Tyrosine kinase inhibitor imatinib augments tumor immunity by depleting effector regulatory T cells.

This report addresses whether small molecules can deplete FoxP3-expressing regulatory T (T reg) cells, thereby augmenting antitumor immunity. Imatinib, a tyrosine kinase inhibitor of oncogenic BCR-ABL protein expressed by chronic myelogenous leukemia (CML) cells, possesses off-targets including LCK expressed in T cells. We showed that imatinib-treated CML patients in complete molecular remission (CMR) exhibited selective depletion of effector T reg (eT reg) cells and significant increase in effector/memory CD8+ T cells while non-CMR patients did not. Imatinib at CML-therapeutic concentrations indeed induced apoptosis specifically in eT reg cells and expanded tumor antigen-specific CD8+ T cells in vitro in healthy individuals and melanoma patients, and suppressed colon tumor growth in vivo in mice. Mechanistically, because of FoxP3-dependent much lower expression of LCK and ZAP-70 in T reg cells compared with other T cells, imatinib inhibition of LCK further reduced their TCR signal intensity, rendering them selectively susceptible to signal-deprived apoptotis. Taken together, eT reg cell depletion by imatinib is instrumental in evoking effective immune responses to various cancers.

Evaluation of Medication Adherence and Pharmacokinetics of Dasatinib for Earlier Molecular Response in Japanese Patients With Newly Diagnosed Chronic Myeloid Leukemia: A Pilot Study.

BACKGROUND: Tyrosine kinase inhibitors markedly improve the survival for patients with chronic myeloid leukemia (CML). However, a decrease in adherence leads to undesired therapeutic outcomes. In this study, the relationships among adherence, pharmacokinetics, response, and adverse effects for dasatinib treatment were prospectively investigated. METHODS: This study was a prospective cohort study of patients with newly diagnosed CML at 4 general hospitals and 1 university hospital. Patients started to receive dasatinib 100 mg once daily. A Medication Event Monitoring System was used to assess medication adherence and the medication possession ratio during the 12 months. Plasma concentrations of dasatinib were measured using liquid chromatograph-tandem mass spectrometry (LC-MS/MS), and therapy responses were assessed at 3, 6, and 12 months after treatment. RESULTS: Ten patients were included. An extremely high medication adherence for dasatinib was observed; the median medication possession ratio was 99.4%. All 9 CML patients with breakpoints in the major BCR-ABL achieved major molecular response (MMR; major BCR-ABL transcript level below 0.1% on the International Scale) within 12 months, and 5 achieved MMR within 6 months. The receiver operating characteristic curve analysis revealed that the cutoff value for the dasatinib area under the concentration-time curve was 336.1 ng × h/mL (accuracy 88.9%, sensitivity 80.0%, specificity 100%, and receiver operating characteristic curve-area under the concentration-time curve 0.800) for achieving MMR within 6 months. Two patients had interrupted dasatinib treatment because of pleural effusion and diarrhea with intestinal edema, respectively. These edematous adverse events developed after plasma dasatinib Cmin surpassed 3.0 ng/mL. CONCLUSIONS: A Medication Event Monitoring System was applied for the direct evaluation of oral dasatinib adherence for the first time, and the clinical effect of dasatinib was investigated under the strict monitoring of patient adherence. Although this study had a small sample size, the plasma concentration monitoring of dasatinib is considered to be useful to predict an earlier molecular response with fewer edematous adverse events.

Final analysis of the JALSG Ph+ALL202 study: tyrosine kinase inhibitor-combined chemotherapy for Ph+ALL.

The Japan Adult Leukemia Study Group (JALSG) Ph+ALL202 study reported a high complete remission (CR) rate for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) patients treated with imatinib-combined chemotherapy. However, the long-term treatment efficacy remains uncertain. Here, we report a final analysis of the JALSG Ph+ALL202 study. The outcomes were compared with those of the JALSG ALL93 and ALL97 studies, which were conducted in the pre-imatinib era. Ninety-nine newly diagnosed Ph+ALL patients were enrolled in Ph+ALL202 (median age, 45 years; median follow-up, 4.5 years). CR was achieved in 96/99 (97%) patients. Fifty-nine of these 96 patients (61%) underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in their first CR (CR1). The 5-year overall and disease-free survival (DFS) rates were 50 and 43%, respectively, which were significantly higher compared to those in the pre-imatinib era (15 and 19%, respectively). Multivariate analysis revealed that imatinib administration, allo-HSCT in CR1, and a white blood cell count < 30 × 109/L were favorable independent prognostic factors for long-term DFS. Improved odds of receiving allo-HSCT and a lower relapse rate leaded to good long-term outcomes. The 3-year DFS tended to be higher in PCR-negative than that in PCR-positive patients (29 vs. 14%) in the non-HSCT patients, and this tendency was also seen in the allo-HSCT patients (59 vs. 50%). The higher rate of CR upon imatinib use may have contributed to these improvements.

