Asparaginase: How to Better Manage Toxicities in Adults.

PURPOSE OF REVIEW: This review aims to help oncologists who predominantly treat adults better understand and manage asparaginase associated toxicities and prevent unnecessary discontinuation or reluctance of its use. RECENT FINDINGS: Given the data supporting the benefit of incorporating multiple doses of asparaginase in pediatric type regimens, it is prudent to promote deeper understanding of this drug, particularly its toxicities, and its use so as to optimize treatment of ALL. Although asparaginase is associated with a variety of toxicities, the vast majority are not life threatening and do not preclude repeat dosing of this important drug. Understanding the pharmacology and toxicity profile of asparaginase is critical to dosing asparaginase appropriately in order to minimize these toxicities.

SOHO State of the Art Updates and Next Questions | Asparaginase-Understanding and Overcoming Toxicities in Adults with ALL.

The adoption of pediatric-inspired regimens in young adults with newly diagnosed acute lymphoblastic leukemia (ALL) has significantly improved their survival outcomes. Pediatric-inspired regimens in ALL rely profoundly on delivering adequate dosing of non-myelosuppressive drugs of which asparaginase, a bacterial derived agent, is a key component. Asparaginase therapy is associated with a spectrum of unique toxicities that are observed more frequently in adult patients compared to children with ALL, and this observation has contributed to the reluctance of adult oncologists to administer the drug to their patients. Understanding the breadth of asparaginase toxicity and the associated risk factors may help in preventing severe manifestations and allow safer treatment for adults with ALL. In this review, we will discuss the different formulations of asparaginase and the appropriate dosing in adults with ALL. We will further discuss the frequency and risk factors for individual toxicities of asparaginase along with strategies for their prevention and management.

Treatment of Patients with Acute Myeloid Leukemia with the Targeted Alpha-Particle Nanogenerator Actinium-225-Lintuzumab.

PURPOSE: The anti-CD33 antibody lintuzumab has modest activity against acute myeloid leukemia (AML). To increase its potency, lintuzumab was conjugated to actinium-225 (225Ac), a radionuclide yielding 4 α-particles. This first-in-human, phase I trial was conducted to determine the safety, pharmacology, and biological activity of 225Ac-lintuzumab. PATIENTS AND METHODS: Eighteen patients (median age, 64 years; range, 45-80) with relapsed or refractory AML received a single infusion of 225Ac-lintuzumab at activities of 18.5 to 148 kBq/kg. RESULTS: The maximum tolerated dose was 111 kBq/kg. Dose-limiting toxicities included myelosuppression lasting > 35 days in one patient receiving 148 kBq/kg and death from sepsis in two patients treated with 111 and 148 kBq/kg. Myelosuppression was the most common toxicity. Significant extramedullary toxicities were limited to transient grade 3 liver function abnormalities. Pharmacokinetics were determined by gamma counting serial whole blood, plasma, and urine samples at energy windows for the 225Ac daughters, francium-221 and bismuth-213. Two-phase elimination kinetics were seen with mean plasma t1/2 - α and t1/2 - ß of 1.9 and 38 hours, respectively. Peripheral blood blasts were eliminated in 10 of 16 evaluable patients (63%) but only at doses of ≥ 37 kBq/kg. Bone marrow blasts were reduced in 10 of 15 evaluable patients (67%), including 3 patients with marrow blasts ≤ 5% and one patient with a morphologic leukemia-free state. CONCLUSIONS: Therapy for AML with the targeted α-particle generator 225Ac-lintuzumab was feasible with an acceptable safety profile. Elimination of circulating blasts or reductions in marrow blasts were observed across all dose levels.

Optimizing use of L-asparaginase-based treatment of adults with acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is a malignancy of lymphoid progenitor cells occurring at an annual incidence rate of approximately 1.1 to 2.1 per 100,000 person-years globally. Approximately 40% of annual ALL cases occur in adults, yet estimated 5-year overall survival rates are about 40% to 50% in adults (and vary broadly by age) compared with 90% in children. Although the addition and/or intensification of asparaginase as a key treatment strategy for pediatric ALL is well recognized, further research is needed to clarify the benefit/risk ratio in adult patients with ALL. This review emphasizes the importance of efficient management of adverse events to increase asparaginase efficacy and explores novel strategies for optimizing asparaginase treatment, including new formulations of asparaginase, pharmacokinetic-based dosing, and pharmacogenetic profiling. Upcoming results of adult ALL trials should further clarify the role of asparaginase, building on the results of the large NOPHO 2008, CALGB 10403, GRAALL-2005, GMALL 07/2003, and UKALL14 trials.

