Progression of organ manifestations upon enzyme replacement therapy in a patient with mucopolysaccharidosis type I/Hurler

Background  

Enzyme replacement therapy (ERT) has been increasingly used as an interim treatment in severe mucopolysaccharidosis type I (MPSI)/Hurler patients prior to hematopoietic stem cell transplantation (HSCT).     

Enzyme replacement therapy: efficacy and limitations

Enzyme replacement therapy (ERT) is available for mucopolysaccharidosis (MPS) I, MPS II, MPS VI, and MPS IVA. The efficacy of ERT has been evaluated in clinical trials and in many post-marketing studies with a long-term follow-up for MPS I, MPS II, and MPS VI. While ERT is effective in reducing urinary glycosaminoglycans (GAGs) and liver and spleen volume, cartilaginous organs such as the trachea and bronchi, bones and eyes are poorly impacted by ERT probably due to limited penetration in the specific tissue. ERT in the present formulations also does not cross the blood–brain barrier, with the consequence that the central nervous system is not cured by ERT. This is particularly important for severe forms of MPS I and MPS II characterized by cognitive decline. For severe MPS I patients (Hurler), early haematopoietic stem cell transplantation is the gold standard, while still controversial is the role of stem cell transplantation in MPS II. The use of ERT in patients with severe cognitive decline is the subject of debate; the current position of the scientific community is that ERT must be started in all patients who do not have a more effective treatment. Neonatal screening is widely suggested for treatable MPS, and many pilot studies are ongoing. The rationale is that early, possibly pre-symptomatic treatment can improve prognosis. All patients develop anti-ERT antibodies but only a few have drug-related adverse reactions. It has not yet been definitely clarified if high-titre antibodies may, at least in some cases, reduce the efficacy of ERT.     

Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme α- l -iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler–Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study.
Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood–brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme alpha-L-iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler-Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study. Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood-brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

Comprehensive and long-term outcomes of enzyme replacement therapy followed by stem cell transplantation in children with Gaucher disease type 1 and 3

Background

Gaucher disease (GD) is a lysosomal storage disorder, characterized by hepatosplenomegaly, pancytopenia, bone diseases, with or without neurological symptoms. Plasma glucosylsphingosine (lyso-Gb1), a highly sensitive and specific biomarker for GD, has been used for diagnosis and monitoring the response to treatment. Enzyme replacement therapy (ERT) is an effective treatment for the non-neurologic symptoms of GD. Neuronopathic GD (type 2 and 3) accounts for 60%–70% of the Asian affected population.

Methods

We explored combination therapy of ERT followed by hematopoietic stem cell transplantation (HSCT) and its long-term outcomes in patients with GD type 3 (GD3).

Results

Four patients with GD3 and one with GD type 1 (GD1) underwent HSCT. The types of donor were one matched-related, one matched-unrelated, and three haploidentical. The age at disease onset was 6–18 months and the age at HSCT was 3.8–15 years in the patients with GD3. The latest age at follow-up was 8–22 years, with a post-HSCT duration of 3–14 years. All patients had successful HSCT. Chronic graft-versus-host disease occurred in one patient. The enzyme activities were normalized at 2 weeks post HSCT. Lyso-Gb1 concentrations became lower than the pathological value. All of the patients are still alive and physically independent. Most of them (4/5) returned to school. None of the patients with GD3 had seizures or additional neurological symptoms after HSCT, but showed varying degrees of cognitive impairment.

Conclusions

ERT followed by HSCT could be considered as an alternative treatment for patients with GD3 who have a high risk of fatal neurological progression.     

