Outcomes and Long-Term Survival of Adolescent and Young Adult Patients Admitted to the Intensive Care Unit Following Allogeneic Hematopoietic Stem Cell Transplantation: A Single-Center Experience of 152 Patients

BACKGROUND AND OBJECTIVES

Prognostic factors reliably predicting outcomes for critically ill adolescent and young adult (AYA) patients undergoing allogeneic hematopoietic cell transplantation (allo-HSCT) are lacking. We assessed transplant and intensive care unit (ICU)-related factors impacting patient outcomes.

PATIENTS AND METHODS

AYA patients who underwent allo-HSCT and required ICU admission at a Tertiary care Centre, during the period of 2003-2013, were included in this retrospective review. This was a non-interventional study. Only outcomes after the first allo-HSCT and index ICU admissions were analyzed. Disease-, transplant-, and ICU-related variables were analyzed to identify risk factors predictive of survival.

RESULTS

Overall, 152 patients were included (males, 60.5%); median age at transplantation was 24 years (interquartile range [IQR] 18-32.5); median age at admission to the ICU was 25.8 years (IQR 19-34). Eighty-four percent underwent transplantation for a hematological malignancy; 129 (85%) received myeloablative conditioning. Seventy-one percent of ICU admissions occurred within the first year after allo-HSCT. ICU admission was primarily due to respiratory failure (47.3%) and sepsis (43.4%). One hundred and three patients (68%) died within 28 days of ICU admission. The 1- and 5-year overall survival rates were 19% and 17%, respectively. Main causes for ICU-related death were refractory septic shock with multiorgan failure (n = 49, 32%) and acute respiratory distress syndrome (ARDS) (n = 39, 26%). Univariate analysis showed that ICU mortality was associated with an Acute Physiology and Chronic Health Evaluation (APACHE) II score >20, a sequential organ failure assessment (SOFA score) > 12, a high lactate level, anemia, thrombocytopenia, leukopenia, hyperbilirubinemia, a high international normalized ratio (INR) and acute graft-versus-host disease (GVHD). Multivariate analysis identified thrombocytopenia, high INR, and acute GVHD as independent predictors of mortality.

CONCLUSIONS

In AYA allo-HSCT patients admitted to the ICU, mortality remains high. Higher SOFA and APACHE scores, the need for organ support, thrombocytopenia, coagulopathy, and acute GVHD predict poor outcomes.

An International Learning Collaborative Phase 2 Trial for Haploidentical Bone Marrow Transplant in Sickle Cell Disease

In the setting of a learning collaborative, we conducted an international multicenter phase 2 clinical trial testing the hypothesis that non-myeloablative related haploidentical BMT with thiotepa and post-transplant cyclophosphamide (PTCy) will result in 2-year event-free survival (no graft failure or death) of at least 80%. A total of 70 participants (median age 19.1 (IQR 14.1 - 25.0) were evaluable based on the conditioning protocol. Graft failure occurred in 11.4% (8/70) and only in participants <18 years (p=0.001); all had autologous reconstitution. After a median follow-up of 2.4 years (IQR 1.5-3.9), the 2-year Kaplan-Meier-based probability of event-free survival was 82.6% (95% CI 71.4%-89.7%). The 2-year overall survival was 94.1% (95% CI 84.9%-97.7%) with no difference between the child and adult participants (p=0.889). After excluding participants with graft failure (n=8), participants with engraftment had median whole blood donor chimerism values at D+180 and D+365 post-transplant of 100.0% (IQR 99.8 - 100.0%; n=59) and 100.0% (IQR 100.0 - 100.0%; n=58), respectively, and 96.6% (57/59) were off immunosuppression at 1-year post-transplant. The 1-year grades III-IV acute graft versus host disease (GvHD) rate was 10.0% (95% CI 4.6 - 18.6%), and the 2-year moderate-severe chronic GvHD rate was 10.0% (95% CI 4.6 - 18.6%). Five participants (7.1%) died from infectious complications. We demonstrate that non-myeloablative haploidentical BMT with thiotepa and PTCy is a readily available curative therapy for most adults, even those with organ damage, instead of the more expensive myeloablative gene therapy and gene editing. Additional strategies are required for children to decrease graft failure rates (ClinicalTrials.gov identifier NCT01850108).

