurrent imatinib administration with chemotherapy improved the outcomes of Ph + MPAL patients to the level seen in Ph+BCP-ALL patients and should, therefore, be considered as the standard therapy for these patients.

Philadelphia chromosome-positive acute lymphoblastic leukemia with extramedullary and meningeal relapse after allogeneic hematopoietic stem cell transplantation that was successfully treated with dasatinib

Central nervous system (CNS) relapse is a critical issue while treating Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL). A 58-year-old woman with Ph-positive ALL who relapsed after bone marrow transplantation for meningeal leukemia was treated with high-dose methotrexate, which resulted in remission. She underwent allogeneic cord blood transplantation followed by reduced intensity conditioning chemotherapy with imatinib; however, she experienced CNS relapse and developed an extramedullary mass on the right side of the temporal region. We treated 40 mg of dasatinib once daily, which had to be temporarily discontinued because she developed grade 2 pleural effusion and grade 2 hematemesis. After reinitiation of dasatinib, the extramedullary mass disappeared and meningeal leukemia ameliorated almost immediately. With 40 mg dasatinib administered once daily, its trough level and cerebrospinal fluid (CSF) concentration were 32 ng/mL and below the sensitivity threshold of 1 ng/mL, respectively. Treatment was continued, and the patient remained in complete remission until she died of pneumonia 7 years after the initial diagnosis of ALL. Dasatinib can be an effective treatment for Ph-positive ALL with CNS relapse. Although the concentration in the CSF seems low, it may be sufficient to exert anti-leukemic effects in the human CNS.

Current concepts in pediatric Philadelphia chromosome-positive acute lymphoblastic leukemia

The t(9;22)(q34;q11) or Philadelphia chromosome creates a BCR-ABL1 fusion gene encoding for a chimeric BCR-ABL1 protein. It is present in 3-4% of pediatric acute lymphoblastic leukemia (Ph(+) ALL), and about 25% of adult ALL cases. Prior to the advent of tyrosine kinase inhibitors (TKI), Ph(+) ALL was associated with a very poor prognosis despite the use of intensive chemotherapy and frequently hematopoietic stem-cell transplantation (HSCT) in first remission. The development of TKIs revolutionized the therapy of Ph(+) ALL. Addition of the first generation ABL1 class TKI imatinib to intensive chemotherapy dramatically increased the survival for children with Ph(+) ALL and established that many patients can be cured without HSCT. In parallel, the mechanistic understanding of Ph(+) ALL expanded exponentially through careful mapping of pathways downstream of BCR-ABL1, the discovery of mutations in master regulators of B-cell development such as IKZF1 (Ikaros), PAX5, and early B-cell factor (EBF), the recognition of the complex clonal architecture of Ph(+) ALL, and the delineation of genomic, epigenetic, and signaling abnormalities contributing to relapse and resistance. Still, many important basic and clinical questions remain unanswered. Current clinical trials are testing second generation TKIs in patients with newly diagnosed Ph(+) ALL. Neither the optimal duration of therapy nor the optimal chemotherapy backbone are currently defined. The role of HSCT in first remission and post-transplant TKI therapy also require further study. In addition, it will be crucial to continue to dig deeper into understanding Ph(+) ALL at a mechanistic level, and translate findings into complementary targeted approaches. Expanding targeted therapies hold great promise to decrease toxicity and improve survival in this high-risk disease, which provides a paradigm for how targeted therapies can be incorporated into treatment of other high-risk leukemias.

Clinical efficacy and safety of imatinib in the management of Ph(+) chronic myeloid or acute lymphoblastic leukemia in Chinese patients

Imatinib mesylate is considered the standard first-line systemic treatment for patients with chronic myeloid leukemia (CML) and functions by targeting BCR-ABL tyrosine kinases. Imatinib has substantially changed the clinical management and improved the prognosis of CML and Philadelphia chromosome-positive acute lymphocytic leukemia (Ph⁺ ALL). Here, we review the pharmacology, mode of action, and pharmacokinetics of imatinib; Chinese efficacy studies in CML and Ph⁺ ALL; safety and tolerability; patient-focused perspectives, such as quality of life, patient satisfaction, acceptability, and adherence; and uptake of imatinib.