Isolated thrombocytosis in chronic myeloid leukemia without significant leukocytosis.

Chronic myeloid leukemia (CML) typically causes leukocytosis rather than thrombocytosis. We encountered two women in their thirties with remarkable thrombocytosis, whose platelet counts were over 3,000×103/µl, and without significant leukocytosis. Although their clinical findings resembled that of essential thrombocythemia (ET), they were diagnosed with CML because of the presence of Philadelphia chromosome. JAK2, CALR, and MPL were unmutated. On fluorescence in situ hybridization analysis, only 19.8% of granulocytes in case 2 were found to be BCR/ABL positive in peripheral blood (PB). We reviewed 11 CML cases whose platelet counts were over 2,000×103/µl, but their WBC counts were not significantly elevated (<12,000/µl). Most of them were young females with a normal or a high neutrophil alkaline phosphatase score and without immature myeloid cells in PB. These findings suggested that there is a subgroup of CML patients with marked thrombocytosis and without significant leukocytosis, which may be misdiagnosed as ET.

Management of Pulmonary Mucormycosis Based on a Polymerase Chain Reaction (PCR) Diagnosis in Patients with Hematologic Malignancies: A Report of Four Cases.

Pulmonary mucormycosis (PM) is a life-threatening fungal infection in patients with hematologic malignancies, and early and accurate diagnostic modalities are urgently needed. We conducted a polymerase chain reaction (PCR) assay targeting these fungi in peripheral blood from four patients with hematologic malignancies who were strongly suspected of having PM. In these four patients, the Rhizopus species was identified in two patients, and the Cunninghamella and Absidia species in one each. Based on these molecular findings, all of the patients were successfully treated via targeted therapy with liposomal amphotericin B. In this report, a PCR analysis proved very useful for managing PM in patients with hematologic malignancies.

[Relapse in the nasal cavity of a patient with extranodal NK/T-cell lymphoma initially presenting as plantar subcutaneous tumor].

A 36-year-old woman complained of a mass on the sole of her foot in February 200X. She was diagnosed with extranodal NK/T-cell lymphoma, nasal type (ENKL) by skin biopsy. Because the lesion was localized on the subcutaneous tissue of the sole, she was treated with RT/2/3DeVIC, resulting in a complete response (CR). In March of the following year, PET/CT showed significant uptake and mucosal thickening in the right nasal cavity, and a mucosal biopsy confirmed ENKL infiltration. Because the lesion was localized in the nasal cavity, she was re-treated with RT/2/3DeVIC, with a focus on local control, and she achieved a second CR. She subsequently received allogeneic hematopoietic stem cell transplantation in the hope of preventing systemic relapse. She has remained in CR for four years since the transplantation. Our case suggests that allogeneic hematopoietic stem cell transplantation to be a potentially promising approach to curative treatment for recurrent ENKL in younger patients. As nasal lesions may subsequently appear during the course of primary non-nasal ENKL, ongoing meticulous evaluation for nasal lesions is important.

A novel FOXP1-PDGFRA fusion gene in myeloproliferative neoplasm with eosinophilia.

We identified a novel fusion gene, FOXP1-PDGFRA, in a patient with myeloproliferative neoplasm (MPN) with eosinophilia, harboring the chromosome abnormality t(3;4)(p13;q12). The patient responded well to imatinib and has remained in molecular remission for 3 years. This is the seventh fusion gene involving PDGFRA in MPN with eosinophilia. PDGFRA was truncated in its autoinhibitory domain, as in other PDGFRA-related MPNs, and was fused to FOXP1 at its functional forkhead domain. Comparing genomic DNA with mRNA sequences provides the possibility that the splicing process near the breakpoint junction in the FOXP1-PDGFRA fusion gene may use the normal splice donor site for intron 23a of FOXP1 and the cryptic splice acceptor site in exon 12 of PDGFRA. This is the first report to describe the FOXP1-PDGFRA fusion gene in MPN.