Myeloablative Haploidentical Donor Hematopoietic Transplantation Using Post-Transplantation Cyclophosphamide and Antithymocyte Globulin

Haploidentical donor (haplo-) hematopoietic stem cell transplantation (HSCT) with post-transplantation cyclophosphamide (PTCy) is now performed on a large scale worldwide. Our patient outcomes did not completely reflect the results published by other groups. We herein present the results of 60 patients with hematologic malignancies treated homogeneously on a modified version of the standard protocol by adding ATG as an additional graft-versus-host disease (GVHD) prophylaxis measure. This was a retrospective analysis of 60 haplo-HSCT recipients using a myeloablative conditioning regimen with antithymocyte globulin and PTCy for GVHD prophylaxis. At 5 years, overall survival was 59.2%, relapse-free survival (RFS) was 48.6%, and chronic GVHD (cGVHD) and relapse-free survival was 40%. The median time to neutrophil and platelet engraftment was 16 days and 28.5 days, respectively. The rates of grade II-IV acute GVHD and extensive cGVHD were 46.7% and 23.3%, respectively. The cumulative incidence of relapse was 30%, nonrelapse mortality was 21.6%, and transplantation-related mortality was 11%. Higher Disease Risk Index and 50% HLA match were associated with lower RFS. Female donor to male recipient and older donor age were associated with an elevated risk of cGVHD. The use of PTCy might not yield the same results in different populations. Many remaining questions need to be addressed in randomized trials, including optimal graft source and donor, date of calcineurin inhibitor initiation, personalized or targeted dose of PTCy, immune reconstitution, and others.

Incidence and risk factors for secondary graft failure in uniformly treated patients with severe aplastic anemia receiving fludarabine and cyclophosphamide for conditioning and matched sibling bone marrow graft as stem cell source

BACKGROUND AIMS

Graft failure after allogeneic transplant for aplastic anemia is problematic. The risk of graft failure depends on multiple variables, including the preparative regimen, donor type, stem cell dose and source among other variables.

METHODS

We performed a retrospective analysis of patients with aplastic anemia who underwent matched-sibling allogeneic transplant at a single center.

RESULTS

We identified 82 patients who fit the inclusion criteria. One had primary graft failure and was excluded from this analysis. The recipient median age was 22 years. The donor median age was 23 years. The median time from diagnosis to transplant was 1.6 months. The median number of red cell transfusions before transplant was nine. The median number of platelet transfusions before transplant was 18. Thirteen patients developed secondary graft failure, with a cumulative incidence at 5 years of 16% and median time to develop secondary graft failure of 129 days. All patients engrafted with a median time for neutrophil engraftment of 19 days and a median time for platelet engraftment of 22 days. The survival of patients with or without secondary graft failure was not different. Major or bidirectional ABO incompatibility and older recipient age were statistically significantly associated with greater risk of secondary graft failure.

CONCLUSIONS

Secondary graft failure is a significant complication after allogeneic transplant for SAA. Identification of recipients at risk and mitigating the potential risks of this complication is warranted.

"Incidence and significance of donor-specific antibodies in haploidentical stem cell transplantation"

PGF is a devastating complication after allogeneic transplant. We retrospectively analyzed our haploidentical transplant registry to report the incidence and impact of DSA and anti-HLA on engraftment. 107 patients were identified. Median recipient-age of 22, median donor-age of 31. Sixty-two patients had AML (58%), 29 had ALL (27%), 16 (15%) had other malignancies. Sixty-one recipients (57%) had positive anti-HLA, 56 of them had the DSA results available, of these 17 patients had DSAs (15% of the total number of patients, or 28% of patients who have anti-HLA antibodies). The median cumulative MFI was 2062. Sixty-three percent of the DSA were against class-II HLA antigens. The OS, CIR, aGvHD, and cGvHD did not differ between patients with and without anti-HLA antibodies, nor between patients with and without DSA. The gender of the recipient and donor, as well as the gender mismatch between recipient and donor, were statistically associated with the incidence of anti-HLA antibodies. Three patients only developed GF (2.8%), one was primary (0.9%) and the other two secondary GF (1.9%). None of the GF cases was in patients with anti-HLA antibodies or DSA. The presence of anti-HLA or DSAs did not affect the outcomes including the incidence of PGF.

Improved survival of adolescents and young adults patients with T-cell acute lymphoblastic leukemia

Aim

The outcome of T-cell acute lymphoblastic leukemia (T-ALL) has improved with the use of pediatric-inspired protocols in the adolescents and young adults (AYA) population. There is limited literature regarding the outcome of T-ALL/lymphoblastic lymphoma (LBL) AYA patients treated with pediatric protocols.

