Currently, limited molecular markers exist that can determine where in the spectrum of chronic myeloid leukemia (CML) progression an individual patient falls at diagnosis. Gene expression profiles can predict disease and prognosis, but most widely used microarray analytical methods yield lengthy gene candidate lists that are difficult to apply clinically. Consequently, we applied a probabilistic method called Bayesian model averaging (BMA) to a large CML microarray dataset. BMA, a supervised method, considers multiple genes simultaneously and identifies small gene sets. BMA identified 6 genes (NOB1, DDX47, IGSF2, LTB4R, SCARB1, and SLC25A3) that discriminated chronic phase (CP) from blast crisis (BC) CML. In CML, phase labels divide disease progression into discrete states. BMA, however, produces posterior probabilities between 0 and 1 and predicts patients in "intermediate" stages. In validation studies of 88 patients, the 6-gene signature discriminated early CP from late CP, accelerated phase, and BC. This distinction between early and late CP is not possible with current classifications, which are based on known duration of disease. BMA is a powerful tool for developing diagnostic tests from microarray data. Because therapeutic outcomes are so closely tied to disease phase, these probabilities can be used to determine a risk-based treatment strategy at diagnosis.

Increasing evidence shows aberrant hypermethylation of genes occurring in and potentially contributing to pathogenesis of myeloid malignancies. Several of these diseases, such as myelodysplastic syndromes (MDSs), are responsive to DNA methyltransferase inhibitors. To determine the extent of promoter hypermethylation in such tumors, we compared the distribution of DNA methylation of 14 000 promoters in MDS and secondary acute myeloid leukemia (AML) patients enrolled in a phase 1 trial of 5-azacytidine and the histone deacetylase inhibitor entinostat against de novo AML patients and normal CD34(+) bone marrow cells. The MDS and secondary AML patients displayed more extensive aberrant DNA methylation involving thousands of genes than did the normal CD34(+) bone marrow cells or de novo AML blasts. Aberrant methylation in MDS and secondary AML tended to affect particular chromosomal regions, occurred more frequently in Alu-poor genes, and included prominent involvement of genes involved in the WNT and MAPK signaling pathways. DNA methylation was also measured at days 15 and 29 after the first treatment cycle. DNA methylation was reversed at day 15 in a uniform manner throughout the genome, and this effect persisted through day 29, even without continuous administration of the study drugs. This trial was registered at www.clinicaltrials.gov as J0443.

Gene transfer into hematopoietic stem cells by gamma-retroviral vectors (RVs) is an effective treatment for inherited blood disorders, although potentially limited by the risk of insertional mutagenesis. We evaluated the genomic impact of RV integration in T lymphocytes from adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) patients 10 to 30 months after infusion of autologous, genetically corrected CD34(+) cells. Expression profiling on ex vivo T-cell bulk population revealed no difference with respect to healthy controls. To assess the effect of vector integration on gene expression at the single-cell level, primary T-cell clones were isolated from 2 patients. T-cell clones harbored either 1 (89.8%) or 2 (10.2%) vector copies per cell and displayed partial to full correction of ADA expression, purine metabolism, and T-cell receptor-driven functions. Analysis of RV integration sites indicated a high diversity in T-cell origin, consistently with the polyclonal T-cell receptor-Vbeta repertoire. Quantitative transcript analysis of 120 genes within a 200-kb window around RV integration sites showed modest (2.8- to 5.2-fold) dysregulation of 5.8% genes in 18.6% of the T-cell clones compared with controls. Nonetheless, affected clones maintained a stable phenotype and normal in vitro functions. These results confirm that RV-mediated gene transfer for ADA-SCID is safe, and provide crucial information for the development of future gene therapy protocols. The trials described herein have been registered at http://www.clinicaltrials.gov as #NCT00598481 and #NCT00599781.

