Haematopoietic stem cell transplantation after reduced intensity conditioning in children and adolescents with chronic myeloid leukaemia: A prospective multicentre trial of the I-BFM Study Group.

This prospective multicentre trial evaluated the safety and the efficacy of a thiotepa/melphalan-based reduced intensity conditioning (RIC) haematopoietic stem cell transplantation (HSCT) in children and adolescents with chronic myeloid leukaemia (CML) in chronic phase (CP). Thirty-two patients were transplanted from matched siblings or matched unrelated donors. In 22 patients, HSCT was performed due to insufficient molecular response or loss of response to first- or second-generation tyrosine kinase inhibitor (TKI), with pretransplant BCR::ABL1 transcripts ranging between 0.001% and 33%. The protocol included a BCR::ABL1-guided intervention with TKI retreatment in the first year and donor lymphocyte infusions (DLI) in the second-year post-transplant. All patients engrafted. The 1-year transplant-related mortality was 3% (confidence interval [CI]: 0%-6%). After a median follow-up of 6.3 years, 5-year overall survival and event-free survival are 97% (CI: 93%-100%) and 91% (CI: 79%-100%) respectively. The current 5-year leukaemia-free survival with BCR::ABL1 <0.01% is 97% (CI: 88%-100%) and the current TKI- and DLI-free survival is 95% (CI: 85%-100%). The incidence of chronic graft-versus-host disease (GvHD) was 32%, being severe in four patients (13%). At last follow-up, 31 patients are GvHD-free and have stopped immunosuppression. RIC HSCT following pretreatment with TKI is feasible and effective in children and adolescents with CP-CML with an excellent disease-free and TKI-free survival.

Prophylaxis with enoxaparin and antithrombin III in drug-induced coagulation alterations in childhood leukemia: a retrospective experience of 20 years.

BACKGROUND: Thromboembolic complications are well known in the treatment of childhood acute lymphoblastic leukemia. Over the years it has not been possible to reach a consensus on a possible prophylaxis of thromboembolic events during intensive therapy. Only the administration of enoxaparin was able to achieve evidence in the literature to date. METHODS: In this retrospective study, 173 childhood leukemia patients were treated over 20 years with a thromboembolic prophylaxis including enoxaparin and AT III during induction therapy with L-asparaginase and cortisone. RESULTS: We here report the effectiveness of administration of enoxaparin and AT III in childhood leukemia, showing a strikingly low prevalence of deep vein thrombosis (2.9%). Especially in adolescent patients, a particularly great need for AT III was demonstrated. CONCLUSIONS: We recommend thromboembolic prophylaxis with enoxaparin and AT III substitution during induction/reinduction therapy with L-asparaginase and glucocorticosteroids, especially from adolescence onwards.

Can virtual care reduce treatment burden in pediatric leukemia? A retrospective cost analysis.

We conducted a retrospective analysis to determine the potential reduction in treatment burden through the expansion of virtual care among children with leukemia (n = 152). Patients living in urban areas traveled median distances of 1555 km compared with 7536 km for patients living in rural areas (p < .05). For the latter group, a median reduction in travel distance of 3560 km (interquartile range [IQR], 2136-5787 km), travel time of 51 h (IQR, 26-78 h), and CO2 emissions of 623 kg (IQR, 374-1013 kg) was estimated, if every second visit was replaced by video consultations.

Disagreement between mothers' and fathers' rating of health-related quality of life in children with cancer.

PURPOSE: Serial assessment of health condition based on self-report made by children and their proxies has consistently shown a lack of congruence. The study explored the discrepancies between mother's, father's, and children's reports on health-related quality of life (HRQOL) during the first two months of pediatric cancer treatment. METHODS: In this cohort study, children and parents completed the generic and cancer-specific Pediatric Quality-of-Life Inventory (PedsQL) questionnaires at initial diagnosis and in the subsequent months. Evaluation of discrepancies included intraclass correlations between mother-child and father-child dyads at different domain levels. RESULTS: Thirty-six children with a diagnosis of cancer between May 2020 and November 2021 and their parents were included in this study. At diagnosis, mother-child dyads showed better agreement on more domains of the PedsQL Generic Core Scale than father-child dyads; moderate agreement persisted for both parents at subsequent time points on the physical domain. The disease-specific PedsQL Cancer Module revealed moderate and better agreement for mother-child dyads during active cancer therapy. In particular, agreement of mother-child dyads was pronounced for domains such as worry (0.77 [95% CI 0.52-0.89, P < 0.001]), whereas fathers tended to overestimate the child's symptom burden for most of the remaining domains of the PedsQL Cancer Module. CONCLUSION: This cohort study shows that both parent proxy reports can provide valid information on child's HRQOL, but that fathers tend to overestimate, particularly for non-observable domains. Proxy reports derived from mothers more closely agreed with children's HRQOL and might be more weighted, if there is uncertainty between parents.