Methods

A total of 35 T-ALL/LBL-AYA patients ages between 14 and 55 years were treated with AYA-15 protocol.

Results

At a median follow-up of 5 years the overall survival, disease-free survival and event-free survival are 71%, 62% and 49.6% respectively. Toxicities were within the expected range.

Conclusion

Our single-center experience real-world data in treating T-ALL/LBL-AYA patients with pediatric-inspired protocol demonstrates encouraging results of high survival rate and excellent tolerability for patients aged 18-55 years.

Prevalence of the BCR/ABL fusion gene and T cell stimulation capacity of dendritic cells in chronic myelogenous leukemia

Dendritic cell (DC) vaccines are promising for immunotherapy, and their production using CD34⁺ hematopoietic stem cells (HPSCs) from patients with chronic myelogenous leukemia (CML) and healthy donors is well established. However, the generation of CD1a⁺CD14^- DCs and their functional properties in patients with CML remain elusive. Here, we aimed to study the biology of DCs generated from CD34^-/low HPSCs and evaluate the status of their BCR/ABL translocation, ability to stimulate T cells, and capacity of endocytosis compared to DCs derived from CD34⁺ HPSCs from both patients with CML and healthy donors. CD1a⁺CD14^- DCs were generated from CD34^-/low HPSCs and evaluated morphologically and functionally. CD34⁺ cells are frequently selected for transplantation and the entire CD34^-/low HPSC fraction is wasted. Here, we anticipated the CD34^- HPSC subset to constitute an invaluable source for acquiring DCs for immunotherapy. CD34⁺ and CD34^- HPSCs were sorted from the bone marrow samples of CML patients and healthy donors and differentiated ex vivo in a similar way. DCs from CD34^-Lin^- and CD34⁺Lin^- HPSCs expressed comparable surface markers (CD80, CD83, CD86, HLA-DR, CD40, and CD54). Functional analysis revealed that DCs acquired from both subsets retained a potent allogeneic T cell stimulatory capacity and an efficient phagocytic ability and showed a similar BCR/ABL translocation status. In conclusion, DCs were successfully differentiated from the CD34^-Lin^- cell subset and showed potent functional capacities, indicating their potential for application in immunotherapy and basic research.

Allogeneic transplant compared to pediatric-inspired therapy for Philadelphia chromosome-negative adolescent and adult ALL in first complete remission

BACKGROUND

Pediatric-inspired non-transplant regimens for adolescent and adult ALL patients are becoming standard in many institutions. We aimed to compare a cohort of patients receiving a pediatric-inspired protocol to a cohort of patients treated with adult type ALL therapy followed by allografting after achieving CR1.

METHOD

Eighty-five adolescent and adult ALL patients treated with CALGB 19802 protocol who received MSD transplant in CR1 were retrospectively compared to a matched cohort of 72 adolescent and adult ALL patients treated with a modified version of Children's Cancer Group (CCG) 1900 protocol.

RESULTS

The five years OS in the allo-HCT cohort was 63.1% compared to 80.2% in the pediatric-inspired chemotherapy arm (P = 0.03). The five years EFS in the allo-HCT arm was 58.8% compared to 61.6% in the pediatric-inspired chemotherapy arm (P = 0.07). The five years DFS in the allo-HCT arm was 58.8% as compared to 71.9% in the pediatric-inspired chemotherapy arm (P = 0.07). The relapse rate in the allo-HCT cohort was 30.58% compared to 21.68% in the pediatric-inspired chemotherapy arm (P = 0.16). The NRM in the allo-HCT cohort was 10.59 as compared to 6.45 in the pediatric-inspired chemotherapy arm (P = 0.3).

CONCLUSION

For adolescent and adult patients with Ph-negative ALL, pediatric-inspired chemotherapy resulted in higher OS compared to allo-HCT.

Improved survival in adolescents and young adults (AYA) patients aged 14-55 years with acute lymphoblastic leukemia using pediatric-inspired protocol - a retrospective analysis of a real-world experience in 79 of patients treated at a national tertiary care referral center

Background

Treating adolescents and young adults (AYA) patients with acute lymphoblastic leukemia (ALL) using pediatric-inspired protocols have shown improvement in outcomes. Most data available in the literature of such protocols is derived from well-controlled clinical trials. This report aims to provide a real-world experience from using a pediatric-inspired protocol in ALL-AYA population in larger number of patients treated at a national tertiary care referral center.