Immunophenotype of acute lymphoblastic leukemia in minorities- analysis from the SEER database.

Acute Lymphocytic Leukemia (ALL) is a malignancy that originates from immature lymphoid cells and is clinically established with flow cytometry through disease-specific markers. Variation between ethnic groups is an epidemiological aspect of ALL. Higher incidence rates have been observed in Latin American patients and ALL in Latinos carries a dismal prognosis. The cell of origin in ALL is derived from immature cells of either the B or T lineage. Most reported data among Latinos either exclusively looks at B cell precursor ALL or do not distinguish between subtypes. We used the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database to delineate the differences in incidence rates of B-ALL and T-ALL across ethnic groups in the United States. Data from SEER-18 was used to compare incidence rates of T-ALL and B-ALL. Due to the utilization of cytogenetics and subsequent changes in ICD coding over the years examined the most recent data reported from 2002 to 2017. We compared rates in Non-Hispanic Whites (NHWs), Latinos, Blacks and Asian-Pacific Islanders (API). Age-adjusted incidence rates per 100,000 person-years were calculated. The incidence rate of B-ALL in the Latino population was consistently higher than other race/ethnicities throughout the years, ranging from 1.0 per 100,000 in 2002 to 2.5 per 100,000 in 2017. Blacks had the lowest age adjusted incidence rate (AAIR) of B-ALL overall, with rates approximately one third of those found in Latinos and the highest AAIR of T-ALL with an AAIR of 0.5 per 100,000.

CNS involvement in AML at diagnosis is rare and does not affect response or survival: data from 11 ECOG-ACRIN trials.

Central nervous system (CNS) involvement in patients with newly diagnosed acute myeloid leukemia (AML) is rare, and systematic data regarding outcome are scarce. This retrospective study summarized data from 11 consecutive Eastern Cooperative Oncology Group-American College of Radiology Imaging Network (ECOG-ACRIN) clinical trials for patients with newly diagnosed AML. In all, 3240 patients with AML were analyzed, and 36 (1.11%) were found to have CNS involvement at diagnosis. The incidence of CNS disease among the 5 studies with per protocol mandatory lumbar puncture (LP) was similar to the incidence among studies in which LP was performed at the discretion of the investigator (0.86% vs 1.41%; P = .18). There was no significant difference in the rate of complete remission (CR) among patients with CNS involvement and those with other extramedullary disease (EMD) sites or those with no EMD (52.8% vs 59.3%-60%). The median overall survival (OS) for patients who were CNS positive, who had other EMD, or who had no EMD was 11.4, 11.3, and 12.7 months, respectively. There was no difference in OS among patients with CNS involvement, those with other EMD (hazard ratio [HR], 0.96; adjusted P = .84), and those with no EMD (HR, 1.19; adjusted P = .44). In conclusion, the reported incidence of CNS involvement in patients with newly diagnosed AML is low (1.1%), irrespective of whether an LP is mandatory or not. The presence of CNS disease at diagnosis in and of itself does not seem to portend a poor prognosis for achieving an initial CR or for OS.

Arsenic trioxide therapy predisposes to herpes zoster reactivation despite minimally myelosuppressive therapy.

Acute Promyelocytic Leukemia (APL) is a unique subtype of acute myeloid leukemia that is highly responsive to minimally myelosuppressive therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). We and others have observed a higher than expected incidence of herpes zoster reactivation in APL patients treated with ATO. Memorial Sloan Kettering Cancer Center (MSKCC) has been using ATO since 1997 in all relapsed APL patients, and more recently has included it in our front-line APL regimens. Here we present a retrospective analysis of the factors contributing to herpes zoster reactivation among APL patients.

Pediatric-inspired chemotherapy incorporating pegaspargase is safe and results in high rates of minimal residual disease negativity in adults up to age 60 with Philadelphia chromosome-negative acute lymphoblastic leukemia.

