[Discontinuation of tyrosine kinase inhibitors before epiphyseal closure leading to improved short stature in pediatric chronic myelogenous leukemia].

A 3-year-old boy was referred to our hospital with splenomegaly. Blood tests revealed hyperleukocytosis and bone marrow examination showed major BCR::ABL1 fusion, leading to the diagnosis of chronic myelogenous leukemia (CML). Due to intolerance, the tyrosine kinase inhibitor (TKI) was changed from imatinib to dasatinib to nilotinib. The patient achieved molecular remission but became markedly short in stature, measuring 129.3 cm (height standard deviation score [SDS] -3.3) at the age of 12. TKI therapy was discontinued at age 12 years and 10 months, which was 9 years and 8 months after the start of TKI and 1 year and 6 months after achievement of MR4.0, as discontinuation before epiphyseal closure would not improve short stature. At 2 years and 6 months after discontinuation, the patient's height improved to 156.1 cm (SDS-2.0) without relapse. Growth suppression by TKIs is a problem in the management of pediatric CML. This case illustrates how improvement in severe short stature can be achieved by discontinuing TKI therapy before epiphyseal closure.

Clinical and Genetic Characterization of Patients with Artemis Deficiency in Japan.

PURPOSE: Artemis is an exonuclease essential for V(D)J recombination and repair of DNA double-stranded breaks. Pathogenic variants in DCLRE1C encoding Artemis cause T-B-NK+ severe combined immunodeficiency (SCID), and patients with Artemis-deficient SCID (ART-SCID) require definitive therapy with allogeneic hematopoietic cell transplantation (HCT). Here we describe the clinical and genetic characteristics of patients with ART-SCID who were diagnosed in Japan from 2003 to 2022. METHODS: Clinical data of ART-SCID patients who were diagnosed between 2003 and 2022 in Japan were collected from their physicians using a questionnaire. RESULTS: ART-SCID diagnosis was made in eight patients from seven families with severe infections within 6 months of life. Two patients had missense variants, five patients had large genomic deletions, and one patient was compound heterozygous for a missense variant and large genomic deletion. All eight underwent allogeneic HCT within 4 months after the diagnosis, 7 receiving a conditioning regimen containing alkylating agents, and one patient without conditioning due to uncontrolled infection. Two patients with poor performance status (PS) died of complications 410 days and 32 days post-HCT, respectively. Of the six surviving patients with a median follow-up time of 8.3 (0.5-17.9) years, three patients had growth retardation. The patients with PS of 0-2 showed a tendency for better overall survival than those with PS 3-4. CONCLUSION: Large deletions were the most common genetic cause of ART-SCID in Japan. To improve HCT outcome, early diagnosis with newborn screening for SCID is urgently needed.

Clinical conditions and risk factors for inhibitor-development in patients with haemophilia: A decade-long prospective cohort study in Japan, J-HIS2 (Japan Hemophilia Inhibitor Study 2).

BACKGROUND: Inhibitor-development is a serious complication in patients with haemophilia (PwH). Previous studies reported that therapeutic and genetic factors could be associated with these alloantibodies. Relevant clinical features such as genetic-background and different treatment regimens in Japan remain unclear, however. AIMS: To analyse a nation-wide Japanese registry for PwH, and to examine risk factors for inhibitor-development. METHODS AND RESULTS: Newly diagnosed patients with haemophilia A (PwHA) or haemophilia B (PwHB) without inhibitors after 2007, and with treatment records traceable from 0 to 75 exposure days (ED), were enrolled in the Japan Hemophilia Inhibitor Study 2 (J-HIS2) initiated in 2008. Of 417 patients (340 PwHA, 77 PwHB) from 46 facilities, 83 (76 PwHA, 7 PwHB) were recorded with inhibitors by July 2020. Inhibitors were observed in 31.0% of severe PwHA, 8.0% moderate and 1.6% mild and in 17.1% of severe PwHB. The majority of inhibitors (89.7% in severe PwHA and 71.4% in severe PwHB) were detected on or before 25ED (median 12ED in PwHA and 19ED in PwHB). Genotyping in these severe patients identified an association between inhibitor-development and null variants of F8 (P < .01) or F9 (P < .05). A lower incidence of inhibitors was recorded in severe PwHA treated with prophylaxis than in those treated on-demand (P < .01). A past-history of intracranial-haemorrhage appeared to be associated with inhibitor-development, while FVIII-concentrates infusion and routine vaccination on the same day was not related to inhibitor-development. CONCLUSION: The J-HIS2 study has identified significant clinical variables associated with inhibitor-development in Japanese PwH, consistent with other global studies.

