Lenalidomide induces ubiquitination and degradation of CK1α in del(5q) MDS.

Lenalidomide is a highly effective treatment for myelodysplastic syndrome (MDS) with deletion of chromosome 5q (del(5q)). Here, we demonstrate that lenalidomide induces the ubiquitination of casein kinase 1A1 (CK1α) by the E3 ubiquitin ligase CUL4-RBX1-DDB1-CRBN (known as CRL4(CRBN)), resulting in CK1α degradation. CK1α is encoded by a gene within the common deleted region for del(5q) MDS and haploinsufficient expression sensitizes cells to lenalidomide therapy, providing a mechanistic basis for the therapeutic window of lenalidomide in del(5q) MDS. We found that mouse cells are resistant to lenalidomide but that changing a single amino acid in mouse Crbn to the corresponding human residue enables lenalidomide-dependent degradation of CK1α. We further demonstrate that minor side chain modifications in thalidomide and a novel analogue, CC-122, can modulate the spectrum of substrates targeted by CRL4(CRBN). These findings have implications for the clinical activity of lenalidomide and related compounds, and demonstrate the therapeutic potential of novel modulators of E3 ubiquitin ligases.

Evolution of acute myelogenous leukemia stem cell properties after treatment and progression.

Most cancers evolve over time as patients initially responsive to therapy acquire resistance to the same drugs at relapse. Cancer stem cells have been postulated to represent a therapy-refractory reservoir for relapse, but formal proof of this model is lacking. We prospectively characterized leukemia stem cell populations (LSCs) from a well-defined cohort of patients with acute myelogenous leukemia (AML) at diagnosis and relapse to assess the effect of the disease course on these critical populations. Leukemic samples were collected from patients with newly diagnosed AML before therapy and after relapse, and LSC frequency was assessed by limiting dilution analyses. LSC populations were identified using fluorescent-labeled cell sorting and transplantation into immunodeficient NOD/SCID/interleukin 2 receptor γ chain null mice. The surface antigen expression profiles of pretherapy and postrelapse LSCs were determined for published LSC markers. We demonstrate a 9- to 90-fold increase in LSC frequency between diagnosis and relapse. LSC activity at relapse was identified in populations of leukemic blasts that did not demonstrate this activity before treatment and relapse. In addition, we describe genetic instability and exceptional phenotypic changes that accompany the evolution of these new LSC populations. This study is the first to characterize the evolution of LSCs in vivo after chemotherapy, identifying a dramatic change in the physiology of primitive AML cells when the disease progresses. Taken together, these findings provide a new frame of reference by which to evaluate candidate AML therapies in which both disease control and the induction of more advanced forms of disease should be considered.

Acute myeloid leukemia ontogeny is defined by distinct somatic mutations.

Acute myeloid leukemia (AML) can develop after an antecedent myeloid malignancy (secondary AML [s-AML]), after leukemogenic therapy (therapy-related AML [t-AML]), or without an identifiable prodrome or known exposure (de novo AML). The genetic basis of these distinct pathways of AML development has not been determined. We performed targeted mutational analysis of 194 patients with rigorously defined s-AML or t-AML and 105 unselected AML patients. The presence of a mutation in SRSF2, SF3B1, U2AF1, ZRSR2, ASXL1, EZH2, BCOR, or STAG2 was >95% specific for the diagnosis of s-AML. Analysis of serial samples from individual patients revealed that these mutations occur early in leukemogenesis and often persist in clonal remissions. In t-AML and elderly de novo AML populations, these alterations define a distinct genetic subtype that shares clinicopathologic properties with clinically confirmed s-AML and highlights a subset of patients with worse clinical outcomes, including a lower complete remission rate, more frequent reinduction, and decreased event-free survival. This trial was registered at www.clinicaltrials.gov as #NCT00715637.

Expression and prognostic impact of lncRNAs in acute myeloid leukemia.