The prognosis of fludarabine (F)-refractory chronic lymphocytic leukemia (CLL) is very poor, and underlying mechanisms are only partly understood. To assess the contribution of p53 abnormalities to F-refractory CLL, we studied TP53 mutations in the CLL2H trial (subcutaneous alemtuzumab; n = 99). We found TP53 mutations in 37% of patients. Twelve of 67 (18%) patients without the 17p deletion showed a TP53 mutation and 50% showed evidence of uniparental disomy. A total of 75% of cases with TP53 mutation (without 17p-) showed clonal evolution/expansion. TP53 mutations had no impact on overall survival (P = .48). CLL with the 17p deletion or TP53 mutation showed very low miR-34a expression. To investigate the mechanisms underlying refractory CLL beyond p53, we studied cases without 17p-/TP53 mutation in detail. In several paired samples before and after F-refractory disease, no change in p21/p53 induction was observed after DNA damage. Although TP53 mutations and 17p deletions are found in a high proportion of F-refractory CLL, more than half of the cases cannot be explained by p53 defects (deletion or mutation), and alternative mechanisms need to be investigated. Alemtuzumab is effective irrespective of genetic high-risk subgroups with TP53 mutations. These clinical trials are registered at www.clinicaltrials.gov as #NCT00274976.

Evans syndrome (ES) is a rare disease characterized by the simultaneous or sequential development of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP) and/or immune neutropenia. To better describe the characteristics and outcome of ES in adults, a survey was initiated in 2005. The data from 68 patients (60% of them women) fulfilling strict inclusion criteria for ES are reported. The mean age at time of ITP and/or AIHA onset was 52 plus or minus 33 years, both cytopenias occurred simultaneously in 37 cases (54.5%). ES was considered as "primary" in 34 patients (50%) but was associated with an underlying disorder in half of the cases, including mainly systemic lupus, lymphoproliferative disorders, and common variable immunodeficiency. All patients were given corticosteroids, but 50 of them (73%) required at least one "second-line" treatment, including splenectomy(n = 19) and rituximab (n = 11). At time of analysis, after a mean follow-up of 4.8 years, only 22 patients (32%) were in remission off treatment; 16 (24%) had died. In elderly patients, the risk of cardiovascular manifestations related to AIHA seems to be higher than the ITP-related risk of severe bleeding. In conclusion, ES is a potentially life-threatening condition that may be associated with other underlying autoimmune or lymphoproliferative disorders.

Adenosine deaminase (ADA) deficiency is a disorder of the purine metabolism leading to combined immunodeficiency and systemic alterations, including skeletal abnormalities. We report that ADA deficiency in mice causes a specific bone phenotype characterized by alterations of structural properties and impaired mechanical competence. These alterations are the combined result of an imbalanced receptor activator of nuclear factor-kappaB ligand (RANKL)/osteoprotegerin axis, causing decreased osteoclastogenesis and an intrinsic defect of osteoblast function with subsequent low bone formation. In vitro, osteoblasts lacking ADA displayed an altered transcriptional profile and growth reduction. Furthermore, the bone marrow microenvironment of ADA-deficient mice showed a reduced capacity to support in vitro and in vivo hematopoiesis. Treatment of ADA-deficient neonatal mice with enzyme replacement therapy, bone marrow transplantation, or gene therapy resulted in full recovery of the altered bone parameters. Remarkably, untreated ADA-severe combined immunodeficiency patients showed a similar imbalance in RANKL/osteoprotegerin levels alongside severe growth retardation. Gene therapy with ADA-transduced hematopoietic stem cells increased serum RANKL levels and children's growth. Our results indicate that the ADA metabolism represents a crucial modulatory factor of bone cell activities and remodeling.

Higher levels of procoagulant factors and factor XII deficiency may be risk factors for first venous thromboembolism (VTE). We studied associations of coagulation factors IX through XIII with risk of future VTE in 2 general population samples. Using a nested case-control study combining the 21 860 participants of the Atherosclerosis Risk in Communities study and the Cardiovascular Health Study, we determined antigenic levels of these coagulation factors in primarily pre-event blood samples from 462 participants who subsequently developed VTE and 1047 participants who remained free of VTE. Only elevated levels of factors IX and XI were associated with increased risk of VTE after adjustment for age, sex, race, and study. For factor IX, the odds ratio (OR) was 1.4 (95% confidence interval [CI], 1.0-2.0) comparing the top to bottom quintile. The OR for factor XI was higher: 2.0 (95% CI, 1.4-2.9). With further adjustment for body mass index and diabetes, only elevated factor XI remained associated with VTE risk: OR 1.8 (95% CI, 1.3-2.7). Associations were similar by study and whether the thrombosis was idiopathic or secondary. Factor XII deficiency was not related to VTE risk. Among these procoagulant factors, only elevated factor XI was a risk factor for VTE.