Effects of cryotherapy on high-dose melphalan-induced oral mucositis in pediatric patients undergoing autologous stem cell transplantation.

Cryotherapy is a conventional method for preventing melphalan-induced oral mucositis (OM) in adult patients. We retrospectively examined the clinical benefits of cryotherapy in 41 pediatric patients undergoing autologous stem cell transplantation using a melphalan-etoposide-carboplatin regimen. Twenty-two patients received cryotherapy. The cumulative incidence of grade 3-4 OM was significantly lower in the cryotherapy group (57.1%) than in the noncryotherapy group (89.5%; P = .041). Multivariate analyses identified cryotherapy and the melphalan dose as independent factors for the lower occurrence of OM. The present study demonstrates the clinically significant efficacy of cryotherapy for preventing melphalan-induced OM in pediatric patients.

Allogeneic Hematopoietic Stem Cell Transplantation for Leukocyte Adhesion Deficiency.

The clinical outcome of allogeneic hematopoietic stem cell transplantation (HSCT) was retrospectively analyzed in 6 patients with leukocyte adhesion deficiency. Of 3 patients transplanted with myeloablative conditioning, 2 patients had complete chimerism and 1 patient had mixed chimerism. By contrast, all 3 patients transplanted with reduced-intensity conditioning (RIC) had mixed chimerism, one of whom progressed to secondary graft failure. All patients with low-level mixed chimerism and secondary graft failure were rescued by donor lymphocyte infusion or a second HSCT. RIC-HSCT is feasible for leukocyte adhesion deficiency, although further refinement/modification of conditioning is required to achieve higher donor chimerism levels.

Comprehensive genetic analysis of donor cell derived leukemia with KMT2A rearrangement.

BACKGROUND: Donor cell leukemia (DCL) occurs after allogeneic hematopoietic stem cell transplantation. Several mechanisms, including occult leukemic/preleukemic subclones in the donor graft and germline predisposition to leukemia, are proposed to be associated with DCL's molecular pathogenesis. We report a comprehensive genetic analysis of a patient with KMT2A-rearranged DCL after allogeneic bone marrow transplantation for refractory cytopenia of childhood. PROCEDURE: We performed a whole-exome sequencing of the recipient's peripheral blood before transplant and the donor's peripheral blood and the recipient's bone marrow at the time of DCL diagnosis. RNA sequencing was also performed to detect fusion genes in DCL blasts. RESULTS: There were no germline mutations that were associated with a predisposition to leukemia in the recipient and donor. Furthermore, there were no detectable somatic alterations except KMT2A-MLLT10 and other related gene fusions in DCL. KMT2A-MLLT10 was not detectable in the donor's bone marrow. CONCLUSION: We propose a novel pattern of the molecular pathogenesis of DCL solely involving a genetic mutation acquired after transplant with no identifiable genetic factor related to the donor and recipient.

Immunosuppressive therapy for patients with Down syndrome and idiopathic aplastic anemia.

Idiopathic aplastic anemia (AA) is a rare hematological complication of Down syndrome (DS). The safety and efficacy of immunosuppressive therapy (IST) in individuals with DS remain unknown. We used a standard regimen of IST, comprising antithymocyte globulin and cyclosporine A, to treat three children with DS and idiopathic acquired AA. Two patients achieved a hematological (complete or partial) response and became transfusion independent at the final follow-up. The third patient failed to respond to IST and underwent bone marrow transplantation from a human leukocyte antigen (HLA)-mismatched unrelated donor. None of the patients experienced severe or unexpected adverse events during IST. Our experience suggests that IST is a safe and reasonable treatment, even in individuals with DS who suffer from AA and lack an HLA-matched sibling donor.