Cardiac functional and histopathologic findings in humans and mice with mucopolysaccharidosis type I: implications for assessment of therapeutic interventions in hurler syndrome

Hurler syndrome (mucopolysaccharidosis type I [MPS I]) is a uniformly lethal autosomal recessive storage disease caused by absence of the enzyme alpha-l-iduronidase (IDUA), which is involved in lysosomal degradation of sulfated glycosaminoglycans (GAGs). Cardiomyopathy and valvar insufficiency occur as GAGs accumulate in the myocardium, spongiosa of cardiac valves, and myointima of coronary arteries. Here we report the functional, biochemical, and morphologic cardiac findings in the MPS I mouse. We compare the cardiac functional and histopathological findings in the mouse to human MPS I. In MPS I mice, we have noted aortic insufficiency, increased left ventricular size, and decreased ventricular function. Aortic and mitral valves are thickened and the aortic root is dilated. However, murine MPS I is not identical to human MPS I. Myointimal proliferation of epicardial coronary arteries is unique to human MPS I, whereas dilation of aortic root appears unique to murine MPS I. Despite the differences between murine and human MPS I, the murine model provides reliable in vivo outcome parameters, such as thickened and insufficient aortic valves and depressed cardiac function that can be followed to assess the impact of therapeutic interventions in preclinical studies in Hurler syndrome.     

Unrelated CD3/CD19-Depleted Peripheral Stem Cell Transplantation for Hurler Syndrome

For patients with mucopolysaccharidosis type IH (MPS1-H; Hurler syndrome), early allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice. One boy and one girl aged 20.5 and 22 months, respectively, with MPS1-H received a conditioning regimen consisting of thiotepa, fludarabine, treosulfan, and ATG. Grafts were peripheral blood stem cells from unrelated donors (10/12 and 11/11 matched), that were manipulated by CD3/CD19 depletion and contained 20.3 and 28.2 × 10⁶ CD34+ cells/kg body weight, respectively. Both patients achieved stable hematopoietic engraftment and stable donor chimerism. Neither acute or chronic graft-versus-host disease (GVHD) nor other severe transplant-related complications occurred. At a follow-up of 48 and 37 months, both patients are alive and well with normal levels of α-L-iduronidase and have made major neurodevelopmental progress. Treosulfan-based conditioning offers the advantage of reduced toxicity; the use of unrelated CD3/CD19-depleted peripheral stem cell grafts allows transfusion of high CD34+ cell numbers together with a “tailored” number of CD3+ cells as well as engraftment facilitating cells in order to achieve rapid hematopoietic engraftment while reducing the risk of graft rejection and GVHD. This regimen might be an additional option when unrelated donor HSCT is considered for a patient with MPS1-H.     

Mucopolysaccharidosis VI: the Italian experience

The current paper describes the natural history and management of mucopolysaccharidosis VI (MPS VI) in all patients currently diagnosed with the disease in Italy. Nine patients (5.5–14.4 years) were included in the data review in March 2008. Gestational and perinatal data were normal for all patients. Median age at diagnosis was 1.9 years. During the course of the disease, all patients developed coarsened facial features, short stature, heart valve disease, eye problems, musculoskeletal problems, hepatosplenomegaly and neurological abnormalities. All patients received rhASB enzyme replacement therapy (ERT) and showed improvement or stabilisation in clinical manifestations after onset of therapy. The most frequently reported improvements were increased joint mobility and reduced hepatosplenomegaly. No relevant safety issues of ERT were reported. In conclusion, patients in Italy with MPS VI are diagnosed early in life. All patients have access to ERT and appear to benefit from this therapy.     

Analysis of factors affecting immune recovery and initial response to tetanus after DTaP vaccination in pediatric allogeneic HSCT patients

Transfer of donor immunity after allo‐HSCT is limited, requiring re‐vaccination after HSCT. The CDC 2009 guidelines introduced earlier vaccination post‐HSCT with a uniform vaccination strategy. This study objective was to describe predictors of immune recovery and initial response to tetanus after DTaP vaccination post‐HSCT. We conducted a retrospective chart review of pediatric allo‐HSCT patients transplanted between July 1, 2007–June 30, 2012 who survived >1 yr without relapse (N = 27). Response to tetanus one month after the initial dose of DTaP was defined as a ≥4 fold increase in tetanus titers ≥1 month after vaccination. Wilcoxon rank‐sum exact test and Kruskall–Wallis tests were used to analyze CD4, CD8, and CD19 counts. Exact conditional logistic regression was utilized to analyze initial tetanus vaccination response. A statistically significant increase in median CD4, CD8, and CD19 counts occurred from six to 12 months post‐HSCT (p ≤ 0.0001, 0.005, 0.004). Only 36% of patients had initial tetanus vaccination response at first attempt post‐HSCT. None of the variables tested were statistically significant in predicting initial tetanus response to vaccination. There was no association between predictors of immune recovery or transplant variables and initial tetanus response. A uniform vaccination strategy is unlikely to provide protective antibodies for many post‐HSCT patients and should be evaluated in larger studies.     