We report outcomes of 932 recipients of unrelated donor peripheral blood stem cell hematopoietic cell transplantation (URD-PBSC HCT) for acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, and myelodysplastic syndrome enrolled on a prospective National Marrow Donor Program trial from 1999 through 2003. Preparative regimens included myeloablative (MA; N = 611), reduced-intensity (RI; N = 160), and nonmyeloablative (NMA; N = 161). For MA recipients, CD34(+) counts greater than 3.8 x 10(6)/kg improved neutrophil and platelet engraftment, whereas improved overall survival (OS) and reduced transplant-related mortality (TRM) were seen for all preparative regimens when CD34(+) cell doses exceeded 4.5 x 10(6)/kg. Higher infused doses of CD34(+) cell dose did not result in increased rates of either acute or chronic graft-versus-host disease (GVHD). Three-year OS and disease-free survival (DFS) of recipients of MA, RI, and NMA approaches were similar (33%, 35%, and 32% OS; 33%, 30%, and 29% DFS, respectively). In summary, recipients of URD-PBSC HCT receiving preparative regimens differing in intensity experienced similar survival. Higher CD34(+) cell doses resulted in more rapid engraftment, less TRM, and better 3-year OS (39% versus 25%, MA, P = .004; 38% versus 21% RI/NMA, P = .004) but did not increase the risk of GVHD. This trial was registered at www.clinicaltrials.gov as #NCT00785525.

Although chronic lymphocytic leukemia (CLL) is a disease of elderly patients, subjects older than 65 years are heavily underrepresented in clinical trials. The German CLL study group (GCLLSG) initiated a multicenter phase III trial for CLL patients older than 65 years comparing first-line therapy with fludarabine with chlorambucil. A total of 193 patients with a median age of 70 years were randomized to receive fludarabine (25 mg/m(2) for 5 days intravenously, every 28 days, for 6 courses) or chlorambucil (0.4 mg/kg body weight [BW] with an increase to 0.8 mg/kg, every 15 days, for 12 months). Fludarabine resulted in a significantly higher overall and complete remission rate (72% vs 51%, P = .003; 7% vs 0%, P = .011). Time to treatment failure was significantly shorter in the chlorambucil arm (11 vs 18 months; P = .004), but no difference in progression-free survival time was observed (19 months with fludarabine, 18 months with chlorambucil; P = .7). Moreover, fludarabine did not increase the overall survival time (46 months in the fludarabine vs 64 months in the chlorambucil arm; P = .15). Taken together, the results suggest that in elderly CLL patients the first-line therapy with fludarabine alone does not result in a major clinical benefit compared with chlorambucil. This trial is registered with www.isrctn.org under identifier ISRCTN 36294212.

To evaluate internal tandem duplication (ITD) insertion sites and length as well as their clinical impact in younger adult patients with FLT3-ITD-positive acute myeloid leukemia (AML), sequencing after DNA-based amplification was performed in diagnostic samples from 241 FLT3-ITD-mutated patients. All patients were treated on 3 German-Austrian AML Study Group protocols. Thirty-four of the 241 patients had more than 1 ITD, leading to a total of 282 ITDs; the median ITD length was 48 nucleotides (range, 15-180 nucleotides). ITD integration sites were categorized according to functional regions of the FLT3 receptor: juxtamembrane domain (JMD), n = 148; JMD hinge region, n = 48; beta1-sheet of the tyrosine kinase domain-1 (TKD1), n = 73; remaining TKD1 region, n = 13. ITD length was strongly correlated with functional regions (P < .001). In multivariable analyses, ITD integration site in the beta1-sheet was identified as an unfavorable prognostic factor for achievement of a complete remission (odds ratio, 0.22; P = .01), relapse-free survival (hazard ratio, 1.86; P < .001), and overall survival (hazard ratio, 1.59; P = .008). ITD insertion site in the beta1-sheet appears to be an important unfavorable prognostic factor in young adult patients with FLT3-ITD-positive AML. The clinical trials described herein have been registered as follows: AML HD93 (already published in 2003), AML HD98A (NCT00146120; http://www.ClinicalTrials.gov), and AMLSG 07-04 (NCT00151242; http://www.ClinicalTrials.gov).

Nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML), which is recognized as a provisional entity in the World Health Organization 2008 classification of myeloid neoplasms, accounts for 30% of AML. We analyzed 1227 diagnostic and follow-up samples in 252 NPM1-mutated AML patients with 17 different NPM1 mutation-specific real-time quantitative polymerase chain reaction (RQ-PCR) assays. Paired diagnostic/relapse samples of 84 patients revealed stable NPM1 mutations in all cases, suggesting that they are pathogenetically early events and thus applicable for minimal residual disease detection. A total of 47 relapses were predictable because of an NPM1 mutation level (%NPM1/ABL1) increase of at least 1 log or in 15 cases because of NPM1 mutation levels not decreasing less than 3 log ranges. A high prognostic value of NPM1 levels was shown for 4 different intervals after therapy was initiated. Furthermore, thresholds of 0.1 and 0.01%NPM1/ABL1 during/after treatment discriminated between prognostic subgroups. Univariate analyses, including age, white blood cell count, blast count, CD34 positivity, FLT3 mutations status, FAB type, karyotype, NPM1 mutation type, and pretreatment NPM1 mutational level, showed that, besides NPM1 mutation level, only age and FLT3-LM mutation status were prognostically significant for EFS. Multivariate analysis, including age, FLT3-LM status, and NPM1 mutation level at different time points, demonstrated that NPM1 level was the most relevant prognostic factor during first-line treatment. Similar results were obtained in patients undergoing second-line chemotherapy or allogeneic stem cell transplantation.

Current treatment strategies for Hodgkin lymphoma result in excellent survival but often confer significant long-term toxicity. We designed ABVE-PC (doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide) to (1) enhance treatment efficacy by dose-dense drug delivery and (2) reduce risk of long-term sequelae by response-based reduction of cumulative chemotherapy. Efficient induction of early response by dose-dense drug delivery supported an early-response-adapted therapeutic paradigm. The 216 eligible patients were younger than 22 years with intermediate- or high-risk Hodgkin lymphoma. ABVE-PC was administered every 21 days. Rapid early responders (RERs) to 3 ABVE-PC cycles received 21 Gy radiation to involved regions; RER was documented in 63% of patients. Slow early responders received 2 additional ABVE-PC cycles before 21 Gy radiation. Five-year event-free-survival was 84%: 86% for the RER and 83% for the slow early responders (P = .85). Only 1% of patients had progressive disease. Five-year overall survival was 95%. With this regimen, cumulative doses of alkylators, anthracyclines, and epipodophyllotoxins are below thresholds usually associated with significant long-term toxicity. ABVE-PC is a dose-dense regimen that provides outstanding event-free survival/overall survival with short duration, early-response-adapted therapy.

This phase 3 prospective randomized trial evaluated the efficacy and long-term safety of erythropoietin (EPO) with or without granulocyte colony-stimulating factor plus supportive care (SC; n = 53) versus SC alone (n = 57) for the treatment of anemic patients with lower-risk myelodysplastic syndromes. The response rates in the EPO versus SC alone arms were 36% versus 9.6%, respectively, at the initial treatment step, 47% in the EPO arm, including subsequent steps. Responding patients had significantly lower serum EPO levels (45% vs 5% responses for levels < 200 mU/mL vs > or = 200 mU/mL) and improvement in multiple quality-of-life domains. With prolonged follow-up (median, 5.8 years), no differences were found in overall survival of patients in the EPO versus SC arms (median, 3.1 vs 2.6 years) or in the incidence of transformation to acute myeloid leukemia (7.5% and 10.5% patients, respectively). Increased survival was demonstrated for erythroid responders versus nonresponders (median, 5.5 vs 2.3 years). Flow cytometric analysis showed that the percentage of P-glycoprotein(+) CD34(+) marrow blasts was positively correlated with longer overall survival. In comparison with SC alone, patients receiving EPO with or without granulocyte colony-stimulating factor plus SC had improved erythroid responses, similar survival, and incidence of acute myeloid leukemia transformation.