Allogeneic hematopoietic stem cell transplantation for Chediak-Higashi syndrome.

The clinical outcome of allogeneic HSCT was retrospectively analyzed in eight patients with CHS. In total, six of these eight patients are alive. Four of five patients transplanted with MAC achieved prompt engraftment, and three of the four patients, including two patients with AP before transplant, are alive without disease. In contrast, three patients transplanted with RIC without active AP disease achieved prompt engraftment and survive long term. RIC-HSCT might be an alternative treatment for CHS similar to other types of HLH, at least for patients without active AP disease.

Outcome of adolescent patients with acute myeloid leukemia treated with pediatric protocols.

As past studies of adolescent and young adults (AYA) with acute myeloid leukemia (AML) reported conflicting results, we conducted a retrospective analysis using data from three Japanese pediatric AML studies. Among the 782 patients with de novo AML, 44 were classified as AYA (age ≥15 years at diagnosis), 164 as infants (0-1 year), 413 as younger children (2-11 years), and 161 as older children (12-14 years). While the 5-year event-free survival rate of AYA was not different among the groups, the five-year survival rate (54.7 %) was significantly lower than that of the other three groups (P = 0.019): 68.7 % for infants, 73.2 % for younger children, and 75.5 % for older children. No difference in the 5-year cumulative incidence of relapse was observed, but treatment-related death (TRD) of AYA was significantly higher (29.4 %) than that in infants (14.8 %), younger children (10.2 %), and older children (13.8 %). Multivariate analysis showed age ≥15 years old at diagnosis was associated with both poor survival rate and high TRD. Adolescents with AML had inferior survival due to a higher incidence of TRD, especially after failure of initial frontline treatment.

Prospective pharmacokinetic study of intravenous busulfan in hematopoietic stem cell transplantation in 25 children.

The aim of this study was to prospectively evaluate the PK and safety of ivBU in 25 Japanese children (median age six yr; range, five months-17 yr) as one of a combination of drugs in a pretransplant regimen. The patients had acute leukemia (n = 14), CML (2), JMML (5), solid tumors (2), chronic granulomatous disease (1), or metachromatic leukodystrophy (1). Five different dose schedules were used according to the patient's ABW: <9 kg (1.0 mg/kg), 9 to <16 (1.2 mg/kg), 16-23 (1.1 mg/kg), >23-34 (0.95 mg/kg), and >34 kg of BW (0.8 mg/kg). Each dose was given over two h, and sample blood was drawn at nine or 11 separate points for analysis by gas chromatography-mass spectrometry. The AUC varied from 796 to 1905 µmol min/L, and 19 of the 25 patients (76%) remained within the target range without dose adjustment. Two were diagnosed with engraftment failure. Hepatic VOD developed in four, and only one of these showed high AUC (>1500 µmol min/L). Toxicities did not correlate with the BU level. Our data showed very similar PK to those in previous studies, and these dose schedules are applicable to Japanese children.

Assessment of corticosteroid-induced osteonecrosis in children undergoing chemotherapy for acute lymphoblastic leukemia: a report from the Japanese Childhood Cancer and Leukemia Study Group.