Long noncoding RNAs (lncRNAs) are transcripts longer than 200 nucleotides, located within the intergenic stretches or overlapping antisense transcripts of protein coding genes. LncRNAs are involved in numerous biological roles including imprinting, epigenetic regulation, apoptosis, and cell cycle. To determine whether lncRNAs are associated with clinical features and recurrent mutations in older patients (aged ≥60 y) with cytogenetically normal (CN) acute myeloid leukemia (AML), we evaluated lncRNA expression in 148 untreated older CN-AML cases using a custom microarray platform. An independent set of 71 untreated older patients with CN-AML was used to validate the outcome scores using RNA sequencing. Distinctive lncRNA profiles were found associated with selected mutations, such as internal tandem duplications in the FLT3 gene (FLT3-ITD) and mutations in the NPM1, CEBPA, IDH2, ASXL1, and RUNX1 genes. Using the lncRNAs most associated with event-free survival in a training cohort of 148 older patients with CN-AML, we derived a lncRNA score composed of 48 lncRNAs. Patients with an unfavorable compared with favorable lncRNA score had a lower complete response (CR) rate [P < 0.001, odds ratio = 0.14, 54% vs. 89%], shorter disease-free survival (DFS) [P < 0.001, hazard ratio (HR) = 2.88] and overall survival (OS) (P < 0.001, HR = 2.95). The validation set analyses confirmed these results (CR, P = 0.03; DFS, P = 0.009; OS, P = 0.009). Multivariable analyses for CR, DFS, and OS identified the lncRNA score as an independent marker for outcome. In conclusion, lncRNA expression in AML is closely associated with recurrent mutations. A small subset of lncRNAs is correlated strongly with treatment response and survival.

MPD-RC 101 prospective study of reduced-intensity allogeneic hematopoietic stem cell transplantation in patients with myelofibrosis.

From 2007 to 2011, 66 patients with primary myelofibrosis or myelofibrosis (MF) preceded by essential thrombocythemia or polycythemia vera were enrolled into a prospective phase 2 clinical trial of reduced-intensity allogeneic hematopoietic stem cell transplantation (AHSCT), Myeloproliferative Disorder Research Consortium 101 trial. The study included patients with sibling donors (n = 32) receiving fludarabine/melphalan (FluMel) as a preparative regimen and patients with unrelated donors (n = 34) receiving conditioning with FluMel plus anti-thymocyte globulin (ATG). Patient characteristics in the 2 cohorts were similar. Engraftment occurred in 97% of siblings and 76% of unrelated transplants, whereas secondary graft failure occurred in 3% and 12%, respectively. With a median follow-up of 25 months for patients alive, the overall survival (OS) was 75% in the sibling group (median not reached) and 32% in the unrelated group (median OS: 6 months, 95% confidence interval [CI]: 3, 25) (hazard ratio 3.9, 95% CI: 1.8,8.9) (P < .001). Nonrelapse mortality was 22% in sibling and 59% in unrelated AHSCT. Survival correlated with type of donor, but not with the degree of histocompatibility match, age, or JAK2(V617F) status. In patients with MF with sibling donors, AHSCT is an effective therapy, whereas AHSCT from unrelated donors with FluMel/ATG conditioning led to a high rate of graft failure and limited survival. This trial was registered at www.clinicaltrials.gov as #NCT00572897.

Adjustment to Acute Leukemia: The Impact of Social Support and Marital Satisfaction on Distress and Quality of Life Among Newly Diagnosed Patients and Their Caregivers.

Little is known about the specific patterns of adjustment among newly diagnosed acute leukemia patients and their caregivers. This study examined the trajectories of patient and caregiver distress over time as well as the extent to which marital satisfaction and social support moderated these trajectories among those with significant-other caregivers. Forty six patient-caregiver dyads provided ratings at four time points: within 1 week of diagnosis (T1), 2 week follow-up (T2), 6 week follow-up (T3) and 12 week follow-up (T4). As anticipated, patients and caregivers reported higher levels of distress around the time of diagnosis than they did during subsequent time points. Marital satisfaction was a significant predictor of distress among patients, whereas among caregivers, social support predicted distress and quality of life. Results support the inclusion of relational variables such as social support and relationship satisfaction in the assessment of newly diagnosed patients and families in order to best identify those at risk for distress over time.

Final analysis of the efficacy and safety of omacetaxine mepesuccinate in patients with chronic- or accelerated-phase chronic myeloid leukemia: Results with 24 months of follow-up.