Preclinical models have demonstrated the efficacy of granulocyte-macrophage colony-stimulating factor-secreting cancer immunotherapies (GVAX platform) accompanied by immunotherapy-primed lymphocytes after autologous stem cell transplantation in hematologic malignancies. We conducted a phase 2 study of this combination in adult patients with acute myeloid leukemia. Immunotherapy consisted of autologous leukemia cells admixed with granulocyte-macrophage colony-stimulating factor-secreting K562 cells. "Primed" lymphocytes were collected after a single pretransplantation dose of immunotherapy and reinfused with the stem cell graft. Fifty-four subjects were enrolled; 46 (85%) achieved a complete remission, and 28 (52%) received the pretransplantation immunotherapy. For all patients who achieved complete remission, the 3-year relapse-free survival (RFS) rate was 47.4% and overall survival was 57.4%. For the 28 immunotherapy-treated patients, the RFS and overall survival rates were 61.8% and 73.4%, respectively. Posttreatment induction of delayed-type hypersensitivity reactions to autologous leukemia cells was associated with longer 3-year RFS rate (100% vs 48%). Minimal residual disease was monitored by quantitative analysis of Wilms tumor-1 (WT1), a leukemia-associated gene. A decrease in WT1 transcripts in blood was noted in 69% of patients after the first immunotherapy dose and was also associated with longer 3-year RFS (61% vs 0%). In conclusion, immunotherapy in combination with primed lymphocytes and autologous stem cell transplantation shows encouraging signals of potential activity in acute myeloid leukemia (ClinicalTrials.gov: NCT00116467).

Sequential administration of DNA methyltransferase (DNMT) inhibitors and histone deacetylase (HDAC) inhibitors has demonstrated clinical efficacy in patients with hematologic malignancies. However, the mechanism behind their clinical efficacy remains controversial. In this study, the methylation dynamics of 4 TSGs (p15(INK4B), CDH-1, DAPK-1, and SOCS-1) were studied in sequential bone marrow samples from 30 patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) who completed a minimum of 4 cycles of therapy with 5-azacytidine and entinostat. Reversal of promoter methylation after therapy was observed in both clinical responders and nonresponders across all genes. There was no association between clinical response and either baseline methylation or methylation reversal in the bone marrow or purified CD34(+) population, nor was there an association with change in gene expression. Transient global hypomethylation was observed in samples after treatment but was not associated with clinical response. Induction of histone H3/H4 acetylation and the DNA damage-associated variant histone gamma-H2AX was observed in peripheral blood samples across all dose cohorts. In conclusion, methylation reversal of candidate TSGs during cycle 1 of therapy was not predictive of clinical response to combination "epigenetic" therapy. This trial is registered with http://www.clinicaltrials.gov under NCT00101179.

The role of reduced-intensity conditioning (RIC) regimens in pediatric cancer treatment is unclear. To define the efficacy of a busulfan/fludarabine/antithymocyte globulin RIC regimen in pediatric patients ineligible for myeloablative transplantation, we completed a trial at 23 institutions in the Pediatric Blood and Marrow Transplant Consortium. Forty-seven patients with hematologic malignancies were enrolled. Sustained engraftment occurred in 98%, 89%, and 90%, and full donor chimerism was achieved in 88%, 76%, and 78% of evaluable related bone marrow/peripheral blood stem cells (BM/PBSCs), unrelated BM/PBSCs, and unrelated cord blood recipients. With a median follow-up of 24 months (range, 11-53 months), 2-year event-free survival, overall survival (OS), transplantation-related mortality, and relapse were 40%, 45%, 11%, and 43%, respectively. Univariate analysis revealed an inferior outcome when patients had undergone previous total body irradiation (TBI)-containing myeloablative transplantation (2-year OS, 23% vs 63% vs 52%, previous TBI transplantation vs no TBI transplantation vs no transplantation, P = .02) and when patients not previously treated with TBI had detectable disease at the time of the RIC procedure (2-year OS, 0% vs 63%, detectable vs nondetectable disease, P = .01). Favorable outcomes can be achieved with RIC approaches in pediatric patients in remission who are ineligible for myeloablative transplantation. This study was registered at www.clinicaltrials.gov as #NCT00795132.