Effect of Genetic Polymorphism of CYP3A5 and CYP2C19 and Concomitant Use of Voriconazole on Blood Tacrolimus Concentration in Patients Receiving Hematopoietic Stem Cell Transplantation.

BACKGROUND: Blood tacrolimus (TAC) concentration delivered via intravenous administration is known to be influenced by genetic polymorphism of CYP3A5 and interaction with triazole antifungal agents. However, interindividual variability of blood TAC concentration is as of yet still difficult to predict during the early stages of hematopoietic stem cell transplantation (HSCT). This study was conducted to assess the wide variability of blood TAC concentrations because of the hepatic metabolic activities of CYP3A and CYP2C19 in HSCT recipients. METHODS: This study is a single-institute prospective study that includes 21 adult patients who underwent HSCT and received 24 hours continuous intravenous administration of TAC at the Mie University Hospital between January 2009 and March 2014. After HSCT, the changes in blood TAC concentration/dose (C/D) ratio and TAC dose reduction from initial dose were investigated. RESULTS: Significant differences between HSCT recipients with CYP3A5*1 allele and CYP3A5*3/*3 genotype were observed with respect to the median TAC C/D ratio on day 14 (563 versus 742 ng/mL per mg/kg, P < 0.01) and day 21 (672 versus 777 ng/mL per mg/kg, P < 0.05) after HSCT. Concomitant administration of voriconazole (VRCZ), but not of lansoprazole, was found to significantly increase the median TAC C/D ratio on day 14 (557 versus 723 ng/mL per mg/kg, P < 0.01). Possession of the CYP3A5*3/*3 genotype (day 14: odds ratio, 32.2; day 21: odds ratio, 33.0; P < 0.05) and concomitant administration of VRCZ (day 14: odds ratio, 37.8; P < 0.05) were found to be independent risk factors, which significantly contributed to an increased TAC C/D ratio. In HSCT recipients with CYP3A5*3/*3 genotype (78.0%), the median TAC dose ratio (day 21/day -1) was significantly lower compared with HSCT recipients with the CYP3A5*1 allele (94.1%), whereas VRCZ administration itself had no significant influence. Interestingly, in HSCT recipients with CYP2C19*1/*1, we found that the influence of VRCZ on the TAC dose ratio (85.7%) was relatively mild, even in a recipient with CYP3A5*3/*3. CONCLUSIONS: In HSCT recipients, the variability of intravenous TAC concentration in the blood could be explained in part by the genetic variation of CYP3A5. The study results also strongly imply that the magnitude of hepatic interaction between TAC and VRCZ is affected by the genetic polymorphism of both CYP3A5 and CYP2C19 genes.

Expression of CD56 is an unfavorable prognostic factor for acute promyelocytic leukemia with higher initial white blood cell counts.

Expression of CD56 has recently been introduced as one of the adverse prognostic factors in acute promyelocytic leukemia (APL). However, the clinical significance of CD56 antigen in APL has not been well elucidated. We assessed the clinical significance of CD56 antigen in 239 APL patients prospectively treated with all-trans retinoic acid and chemotherapy according to the Japan Adult Leukemia Study Group APL97 protocol. All patients were prospectively treated by the Japan Adult Leukemia Study Group APL97 protocol. The median follow-up period was 8.5 years. Positive CD56 expression was found in 23 APL patients (9.6%). Expression of CD56 was significantly associated with lower platelet count (P = 0.04), severe disseminated intravascular coagulation (P = 0.04), and coexpression of CD2 (P = 0.03), CD7 (P = 0.04), CD34 (P < 0.01) and/or human leukocyte antigen-DR (P < 0.01). Complete remission rate and overall survival were not different between the two groups. However, cumulative incidence of relapse and event-free survival (EFS) showed an inferior trend in CD56(+) APL (P = 0.08 and P = 0.08, respectively). Among patients with initial white blood cell counts of 3.0 × 10(9)/L or more, EFS and cumulative incidence of relapse in CD56(+) APL were significantly worse (30.8% vs 63.6%, P = 0.008, and 53.8% vs 28.9%, P = 0.03, respectively), and in multivariate analysis, CD56 expression was an unfavorable prognostic factor for EFS (P = 0.04). In conclusion, for APL with higher initial white blood cell counts, CD56 expression should be regarded as an unfavorable prognostic factor.

Clinical utility of a panfungal polymerase chain reaction assay for invasive fungal diseases in patients with haematologic disorders.