Administration of pediatric-inspired chemotherapy to adults up to age 60 with acute lymphoblastic leukemia (ALL) is challenging in part due to toxicities of asparaginase as well as myelosuppression. We conducted a multicenter phase II clinical trial (NCT01920737) investigating a pediatric-inspired regimen, based on the augmented arm of the Children's Cancer Group 1882 protocol, incorporating 6 doses of pegaspargase 2000 IU/m2, rationally synchronized to avoid overlapping toxicity with other agents. We treated 39 adults ages 20-60 years (median, 38 years) with newly-diagnosed ALL (n=31) or lymphoblastic lymphoma (n=8). Grade 3-4 hyperbilirubinemia occurred frequently and at higher rates in patients 40-60 (n=18) vs 18-39 (n=21) years (44 vs 10%, p=0.025). However, 8/9 patients re-challenged with pegaspargase did not experience recurrent grade 3-4 hyperbilirubinemia. Grade 3-4 hypertriglyceridemia and hypofibrinogenemia were common (each 59%). Asparaginase activity at 7-days post-infusion reflected levels associated with adequate asparagine depletion, even among those with antibodies to pegaspargase. Complete response (CR)/CR with incomplete hematologic recovery was observed post-induction in 38/39 (97%) patients. Among patients with ALL, rates of MRD negativity by multiparameter flow cytometry were 33% and 83% following Induction Phase I and Phase II, respectively. Event-free and overall survival at 3 years (67.8 and 76.4%) compare favorably to outcomes observed in other series. These results demonstrate pegaspargase can be administered in the context of intensive multi-agent chemotherapy to adults age ≤60 with manageable toxicity. This regimen may serve as an effective backbone into which novel agents may be incorporated in future frontline studies.

Managing toxicities with asparaginase-based therapies in adult ALL: summary of an ESMO Open-Cancer Horizons roundtable discussion.

With recent prospective clinical trials that used paediatric regimens with multiple doses of pegylated form of asparaginase (PEG asparaginase) in adults reporting significantly improved survival compared with historical data with regimens that used less asparaginase, PEG asparaginase is increasingly being used in the treatment of adult acute lymphoblastic leukaemia (ALL). However, administering asparaginase still comes with its challenges, especially in adult patients. Therefore, it is important to understand how to manage its toxicities properly. An expert group met in November 2019 in London to discuss recent data of paediatric as well as adult studies using paediatric regimens with regard to the best management of several key toxicities that can occur in adults treated with asparaginase including hepatotoxicity, pancreatitis, hypertriglyceridaemia, thrombosis and hypersensitivity. Several recommendations were made for each one of these toxicities, with the goal of safe administration of the drug and to educate clinicians when the drug can be continued despite side effects.

At three years, patients with acute lymphoblastic leukaemia are still at risk for relapse. Results of the international MRC UKALLXII/ECOG E2993 trial.

Late relapse [>3 years from complete remission (CR)] in acute lymphoblastic leukaemia (ALL), is unusual. Data from the MRC UKALLXII/ECOG E2993 trial are presented to evaluate the incidence and characteristics of late relapse in adult ALL. Of 1,909 patients, 1,752 (92%) achieved CR and among these 757 (43·2%) relapsed; 691 (91·3%) within three years and 66 (8·7%) beyond. Among these 66 patients, median time to relapse was 47 (37-144) months. Relapse beyond three years occurred in 3·8% of all who achieved CR. The cumulative risk of relapse was 40%, 43% and 45% at three, five and ten years respectively. Out of the 1 752 patients who achieved CR, 11·7% underwent autologous and 40·6% allogeneic transplant, while in CR1. Of the autologous patients, 43·2% relapsed early and 3·4% relapsed late. However, among the allogeneic patients, 13·2% relapsed early and only 1·3% late. The five-year overall survival from relapse was 5·8% and 20% in the early and late relapse patients respectively. In conclusion, late relapse in adults with ALL is not uncommon, and is associated with better outcome after relapse compared to early relapse.

How I treat the toxicities of pegasparaginase in adults with acute lymphoblastic leukemia.

Administering asparaginase has always been problematic in adults because most general oncologists who treat adults are not familiar with its usage and toxicity. The toxicity profile of the drug is unique and is not observed with any other chemotherapy agent. Furthermore, asparaginase is almost exclusively used in acute lymphoblastic leukemia (ALL), which is a very rare cancer in adults. Currently, the long-acting pegylated form (pegasparaginase) is the only Escherichia coli-derived asparaginase available in the United States. The use of pediatric regimens is likely to lead to more adult patients receiving multiple doses of pegasparaginase. However, oncologists who treat adults may be reluctant to use pegasparaginase or may unnecessarily discontinue administering it because of certain adverse effects. As a result, the clinical benefit of multiple doses of pegasparaginase will be missed. Despite the fact that pegasparaginase is associated with unique toxicities, the majority are nonfatal, manageable, and reversible. Here, we describe real-life cases of adults with ALL who were treated with pediatric-inspired regimens that incorporated pegasparaginase to illustrate the management of several pegasparaginase-associated adverse effects and guide whether and how to continue the drug.