Steroid-induced osteonecrosis (ON) is a challenging complication encountered during modern chemotherapy for childhood acute lymphoblastic leukemia (ALL). We retrospectively assessed the incidence of ON and its risk factors in a total of 1095 patients enrolled in 3 consecutive Japanese Children's Cancer and Leukemia Study Group ALL studies (ALL941 [1994 to 2000], n=464; ALL2000 [2000 to 2004], n=305; and ALL2004 [2004 to 2010], n=326). ON was diagnosed in 16 patients, of whom 15 were symptomatic. The cumulative incidence of ON was 0.76% in ALL941, 0.35% in ALL2000, and 3.6% in ALL2004. The incidence of ON in ALL941/2000, in which only prednisolone was administered as a steroid, was significantly lower than that in ALL2004, in which dexamethasone was used as a partial substitute for prednisolone (P<0.01). In ALL2004, sex and age were significantly correlated with the incidence of ON (1.3% in boys vs. 6.7% in girls, P=0.0132; 0.42% for age <10 y vs. 15.6% for age ≥10 y, P<0.0001), suggesting that girls aged 10 years and above are at a greater risk of ON onset. These results indicate that the risk of ON should be considered when administering dexamethasone as part of ALL protocol treatment in girls aged 10 years and above.

Total body irradiation and melphalan as a conditioning regimen for children with hematological malignancies undergoing transplantation with stem cells from HLA-identical related donors.

Although some studies have reported that TBI and MEL offer an effective conditioning regimen for autologous SCT in acute leukemia, little has been reported regarding outcomes of allogeneic SCT. We retrospectively evaluated outcomes for 50 pediatric patients who underwent allo-SCT conditioned with intravenous MEL (180-210 mg/m(2) ) and fractionated TBI (12-13.2 Gy) from HLA-identical related donors. Nineteen patients were in CR1, 18 were in CR2, and 13 showed advanced-stage disease (≥ CR3). Patients had received allo-SCT from HLA-identical siblings (n = 45) or phenotypically HLA-identical family donors (n = 5). Median duration of follow-up for all disease-free patients was 61 months (range, 8.8-177 months). At the time of analysis, 12 patients had died. Eleven of those died of relapse, and one died of TRM. DFS rates for all patients, patients with AML (n = 12), and patients with lymphoid malignancy (n = 38) were 61.4% and 82.1%, respectively. DFS rates for CR1, CR2, and ≥CR3 cases were 89.2%, 88.1%, and 23.1%, respectively (p < 0.05). MEL/TBI for pediatric patients with hematological malignancies was associated with lower relapse rates and no increase in toxicity, resulting in better survival.

Continuous and high-dose cytarabine combined chemotherapy in children with down syndrome and acute myeloid leukemia: Report from the Japanese children's cancer and leukemia study group (JCCLSG) AML 9805 down study.

BACKGROUND: The aim of the JCCLSG AML 9805 Down study was to evaluate the effect of continuous and high-dose cytarabine combined chemotherapy on the survival outcome of acute myeloid leukemia (AML) with Down syndrome (DS). PROCEDURE: From May 1998 to December 2006, DS patients with newly diagnosed AML were enrolled. Remission induction therapy consisted of two courses of pirarubicin, vincristine, and continuous-dose cytarabine (AVC1). The patients who achieved complete remission (CR) after two courses of AVC1 were subsequently treated with mitoxantrone and continuous-dose cytarabine (MC), etoposide and high-dose cytarabine (EC) and pirarubicin, vincristine, and continuous-dose cytarabine (AVC2). RESULTS: Twenty-four patients were enrolled. All patients were younger than 4 years and diagnosed as having acute megakaryoblastic leukemia. Twenty-one patients achieved CR. Three patients died during remission induction therapy due to serious infection. No toxic deaths were observed during remission. All but one patient maintained CR without serious complications. The 5-year overall and event-free survivals were 87.5% ± 6.8% and 83.1% ± 7.7%, respectively. CONCLUSIONS: Continuous and high-dose cytarabine combined chemotherapy with reduced intensity would be effective in DS children with AML.

Assessment of late cardiotoxicity of pirarubicin (THP) in children with acute lymphoblastic leukemia.