OBJECTIVES: Invasive fungal diseases (IFDs) are life-threatening events in patients with haematologic disorders, and the spectrum of the aetiological pathogens continues to expand. This study aimed to evaluate the clinical utility of a panfungal polymerase chain reaction (PCR) assay for the management of IFDs in such patients. METHODS: We prospectively analysed 273 consecutive blood samples from 64 risk episodes in 51 patients with haematologic disorders at high risk for IFD who were treated at our hospital between April 2007 and October 2010. RESULTS: PCR-positive results were obtained in 18 of 64 risk episodes (35.3%). IFD was documented in 14 episodes (21.9%, 9 probable IFDs and 5 possible IFDs) according to the revised criteria of the European Organization for Research and Treatment of Cancer/Mycoses Study Group. PCR was positive in all of these 14 episodes, and in 4 of the 50 episodes with no IFD category. Sensitivity, specificity, positive predictive value, and negative predictive value of our assay were 100%, 92%, 78% and 100% respectively. A considerable number of fungi (44.4%) that are less common than Aspergillus and Candida species were positive by PCR. Molecular diagnoses of Cunninghamella species, Aspergillus ustus, Fusarium species, Scedosporium apiospermum, Rhodotorula species and Rhizopus species were beneficial in selecting suitable treatments. CONCLUSIONS: Our panfungal PCR approach allows for the highly sensitive and specific detection and identification of a wide spectrum of fungal pathogens, which provides indispensable information for managing IFDs, especially refractory or breakthrough IFDs during antifungal therapy in high-risk patients with haematologic disorders.

Long-term outcome and prognostic factors of elderly patients with acute promyelocytic leukemia.

Studies focused on elderly acute promyelocytic leukemia (APL) are relatively limited. To evaluate prognostic impact in elderly APL, we compared the long-term outcome of elderly APL patients (60-70 years) with younger patients (15-59 years) treated with all-trans retinoic acid combined with anthracycline and cytarabine in the Japan Adult Leukemia Study Group (JALSG) APL97 study. Of 283 evaluable patients, 46 (16.3%) were elderly who had more frequent lower platelet (P = 0.04), lower albumin (P = 0.006) and performance status 3 (P = 0.02), higher induction death rate due to differentiation syndrome (P = 0.03), and non-relapse mortality (NRM) during consolidation therapy (P = 0.001). Overall survival was significantly inferior in elderly patients (P = 0.005), but disease-free survival and cumulative incidence of relapse were not. Better therapeutic approaches should be considered to reduce NRM during induction and consolidation therapy in elderly APL. This study was registered at http://www.umin.ac.jp/ctrj/ under C000000206.

IKAROS isoform 6 enhances BCR-ABL1-mediated proliferation of human CD34+ hematopoietic cells on stromal cells.

The BCR-ABL1 induces chronic myelogenous leukemia (CML) and Ph+ acute lymphoblastic leukemia (ALL). Recent studies revealed high ratios of loss of the IKZF1 gene which encodes IKAROS in BCR-ABL1+ ALL and lymphoblastic crisis (LBC) of CML. However, little is known about the cooperativity between the aberrant IKAROS and BCR-ABL1 in primary human hematopoietic cells. We investigated the effects of expression of BCR-ABL1 and/or IK6, a natural dominant negative isoform of IKAROS, on proliferation and differentiation of human CD34+ cord blood cells with or without human bone marrow-derived stromal cells which support early B cell differentiation. Cell proliferation was remarkably enhanced by co-expression of BCR-ABL1 and IK6, with reduced expression of glycophorin A and increased expression of CD41, especially on stromal cells, compared with expression of BCR-ABL1 alone that resulted in expansion of erythroid progenitors. Interestingly, p190BCR-ABL1 showed higher dependency on stromal cells to stimulate cell growth with IK6, than p210BCR-ABL1. Furthermore, the cooperation was found to depend on direct cell adhesive interaction of hematopoietic progenitors with stromal cells. These findings suggest that IK6 and BCR-ABL1 synergistically contribute to leukemogenesis in human bone marrow stromal microenvironment, and may provide a clue to elucidate the mechanisms of leukemogenesis of Ph+ ALL and CML-LBC.

Hepatic drug interaction between tacrolimus and lansoprazole in a bone marrow transplant patient receiving voriconazole and harboring CYP2C19 and CYP3A5 heterozygous mutations.