Therapy-related acute lymphoblastic leukemia: Where do we stand with regards to its definition and characterization?

Acute lymphoblastic leukemia (ALL) arising in patients with prior malignancy is increasingly being reported. Although terms such as 'secondary' and 'therapy-related' have been interchangeably used to characterize these cases of ALL in a similar fashion to acute myeloid leukemia (AML), it must be noted that some reported cases have not had exposure to cytotoxic therapy and hence a causal relationship between the prior malignancy and subsequent ALL is difficult to establish. Therefore, the use of the term secondary ALL to describe such cases without exposure to cytotoxic therapy is preferably avoided and will not be discussed here. ALL related to prior cytotoxic therapy (t-ALL) appears to be a distinct entity when compared to the de novo ALL, with characteristics including older age at the time of onset, female predominance and leukemia genetics enriched with KMT2A (MLL) gene rearrangement and chromosomes 5/7 abnormalities. Outcome of t-ALL appears inferior to de novo ALL when treated with conventional combination chemotherapy and this adverse outcome may be related to unfavorable patient factors as well as high risk genetic features of the disease itself. Additional genomic and molecular studies are needed to better characterize pathologic features of ALL arising after exposure to cytotoxic therapy in patients with prior malignancies.

Combination chemotherapy plus dasatinib leads to comparable overall survival and relapse-free survival rates as allogeneic hematopoietic stem cell transplantation in Philadelphia positive acute lymphoblastic leukemia.

BACKGROUND: The Philadelphia chromosome is associated with a poor prognosis in acute lymphoblastic leukemia (ALL). While hematopoietic stem cell transplantation (HSCT) has been regarded as a favorable treatment option in adult Philadelphia-positive (Ph+) ALL, its benefit is less clear in the era of newer generation tyrosine kinase inhibitors (TKIs) like dasatinib. METHODS: This was a retrospective study that analyzed the outcomes of adult patients with Ph+ ALL treated with either combination chemotherapy plus dasatinib or combination chemotherapy plus dasatinib followed by allogeneic HSCT. RESULTS: A total of 70 patients were included; 30 (42.9%) underwent allogeneic HSCT while 40 (57.1%) received only chemotherapy plus dasatinib. In comparing overall survival (OS) rates, results between the 2 groups were similar with a 1-year OS of 93.3% versus 100% (P = 0.20), 2-year OS of 89.8% versus 86.2% (P = 0.72), and 3-year OS of 76% versus 71.3% (P = 0.56) in the transplant versus nontransplant groups, respectively. The 3-year relapse-free survival (RFS) rates were also similar at 70.5% in the transplant group and 80.1% in the nontransplant group (P = 0.94). Subgroup analyses were performed for patients with specific poor prognostic factors (higher white blood count, older age, positive minimal residual disease status), but results again showed no significant survival difference between transplant and nontransplant patients. CONCLUSIONS: While HSCT has historically led to a survival advantage in Ph+ ALL, the results of our study demonstrate that it may have a less beneficial role in the era of newer generation TKIs such as dasatinib.

The emerging story of acute lymphoblastic leukemia among the Latin American population - biological and clinical implications.

Higher incidence rates and poor outcomes have been reported among Latin American patients (Latinos) with acute lymphoblastic leukemia (ALL). Distinct patterns in recent genomic studies allude to a predisposing genetic component. In this review, we critically examine the increasing amount of empirical information on the epidemiology, outcomes and genomics of Latinos with ALL. We discuss the immense diversity within the Latino community and varying definitions of what is considered Latino, which pose an epidemiological challenge. Environmental factors have been evaluated as possible predisposing factors in the development of ALL but studies have produced conflicting results. In this review we describe chromosomal abnormalities and the specific genomic landscape in Latinos with ALL and their association with unfavorable prognosis, focusing on the higher frequency of Philadelphia chromosome-Like ALL. Recent data suggest an association between polymorphisms that are commonly found in indigenous Americans and high rates of ALL. The review compares the distribution of ALL throughout the various countries in Latin America in an attempt to shed some epidemiological light on the genetic ancestry of ALL. We additionally identify areas where research is warranted in efforts toward the advent of novel targeted agents that are relevant in improving outcomes within the Latino community.