Incidence and Risk Factors of Venous Thromboembolism in Childhood Acute Lymphoblastic Leukaemia - a Population-Based Analysis of the Austrian Berlin-Frankfurt-Münster (BFM) Study Group.

Venous thromboembolism (VTE) is a well-known complication of the treatment of pediatric acute lymphoblastic leukemia (ALL). We analyzed 1026 ALL patients 1-18-years-old, who were enrolled into the AIEOP-BFM ALL 2000 or 2009 studies in Austria, with regard to the incidence and risk factors of VTE. The 2.5-year cumulative incidence (CI) of VTE ≥ grade 2 was 4%±1% (n = 36/1026). Twenty VTE (56%) were found in the central nervous system (19 cerebral venous sinus and 1 cortical vein thrombosis), and 16 (44%) at other sites (7 deep vein thromboses (DVT) of the lower extremity, 4 DVT of the upper extremity, 4 central venous line-thromboses, 1 pulmonary embolism). Most VTE occurred during induction and early consolidation therapy (81%) and were associated with L-asparaginase within 4 and corticosteroids withing 1 week(s) preceding the event (89 and 86%, respectively). In multivariable analysis, two independent risk factors were found. Patients 10-18-years-old had an increased (hazard-ratio: 2.156, p = 0.0389), whereas treatments in trial AIEOP-BFM ALL 2009 had a lower risk for VTE (hazard-ratio: 0.349, p = 0.0270). In conclusion, the 2.5-year CI of VTE among our pediatric patient cohort was <5% and adolescent age was the main patient-related risk factor. This older age group might benefit from primary prophylactic measures.

New Therapeutic Approach in an Infant With Systemic Myofibromatosis and Intestinal Hemorrhage.

We report the case of an infant with multicentric myofibromatosis affecting the gastric and intestinal mucosa, leading to continuous intestinal hemorrhage and iron deficiency. Conventional vinblastine and methotrexate combination treatment was administered for 4 months, but persistent intestinal blood loss required repeated blood transfusions. Because of insufficient tumor response to treatment, we opted for the experimental combination of rapamycin and dasatinib. Six weeks after the start of this therapy, hemoglobin levels stabilized without transfusions, and no fecal blood loss was detected. In addition, a follow-up magnetic resonance imaging excluded tumor progression. We here show the effectiveness of an experimental therapy with rapamycin and dasatinib in a child with multicentric myofibromatosis after the failure of conventional therapy with vinblastine and methotrexate.

Pediatric Malignant Peritoneal Mesothelioma With Meningeal Metastasis.

Malignant peritoneal mesothelioma (MPM) is an extremely rare entity with a poor prognosis. We report on a 16-year-old boy with ascites and abdominal distension. A computed tomography scan showed peritoneal thickening and a mass adjacent to the transverse colon. Neither repeated cytologic testing of ascitic fluid, nor peritoneal tissue biopsy detected malignant cells. After the patient became progressively comatose, a magnetic resonance imaging scan of the brain showed leptomeningeal enhancement. An autopsy showed MPM infiltrating the pleura and the meninges. This is the first report on meningeal metastasis of MPM in a pediatric patient illustrating the enigmatic behavior of the tumor and highlighting the diagnostic pitfalls.

Clear cell sarcoma of the kidney in Austrian children: Long-term survival after relapse.