BACKGROUND: Omacetaxine, a protein synthesis inhibitor, is indicated in the United States for the treatment of patients with chronic-phase (CP) or accelerated-phase (AP) chronic myeloid leukemia (CML) with resistance and/or intolerance to 2 or more tyrosine kinase inhibitors. METHODS: The final analysis, with 24 months of follow-up, included additional efficacy and safety analyses to assess the benefit of long-term omacetaxine administration (1.25 mg/m(2) twice daily for 14 days every 28 days followed by 7 days every 28 days) in CP-CML and AP-CML patients receiving >3 cycles. RESULTS: Eighteen percent of CP-CML patients achieved a major cytogenetic response (MCyR) with a median duration of 12.5 months (95% confidence interval [CI], 3.5 months to not reached [NR]); responses were maintained for ≥12 months in 3 of 14 responders, and the median overall survival (OS) was 40.3 months (95% CI, 23.8 months to NR). Among patients with AP-CML, 14% achieved or maintained a major hematologic response for a median of 4.7 months (95% CI, 3.6 months to NR); MCyR was not achieved, and the median OS was 14.3 months (95% CI, 6.7-18.7 months). In patients with CP-CML and patients with AP-CML who received >3 cycles of treatment (n = 50 and n = 14, respectively), the median OS was 49.3 months (95% CI, 23.8 months to NR) and 24.6 months (95% CI, 12-37.2 months), respectively. Grade 3 or higher hematologic toxicities were the major side effects (79% and 73% for CP-CML and AP-CML, respectively), with discontinuation due to toxicity in 10% of CP patients and in 5% of AP patients. CONCLUSIONS: These results suggest that the long-term administration of omacetaxine is feasible with dose adjustments to manage toxicities and that omacetaxine provides a durable benefit for some patients.

Tamibarotene in patients with acute promyelocytic leukaemia relapsing after treatment with all-trans retinoic acid and arsenic trioxide.

Treatment of acute promyelocytic leukaemia (APL) with arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) is highly effective first-line therapy, although approximately 5-10% of patients relapse. Tamibarotene is a synthetic retinoid with activity in APL patients who relapse after chemotherapy and ATRA, but has not been studied in relapse after treatment with ATO and ATRA. We report on a phase II study of tamibarotene in adult patients with relapsed or refractory APL after treatment with ATRA and ATO (n = 14). Participants were treated with tamibarotene (6 mg/m(2) /d) during induction and for up to six cycles of consolidation. The overall response rate was 64% (n = 9), the rate of complete cytogenetic response was 43% (n = 6) and the rate of complete molecular response was 21% (n = 3). Relapse was frequent with 7 of 9 responders relapsing after a median of 4·6 months (range 1·6-26·8 months). The median event-free survival (EFS) was 3·5 months [95% confidence interval (CI) 0-8·6 months] and the median overall survival (OS) was 9·5 months (95% CI 5·9-13·1 months). These results demonstrate that tamibarotene has activity in relapsed APL after treatment with ATO and ATRA and further studies using tamibarotene as initial therapy and in combination with ATO are warranted.

Historical views, conventional approaches, and evolving management strategies for myeloproliferative neoplasms.

The classical Philadelphia chromosome-negative myeloproliferative neoplasms (MPN), which include essential thrombocythemia, polycythemia vera, and myelofibrosis (MF), are in a new era of molecular diagnosis, ushered in by the identification of the JAK2(V617F) and cMPL mutations in 2005 and 2006, respectively, and the CALR mutations in 2013. Coupled with increased knowledge of disease pathogenesis and refined diagnostic criteria and prognostic scoring systems, a more nuanced appreciation has emerged of the burden of MPN in the United States, including the prevalence, symptom burden, and impact on quality of life. Biological advances in MPN have translated into the rapid development of novel therapeutics, culminating in the approval of the first treatment for MF, the JAK1/JAK2 inhibitor ruxolitinib. However, certain practical aspects of care, such as those regarding diagnosis, prevention of vascular events, choice of cytoreductive agent, and planning for therapies, present challenges for hematologists/oncologists, and are discussed in this article.

Revisiting the role of cladribine in acute myeloid leukemia: an improvement on past accomplishments or more old news?

Originally studied in lymphoid diseases, cladribine (CdA) is an adenosine deaminase resistant analog of adenosine that was later discovered to induce myeloid cell apoptosis. The activity of CdA in myeloid malignancies was first reported in relapsed/refractory (RR) pediatric acute myeloid leukemia (AML) with complete response (CR) rates of up to 47%. Consequently, several studies have confirmed the efficacy of single agent CdA or CdA combination regimens in AML. Established CR rates for combination regimens in RR adults are approximately 50%, while CR rates for newly diagnosed (ND) adults are approximately 70% and show similar toxicity profiles to previously used regimens. Despite these promising data, many centers have yet to adopt CdA combination regimens for these difficult to treat populations. We review the pharmacology, pharmacokinetics, clinical data, and safety of CdA monotherapy and combination regimens for the management of pediatric and adult ND and RR-AML.