High-Dose Vincristine Sulfate Liposome Injection, for Advanced, Relapsed, or Refractory Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia in an Adolescent and Young Adult Subgroup of a Phase 2 Clinical Trial.

PURPOSE: A study of vincristine sulfate (VCR) liposome injection (VSLI) was conducted in patients with advanced, relapsed, or refractory, Philadelphia chromosome-negative acute lymphoblastic/lymphocytic leukemia (ALL). A retrospective subgroup analysis of the results was performed to evaluate the safety and efficacy of VSLI in the adolescent and young adult (AYA) patients. METHODS: Of the 65 patients treated in the pivotal Phase 2 Study HBS407 (NCT00495079), 44 patients were aged ≤39 years (median 27 [range 19-39] years) and were included in this analysis. Patients received VSLI (2.25 mg/m2 intravenously every 7 ± 3 days) without dose capping or concurrent steroid administration in continuous 28-day cycles. RESULTS: VSLI was well tolerated in the AYA patients over a median of 5 (range 1-15) doses administered. One-third of patients (36%) experienced treatment-related serious adverse events (AEs) with peripheral neuropathy (7%), tumor lysis syndrome (7%), and febrile neutropenia (5%) in >1 patient. Neuropathy-associated AEs occurred in 82% patients; no neuropathy-related deaths occurred. The rate of complete remission (CR) (with or without complete blood count recovery) by investigator assessment was 25% in AYA patients, and the overall response rate was 39%. Median leukemia-free survival in AYA patients attaining CR was 135 (range 32-463) days, and median overall survival was 141 (range 13-620) days. CONCLUSION: VSLI provided a meaningful clinical benefit to AYA patients with ALL, and its safety profile was comparable to that of VCR despite the delivery of higher doses (individual and cumulative).

Treatment of young adults with Philadelphia-negative acute lymphoblastic leukemia and lymphoblastic lymphoma: Hyper-CVAD vs. pediatric-inspired regimens.

For young adults with acute lymphoblastic leukemia, pediatric-based regimens are likely to provide the following when compared to hyper-CVAD regimens: better disease control, less hospitalization time, diminished acute toxicities, decreased financial cost, more quality-adjusted life years, and fewer adverse late effects, such as infertility, myelodysplasia, and second malignant neoplasms. There are also reasons to expect less cardiac and cognitive dysfunction after pediatric regimens. The improved quality and quantity of life associated with pediatric regimens renders them preferable to hyper-CVAD regimens for the treatment of Philadelphia-negative B-precursor or T-cell acute lymphoblastic leukemia and lymphoblastic lymphoma in young adults.

Very poor long-term survival in past and more recent studies for relapsed AML patients: The ECOG-ACRIN experience.

This study examines the long-term OS of relapsed AML patients who were enrolled to 9 successive ECOG-ACRIN trials for newly diagnosed AML, during 1984-2008. The objectives were to examine whether there is a trend of improvement in the survival of relapsed AML patients in the more recent studies and to search for prognostic factors that are associated with long-term OS after relapse. A total of 3012 patients were enrolled, 1779 (59.1%) achieved CR1 and of these, 58.9% relapsed. The median follow-up was 9.7 years. The median OS from relapse was 0.5 years and the 5-year OS was 10 (±1)%. These results were similar even for the most recent studies. A multivariate model showed that age, cytogenetics at diagnosis, duration of CR1 and undergoing allogeneic transplantation were significantly associated with OS from relapse. Even among patients who relapsed with better prognostic factors; age < 40 and CR1 > 12 months, there was no significant OS difference between the studies. In conclusion, this large cohort appears to confirm that the survival of AML patients postrelapse continues to be dismal and has not improved during the past quarter of a century.

Pediatric-Inspired Treatment Regimens for Adolescents and Young Adults With Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia: A Review.