INTRODUCTION: Clear cell sarcoma of the kidney (CCSK) is a rare malignant childhood renal tumour. Recently, the central nervous system (CNS) was found to be the most frequent site of relapse associated with a poor outcome. Optimal treatment strategies are scarce. PATIENTS AND METHODS: Retrospective data analysis of all Austrian children with CCSK. They were enrolled in the Austrian-Hungarian Wilms Tumour Study (AHWTS) 1989, the SIOP93-01 or the SIOP2001 study between 1990 and 2019. Demographic, diagnostic, treatment-related variables and survival data were analysed. RESULTS: We identified 12 children with CCSK (M = 7, F = 5; median age 1.6 years). All had localised disease (stage I: 2; stage II: 2; stage III: 8) at diagnosis, and a first complete remission (CR1) was achieved in 12/12. Six patients are in an ongoing CR1 (median follow-up 10 years). Six other patients had a relapse (local 1; brain 5) a median time of 2.4 years from diagnosis. Two patients died of the disease 4 months and 2.8 years after first relapse. Four of five patients with CNS relapse are in CR2 with a median follow-up time of 9.3 years after relapse diagnosis. Relapse treatment included a combination of chemotherapy, radiation and surgery. Two children received high-dose chemotherapy followed by autologous stem cell rescue, and one child received intrathecal mafosphamide. Long-term side effects after treatment were impaired tubular renal function (n = 4), cardiomyopathy (n = 1) and growth disorders (n = 1). CONCLUSIONS: In this series, the brain was the most common site of relapse. Long-term survival after recurrence was achievable with intensive multimodal therapy.

Implementation of daily patient-reported outcome measurements to support children with cancer.

BACKGROUND: Several stakeholders, including patients and health care providers, suggest symptom self-reporting measurements for a more patient-directed cancer control approach. However, services tailored to measure daily reporting and implementing it in clinical care are lacking. This study aimed to evaluate the feasibility and value of daily patient-reported outcome measures (PROMs) by children receiving chemotherapy for cancer. METHODS: Health status was recorded daily with a web-based child-friendly patient portal (ePROtect). Following aspects of feasibility and usability were assessed: (a) the completion rate and time, (b) user feedback on usability and satisfaction, and (c) the performed interventions if moderate to severe symptom deterioration was noted. RESULTS: Twelve children (median age: 7.2 years) were included. A total number of 891 daily reports were collected during the study period; the median percentage of ePROtect completion days was 85.3% (interquartile range [IQR] 64.2-100.0) and 55.9% (IQR 51.9-76.9) for inpatient and outpatient stay, respectively. Mean time to complete the questionnaire was 47.6 seconds. Severe symptoms were reported in 14.7% of measurement time points, which led to prompt health care interventions in 57 cases, including extension of supportive care (n = 37) and pre-emptive inpatient admissions (n = 5). Over 80% of the patients (10/12) and their proxies (16/18) provided feedback with high rating for satisfaction (>90%) and usefulness (>80%) of ePROtect. CONCLUSION: Our study shows that daily symptom monitoring is feasible for all children with newly diagnosed cancer aged 5-18 years. Monitoring offers the opportunity to identify symptoms early and trigger appropriate clinical action.

Benefits of risk-adapted and mould-specific antifungal prophylaxis in childhood leukaemia.

Fluconazole is one of the most commonly used drugs for antifungal prophylaxis in childhood leukaemia. However, its interaction with vincristine may induce neuropathy and the emergence of antifungal drug resistance contributes to substantial mortality caused by invasive fungal infections (IFIs). In a retrospective single-centre study, we compared tolerability and outcome of different antifungal prophylaxis strategies in 198 children with acute leukaemia (median age 5·3 years). Until 2010, antifungal prophylaxis with fluconazole was offered to most of the patients and thereafter was replaced by liposomal amphotericin-B (L-AMB) and restricted to high-risk patients only. Vincristine-induced neurotoxicity was significantly reduced under L-AMB, as the percentage of patients with severe constipation decreased (15·4% vs. 3·7%, before vs. after 31 December·2010, P = 0·01) and stool frequency increased by up to 38% in polyene-treated patients (P = 0·005). Before 2011, 10 patients developed confirmed IFIs, most of them were infected with Aspergillus species. After risk adaption in 2011, IFIs were completely prevented (P = 0·007). L-AMB prophylaxis is beneficial in childhood leukaemia patients, as it offers effective antifungal activity with improved tolerability as compared to fluconazole. The potential impact of our risk-adapted antifungal treatment should be included in current prophylaxis guidelines for childhood leukaemia.

Stereotactic radiofrequency ablation of a variety of liver masses in children.