Hematopoietic stem cell transplantation for children with primary immunodeficiency diseases: Single center experience in Jordan

HSCT can be curative for many PID. Little is known about the outcome of HSCT for patients with PID in the developing countries. We retrospectively reviewed all children with PID who received HSCT at KHCC in Jordan between August 2003 and October 2011. Twenty‐eight patients were identified. The median age was 16 months (3 months–17 yr). Patients' diagnoses were SCID (n = 16), CHS (n = 3), HLH (n = 3), WAS (n = 2), Griscelli syndrome (n = 1), ALPS (n = 1), Omenn's syndrome (n = 1), and DiGeorge syndrome (n = 1). Seventeen patients received HLA‐matched related HSCT, eight received maternal un‐manipulated haploidentical HSCT, and three received unrelated cord blood transplantation. Nine patients (32%) developed BCGosis secondary to reactivation of pretransplant vaccination. Three died while still receiving anti‐tuberculosis drugs, one still on treatment, and all others have recovered. Six patients had graft failure; four of them received no conditioning regimens. At a median follow up of 32 months (range 1‐67), 21 patients are alive, with overall survival of 72%. We conclude that HSCT for PID patients can be performed with a good outcome in developing countries; however, delayed diagnosis or referral and BCG reactivation are unique challenges.     

Pericardial effusion following hematopoietic stem cell transplantation in children: Incidence,risk factors,and outcomes

PCE is a complication of HSCT that has previously been described in small single‐center studies. This study aimed to assess the frequency of, risk factors for, and outcomes of children with a PCE following HSCT across a large multi‐center cohort. All patients ≤21 years undergoing first HSCT (1/2005‐9/2015) were identified from the Pediatric Health Information System. ICD‐9 codes were used to identify patients with a PCE during or following the transplant encounter. Multivariable modeling assessed risk factors for developing a PCE and assessed the impact of PCE on patient outcome. Of 10 455 included patients, 739 (7.1%) developed a PCE (median 69 days post‐HSCT, interquartile range 33‐165 days). PCE developed more commonly in allogeneic vs autologous HSCT recipients (9.1% vs 2.9%, P < .001). Among allogeneic HSCT recipients, independent risk factors for PCE included thrombotic microangiopathy (AHR 2.94, 95% CI 2.16‐4.00), heart failure (AHR 2.07, 95% CI 1.61‐2.66), PCE pre‐HSCT (AHR 1.92, 95% CI 1.19‐3.09), arrhythmia (AHR 1.76, 95% CI 1.44‐2.16), graft‐versus‐host disease (AHR 1.31, 95% CI 1.05‐1.62), female sex (AHR 1.28, 95% CI 1.07‐1.52), and malignancy (AHR 1.28, 95% CI 1.02‐1.60). Allogeneic HSCT patients with PCE demonstrated worse survival than those without PCE (5‐year survival 50.8% vs 76.9%, P < .001). PCE was independently associated with mortality (AHR 1.96, 95% CI 1.62‐2.37) following allogeneic HSCT and was not impacted by pericardial intervention. PCE occurs more commonly in patients following allogeneic (vs autologous) HSCT and is associated with inferior outcomes.     