Importance: The incidence of acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) in adolescent and young adult (AYA) patients (age range, 15-39 years) in the United States is increasing at a greater rate than in younger or older persons. Their optimal treatment has been increasingly debated as pediatric regimens have become more widely used in the age group. This review compares the basic features of pediatric and adult chemotherapy regimens for ALL and LBL, recognizes and describes the challenges of the pediatric regimen, and suggests strategies to facilitate its adoption for AYAs with ALL and LBL. Observations: All but 2 of 25 published comparisons of outcomes with pediatric and adult regimens for ALL and LBL in AYAs and 1 meta-analysis favor the pediatric regimen. After more than a half-century of clinical trials of the pediatric regimens, including at least 160 phase 3 trials in the United States, the pediatric regimens have become far more complex than most adult regimens. Asparaginase, a critical component of the pediatric regimens, is more difficult to administer to AYAs (and older patients) but nonetheless has a favorable benefit to toxicity ratio for AYAs. A dramatic reduction in outcome of ALL and LBL during the AYA years (the "survival cliff") is coincident with similar reductions in proportions of AYAs referred to academic centers and enrolled on clinical trials (the "accrual cliff" and "referral cliff"). Conclusions and Relevance: The accumulating data increasingly support treating AYAs with ALL and LBL with a pediatric-inspired regimen or an approved institutional or national clinical trial tailored for this patient group. A need to develop clinical trials specifically for AYAs and to encourage their participation is paramount, with a goal to improve both the quantity and quality of survival.

Pegaspargase-related high-grade hepatotoxicity in a pediatric-inspired adult acute lymphoblastic leukemia regimen does not predict recurrent hepatotoxicity with subsequent doses.

Pediatric acute lymphoblastic leukemia (ALL) regimens, including higher cumulative asparaginase doses, have been investigated in adult ALL to improve outcomes. Preliminary results are promising, but hepatotoxicity rates with long-acting pegaspargase are greater in adults than children. However, adult pegaspargase-related hepatotoxicity is not as clearly defined despite being the commonest adult toxicity. We studied the frequency and characteristics of high-grade pegaspargase-related hepatotoxicity in newly diagnosed adults on a pediatric-inspired regimen that included six planned pegaspargase doses, 2000 IU/m2/dose intravenously, with doses given at least four weeks apart and not discontinued or dose-reduced for previous hepatotoxicity. Pegaspargase-related toxicity was monitored weekly after 185 delivered doses and reported by NCI CTCAE v3.0. Fifty-one patients, aged 18-57, received 192 pegaspargase doses (3.8 doses/patient). High-grade hyperbilirubinemia occurred in 16 (31.4%) patients and 23 (12.4%) doses; high-grade transaminitis occurred in 33 (64.7%) patients and 62 (33.5%) doses. Of 11 patients with high-grade hyperbilirubinemia who received at least one subsequent pegaspargase dose, six (54.5%) experienced recurrent toxicity; of 24 patients with high-grade transaminitis who received at least one subsequent pegaspargase dose, 15 (62.5%) developed recurrent toxicity. Pegaspargase at this dose and interval is associated with high hepatotoxicity rates, but patients can be rechallenged despite earlier pegaspargase-related hepatotoxicity.

Phase 2 trial of a multivalent WT1 peptide vaccine (galinpepimut-S) in acute myeloid leukemia.

A National Cancer Institute consensus study on prioritization of cancer antigens ranked the Wilms tumor 1 (WT1) protein as the top immunotherapy target in cancer. We previously reported a pilot study of a multivalent WT1 peptide vaccine (galinpepimut-S) in acute myeloid leukemia (AML) patients. We have now conducted a phase 2 study investigating this vaccine in adults with AML in first complete remission (CR1). Patients received 6 vaccinations administered over 10 weeks with the potential to receive 6 additional monthly doses if they remained in CR1. Immune responses (IRs) were evaluated after the 6th and 12th vaccinations by CD4+ T-cell proliferation, CD8+ T-cell interferon-γ secretion (enzyme-linked immunospot), or the CD8-relevant WT1 peptide major histocompatibility complex tetramer assay (HLA-A*02 patients only). Twenty-two patients (7 males; median age, 64 years) were treated. Fourteen patients (64%) completed ≥6 vaccinations, and 9 (41%) received all 12 vaccine doses. Fifteen patients (68%) relapsed, and 10 (46%) died. The vaccine was well tolerated, with the most common toxicities being grade 1/2 injection site reactions (46%), fatigue (32%), and skin induration (32%). Median disease-free survival from CR1 was 16.9 months, whereas the overall survival from diagnosis has not yet been reached but is estimated to be ≥67.6 months. Nine of 14 tested patients (64%) had an IR in ≥1 assay (CD4 or CD8). These results indicated that the WT1 vaccine was well tolerated, stimulated a specific IR, and was associated with survival in excess of 5 years in this cohort of patients. This trial was registered at www.clinicaltrials.gov as #NCT01266083.