BACKGROUND: A drug interaction between oral tacrolimus (TAC) and lansoprazole (LAN) has been reported in patients with CYP2C19 hetero/homozygous mutations and the CYP3A5 *3/*3 genotype. A PubMed search (implemented March 16, 2011) using search terms drug interaction, tacrolimus, and lansoprazole failed to identify drug interactions in CYP3A5 extensive metabolizers and parenterally administered TAC. OBJECTIVE: The purpose of this study was to report a case of drug interaction between intravenously administered TAC and LAN in a patient being treated with voriconazole (VCZ) and harboring CYP2C19 and CYP3A5 heterozygous mutations. CASE SUMMARY: An 18-year-old Japanese man weighing 53 kg with an anaplastic large cell lymphoma received continuous IV administration of TAC as post-transplantation prophylaxis against graft-versus-host disease (GVHD) after an allogeneic bone marrow transplantation (BMT). He began receiving IV LAN 60 mg/d and VCZ 400 mg/d initiated the day before BMT. His blood TAC concentrations were within the range of 9-16 ng/mL from post-BMT day 5 to 26. The engraftment of the donor's hematopoietic cells was observed on day 17. The LAN dose was reduced to 15 mg/d PO on day 26, and the blood TAC concentration subsequently decreased to 6.6 ng/mL, with GVHD-related symptoms emerging on day 28. Consequently, the plasma VCZ concentration also decreased from 5.0 ng/mL to 2.5 ng/mL after reducing the LAN dose. VCZ was switched to liposomal amphotericin B on day 48. Thereafter, the blood TAC concentration decreased to 4.4 ng/mL on day 51. Ultimately, the patient died on day 77 because of the recurrence and progression of lymphoma. Other drugs taken were acyclovir, ursodeoxycholic acid, cefepime, meropenem, vancomycin, lenograstim, and dopamine hydrochloride. The genotyping analyses using the pre-BMT and post-engraftment (day 33) samples indicated that both were CYP2C19 *1/*2, CYP3A5 *1/*3 and CYP2C9 *1/*1. The calculated Drug Interaction Probability Score between TAC and LAN was 6, indicating a probable interaction. TAC and VCZ concentrations were measured by an affinity column-mediated immunometric assay and HPLC, respectively. Mutant alleles were examined using the multiplex extension of unlabeled oligonucleotide primers with fluorescently labeled dideoxynucleoside triphosphates. CONCLUSIONS: In a BMT patient with CYP2C19 and CYP3A5 heterozygous mutations, blood TAC concentration decreased after reducing the LAN dose, which appeared to be caused by a reduction in plasma VCZ concentration.

Diagnostic value of PCR analysis of bacteria and fungi from blood in empiric-therapy-resistant febrile neutropenia.

This study aimed to assess the clinical utility of PCR for the analysis of bacteria and fungi from blood for the management of febrile neutropenic patients with hematologic malignancies. Using a PCR system able to detect a broad range of bacteria and fungi, we conducted a prospective pilot study of periodic analyses of blood from patients following intensive chemotherapy. When fever occurred, it was treated with empirical antibiotic therapy, basically without knowledge of the PCR results. In 23 febrile episodes during the neutropenic period, bacteria were detected by PCR in 11 cases, while the same species were identified by blood culture in 3 cases. In 10 out of 11 PCR-positive cases, fever could be managed by empirical therapy. In the empirical-therapy-resistant case, the identification of Stenotrophomonas maltophilia by PCR led to improvement of fever. No fungi were detected by PCR in febrile cases, while Aspergillus fumigatus was detected in one afebrile patient, several days before a clinical diagnosis was made. In subsequent sporadic PCR analyses in 15 cases of febrile neutropenia, bacteria were detected by both PCR and blood culture in 7 cases and by PCR alone in 6. Fungi were not detected. While fever was improved by empirical therapy in 12 out of the 13 PCR-positive cases, the identification of Pseudomonas aeruginosa by PCR in one therapy-resistant case contributed to the successful treatment of persistent fever. Our results indicate that PCR analysis of bacteria from blood provides essential information for managing empirical-therapy-resistant febrile neutropenia.

A potential activity of valproic acid in the stimulation of interleukin-3-mediated megakaryopoiesis and erythropoiesis.