Pretransplant administration of imatinib for allo-HSCT in patients with BCR-ABL-positive acute lymphoblastic leukemia

We aimed to evaluate the impact of pretransplant imatinib administration on the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adults with Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL). We retrospectively analyzed 738 patients with Ph(+) ALL that underwent allo-HSCT between 1990 and 2010 using data from the Transplant Registry Unified Management Program of the Japan Society of Hematopoietic Cell Transplantation. We compared the allo-HSCT outcomes between 542 patients who received imatinib before allo-HSCT during the initial complete remission period (imatinib cohort) and 196 patients who did not receive imatinib (non-imatinib cohort). The 5-year overall survival after allo-HSCT was significantly higher in the imatinib cohort than in the non-imatinib cohort (59% vs 38%; 95% confidence interval [CI], 31-45%; P < .001). Multivariate analysis indicated that pretransplant imatinib administration had beneficial effects on overall survival (hazard ratio [HR], 0.57; 95% CI, 0.42-0.77; P < .001), relapse (HR, 0.66; 95% CI, 0.43-0.99; P = .048), and nonrelapse mortality (HR, 0.55; 95% CI, 0.37-0.83; P = .005). In conclusion, our study showed that imatinib administration before allo-HSCT had advantageous effects on the clinical outcomes of allo-HSCT in patients with Ph(+) ALL.

Phase II trial of hyper CVAD and dasatinib in patients with relapsed Philadelphia chromosome positive acute lymphoblastic leukemia or blast phase chronic myeloid leukemia

Dasatinib is a second generation tyrosine kinase inhibitor, with activity in imatinib resistant Ph-positive ALL.We have treated 34 patients with relapsed Philadelphia chromosome positive acute lymphoblastic leukemia(ALL) (n519) or lymphoid blast phase of chronic myelogenous leukemia (CML-LB) (n515) with the combination of dasatinib and the hyper CVAD regimen. Prior regimens included hyper CVAD plus imatinib(n511, 4 had transplant in first CR), other combination chemotherapy (n512), monotherapy with kinase inhibitors other than dasatinib (n59), and investigational agents (n52). Pretreatment ABL mutations were noted in 10 patients. The overall response rate was 91%, with 24 patients (71%) achieving complete response(CR), and 7(21%) CR with incomplete platelet recovery (CRp). Two patients died during induction and one had progressive disease. Twenty-six patients (84%) achieved complete cytogenetic remission after one cycle of therapy. Overall, 13 patients (42%) achieved complete molecular response, and 11 patients (35%) had major molecular response (BCR-ABL/ABL<0.1%). Nine patients proceeded to allogeneic transplantation.Grades 3 and 4 toxicities included hemorrhage, pleural and pericardial effusions and infections. The median follow-up for patients with CML-LB is 37.5 months (range, 7–70 months) with a 3-year overall survival of 70%;68% remained in CR at 3 years. For ALL patients, the median follow-up is 52 months (range, 45–59 months)with a 3-year survival of 26%; 30% remain in CR at 3 years. The combination of Hyper CVAD regimen with dasatinib is effective in patients with relapsed Ph-positive ALL and CML-LB.

Blood and Marrow Transplant Clinical Trials Network: progress since the State of the Science Symposium 2007

Outcomes of hematopoietic cell transplantation continue to improve. New techniques have reduced transplant toxicities, and there are new sources of hematopoietic stem cells from related and unrelated donors. In June 2007, the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) convened a State of the Science Symposium (SOSS) in Ann Arbor and identified 11 high priority clinical trials for the network to pursue. This article reviews both the status of those trials and the record of achievement of the BMT CTN as it convenes another SOSS in Grapevine, Texas in February 2014.

