Stable mixed chimerism after hematopoietic stem cell transplantation in Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency disease characterized by thrombocytopenia, eczema, impaired cellular and humoral immunity, and increased susceptibility to malignancy and autoimmunity. The only curative treatment for WAS is hematopoietic stem cell transplantation, especially in the presence of a matched sibling donor or matched unrelated donor. Here, we report the case of a 2.5-yr-old boy with WAS that resulted in mixed chimerism after having received bone marrow from his phenotypically identical grandfather. Although the patient has persistent thrombocytopenia (platelet counts 50-80 x 10(9)/L), he is currently alive and doing well at 36 months post-transplant and is free of any bleeding episodes.     

Early mixed T‐cell chimerism is predictive of pediatric AML or MDS relapse after hematopoietic stem cell transplant

Patients with acute myeloid leukemia (AML) who relapse after hematopoietic stem cell transplantation (HCT) have dismal outcomes. Our ability to predict those at risk for relapse is limited. We examined chimerism trends post‐HCT in 63 children who underwent HCT for AML or myelodysplastic syndrome (MDS). Mixed T‐cell chimerism at engraftment and absence of chronic graft versus host disease (cGVHD) were associated with relapse (P = 0.04 and P = 0.02, respectively). Mixed T‐cell chimerism at engraftment was predictive in patients without cGVHD (P = 0.03). Patients with engraftment mixed T‐cell chimerism may warrant closer disease monitoring and consideration for early intervention.     

Allogeneic hematopoietic stem cell transplantation in children with sickle cell disease

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) represents the only curative treatment for sickle cell disease (SCD), being successful in around 85-90% of patients. Mortality and long-term morbidity (including infertility, gonadal failure, and chronic graft-vs.-host disease) associated with conventional approaches curtail the number of patients who undergo allo-HSCT. Recently, it has been demonstrated that cord blood is as effective as and possibly safer than bone marrow in pediatric patients with SCD. Likewise, transplant strategies based on the use of reduced-intensity regimens and the induction of mixed chimerism have been explored to decrease allo-HSCT short- and long-term complications.     

Skin transplantation to monitor clinical donor-related tolerance in mixed hematopoietic chimerism

Mixed hematopoietic chimerism usually carries with it the tolerance to any other tissue from the same donor. Consequently, the establishment of a sustained chimerism may allow long-term acceptance of transplanted organs without immunosuppression. We report a girl with refractory severe aplastic anemia who developed low recipient level hematopoietic chimerism following transplantation of maternal highly purified CD34+ cells without prophylactic immunosuppression. Renal thrombotic microangiopathy led to chronic renal failure and she received skin allografts from her mother in view of a future kidney donation. The maternal skin grafts were accepted without immunosuppression and the hematopoietic chimerism remained stable. Skin transplantation may be a helpful and easily applicable tool to monitor donor-related tolerance in hematopoietic chimerism clinically. It should contribute to minimize the risks of subsequent solid organ transplantation from the same donor without immunosuppression.     

The incidence of autoimmune hemolytic anemia in pediatric hematopoietic stem cell recipients post‐first and post‐second hematopoietic stem cell transplant

The reported incidence of post‐allogeneic HSCT AIHA was between 4.4% and 6% following a single transplant. Cord blood transplantation, T‐cell depletion, and chronic GvHD are significantly associated with post‐transplant AIHA. During an 11‐yr period, data for 500 pediatric HSCT recipients were eligible for evaluation of the incidence of AIHA post‐first and post‐second transplants. Demographic, transplant, and post‐transplant‐related variables were analyzed. Twelve of 500 (2.4%) recipients at a median of 273 days and seven of 72 (9.7%) recipients at a median of 157 days developed AIHA post‐first and post‐second HSCT, respectively. Post‐first HSCT, none of the MRD recipients developed AIHA (0/175 MRD vs. 12/325 other donors, p = 0.04). Four of 12 required a second HSCT to control the AIHA. After the second HSCT, MUD was significantly associated with the development of AIHA. No other variables were associated with the post‐second transplant AIHA. The incidence of AIHA post‐first and post‐second HSCT was less than the reported. The increased incidence of AIHA among recipients of second HSCT is most likely due to the profound immune dysregulation. A much larger, prospective study would be needed to evaluate the incidence, complications, and management of post‐transplant AIHA.     

Megakaryocyte chimerism after allogeneic stem cell transplantation in children

The aim of this study was to investigate the extent and the clinical implications of mixed chimerism in megakaryocytes after stem cell transplantation (SCT). Polymerase chain reaction analyzing allele length polymorphisms was used to determine the origin of immunomagnetically isolated megakaryocytes and leukocyte subpopulations after SCT in 13 children. Eleven were unselected consecutive cases while two were included due to known leukocyte mixed chimerism. Recipient DNA was detected in the megakaryocytes in six out of the 11 cases at levels between 1 and 100%. Coinciding mixed chimerism in the leukocyte populations was detected in two of the 11 cases. Of the two selected cases with known leukocyte mixed chimerism, two boys with aplastic anemia and Wiskott-Aldrich syndrome had 1-5 and 70% recipient megakaryocytes, respectively. Although the four relapses or deaths, within the 13 months of observation, were restricted to patients with multilineage or isolated megakaryocyte (n = 1) mixed chimerism, it was not possible to link any other apparent clinical problems, except a prolonged thrombocytopenia in one case, to the mixed chimerism in this limited study group.     