BACKGROUND AND AIMS: Surgical resection is currently the cornerstone of liver tumor treatment in children. In adults radiofrequency ablation (RFA) is an established minimally invasive treatment option for small focal liver tumors. Multiprobe stereotactic RFA (SRFA) with intraoperative image fusion to confirm ablation margins allows treatment for large lesions. We describe our experience with SRFA in children with liver masses. METHODS: SRFA was performed in 10 patients with a median age of 14 years (range 0.5-17.0 years) suffering from liver adenoma (n = 3), hepatocellular carcinoma (n = 1), hepatoblastoma (n = 2), myofibroblastic tumor (n = 1), hepatic metastases of extrahepatic tumors (n = 2) and infiltrative hepatic cysts associated with alveolar echinococcosis (n = 1). Overall, 15 lesions with a mean lesion size of 2.6 cm (range 0.7-9.5 cm) were treated in 11 sessions. RESULTS: The technical success rate was 100%, as was the survival rate. No transient adverse effects higher than grade II (Clavien and Dindo) were encountered after interventions. The median hospital stay was 5 d (range 2-33 d). In two patients who subsequently underwent transplant hepatectomy complete ablation was histologically confirmed. Follow-up imaging studies (median 55 months, range 18-129 months) revealed no local or distant recurrence of disease in any patient. CONCLUSIONS: SRFA is an effective minimal-invasive treatment option in pediatric patients with liver tumors of different etiologies.

Newly Diagnosed Metastatic Intracranial Ependymoma in Children: Frequency, Molecular Characteristics, Treatment, and Outcome in the Prospective HIT Series.

BACKGROUND: Data on frequency, clinical presentation, and outcome of primary metastatic intracranial ependymoma in children are scarce. PATIENTS AND METHODS: Prospective data on patients younger than 21 years with metastatic intracranial ependymoma at first diagnosis, registered from 2001 to 2014 in the HIT-2000 trial and the HIT-2000 Interim Registry, were analyzed. RESULTS: Of 453 registered patients with intracranial ependymoma and central neuropathology review, initial staging included spinal magnetic resonance imaging in all patients and lumbar cerebrospinal fluid (CSF) analysis in 402 patients. Ten patients (2.2%) had metastatic disease, including three with microscopic CSF positivity only (M1 metastasis stage, 0.7% of patients with CSF staging). Location of the primary tumor was supratentorial in four patients (all supratentorial RELA-fused ependymoma [ST-EPN-RELA]) and within the posterior fossa in five patients (posterior fossa ependymoma type A [PF-EPN-A], n = 4; posterior fossa ependymoma not further classifiable, n = 1), and multifocal in one patient.All four patients with ST-EPN-RELA were alive in first or second complete remission (CR) 7.5-12.3 years after diagnosis. All four patients with macroscopic metastases of posterior fossa or multifocal ependymoma died. Three patients with initial M1 stage (ST-EPN-RELA, n = 1; PF-EPN-A, n = 2) received chemotherapy and local irradiation and were alive in second or third CR 3.0-9.7 years after diagnosis. Progression-free and overall survival of the entire cohort at 5 years was 13% (±6%), and 58% (±16%), respectively. CONCLUSION: Primary metastatic disease is rare in children with intracranial ependymoma. Prognosis may depend on molecular subgroup and extent of dissemination, and relevance of CSF analysis for initial staging remains to be clarified. IMPLICATIONS FOR PRACTICE: Childhood ependymoma presenting with metastasis at first diagnosis is very rare with a frequency of 2.4% in this population-based, well-characterized cohort. Detection of microscopic metastases in the cerebrospinal fluid was extremely rare, and impact on prognosis and respective treatment decision on irradiation field remains unclear. Initial metastatic presentation occurs in both supratentorial RELA-fused ependymoma and posterior fossa ependymoma. Prognosis may differ according to extent of metastasis and biological subgroup, with poor prognosis in diffusely spread metastatic posterior fossa ependymoma even after combination therapy with both intensive chemotherapy and craniospinal irradiation, which may help to guide individual therapeutic decisions for future patients.

The various clinical spectra of juvenile xanthogranuloma: imaging for two case reports and review of the literature.