OBJECTIVE: Although the anticancer activities of histone deacetylase (HDAC) inhibitors have been studied, a role for HDAC in normal hematopoiesis has not been clearly defined. Previous studies have shown that the potent HDAC inhibitor FK228 stimulates interleukin (IL)-3-mediated erythropoiesis. Here, we examined whether the widely used valproic acid (VPA) affects megakaryopoiesis as well as erythropoiesis. MATERIALS AND METHODS: CD34(+) cells were incubated in serum-free or serum-containing cultures with cytokines, with or without VPA. RESULTS: In the serum-free cultures containing IL-3+stem cell factor (SCF), VPA significantly increased generation of CD61(+)GPA(-) megakaryocytic and a CD61(+)GPA(+) mixture of megakaryocytic and erythroid precursors from CD34(+) hematopoietic precursors at a pharmacological concentration (100 microg/mL). The increase in generation of megakaryocytic and erythroid precursors by VPA was confirmed by replating cultured cells with thrombopoietin+SCF and erythropoietin+SCF, respectively. VPA was as potent as FK228. In cultures with granulocyte-macrophage colony-stimulating factor+SCF, where CD61(-)GPA(+) erythroid precursors were mostly developed, VPA mainly enhanced the generation of CD61(-)GPA(+) erythroid precursors. In serum-containing cultures, only low numbers of CD61(+) or GPA(+) cells were developed with IL-3+SCF. Nevertheless, a substantial number of these cells were generated with VPA. Furthermore, these stimulating effects of VPA were observed by incubating CD34(+) cells from patients with myelodysplastic syndrome. Quantitative reverse transcription polymerase chain reaction showed that VPA enhanced GATA-2, but not GATA-1, messenger RNA expression with IL-3+SCF. CONCLUSIONS: These results indicate a novel role for VPA in enhancing the potential of IL-3 to stimulate megakaryopoiesis as well as erythropoiesis and suggest a new therapeutic approach of epigenetic therapy for hematological disease.

[Management of microbial infections in myeloid leukemia].

The management of microbial infection is one of the important issues for patients with acute myeloid leukemia (AML). They are considered to be at high risk for infection. They should be provided appropriate antimicrobial agents recommended by the Infectious Diseases Society of America (IDSA). Recently, there have been several significant changes in IDSA guidelines especially in the treatment of invasive fungal infection because of developments in several antifungal agents. This document constitutes the recommendations for the management of infection in patients with AML according to the updated guidelines of the IDSA. Evidence about infection control in AML is not enough in contrast to hematopoietic stem cell transplantation. Further studies are necessary to establish the strategy for microbial infections in AML.

[Long-term remission of a nasal NK/T-cell lymphoma patient with massive involvement of the orbita and liver dysfunction].

A 49-year-old woman with high fever and diffuse swelling of the right cheek was referred to our hospital. Computed tomography showed right orbital tumor with massive involvement. Histopathologic examination of the biopsied right orbital tumor demonstrated extranodal NK/T-cell lymphoma, nasal-type. She was treated with six courses of chemotherapy consisting of etoposide and dexamethasone with 50 Gy of concurrent involved-field radiotherapy. Facial swelling and liver dysfunction improved immediately, and after five courses of chemotherapy, she achieved partial remission without any severe adverse events. L-asparaginase was administered in the final course of chemotherapy. There is no evidence of recurrence 56 months after diagnosis.

Myeloablative unrelated cord blood transplantation for acute leukemia patients between 50 and 55 years of age: single institutional retrospective comparison with patients younger than 50 years of age.

Increasing recipient age is a well-known risk factor for graft-versus-host disease (GVHD) and treatment-related mortality (TRM) and has a negative impact on allogeneic hematopoietic stem cell transplantation. Since the incidence of severe GVHD after cord blood transplantation (CBT) is lower than that after transplants using bone marrow or mobilized peripheral blood grafts from adult cells, we should expect better outcomes from CBT in older patients. To evaluate the feasibility and efficacy of myeloablative unrelated CBT in patients aged between 50 and 55 years, we performed a retrospective comparison of 100 patients with acute leukemia who received cord blood grafts at our institution. Nineteen older patients (median age, 52; range, 50-55) and 81 younger patients (median, 36; range, 16-49) received a myeloablative conditioning regimen including 12 Gy of total body irradiation and chemotherapy. GVHD prophylaxis included cyclosporine with (n = 96) or without (n = 4) methotrexate. There were no significant differences in the incidences of grades II to IV acute GVHD, extensive-type chronic GVHD, TRM, and the probability of overall and disease-free survival between these groups. These results suggest that, in patients with acute leukemia, myeloablative CBT might be as safe and effective in patients aged between 50 and 55 years as in younger patients.