Presence of isocitrate dehydrogenase mutations may predict clinical response to hypomethylating agents in patients with acute myeloid leukemia.

Mutations in IDH1 and IDH2 occur in 15-20% of AML cases, resulting in the production of 2-hydroxyglutarate, which promotes aberrant hypermethylation of DNA in leukemic cells. Although these mutations have been shown to have prognostic implications for patients with AML, optimal treatment strategies have yet to be defined. We retrospectively identified forty-two patients with AML treated with DNA methyltransferase inhibitors (DNMTIs) decitabine (n = 36) or azacitidine (n = 6) and performed analysis of stored samples for the presence of IDH1 and IDH2 mutations. Of the forty-two samples analyzed, seven (16.7%) had IDH mutations. Thirteen patients (31%) achieved remission [(complete remission (CR)/complete remission with incomplete count recovery (CRi)/partial response (PR)] after treatment with a DNMTI, five of seven (71.4%) with IDH mutations and eight of thirty-five (22.9%) without IDH mutations (P = 0.01). When adjusted for age at diagnosis, sex, bone marrow blast percentage and cytogenetic, the odds of achieving response after administration of a DNMTI among patients with an IDH mutation was 14.2 when compared to patients without an IDH mutation (95%CI: 1.3-150.4). IDH1 and IDH2 mutations may predict a favorable response to DNMTI in patients with AML.

Comparison of epigenetic versus standard induction chemotherapy for newly diagnosed acute myeloid leukemia patients ≥60 years old.

Older patients with acute myeloid leukemia (AML) have poor outcomes with standard induction chemotherapy. We retrospectively reviewed our institute's experience with epigenetic (Epi) versus cytarabine- and anthracycline-based intensive chemotherapy (IC) as induction in newly diagnosed AML patients aged 60 years and older. One hundred sixty-seven patients (n = 84, IC; n = 83, Epi) were assessed; 69 patients received decitabine and 14 azacitidine. Baseline characteristics between the IC and Epi patient cohorts were not statistically different except for age, initial white blood cell count, and comorbidity index. Overall response rate (ORR, 50% vs. 28%, respectively, P < 0.01) and complete response rate (CRR, 43% vs. 20%, respectively, P < 0.01) were superior following IC vs. Epi. Although univariate analysis demonstrated longer overall survival after IC (10.7 vs. 9.1 months, P = 0.012), multivariate analysis showed no independent impact of induction treatment. Treatment-related mortality was not statistically different in the two groups. Outcomes of patients with secondary, poor cytogenetic risk, FLT-3 mutated AML, or relapsed/refractory disease after IC or Epi were not significantly different. Outcomes of patients receiving IC versus a 10-day decitabine regimen (n = 63) also were not significantly different. Our results suggest that IC and Epi therapy are clinically equivalent approaches for upfront treatment of older patients with AML and that other factors (feasibility, toxicity, cost, etc.) should drive treatment decisions. Prospective randomized trials to determine the optimal induction approach for specific patient subsets are needed.

Acceptability, feasibility, and efficacy of a supportive group intervention for caregivers of newly diagnosed leukemia patients.

This study describes the development of a supportive group-based intervention for family caregivers of newly diagnosed leukemia patients. We assessed the feasibility, acceptability, and efficacy of the group on caregiver distress and quality of life, as well as patient distress utilizing a sequential cohort design comparing a pre-intervention control group with the intervention group. Patients and caregiver dyads completed measures at 4 time points: within 1 week of diagnosis (T1), 2-week follow-up (T2), 6-week follow-up (T3), and 12-week follow-up (T4). Significant interaction effects were observed for both caregiver distress and quality of life, whereby those receiving the intervention demonstrated improved quality of life and reduced distress over time. Overall, results support the acceptability, feasibility, and preliminary efficacy of the group intervention.

Early versus late preemptive allogeneic hematopoietic cell transplantation for relapsed or refractory acute myeloid leukemia.