Effects of stem cell transplantation on bone mineral density and vitamin D status in children with thalassemia major

HSCT is a curative treatment in TM, but conditioning and immunosuppressive treatment may affect bone metabolism. In this retrospective study, we aimed to compare BMD, vitamin D status, and growth in children with TM who underwent HSCT to those in children with TD TM. Twenty‐three children with TM who underwent HSCT (mean age 7.1 years [1.03‐14.7]) and 24 children with TD thalassemia (mean age 9.8 years [1.6‐14]) were recruited. Lumbar spine BMD of TD thalassemia patients was higher than those in patients who had HSCT at both baseline and second‐year assessments (P=.009, P<.001, respectively). However, BMD Z scores or serum 25‐OH vitamin D levels were not different in two groups. Being >10 years of age was a significant risk factor for low BMD, height, and weight Z score for both groups. Patients who underwent HSCT with Pesaro risk class II or III had higher risk for low BMD compared to those risk class I patients (P=.044). In conclusion, children with TM who were >10 years at HSCT are at risk for low BMD and growth retardation. HSCT had no effect on BMD deficit in children with TM.     

Pulmonary function following allogeneic stem cell transplantation in childhood: A retrospective cohort study of 51 patients

HSCT is associated with a high risk of late morbidity. The aim of this study was to evaluate the frequency, time frame, risk factors, and possible etiology of pulmonary dysfunction following allogeneic HSCT in childhood. We evaluated the pulmonary function of 51 HSCT patients (>6 yr), by including FVC and FEV1 values prior to (baseline) and annually up to five yr after HSCT. A Cox proportional hazards model was used to analyze the risk factors for a pulmonary event. Over half (59%) of the patients developed pulmonary dysfunction, mainly consisting of restrictive abnormalities. Acute GvHD (HR 4.31, 95% CI 1.47–12.63), chronic GvHD (HR 10.20, 95% CI 2.42–43.03), and an abnormal baseline pulmonary function (HR 4.82, 95% CI 1.02–22.84) were associated with post‐transplant dysfunction. FEV1 (p < 0.001) and FVC (p < 0.001) declined significantly by 12 months after HSCT and both remained below the pre‐HSCT level at up to four yr post‐transplantation. HSCT in childhood is associated with early and persistent restrictive impairment of pulmonary function. Patients with extensive chronic GvHD are particularly vulnerable to severe pulmonary dysfunction. Scheduled pulmonary function testing is warranted as part of the follow‐up of survivors of HSCT in childhood.     

Risk factors for oral mucositis in children receiving hematopoietic cell transplantation for primary immunodeficiencies: A retrospective study

OM is a frequent complication for patients undergoing HSCT. The aim of this study was to evaluate the possible risk factors for OM in children undergoing HSCT for PI. A retrospective study was carried out on 55 consecutive medical records of patients with PI (including osteopetrosis) who underwent HSCT. Age at the time of HSCT, gender, diagnosis, type of donor, conditioning regimen, engraftment, graft‐versus‐host disease, and severity and duration of OM were collected at the beginning of the conditioning until day 100 post‐HSCT or death. OM was measured using the WHO scale. Patients' age range at the time of HSCT was quite wide; 59.2% of the patients who were under nine months (n = 13) developed OM vs. 87.8% of the patients older than nine months (n = 29) (p = 0.01). T‐cell positive patients had a statistically significant higher risk of developing OM (p = 0.04), as did those receiving a more intensive conditioning regimen (p < 0.01). PI patients undergoing HSCT are at higher risk of developing OM if the PI is a T‐lymphocyte‐positive disease and/or if the HSCT recipient is over nine months of age.     

Incidence,risk factors,and outcome of blood stream infections during the first 100 days post‐pediatric allogeneic and autologous hematopoietic stem cell transplantations