Treatment of Philadelphia-positive acute lymphoid leukemia

SUMMARY Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) represents approximately 15–30% of ALL in adults and is characterized by the expression of the fusion protein BCR–ABL with oncogenic activity. Remission and survival rates were lower whereas relapse risk was increased in Ph+ compared with Philadelphia-negative ALL, until remarkable improvements in the management of Ph+ ALL were achieved through the introduction of tyrosine kinase inhibitors that reduce the activity of the BCR–ABL protein. However, in patients achieving complete remission, allogeneic hematopoietic stem cell transplantation is in most cases a mandatory therapeutic step because rate of relapses are still high. This review will illustrate the current therapeutic options for the management of Ph+ ALL and indicate how better curative options may stem from appropriate implementation of tyrosine kinase inhibitors and novel antitumoral agents.

Drug resistance and BCR-ABL kinase domain mutations in Philadelphia chromosome-positive acute lymphoblastic leukemia from the imatinib to the second-generation tyrosine kinase inhibitor era: The main changes are in the type of mutations, but not in the frequency of mutation involvement

BACKGROUND

Patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) frequently relapse on imatinib with acquisition of BCR-ABL kinase domain (KD) mutations. To analyze the changes that second-generation tyrosine kinase inhibitors (TKIs) have brought in mutation frequency and type, a database review was undertaken of the results of all the BCR-ABL KD mutation analyses performed in the authors' laboratory from January 2004 to January 2013.

METHODS

Interrogation of the database retrieved 450 mutation analyses in 272 patients with Ph+ ALL. Prescreening of samples was performed with denaturing high-performance liquid chromatography (D-HPLC), followed by direct sequencing of D-HPLC-positive cases.

RESULTS

BCR-ABL KD mutations were detected in 70% of imatinib-resistant patients, with T315I, E255K, and Y253H mutations accounting for 75% of cases. Seventy-eight percent of the patients reported to be resistant to second-generation TKIs after imatinib failure were positive for mutations, and 58% of them had multiple mutations. Analysis of patients relapsing on dasatinib revealed a newly acquired T315I mutation in almost two-thirds of the cases. Direct sequencing detected no mutations at diagnosis, even in patients who relapsed after a few months.

CONCLUSIONS

Second-generation TKIs ensure a more rapid debulking of the leukemic clone and have much fewer insensitive mutations, but long-term disease control remains a problem, and the T315I mutation is revealed to be an even more frequent enemy. BCR-ABL KD mutation screening of patients with Ph+ ALL who are receiving imatinib or second-generation TKIs would be a precious ally for timely treatment optimization. In contrast, the clinical usefulness of conventional direct sequencing at diagnosis seems to be very low. American Cancer Society.

Improving results of autologous stem cell transplantation for Philadelphia-positive acute lymphoblastic leukaemia in the era of tyrosine kinase inhibitors: a report from the Acute Leukaemia Working Party of the European Group for Blood and Marrow Transplantation

BACKGROUND

Outcome of Philadelphia-positive acute lymphoblastic leukaemia (Ph+ ALL) improved significantly with the introduction of tyrosine kinase inhibitors (TKIs). Autologous stem cell transplantation (ASCT) has never been considered a standard of care in this setting. The aim of our study was to analyse if results of ASCT improved in the era of TKIs.

PATIENTS AND METHODS

One-hundred and seventy-seven adults with Ph+ ALL treated with ASCT in first complete remission were analysed for the impact of year of transplantation on outcome. Additional analysis was performed including 32 patients for whom detailed data on the use of TKIs and the status of minimal residual disease were collected.