Many patients with relapsed or refractory acute myeloid leukemia (AML) do not receive allogeneic hematopoietic cell transplantation (alloHCT) because they are unable to achieve a complete remission (CR) after reinduction chemotherapy. Starting in January 2003, we prospectively assigned patients with AML with high-risk clinical features to preemptive alloHCT (p-alloHCT) as soon as possible after reinduction chemotherapy. High-risk clinical features were associated with poor response to chemotherapy: primary induction failure, second or greater relapse, and first CR interval <6 months. We hypothesized that any residual disease would be maximally reduced at the time of transplant, resulting in the best milieu and most lead time for developing a graft-versus-leukemia effect and in improved long-term overall survival (OS) without excess toxicity. This analysis studied the effect of transplant timing on p-alloHCT in 30 patients with high-risk clinical features of 156 consecutive AML patients referred for alloHCT. We compared early p-alloHCT within 4 weeks of reinduction chemotherapy before count recovery with late p-alloHCT 4 weeks after reinduction chemotherapy with count recovery. OS and progression-free survival (PFS) at 2 years were not significantly different for early versus late p-alloHCT (OS 23% versus 33%, respectively, P > .1; PFS 18% versus 22%, respectively, P > .1). Day 100 and 1-year transplant-related mortality were similar (33.3% versus 22.2%, P > .1; 44.4% versus 42.9%, P > .1, respectively). Preemptive alloHCT allowed 30 patients to be transplanted who would normally not receive alloHCT. Clinical outcomes for early p-alloHCT are similar to those for late p-alloHCT without excess toxicity. Early p-alloHCT is a feasible alternative to late p-alloHCT for maximizing therapy of AML that is poorly responsive to induction chemotherapy.

Low 25(OH) vitamin D3 levels are associated with adverse outcome in newly diagnosed, intensively treated adult acute myeloid leukemia.

BACKGROUND: Several studies have suggested that low 25(OH) vitamin D3 levels may be prognostic in some malignancies, but no studies have evaluated their impact on treatment outcome in patients with acute myeloid leukemia (AML). METHODS: Vitamin D levels were evaluated in 97 consecutive, newly diagnosed, intensively treated patients with AML. MicroRNA expression profiles and single nucleotide polymorphisms (SNPs) in the 25(OH) vitamin D3 pathway genes were evaluated and correlated with 25(OH) vitamin D3 levels and treatment outcome. RESULTS: Thirty-four patients (35%) had normal 25(OH) vitamin D3 levels (32-100 ng/mL), 34 patients (35%) had insufficient levels (20-31.9 ng/mL), and 29 patients (30%) had deficient levels (<20 ng/mL). Insufficient/deficient 25(OH) vitamin D3 levels were associated with worse relapse-free survival (RFS) compared with normal vitamin D3 levels. In multivariate analyses, deficient 25(OH) vitamin D3 , smoking, European Leukemia Network genetic group, and white blood cell count retained their statistical significance for RFS. Several microRNAs and SNPs were associated with 25(OH) vitamin D3 levels, although none remained significant after multiple test corrections; one 25(OH) vitamin D3 receptor SNP, rs10783219, was associated with a lower complete remission rate (P = .0442) and with shorter RFS (P = .0058) and overall survival (P = .0011). CONCLUSIONS: It remains to be determined what role microRNA and SNP profiles play in contributing to low 25(OH) vitamin D3 level and/or outcome and whether supplementation will improve outcomes for patients with AML.

Genetics on a WHIM.

We initially described the WHIM syndrome based on the combination of Warts, Hypogammaglobulinaemia, Infections and Myelokathexis (neutrophil retention in the bone marrow). Translational research led to the discovery that this rare immunodeficiency disease is caused by a heterozygous mutation in the CXCR4 gene. Recently, Plerixafor has been suggested as a treatment for WHIM syndrome due to its efficacy as a CXCR4 antagonist, closing the translational research loop. In this review, we will focus on the clinical manifestations, pathophysiology, diagnosis and possible therapies for this rare entity.

Arsenic trioxide during consolidation for patients with previously untreated low/intermediate risk acute promyelocytic leukaemia may eliminate the need for maintenance therapy.

Aa total of 105 patients (age ≥18 years) with newly diagnosed low or intermediate risk acute promyelocytic leukaemia (APL) were treated with a standard induction and consolidation regimen including arsenic trioxide (ATO). Sixty-eight patients who were polymerase chain reaction (PCR) negative for PML-RARA post-consolidation were randomized to either 1 year of maintenance with tretinoin, mercaptopurine and methotrexate, or observation. Enrollment in this non-inferiority trial was stopped prematurely due to slow accrual. With a median follow up of 36·1 months, the overall survival of the 105 patients was 93%, and there have been no relapses in the patients randomized to maintenance or observation. These results demonstrate that cures can be expected in >90% of patients with low and intermediate risk APL and suggest that maintenance therapy may not be needed if patients are treated with an intensive post-remission regimen including ATO. This trial was registered at clinicaltrials.gov as #NCT00492856.

miR-3151 interplays with its host gene BAALC and independently affects outcome of patients with cytogenetically normal acute myeloid leukemia.