Bloodstream infections (BSI) are a frequently observed complication after hematopoietic stem cell transplant (HSCT). Retrospective analysis of clinical and microbiological data during the first 100 days from 302 consecutive pediatric patients who underwent HSCT for a malignant disease at our institute between January 2013 and June 2017. A total of 164 patients underwent autologous and 138 allogeneic HSCT. The overall incidence of BSI was 37% with 92% of infectious episodes occurring during the pre‐engraftment phase. Gram‐positive bacteria (GPB) accounted for 54.6% of the isolated pathogens, gram‐negative bacteria (GNB) for 43.9%, and fungi for 1.4%. Coagulase‐negative staphylococci and Escherichia coli were the most commonly isolated GPB and GNB, respectively. Forty‐five percent of GNB were extended‐spectrum beta‐lactamase producers and 21% were multidrug‐resistant organisms. Fluoroquinolone resistance was 92% and 68%, among GPB and GNB, respectively. Risk factors for BSI in univariate analysis were allogeneic HSCT, delayed time to engraftment more than 12 days, previous BSI before HSCT, and alternative donor. In multivariate analysis, only HSCT type (allogeneic vs autologous P = .03) and previous BSI within 6 months before HSCT (P = .016) were significant. Overall survival at day 100 was 98% and did not differ significantly between patients with and without BSI (P = .76). BSI is common in children undergoing HSCT for malignant diseases. Allogeneic HSCT recipients and previous BSI within 6 months before HSCT are associated with increased risk of post‐transplant BSI. With current supportive measures, BSI does not seem to confer an increased risk for 100‐day mortality.     

Incidence and prevalence of mucopolysaccharidosis type 1 in the Irish republic

Mucopolysaccharidosis type 1 (MPS1) is an autosomal recessive disorder with severe, moderate and mild phenotypes: Hurler, Hurler-Scheie and Scheie syndromes. We estimated incidence (2001-2006) and prevalence (2002 census) of MPS1 in the Irish Republic (ROI) using population data, database and chart review of all live MPS1 patients attending two specialised centres. Patient genotypes, ethnicity, province of origin, age at diagnosis and presenting features were recorded. Thirty-one patients (14 females, 17 males) were alive, 27 of whom were <15 years. Twenty-six patients had Hurler syndrome, four had Hurler-Scheie and one had Scheie syndrome. The birth incidence was 1 in 26 206 births with a carrier frequency of 1 in 81. Of note, 19/26 (73%) Hurler patients were Irish Travellers. Amongst Irish Travellers the incidence was 1 in 371 with a carrier frequency of 1 in 10. This is the highest recorded incidence worldwide. Given the morbidity and mortality associated with delayed treatment we recommend targeted newborn screening for this population.     

Taste dysfunction in patients undergoing hematopoietic stem cell transplantation: Clinical evaluation in children

The aim of this study was to determine the variability of TD in children undergoing HSCT. Cases were identified as consecutively enrolled children in the period January 2011–January 2013 among patients attending the Paediatric Department of Spedali Civili of Brescia and all candidates to HSCT. The TST was conducted in two phases: identification of threshold values and identification of perceived stimulus intensity. Sixteen sapid solutions with four flavors (sucrose, sodium chloride, citric acid, and quinine hydrochloride) at four different concentrations were administered in a random sequence. The same protocol was administered at different time intervals: before starting the conditioning therapy (T0), during the conditioning therapy (T1) (two times), and every three months (two times) after engraftment post‐HSCT (T2). A p‐value < 0.05 was considered statistically significant. Fifty‐one children (29 female and 22 male, mean age 5.2 ± 0.7 yr) were enrolled. Threshold value means for the four flavors increased during HSCT conditioning therapy (T1) (p < 0.01); intensity of perceived stimulus decreased during HSCT conditioning therapy (p < 0.01). At six months after engraftment (T2), both parameters had returned to starting values (T0). Changes in taste perception in children undergoing HSCT seem to occur especially during the conditioning therapy and resolve in about six months after engraftment post‐HSCT.     