Rare complications after second hematopoietic stem cell transplantation for thalassemia major

We describe an 11-year-old girl with thalassemia major who underwent a second hematopoietic stem cell transplantation from a matched related donor and who subsequently developed posttransplant lymphoproliferative disorder complicated by severe ascending paralysis resembling Guillian-Barré syndrome. Six months later she developed a massive pericardial effusion. She received a multimodal treatment for these complications and currently, 18 months after transplantation, she is in a good clinical condition, is transfusion independent, with no evidence of graft-versus-host disease and off all treatment. This case highlights the dilemma surrounding second hematopoietic stem cell transplantations in hemoglobinopathies and the need for a careful, well informed, and collaborative decision-making process by patients, families, and medical professionals.     

Evaluation of chimerism by quantitative PCR analysis of DNA polymorphism after allogeneic hematopoietic stem cell transplantation in a pediatric population with malignancies

Relapse remains the major pitfall to success for Allo-HSCT in children with malignancies. Ninety-one patients undergoing Allo-HSCT were retrospectively reviewed. Chimerism status was evaluated at days +30, +60, and +100 in PB. VNTR-PCR and STR-PCR were used for this purpose. Thirty-one patients recurred (34%) and none survived. Thirty-two remain alive in CR (35%). Patients who achieved a CC at those days had a significant higher RFS and OS than patients who did not. Twelve patients showing PMC had an increased risk of recurrence (p=0.02. OR 7.7). In the univariate analysis, the probability of death was higher in patients who were not in first CR before transplant (p=0.008.OR 2.09) and in those receiving cells not from PB (p=0.002.OR 2.03). In the multivariate analysis, the absence of CC at day +100 was associated with a higher probability of relapse (p=0.004. OR 10.8) and death (p=0.016. OR 9.3). Serial chimerism PCR-based analyses of polymorphic DNA markers can predict relapse. Patients with PMC are at the highest risk of recurrence. Patients receiving an Allo-HSCT in first CR from PB who achieve a CC at day +100 have a better outcome.     

Chimerism analysis in clinical practice and its relevance for the detection of graft rejection and malignant relapse in pediatric hematopoietic stem cell transplant patients

Chimerism and clinical outcome data from 244 hematopoietic stem cell transplants in 218 children were retrospectively analyzed to assess their relevance for the detection of graft rejection and malignant relapse. Patients transplanted for a non‐malignant disease had significantly higher proportions of residual recipient T cells in peripheral blood at one, three, and six months compared with patients transplanted for malignant disease. Recipient T‐cell levels were below 50% at one month after transplantation in most patients (129 of 152 transplants). Graft rejection occurred more frequently in the group of patients with high levels of recipient cells at one month (10 graft rejections in the 23 patients with recipient T cells >50% at one month as compared to seven graft rejections occurred in 129 patients with recipient T cells <50% (p < 0.001). Multilineage chimerism data in 87 children with leukemia at one, three, and six months after transplantation were not correlated with subsequent relapse of malignant disease. In conclusion, early analysis of lineage‐specific chimerism in peripheral blood can be used to identify patients who are at high risk of graft rejection. However, the efficacy of early chimerism analysis for predicting leukemia relapse was limited.     

Hematopoietic stem cell transplantation for children with thalassemia major in China

Thalassemia is the most common single-gene disorder worldwide that is considered a major public health issue. Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for thalassemia major, the form of the disease reflecting homozygosity for a mutant allele. In China, many patients with thalassemia major cannot financially afford life-long regular supportive care with blood transfusions and iron chelation. Although HSCT is expensive, it is a one-time treatment that is possible in some patients. Disease-free survival rates have been 52-82% after HSCT in China. Graft rejection is the main cause of failure following HSCT. Humoral immune activity may play an important role in engraftment of donor cells. This article reviews the current status of HSCT for children with thalassemia major in China.     