BACKGROUND: Juvenile xanthogranuloma (JXG) belongs to the heterogeneous group of non-Langerhans cell histiocytosis and is caused by an accumulation and proliferation of macrophages. In the majority of cases JXG is a disorder of early childhood presenting during the first 2 years of life. The typical presentation is a solitary reddish or yellowish skin papule or nodule with spontaneous regression and no need for treatment. CASE PRESENTATION: Two infants with an atypical presentation of JXG, one with multiple blueberry muffin rash-like skin lesions and the other with severe multi-systemic involvement, are reported. Diagnosis was established by skin biopsy including histological work-up and immunostaining, where markers for macrophages (CD68 and CD163) exhibited significant reactivity. CONCLUSION: JXG is the most common of the non-Langerhans cell histiocytosis. The typical presentation is a solitary skin lesion. The purpose of this report is to familiarize paediatricians with an unusual variant of this entity in order to facilitate early diagnosis and raise awareness for possible visceral complications and associated medical conditions.

Low incidence of symptomatic osteonecrosis after allogeneic HSCT in children with high-risk or relapsed ALL - results of the ALL-SCT 2003 trial.

Osteonecrosis (ON) was prospectively assessed in 557 children and adolescents in the Berlin-Frankfurt-Münster Stem Cell Transplantation in children with acute lymphoblastic leukaemia 2003 trial. Median age at haematopoietic stem cell transplantation (HSCT) was 10·3 years (range 0·5-26). Cumulative incidence of symptomatic ON (sON) was 9% at 5 years (standard deviation 1%), median time from HSCT to diagnosis of sON was 12·4 months (range 1-126). Multivariate analysis identified age at HSCT [10-15 years vs. <10 years: hazard ratio (HR) 3·73, P = 0·009; >15 years vs. <10 years: HR 5·46, P = 0·001], diagnosis of sON prior to HSCT and chronic graft-versus-host disease (yes versus no: HR 2·696, P = 0·015) as significant independent risk factors for the development of sON.

Hemophagocytic lymphohistiocytosis after allogeneic bone marrow transplantation during chronic norovirus infection.

Hemophagocytic lymphohistiocytosis (HLH) is a macrophage activating syndrome that is known to develop in patients with autoimmune disease, malignancies or infection, for example with Epstein-Barr virus, cytomegalovirus or varicella zoster virus. We describe a 24-month old boy with acute myelogenous leukaemia relapse and allogeneic bone marrow transplantation, who developed HLH on day +40 during chronic infection with norovirus. Here, we report for the first time the development of HLH in combination with chronic norovirus infection after allogeneic bone marrow transplantation in a hematopoietic malignancy.

Computed tomography guided percutaneous lung biopsies and suspected fungal infections in pediatric cancer patients.

BACKGROUND: The spectrum of potential fungal pathogens known to cause invasive pulmonary infections has grown as a result of intensified immunosuppressive therapy and the emergence of antifungal resistance. PROCEDURE: In a retrospective single center study, we investigated computed tomography guided percutaneous lung biopsies in 16 childhood patients with suspected fungal infections. Microbiological analysis consisted of microscopic examination, culture, and a broad-range fungal polymerase chain reaction for detection of either Aspergillus or Mucorales species. RESULTS: In 14 patients (88%), invasive fungal infection with Aspergillus species including A. terreus, Mucormycetes, and Saccharomyces cerevisiae being the main pathogens was confirmed, including patients with a double infection (19%). In two cases, the most likely diagnosis of primary bronchiolitis obliterans organizing pneumonia was established based on the results of typical histopathologic features, negative culture results, and symptoms resolved after treatment with high-dose cortisone. Diagnosis of invasive fungal pneumonia led to an immediate interruption of antineoplastic treatment in 100%, reduction of antibiotic drugs in 76%, and change of empirical to targeted antifungal therapy in 63%. The safety of lung biopsy was guaranteed by lack of any complications, such as bleeding or pneumothorax. CONCLUSIONS: The increased detection of rare fungal infections by computed tomography guided biopsy supports the need for a rapid and precise diagnosis, as most of the fungal pathogens are at least partially resistant to available antifungal therapy and proper treatment is essential for best practice in patient management.

Retrospective identification of the first cord blood-transplanted severe aplastic anemia in a STAT1-associated chronic mucocutaneous candidiasis family: case report, review of literature and pathophysiologic background.