RESULTS

The probability of the overall survival (OS) at 3 years increased from 16% for transplants performed between 1996 and 2001 to 48% between 2002 and 2006 and 57% between 2007 and 2010 (P<.0001). Leukaemia-free survival (LFS) was 11%, 39% and 52%, respectively (P<.0001). Relapse incidence decreased from 70% to 45% and 45% (P=.01), respectively, while non-relapse mortality was 19%, 15% and 3% (P=.08). In a multivariate analysis, year of ASCT was the only independent factor influencing the risk of treatment failure (hazard ratio (HR)=0.37; P<.001). In a subgroup of 22 patients actually treated with TKIs and being in complete molecular remission at the time of ASCT, the LFS rate at 3 years was 65%.

CONCLUSIONS

Results of ASCT for Ph+ ALL improved significantly over time. Prospective, innovative studies are needed to verify the role of ASCT in this patient setting.

Treating relapsed or refractory Philadelphia chromosome-negative acute lymphoblastic leukemia: liposome-encapsulated vincristine

Acute lymphoblastic leukemia (ALL) remains a disease with poor outcomes in adults. While induction chemotherapy achieves a complete remission in almost 90% of patients, the majority will relapse and die of their disease. Relapsed ALL is associated with a high reinduction mortality and chemotherapy resistance, with allogeneic hematopoietic stem cell transplantation offering the only therapy with curative potential. However, there is no efficacious and well tolerated standard regimen accepted as a “bridge” to allogeneic stem cell transplantation or as definitive treatment for patients who are not transplant candidates. Vincristine is an active drug in patients with ALL, but its dose intensity is limited by neurotoxicity, and its full potential as an anticancer drug is thus not realized. Encapsulation of vincristine into sphingomyelin and cholesterol nanoparticle liposomes facilitates dose-intensification and densification to enhanced target tissues with reduced potential for toxicity. Vincristine sulfate liposome injection (VSLI) is associated with significant responses in clinically advanced ALL, and has recently been approved by the US Food and Drug Administration for treatment of relapsed and clinically advanced Philadelphia chromosome-negative ALL. This review provides an overview of the preclinical and clinical studies leading to the approval of VSLI for the treatment of relapsed and refractory ALL, and suggests potential areas of future clinical development.

Comparable long-term outcomes after reduced-intensity conditioning versus myeloablative conditioning allogeneic stem cell transplantation for adult high-risk acute lymphoblastic leukemia in complete remission

The role of reduced-intensity conditioning (RIC) in adult acute lymphoblastic leukemia (ALL) remains unclear because of the small sample size, short follow-up duration, various regimens for conditioning and graft-versus-host disease (GVHD) prophylaxis, and the heterogeneity of selection criteria for transplantation. We compared long-term outcomes of 60 consecutive RIC transplants (fludarabine plus melphalan) with 120 myeloablative conditioning (MAC) transplants (total body irradiation plus cyclophosphamide) for adult high-risk ALL in first or second complete remission. All transplants received a uniform strategy of pretransplant chemotherapy and GVHD prophylaxis. Compared to MAC transplants, RIC transplants had older age (46 years vs. 33 years, P < 0.001) and higher proportions of transplantation using peripheral blood (93.3% vs. 13.3%; P < 0.001) but otherwise showed similar characteristics. After a median follow-up of 67 months, RIC transplants showed comparable nonrelapse mortality (21.2% vs. 24.3%) and disease-free survival (50.8% vs. 54.9%) to MAC transplants, although relapse risk was higher (34.2% vs. 26.4%; HR, 2.07; P = 0.019) in multivariate analysis. Other independent factors associated with better outcomes were the presence of chronic GVHD and transplantation in first complete remission. Interestingly, the negative impact of RIC on relapse risk was seen only for Philadelphia-positive ALL transplants (32.7% vs. 19.6%; HR, 3.46; P = 0.020), while no difference was found between RIC and MAC for Philadelphia-negative ALL transplants (35.0% vs. 32.1%; HR, 1.39; P = 0.429). RIC can be considered as a reasonable choice for providing a sufficient long-term graft-versus-leukemia effect for adult high-risk ALL patients ineligible for MAC.