Highly sensitive chimerism detection in blood is associated with increased risk of relapse after allogeneic hematopoietic cell transplantation in childhood leukemia

Analysis of chimerism in blood post‐HCT using STR‐PCR is routinely applied in parallel with quantification of MRD to predict relapse of leukemia. RQ‐PCR chimerism is 10‐ to 100‐fold more sensitive, but clinical studies in children are sparse. We analyzed IMC in blood samples following transplantation for acute lymphoblastic or myeloid leukemia in 56 children. IMC was defined as a minimum increase of (a) 0.1% or (b) 0.05% recipient DNA between two samples. The risk of relapse was higher in children with IMC of both 0.1% and 0.05% compared to children without IMC (HR 12.8 [95% CI: 3.9‐41.4; P < .0001] and 7.6 [95% CI: 2.2‐26.9; P < .01], respectively). The first IMC was detected at a median of 208 days prior to relapse. The 5‐year cumulative incidence of relapse for children with a single IMC was 45.5% (CI 12.3‐74.4) and 41.0% (14.2‐66.6) for IMC above 0.1% and 0.05%, respectively. However, in 47 and 38 children never attaining IMC > 0.1% and >0.05%, 10 and 8 children relapsed, respectively. In a landmark analysis, no association was found between IMC prior to 90 days post‐HCT and subsequent relapse by either classification of IMC and AUC for RQ‐PCR chimerism was 54.2% (95 CI 27.7‐ 84.8). Although limited by a retrospective design, these results indicate that monitoring of RQ‐PCR chimerism in peripheral blood may have a role in early detection of relapse in acute childhood leukemia .     

Acanthamoeba granulomatous amoebic encephalitis after pediatric hematopoietic stem cell transplant

Acanthamoeba encephalitis is a rare, often fatal condition, particularly after HSCT, with 9 reported cases to date in the world literature. Our case was originally diagnosed with ALL at age 3 years, and after several relapses underwent HSCT at age 9 years. At 17 years of age, he was diagnosed with secondary AML for which he underwent a second allogeneic HSCT. He presented with acute‐onset worsening neurological deficits on day +226 after the second transplant and a post‐mortem diagnosis of Acanthamoeba encephalitis was established, with the aid of the CDC.     

Insulin-related metabolism following hematopoietic stem cell transplantation in childhood

Objectives:  To assess insulin-related metabolism following hematopoietic stem cell transplantation (HSCT) in childhood.
Study design:  Thirty-four patients who underwent HSCT were compared with 21 patients with similar diseases who were not transplanted. Median follow-up was 3.6 yr after HSCT. Anthropometric parameters, fasting plasma glucose and insulin levels, hemoglobin A_1c (HbA_1c) and lipid profile were measured and compared.
Results:  HbA_1c was significantly higher (p = 0.001) in the study group. Two (5.8%) patients in the study group developed type 2 diabetes mellitus. Among thalassemic patients, significantly lower insulin resistance indices (p = 0.05) and fasting plasma insulin levels (p = 0.033) were found in the study group compared with the control group.
Conclusions:  Attentive follow-up of insulin-related metabolism following HSCT in children is needed. The significance of the higher HbA1c values in the study group remains to be evaluated in a larger cohort of patients.     

Successful treatment of disseminated mixed invasive fungal infection after hematopoietic stem cell transplantation for severe aplastic anemia

Concomitant infections are frequent and usually the causes of death in patients with severe AA. HSCT can restore hematopoiesis in AA, but it is usually life threatening when patients simultaneously have an IFI. Mixed IFIs have been reported on rare occasions. The exact diagnosis of IFIs is difficult because of low fungus culture rate, difficultly obtaining tissue specimens in severely immunocompromised patients or those with bleeding tendencies. Otherwise, treatment with anti-fungal drugs alone for DMIFI was always lethal in previous reports. Surgical resection is crucial for invasive zygomycosis, but severe pancytopenia and bleeding tendency make therapy difficult. Herein, we report that with a combination of aggressive anti-fungal drugs, HSCT, and surgery, we successfully treated a 10-yr-old boy with severe AA and pulmonary zygomycosis before HSCT and disseminated mixed invasive zygomycosis and aspergillosis after HSCT.     

High incidence of BK virus‐associated hemorrhagic cystitis in children after second or third allogeneic hematopoietic stem cell transplantation

BKV‐HC is a serious complication of allogeneic HSCT. To characterize the incidence, risk factors, and clinical outcomes of post‐HSCT BKV‐HC, we retrospectively analyzed 112 patients who underwent one or more allogeneic HSCTs at our hospital between 2001 and 2017. Twenty underwent second or third HSCT thereafter. Ten patients developed BKV‐HC at a median of 30 days after HSCT. The 100‐day cumulative incidences of grade 0‐4 and grade 2‐4 BKV‐HC were 7.8% and 6.2%, respectively. HSCTs performed in 2011‐2017 associated with significantly higher 100‐day cumulative incidence of grade 2‐4 BKV‐HC (14.0%) than HSCTs performed in 2001‐2010 (1.3%, P = 0.004). On multivariate analysis, second or third HSCT was the only independent significant risk factor for development of grade 2‐4 BKV‐HC (P = 0.015). Serial PCR monitoring of urine and blood BKV load did not predict BKV‐HC. The recent increase in the incidence of BKV‐HC may reflect recent innovations in transplant technologies that facilitate second or third HSCT, which are known to cause prolonged immune deficiency. If safe and effective treatment or prophylaxis becomes available, it could be used to target the high‐risk patients for BKV‐HC.