Methods

Newly diagnosed Philadelphia negative ALL-AYA patients ages between 14 and 55 years of age were treated on an institutional protocol (AYA-15 protocol) adopted from a modified version of Children's Cancer Group (CCG) 1900 protocol. At the time of this publication, a total of 79 patients were treated using the AYA-15 protocol between 2015 and 2020). Event-free survival (FFS), disease-free survival (DFS), and overall survival (OS) were analyzed using cumulative incidence and Kaplan-Meier methods.

Results

The median age at diagnosis was 18 years (14–51 years) with 63% male patients. Complete remission (CR) at day 28 of induction was achieved in 88.6% of which 73.4% were minimal residual disease (MRD) negative. At a median follow up of 5 years, EFS, DFS and OS were 57.5%, 69.2% and 75.8% respectively. Toxicities were within the expected range with infections and transaminitis being the most common adverse events.

Conclusion

Our single-center experience real-world data in treating AYA-ALL patients with pediatric-inspired protocol demonstrates encouraging results of high survival rate and excellent tolerability for patients aged 18–55 years.

The outcomes of secondary AML post allogeneic hematopoietic cell transplantation significantly depend on the presence of poor‐risk cytogenetic abnormalities

Secondary acute myeloid leukemia (sAML) includes AML as a complication of an antecedent hematological disorder or a therapy‐related AML. Large registry‐based data identified sAML as an independent poor‐outcome type of AML post allogeneic hematopoietic cell transplantation (allo‐HCT). In our study, we tried to define factors affecting outcomes of sAML post allo‐HCT, and identify patients with sAML who may truly benefit from allo‐HCT. We retrospectively analyzed the data of 64 patients aged (14‐61 years) with sAML who received allo‐HCT between September 2010 and February 2018 at our institute. Most of the patients were transplanted from matched related donors (MRD; 54, 84.4%). Our results showed that poor‐risk cytogenetics were identified in 31 patients (48.4%), and their presence was an indicator of poor overall survival (OS) and disease‐free survival (DFS; P‐value = .009, and .004, respectively). The cumulative incidence of chronic graft‐versus‐host disease (cGVHD) was significantly lower in sAML patients with poor‐risk cytogenetics (P‐value = .003) resulting in a high risk of death without cGVHD in this group of patients (P‐value = .02). Besides, GVHD relapse‐free survival (GRFS) analysis showed that most of our studied patients experienced either relapse or debilitating grade II‐IV cGVHD in the first 2 years post allo‐HCT. We conclude that sAML patients with poor‐risk cytogenetics have a significantly lower DFS post allo‐HCT with a high risk of death without active cGVHD.

Systematic Review/Meta-Analysis on Efficacy of Allogeneic Hematopoietic Cell Transplantation in Sickle Cell Disease: An International Effort on Behalf of the Pediatric Diseases Working Party of European Society for Blood and Marrow Transplantation and the Sickle Cell Transplantation International Consortium

Sickle cell disease (SCD) affects more than 300,000 children annually worldwide. Despite improved supportive care, long-term prognosis remains poor. Allogeneic hematopoietic cell transplantation (allo-HCT) is the sole validated curative option, resulting in sustained resolution of the clinical phenotype. The medical literature on allo-HCT for SCD is largely limited to children. Recent studies have evaluated allo-HCT efficacy in adults. Here, we conducted a systematic review/meta-analysis to assess the totality of evidence on the efficacy, or lack thereof, of allo-HCT in treating SCD. We performed a comprehensive literature search using PubMed/Medline, Embase, and Cochrane library databases on November 13, 2019. Four authors independently extracted data on clinical outcomes related to benefits (overall survival [OS] and disease-free survival [DFS]) and harms (acute graft-versus-host disease [aGVHD], chronic graft-versus-host disease [cGVHD], nonrelapse mortality [NRM], and graft failure [GF]). Our search identified a total of 1906 references. Only 33 studies (n= 2853 patients) met our inclusion criteria. We also performed a subset analysis by age. Analyses of all-age groups showed pooled rates of 96% for OS, 90% for DFS, 20% for aGVHD, 10% for cGVHD, 4% for NRM, and 5% for GF. In the pediatric population, pooled rates for OS, DFS, aGVHD, cGVHD, NRM, and GF were 97%, 91%, 26%, 11%, 5%, and 3%, respectively. In adults, pooled rates for OS, DFS, aGVHD, cGVHD, NRM, and GF were 98%, 90%, 7%, 1%, 0%, and 14%, respectively. Our data show that allo-HCT is safe and effective, yielding pooled OS rates exceeding 90%. The high GF rate of 14% in adults is concerning and emphasizes the need to evaluate new strategies.