Detection of MRD may predict the outcome of patients with Philadelphia chromosome-positive ALL treated with tyrosine kinase inhibitors plus chemotherapy

From 2001 to 2011, 122 patients with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia were treated with chemotherapy + imatinib (n = 54) or + dasatinib (n = 68). One hundred fifteen (94%) achieved complete remission (CR) including 101 patients who achieved it with only 1 induction course and had at least 1 minimal residual disease (MRD) assessment; 25 patients underwent an allogeneic stem cell transplant in first CR and were excluded, leaving 76 patients as the subject of this report. MRD monitoring by multiparameter flow cytometry (MFC) and real-time quantitative polymerase chain reaction (PCR) was performed at the end of induction and at ~3-month intervals thereafter. Median age was 54 years (range, 21-84 years). There was no difference in survival by achievement of at least a major molecular response (MMR; BCR-ABL/ABL < 0.1%) at CR (P = .22). Patients achieving MMR at 3, 6, 9, and 12 months had a better survival (P = .02, .04, .05, and .01, respectively). Negative MFC at CR did not predict for improved survival (P = .2). At 3 and 12 months, negative MRD by MFC was associated with improved survival (P = .04 and .001). MRD monitoring by PCR and MFC identifies patients who benefit from treatment intensification in first CR.

Hematopoietic stem cell transplant versus chemotherapy plus tyrosine kinase inhibitor in the treatment of pediatric Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL)

BACKGROUND

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) remained until recently the molecular genetic abnormality associated with the worst outcome. Hematopoietic stem cell transplant (HSCT) was considered the treatment of choice, however, recent data have indicated that chemotherapy plus tyrosine kinase inhibitor (TKI) maybe an alternative effective therapy.

METHODS

We conducted a retrospective analysis of children (<18 years) with Ph+ ALL who were treated at King Hussein Cancer Center (KHCC) from January 2003 till December 2011.

RESULTS

Over a 9 year period, 411 children were diagnosed and treated for ALL at KHCC. Twenty three (6.6%) had Ph+ ALL; 16 males and 7 females. Median age at diagnosis was 9.5 years (range 1.67-17). The median white blood cell count was 58.6×10(3)/μL (range 1.6-459). Twelve patients underwent HSCT from a full matched related donor; and 10 were treated with intensive chemotherapy plus TKI (imatinib). Those who underwent HSCT were significantly older (P=0.004) and had a higher leukocyte count at diagnosis (P=0.53). After a median follow up of 42.2 months (range 12.7-107), the estimated 5 year event free survival (EFS) and overall survival (OS) were 75% and 91.6%, respectively, for those who underwent HSCT as primary therapy and 49.3% and 83.3%, respectively, for those treated with chemotherapy plus imatinib. There was no significant difference in EFS (P=0.98) or OS (P=1) between the two treatment modalities.

CONCLUSIONS

Our results indicate that chemotherapy plus TKI may be a reasonable treatment option for some children with Ph+ ALL.

Criteria for and outcomes of allogeneic haematopoietic stem cell transplant in children, adolescents and young adults with acute lymphoblastic leukaemia in first complete remission

Most children, adolescents and young adults with acute lymphoblastic leukaemia (ALL) in first complete remission (CR1) have an excellent prognosis with multi-agent chemotherapy in induction, consolidation, re-induction and maintenance therapy. However, there is a subset of patients with a more guarded prognosis using this approach, who may benefit from haematopoietic allogeneic stem cell transplantation (alloHSCT). Commonly used criteria for alloHSCT in children, adolescents and young adults with ALL in CR1 include: induction failure, poor cytogenetics, persistent minimal residual disease (MRD), age, immunophenotype, white blood cell count at diagnosis and rapidity of induction response. Two-year event-free survival following alloHSCT in patients with ALL in CR1 ranges from 50 to 80% depending on disease status, donor source, conditioning therapy, age and other risk factors. Future studies should focus on more precisely identifying poor-risk features, such as disease genomics and host pharmacogenomics, refining MRD measurements, improving unrelated donor matching, reducing MRD prior to alloHSCT, and developing post-alloHSCT humoral and cellular therapy approaches.