High BAALC expression levels are associated with poor outcome in cytogenetically normal acute myeloid leukemia (CN-AML) patients. Recently, miR-3151 was discovered in intron 1 of BAALC. To evaluate the prognostic significance of miR-3151 expression levels and to gain insight into the biologic and prognostic interplay between miR-3151 and its host, miR-3151 and BAALC expression were measured in pretreatment blood of 179 CN-AML patients. Gene-expression profiling and miRNA-expression profiling were performed using microarrays. High miR-3151 expression was associated with shorter disease-free and overall survival, whereas high BAALC expression predicted failure of complete remission and shorter overall survival. Patients exhibiting high expression of both miR-3151 and BAALC had worse outcome than patients expressing low levels of either gene or both genes. In gene-expression profiling, high miR-3151 expressers showed down-regulation of genes involved in transcriptional regulation, posttranslational modification, and cancer pathways. Two genes, FBXL20 and USP40, were validated as direct miR-3151 targets. The results of the present study show that high expression of miR-3151 is an independent prognosticator for poor outcome in CN-AML and affects different outcome end points than its host gene, BAALC. The combination of both markers identified a patient subset with the poorest outcome. This interplay between an intronic miR and its host may have important biologic implications.

Intensive induction is effective in selected octogenarian acute myeloid leukemia patients: prognostic significance of karyotype and selected molecular markers used in the European LeukemiaNet classification.

We investigated whether octogenarian patients with acute myeloid leukemia enrolled onto Cooperative Group clinical trials and treated with intensive induction therapy could be cured, and whether karyotype and selected molecular markers had any prognostic significance in these patients. Among 138 patients with cytogenetic information, normal karyotype was the most common (47.1%) followed by complex karyotype (14.5%) and sole +8 (9.4%). Among these patients, the relapse-free survival rate at 1 year was 37% and 13% at 3 years, and the respective overall survival rates were 24% and 8%. Whereas the 90 patients who survived beyond 30 days had the same relapse-free survival rates, their 1-year and 3-year overall survival rates were 36% and 11%, respectively. Of the 66 patients surviving beyond 30 days who could be classified into European LeukemiaNet genetic groups, those in the intermediate-I group had better overall survival than patients in the adverse group (P=0.01). Among patients with cytogenetically normal acute myeloid leukemia who were tested for the European LeukemiaNet-associated molecular alterations, FLT3-internal tandem duplication and NPM1 mutations, it was found that FLT3-internal tandem duplication (detected in 29% of patients) did not associate with overall survival (P=0.31), whereas NPM1 mutations (30%) were associated with a significantly longer overall survival (P=0.002). We conclude that intensive induction is effective and indicated in selected octogenarians with acute myeloid leukemia, that their overall survival varies among the European LeukemiaNet genetic groups and that NPM1 mutations may be of prognostic significance among octogenarian patients with cytogenetically normal acute myeloid leukemia.

Autologous transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia achieves outcomes similar to allogeneic transplantation: results of CALGB Study 10001 (Alliance).

Allogeneic stem cell transplantation is the standard approach to Philadelphia chromosome positive acute lymphoblastic leukemia. We hypothesized that imatinib plus sequential chemotherapy will result in significant leukemia cell cytoreduction in patients with Philadelphia chromosome positive acute lymphoblastic leukemia, allowing collection of normal hematopoietic stem cells uncontaminated by residual BCR/ABL1(+) lymphoblasts and thus reduce the likelihood of relapse after autologous stem cell transplantation for patients under 60 years of age without sibling donors. We enrolled 58 patients; 19 underwent autologous and 15 underwent allogeneic stem cell transplantation on study. Imatinib plus sequential chemotherapy resulted in reverse-transcriptase polymerase chain reaction-negative stem cells in 9 patients and remained minimally positive in 4 (6 were not evaluable). Overall survival (median 6.0 years vs. not reached) and disease-free survival (median 3.5 vs. 4.1 years) were similar between those who underwent autologous and those who underwent allogeneic stem cell transplantation. We conclude that autologous stem cell transplantation represents a safe and effective alternative for allogeneic stem cell transplantation in Philadelphia chromosome positive acute lymphoblastic leukemia patients without sibling donors (clinicaltrials.gov identifier:00039377).