Hematopoietic stem cell transplantation in Saudi Arabia between 1984 and 2016: Experience from four leading tertiary care hematopoietic stem cell transplantation centers

Saudi Arabia is the largest of the Arabian Gulf countries with a total population of 33.41 million as of 2017. This report summarizes the experience from four leading tertiary care hematopoietic stem cell transplantation (HSCT) centers in Saudi Arabia representing more than 90% of all HSCTs performed in the country. Between 1984 and 2016, a total of 6,184 HSCTs were performed. Of these, 3,586 HSCTs were performed in adults and 2,598 HSCTs were performed in pediatric patients. Malignancy was the main indication for transplantation (47%). While most transplants were performed from an identical sibling donor, HSCTs from cord blood, unrelated and, more recently, haploidentical donors have also been performed. Relative shortage of HSCT bed capacity is perceived to be a limiting factor in Saudi Arabia. Lately, more HSCT centers are emerging with rapid growth, which may significantly improve the access to HSCT in the country in the near future.

Lessons Learned from Large-Scale, First-Tier Clinical Exome Sequencing in a Highly Consanguineous Population

We report the results of clinical exome sequencing (CES) on >2,200 previously unpublished Saudi families as a first-tier test. The predominance of autosomal-recessive causes allowed us to make several key observations. We highlight 155 genes that we propose to be recessive, disease-related candidates. We report additional mutational events in 64 previously reported candidates (40 recessive), and these events support their candidacy. We report recessive forms of genes that were previously associated only with dominant disorders and that have phenotypes ranging from consistent with to conspicuously distinct from the known dominant phenotypes. We also report homozygous loss-of-function events that can inform the genetics of complex diseases. We were also able to deduce the likely causal variant in most couples who presented after the loss of one or more children, but we lack samples from those children. Although a similar pattern of mostly recessive causes was observed in the prenatal setting, the higher proportion of loss-of-function events in these cases was notable. The allelic series presented by the wealth of recessive variants greatly expanded the phenotypic expression of the respective genes. We also make important observations about dominant disorders; these observations include the pattern of de novo variants, the identification of 74 candidate dominant, disease-related genes, and the potential confirmation of 21 previously reported candidates. Finally, we describe the influence of a predominantly autosomal-recessive landscape on the clinical utility of rapid sequencing (Flash Exome). Our cohort's genotypic and phenotypic data represent a unique resource that can contribute to improved variant interpretation through data sharing.

Physical therapy pathway and protocol for patients undergoing hematopoietic stem cell transplantation: Recommendations from The Eastern Mediterranean Blood and Marrow Transplantation (EMBMT) Group

BACKGROUND

Patients undergoing hematopoietic stem cell transplantation (HSCT) are often referred for physical therapy (PT) to help improve their quality of life. However, to our knowledge there is no clear PT pathway to guide therapists and patients before, during, and after HSCT.

METHODS

A comprehensive literature review was carried out exploring the role and benefits of PT in HSCT patients. The current evidence was comlimented with recommendations and opinions from the experts in the field, which included PT's and hematology consultants from PTAGVHD and the EMBMT group.

RESULT

A clear pathway and protocol as a working guide for rehabilitation professionals working with the HSCT patient's was developed.

CONCLUSION

This paper not only reviews the current evidence on safe PT practice but also puts forward a protocol and pathway for HSCT rehabilitation, highlights the importance of individualized exercise intervention for HSCT patients, and outlines safe practice guidelines for the physical therapists working in this field.

Protein signatures as potential surrogate biomarkers for stratification and prediction of treatment response in chronic myeloid leukemia patients