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure syndrome whose development can be triggered by environmental, autoimmune, and/or genetic factors. The latter comprises germ line pathogenic variants in genes that bring about habitually predisposing syndromes as well as immune deficiencies that do so only occasionally. One of these disorders is the autosomal dominant form of chronic mucocutaneous candidiasis (CMC), which is defined by germ line STAT1 gain-of-function (GOF) pathogenic variants. The resultant overexpression and constitutive activation of STAT1 dysregulate the Janus kinase/signal transducer and activator of transcription 1 (STAT) signaling pathway, which normally organizes the development and proper interaction of different components of the immunologic and hematopoietic system. Although SAA is an extremely rare complication in this disorder, it gained a more widespread interest when it became clear that the underlying causative pathomechanism may, in a similar fashion, also be instrumental in at least some of the idiopathic SAA cases. Based on these premises, we present herein what is the historically most likely first cord blood-transplanted SAA case in a CMC family with a documented STAT1 GOF pathogenic variant. In addition, we recapitulate the characteristics of the six CMC SAA cases that have been reported so far and discuss the significance of STAT1 GOF pathogenic variants and other STAT1 signaling derangements in the context of these specific types of bone marrow failure syndromes. Because a constitutively activated STAT1 signaling, be it driven by STAT1 GOF germ line pathogenic variants or any other pathogenic variant-independent events, is apparently important for initiating and maintaining the SAA disease process, we propose to acknowledge that SAA is one of the definite disease manifestations in STAT1-mutated CMC cases. For the same reason, we deem it necessary to also incorporate molecular and functional analyses of STAT1 into the diagnostic work-up of SAA cases.

Utility of PCR in diagnosis of invasive fungal infections: real-life data from a multicenter study.

Prospective studies addressing the clinical value of broad-range PCR using the internal transcribed spacer region (ITS) for diagnosis of microscopy-negative fungal infections in nonselected patient populations are lacking. We first assessed the diagnostic performance of ITS rRNA gene PCR compared with that of routine microscopic immunofluorescence examination. Second, we addressed prospectively the impact and clinical value of broad-range PCR for the diagnosis of infections using samples that tested negative by routine microscopy; the corresponding patients' data were evaluated by detailed medical record reviews. Results from 371 specimens showed a high concordance of >80% for broad-range PCR and routine conventional methods, indicating that the diagnostic performance of PCR for fungal infections is comparable to that of microscopy, which is currently considered part of the "gold standard." In this prospective study, 206 specimens with a negative result on routine microscopy were analyzed with PCR, and patients' clinical data were reviewed according to the criteria of the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group. We found that broad-range PCR showed a sensitivity, specificity, positive predictive value, and negative predictive value of 57.1%, 97.0%, 80%, and 91.7%, respectively, for microscopy-negative fungal infections. This study defines a possible helpful role of broad-range PCR for diagnosis of microscopy-negative fungal infections in conjunction with other tests.

Radioimmunotherapy-based conditioning for hematopoietic cell transplantation in children with malignant and nonmalignant diseases.

Targeted irradiation of the bone marrow with radiolabeled monoclonal antibodies (radioimmunotherapy) represents a novel therapeutic approach with both myeloablative and antileukemic potential. In an open-label, single-center pilot study, 30 pediatric and adolescent patients undergoing hematopoietic cell transplantation for malignant (n = 16) and nonmalignant (n = 14) disorders received treatment with a 9°Y-labeled anti-CD66 monoclonal antibody. Patients with a high risk of relapse (n = 7) received additional treatment with standard conditioning based on either total body irradiation or busulfan to intensify the antileukemic effect. In patients with comorbidities (n = 23), radioimmunotherapy was combined with a reduced-intensity conditioning regimen to reduce systemic toxicity. Preferential irradiation of the bone marrow was achieved in all patients. Nonrelapse mortality was 4 (13%) of 30 patients. In patients with malignant diseases, the probabilities of overall and disease-free survival at 2 years were 0.69 (95% confidence interval 0.37-0.87) and 0.46 (95% confidence interval 0.19-0.70), respectively. In patients with nonmalignant diseases, the probability of both overall and disease-free survival at 2 years was 0.94 (95% confidence interval 0.63-0.99). This pilot study demonstrates that radioimmunotherapy is effective in achieving myeloablation with low additional toxicity when used in combination with standard or reduced-intensity conditioning in young patients.