BACKGROUND: Pirarubicin (tetrahydropyranyl-adriamycin: THP) is a derivative of doxorubicin with reportedly less cardiotoxicity in adults. However no studies of cardiotoxicity in children treated with THP have been reported. This study was performed to assess the THP-induced cardiotoxicity for children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: This study comprised 61 asymptomatic patients aged from 7.6 to 25.7 years old. Median follow-up time after completion of anthracycline treatment was 8.1 years (range: 1.7-12.5). The cumulative dose of THP ranged from 120 to 740 mg/m(2) with a median of 180 mg/m(2) . Patients underwent electrocardiogram (ECG), echocardiography, the 6-min walk test (6MWT), and measurements of serum brain natriuretic peptide (BNP) before and after exercise. RESULTS: All subjects showed normal left ventricular function assessed by echocardiography. Ventricular premature contraction in Holter ECG and reduced exercise tolerance in the 6MWT were detected in 2/46 (3.3%) and 5/41(12.2%), respectively. Abnormal BNP levels were detected in 6/60 (10%) both before and after exercise. The cumulative dose of THP was significantly correlated with BNP levels after exercise (r = 0.27, P = 0.03), but not with any other cardiac measurements. Further analysis revealed that subjects with a high cumulative dose ≧300 mg/m(2) had significantly higher BNP levels after exercise compared with subjects with a low cumulative dose <300 mg/m(2) (P = 0.04). CONCLUSIONS: No significant cardiac dysfunction was detected in long-term survivors who received THP treatment. The use of post-exercise BNP level to indicate high cardiotoxicity risk should be verified by further study.

Minimal residual disease-based augmented therapy in childhood acute lymphoblastic leukemia: a report from the Japanese Childhood Cancer and Leukemia Study Group.

BACKGROUND: The majority of minimal residual disease (MRD)-positive patients with acute lymphoblastic leukemia (ALL) have poor outcomes. The ALL2000 study was performed to evaluate the efficacy of augmented chemotherapy based on MRD-restratification in childhood ALL. PROCEDURE: Between 2000 and 2004, 305 eligible patients with precursor B or T-cell ALL were enrolled in the ALL2000 study. The ALL941-based therapy protocol utilized PCR MRD assays using Immunoglobulin and T-cell receptor gene rearrangements. They were initially stratified into three risk-groups according to leukocyte count and age, and MRD levels were measured at weeks 5 (TP1) and 12 (TP2) for a second stratification. From week 14, patients with MRD levels ≥ 10(-3) received an increase in therapy (one risk group higher), while the remainder continued to receive the initial risk-adapted therapy. RESULTS: The overall 5-year event-free survival (EFS) rate for ALL2000 was 79.7 ± 2.4%. MRD stratification was feasible for 234 of 301 patients (77%) who achieved complete remission. The EFS rate of the MRD stratifiable (MRD) group was 82.5 ± 2.6%, considerably superior to the 74.7 ± 5.7% of MRD non-stratifiable (Non-MRD) group (P = 0.084) and the 74.4 ± 2.1% for ALL 941 (P = 0.012). MRD-positive patients at TP2 showed inferior outcomes as compared with MRD-negative cases, but the difference did not reach a statistically significant level in any risk groups or immunophenotypes. CONCLUSIONS: These results suggest that augmented therapy for MRD-positive patients at TP2 contributed to better outcomes of the ALL2000 study.

[Effectiveness of remission induction with high-dose cytarabine for relapsed or refractory pediatric acute leukemia].

We conducted a multicenter postmarketing study to investigate the efficacy and safety of reinduction therapy with a high-dose cytarabine-containing regimen for pediatric patients with relapsed or refractory acute leukemia. Seven of 13 patients (53.8%) with ALL achieved complete or partial remission, and only 1 of 6 patients (16.7%) with AML achieved partial remission. The frequent non-hematologic adverse events were gastrointestinal toxicities, such as vomiting, diarrhea and abdominal pain, as well as pyrexia and headache. Infection appeared in 9 of 20 (45%) patients. There were two death during reinduction therapy. One died of invasive bronchopulmonary aspergillosis, and the other died of intracranial hemorrhage and renal failure. These results indicated that a high-dose cytarabine regimen is effective as reinduction therapy in pediatric patients with relapsed ALL, and supportive care is essential to prevent or control treatment-related adverse events, such as infection.