Philadelphia-positive acute lymphoblastic leukemia: current treatment options

The Philadelphia chromosome (Ph), t(9;22), is seen in about 20 % to 30 % of adults diagnosed with acute lymphoblastic leukemia (ALL). It has been associated with poorer prognosis compared with Ph-negative ALL. Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogenic protein from this translocation have been incorporated into treatment regimens used to treat patients with Ph-positive ALL. Imatinib has been the most widely used TKI with several published trials showing it produced better outcomes when combined with chemotherapy. Dasatinib, a more potent inhibitor than imatinib, has also been evaluated with promising results. However, relapses still occur at a high rate, and allogeneic stem cell transplant is considered, so far, a better curative option in first remission. Additional strategies have also included incorporation of TKIs in the post-transplant setting and the use of newer third generation TKIs. This review provides an update on emerging therapies for adults with Ph-positive ALL.

IK6 isoform with associated cytogenetic and molecular abnormalities in Chinese patients with Philadelphia chromosome-positive adult acute lymphoblastic leukemia

The IK6 isoform plays an important role in Philadelphia chromosome-positive adult acute lymphoblastic leukemia (Ph + ALL). This study was designed to monitor the expression of the IK6 isoform with associated cytogenetic and molecular abnormalities. The IK6 isoform, cytogenetic and molecular abnormalities were detected in 100 Chinese patients with de novo Ph+ adult ALL. Expression levels of the IK6 isoform and BCR-ABL1 transcripts were monitored during treatment. BCR-ABL1 mutation was identified in 45 paired samples. Strong correlations were found between the expression status of the IK6 isoform and blast cells, additional cytogenetic abnormalities, BCR-ABL1 transcripts, increased risk of relapse, shorter relapse-free survival and overall survival at diagnosis. Higher frequencies of single IK6 expression and ABL mutation, including the types and shifts thereof, were confirmed in relapsed patients. Furthermore, expression of the IK6 isoform was dynamically consistent with BCR-ABL1 transcript levels during treatment in the single expression group, whereas no such correlation was observed in the co-expression group. The expression pattern of the IK6 isoform was altered in three patients from the co-expression group. The findings of this study in Chinese patients with Ph+ adult ALL exhibit some discrepancies with data reported in other countries, thereby enhancing current knowledge on the therapeutic response and prognosis of this disease.

Randomized comparison of prophylactic and minimal residual disease-triggered imatinib after allogeneic stem cell transplantation for BCR-ABL1-positive acute lymphoblastic leukemia

Minimal residual disease (MRD) after allogeneic stem cell transplantation (SCT) for Ph+ acute lymphoblastic leukemia (ALL) is predictive of relapse. Imatinib administration subsequent to SCT may prevent relapse, but the role of scheduling and its impact on outcome are not known. In a prospective, randomized multicenter trial, we compared the tolerability and efficacy of post-transplant imatinib administered either prophylactically (arm A; n=26) or following detection of MRD (arm B; n=29). Prophylactic imatinib significantly reduced the incidence of molecular recurrence after SCT compared with MRD-triggered imatinib (40% vs 69%; P=0.046). Median duration of PCR negativity was 26.5 and 6.8 months, respectively (P=0.065). Five-year survival in both interventional groups was high (80 and 74.5%), despite premature discontinuation of imatinib in the majority of patients because of poor tolerability. Relapse probability was significantly higher in patients who became MRD positive (P=0.017). In conclusion, post-transplant imatinib results in a low relapse rate, durable remissions and excellent long-term outcome in patients with BCR-ABL1-positive ALL irrespective of whether it is given prophylactically or MRD-triggered. Reappearance of BCR-ABL1 transcripts early after SCT or at higher levels identifies a small subset of patients who do not benefit sufficiently from imatinib, and in whom alternative approaches should be explored.