Hemophagocytic lymphohistiocytosis is a sign of poor outcome in pediatric Epstein‐Barr virus‐associated post‐transplant lymphoproliferative disease after allogeneic hematopoietic stem cell transplantation

EBV‐related PTLD developing after HSCT is a potentially life‐threatening disease. HLH is uncommon after allogeneic HSCT. Data on outcome of patients with PTLD and concomitant HLH after allogeneic HSCT are limited. In this retrospective study, we collected demographic, clinical, laboratory, and outcome data for 408 patients who underwent allogeneic HSCT from 2006 to 2015. Graft source included CB (n = 135; 33.1%), PBSCs (n = 34; 8.3%), and BM (n = 239; 58.6%). Eight out of 408 patients (2%) developed EBV‐PTLD with a median age at HSCT of 5.9 years (range: 2.3‐17.3). All eight patients received ATG as part of the conditioning regimen. Graft source was PBSC in three patients (37.5%), BM in four patients (50%), and CB in one patient (12.5%). Donors were matched unrelated in five patients (62.5%) and matched sibling in three patients (37.5%). Seven out of eight patients developed EBV‐PTLD within the first 100‐day post‐HSCT. Lymph node biopsy revealed early lesions in three patients, polymorphic in three patients, and monomorphic PTLD in two patients. Three patients (37.5%) died within 1 month of EBV‐PTLD diagnosis. All deceased patients developed HLH manifestations with two of them meeting HLH diagnostic criteria and one having an incomplete workup. PTLD after allogeneic HSCT with manifestations of HLH is associated with high mortality. Early identification and treatment of EBV‐PTLD seems imperative to control the disease, especially if signs of HLH are evolving.     

Challenging symptoms in children with rare life-limiting conditions: findings from a prospective diary and interview study with families

Aim: The aim was to describe the nature, frequency, severity and management challenges of symptoms in children with two rare life‐limiting conditions [Mucopolysaccharide (MPS) and Batten disease]. Methods: This was an embedded mixed‐method study set in the UK between 2009 and 2011. Twenty‐six children from 23 families took part. Seventeen children had an MPS condition [MPS III (Sanfilippo) n = 15; MPS I (Hurler) n = 1; MPS IVA (Morquio); n = 1]. Nine children had Batten disease. Prospective data relating to symptoms were collected over 8 weeks using a symptom diary, and qualitative retrospective interviews with families were conducted. Main outcome measures included frequency, severity rating and identification of most challenging symptoms to manage. Results: The most common and severe symptoms in MPS III were agitation, repetitive behaviours, hyperactivity and disturbed sleep, and in Batten disease were agitation, joint stiffness, secretions, and disturbed sleep. The data highlighted the high prevalence of behavioural symptoms. Distress caused to families by symptoms was not related simply to their occurrence, but to difficulty in management, likelihood of control and extent to which they signalled disease progression and decline. Conclusion: In challenging contrast to the dominant biomedical framing of these rare conditions it was behavioural symptoms, rather than the physical ones, that families documented as most frequent, severe and challenging to manage. The diary developed for this study has potential use in aiding parents and clinicians to document and communicate concerns about symptoms.     

Haploidentical parental hematopoietic stem cell transplantation in pediatric refractory Langerhans cell histiocytosis

Children with MS‐LCH that fail to respond to conventional chemotherapy have poor outcomes. HSCT represents a potential salvage approach. It has been applied in over 50 cases in recent years. HSCT can achieve greater disease control than chemotherapy, but it carries a high risk of transplant‐related mortality; thus, the haploidentical parental HSCT is used infrequently in pediatric refractory LCH. We report the first successful haploidentical parental HSCT, with no T‐cell depletion, in two girls, aged 26 months and five months, with refractory MS‐LCH. The mothers were donors with 5/6 and 4/6 HLA matches, respectively. The conditioning regimen included busulfan + cyclophosphamide + etoposide + antithymocyte‐globulin ± fludarabine; the GVHD prophylaxis was based on cyclosporine + methotrexate ± mycophenolate‐mofetil ± zenapax. In both cases, the stem cells were sourced from peripheral blood and BM, which included CD34+ cells (13.17 × 10⁶/kg and 40.23 × 10⁶/kg, respectively). These patients survived and showed no signs of disease activity in 54‐ and 44‐month post‐HSCT follow‐ups. Our results indicated that, for patients that fail chemotherapy delivered early in the disease, but do not show organ dysfunction progression, it may be possible to achieve successful haploidentical parental HSCT with a strong myeloablative regimen.