The importance of donor-recipient human leukocyte antigen (HLA)-DPB1 matching for the clinical outcome of unrelated hematopoietic stem cell transplantation (HSCT) is controversial. We have previously described an algorithm for nonpermissive HLA-DPB1 disparities involving HLA-DPB1*0901,*1001,*1701,*0301,*1401,*4501, based on T-cell alloreactivity patterns. By revisiting the immunogenicity of HLA-DPB1*02, a modified algorithm was developed and retrospectively tested in 621 unrelated HSCTs facilitated through the Italian Registry for oncohematologic adult patients. The modified algorithm proved to be markedly more predictive of outcome than the original one, with significantly higher Kaplan-Meier probabilities of 2-year survival in permissive compared with nonpermissive transplantations (55% vs 39%, P = .005). This was the result of increased adjusted hazards of nonrelapse mortality (hazard ratio [HR] = 1.74; confidence interval [CI], 1.19-2.53; P = .004) but not of relapse (HR = 1.02; CI, 0.73-1.42; P = .92). The increase in the hazards of overall mortality by nonpermissive HLA-DPB1 disparity was similar in 10 of 10 (HR = 2.12; CI, 1.23-3.64; P = .006) and 9 of 10 allele-matched transplantations (HR = 2.21; CI, 1.28-3.80; P = .004), both in early-stage and in advanced-stage disease. These data call for revisiting current HLA matching strategies for unrelated HSCT, suggesting that searches should be directed up-front toward identification of HLA-DPB1 permissive, 10 of 10 or 9 of 10 matched donors.

Landmark analyses are used to investigate the importance for survival of achieving complete response (CR), an important initial goal of myeloma therapy. With median times to CR in Total Therapy (TT) trials of approximately 1 year, this approach excludes a sizeable fraction of patients dying before such a landmark. To permit inclusion of all trial participants, we investigated the prognostic implications of both onset and duration of CR as time-dependent variables. Superseding the adverse effects of cytogenetic abnormalities and other standard prognostic parameters, both failure to achieve CR (non-CR) and, especially, loss of CR (los-CR) were independently associated with inferior survival in TT1, TT2, and TT3 protocols. In the context of gene array-defined risk, available in TT2 and TT3 subsets, both los-CR and non-CR terms were retained in the survival model as dominant adverse variables, stressing the prognostic importance of sustaining CR status, especially in high-risk disease.

In a clinical trial for adeno-associated virus serotype 1 (AAV-1)-mediated gene transfer to muscle for lipoprotein lipase (LPL) deficiency, 1 subject from the high-dose cohort experienced a transient increase in the muscle enzyme creatine phosphokinase (CPK) 4 weeks after gene transfer. Simultaneously, after an initial downward trend consistent with expression of LPL, plasma triglyceride levels returned to baseline. We characterized B- and T-cell responses to the vector and the transgene product in the subjects enrolled in this study. IFN-gamma enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining assays performed on peripheral blood mononuclear cells (PBMCs) from the subject who experienced the CPK elevation showed the activation of capsid-specific CD4(+) and CD8(+) T cells. Four of 8 subjects had detectable T-cell responses to capsid with dose-dependent kinetics of appearance. Subjects with detectable T-cell responses to capsid also had higher anti-AAV-1 IgG3 antibody titer. No subject developed B- or T-cell responses to the LPL transgene product. These findings suggest that T-cell responses directed to the AAV-1 capsid are dose-dependent. Whether they also limit the duration of expression of the transgene at higher doses is unclear, and will require additional analyses at later time points.

New treatment options are required for primary systemic AL amyloidosis (AL). This phase 1 dose-escalation component of a phase 1/2 study in relapsed AL aimed to determine the maximum tolerated dose (MTD) of bortezomib once weekly (0.7-1.6 mg/m(2); days 1, 8, 15, and 22; 35-day cycles) and twice weekly (0.7-1.3 mg/m(2); days 1, 4, 8, and 11; 21-day cycles) and assess preliminary hematologic responses. Thirty-one patients with relapsed AL were enrolled across 7 cohorts. Dose-limiting toxicity included grade 3 congestive heart failure in 2 patients (1 at once weekly, 1.6 mg/m(2), and 1 at twice weekly, 1.0 mg/m(2)). MTD was not defined for either schedule; the maximum doses of 1.6 mg/m(2) (once weekly) and 1.3 mg/m(2) (twice weekly) are being used in phase 2 evaluation. Most commonly reported toxicities on both schedules included gastrointestinal events, fatigue, and nervous system disorders. Discontinuations and dose reductions for toxicity were reported in 12 and 4 patients, respectively. No treatment-related deaths occurred. Hematologic responses occurred in 15 (50%) of 30 evaluable patients, including 6 (20%) complete responses. Median time to first response was 1.2 months. Once-weekly and twice-weekly bortezomib appear generally well tolerated in relapsed AL, with promising hematologic responses. This study is registered with http://ClinicalTrials.Gov under identifier NCT00298766.