There is unmet need for prediction of treatment response for chronic myeloid leukemia (CML) patients. The present study aims to identify disease-specific/disease-associated protein biomarkers detectable in bone marrow and peripheral blood for objective prediction of individual’s best treatment options and prognostic monitoring of CML patients. Bone marrow plasma (BMP) and peripheral blood plasma (PBP) samples from newly-diagnosed chronic-phase CML patients were subjected to expression-proteomics using quantitative two-dimensional gel electrophoresis (2-DE) and label-free liquid chromatography tandem mass spectrometry (LC-MS/MS). Analysis of 2-DE protein fingerprints preceding therapy commencement accurately predicts 13 individuals that achieved major molecular response (MMR) at 6 months from 12 subjects without MMR (No-MMR). Results were independently validated using LC-MS/MS analysis of BMP and PBP from patients that have more than 24 months followed-up. One hundred and sixty-four and 138 proteins with significant differential expression profiles were identified from PBP and BMP, respectively and only 54 proteins overlap between the two datasets. The protein panels also discriminates accurately patients that stay on imatinib treatment from patients ultimately needing alternative treatment. Among the identified proteins are TYRO3, a member of TAM family of receptor tyrosine kinases (RTKs), the S100A8, and MYC and all of which have been implicated in CML. Our findings indicate analyses of a panel of protein signatures is capable of objective prediction of molecular response and therapy choice for CML patients at diagnosis as ‘personalized-medicine-model’.

Trends of hematopoietic stem cell transplantation in the Eastern Mediterranean region, 1984-2007

Hematopoietic stem cell transplantation (HSCT) activity was surveyed in the 9 countries in the World Health Organization Eastern Mediterranean region that reported transplantation activity. Between the years of 1984 and 2007, 7933 transplantations were performed. The number of HSCTs per year has continued to increase, with a plateau in allogeneic HSCT (allo-HSCT) between 2005 and 2007. Overall, a greater proportion of transplantations were allo-HSCT (n = 5761, 77%) compared with autologous HSCT (ASCT) (n = 2172, 23%). Of 5761 allo-HSCT, acute leukemia constituted the main indication (n = 2124, 37%). There was a significant proportion of allo-HSCT for bone marrow failures (n = 1001, 17%) and hemoglobinopathies (n = 885, 15%). The rate of unrelated donor transplantations remained low, with only 2 matched unrelated donor allo-HSCTs reported. One hundred umbilical cord blood transplantations were reported (0.017% of allo-HSCT). Peripheral blood stem cells were the main source of graft in allo-HSCT, and peripheral blood stem cells increasingly constitute the main source of hematopoietic stem cells overall. Reduced-intensity conditioning was utilized in 5.7% of allografts over the surveyed period. ASCT numbers continue to increase. There has been a shift in the indication for ASCT from acute leukemia to lymphoproliferative disorders (45%), followed by myeloma (26%). The survey reflects transplantation activity according to the unique health settings of this region. Notable differences in transplantation practices as reported to the European Group for Blood and Marrow Transplantation over recent years are highlighted.

The Wilms' tumor antigen is a novel target for human CD4+ regulatory T cells: implications for immunotherapy

Compelling evidences indicate a key role for regulatory T cells (T(reg)) on the host response to cancer. The Wilms' tumor antigen (WT1) is overexpressed in several human leukemias and thus considered as promising target for development of leukemia vaccine. However, recent studies indicated that the generation of effective WT1-specific cytotoxic T cells can be largely affected by the presence of T(regs). We have generated T-cell lines and clones that specifically recognized a WT1-84 (RYFKLSHLQMHSRKH) peptide in an HLA-DRB1*0402-restricted manner. Importantly, they recognized HLA-DRB1*04-matched fresh leukemic cells expressing the WT1 antigen. These clones exerted a T helper 2 cytokine profile, had a CD4(+)CD25(+)Foxp3(+)GITR(+)CD127(-) T(reg) phenotype, and significantly inhibited the proliferative activity of allogeneic T cells independently of cell contact. Priming of alloreactive T cells in the presence of T(regs) strongly inhibited the expansion of natural killer (NK), NK T, and CD8(+) T cells and had an inhibitory effect on NK/NK T cytotoxic activity but not on CD8(+) T cells. Furthermore, priming of T cells with the WT1-126 HLA-A0201-restricted peptide in the presence of T(regs) strongly inhibited the induction of anti-WT1-126 CD8(+) CTL responses as evidenced by both very low cytotoxic activity and IFN-gamma production. Moreover, these T(reg) clones specifically produced granzyme B and selectively induced apoptosis in WT1-84-pulsed autologous antigen-presenting cells but not in apoptotic-resistant DR4-matched leukemic cells. Importantly, we have also detected anti-WT1-84 interleukin-5(+)/granzyme B(+)/Foxp3(+) CD4(+) T(regs) in five of eight HLA-DR4(+) acute myeloid leukemia patients. Collectively, our in vitro and in vivo findings strongly suggest important implications for the clinical manipulation of T(regs) in cancer patients.