Jacek Wachowiak

Pharmacokinetics of high-dose i.v. treosulfan in children undergoing treosulfan-based preparative regimen for allogeneic haematopoietic SCT

Pharmacokinetic studies of high-dose treosulfan were carried out in seven paediatric patients (age range: 2–15 years) undergoing treosulfan-based conditioning regimen prior to allogeneic haematopoietic SCT. Treosulfan was administered intravenously in a daily dose of 10, 12 or 14 g/m2 within 2 h. Five out of seven patients received 12 g/m2. The plasma concentrations of treosulfan and its quantity eliminated with urine were determined using a validated HPLC method with refractometric detection. Pharmacokinetic parameters were evaluated following first dose using a two-compartment disposition model. These studies demonstrated a dose-dependent increase of area under the concentration (AUC) and maximum concentrationplasma (Cmax), but there was variability of these parameters. Rapid clearance of tresoulfan was observed, especially in 10 and 12 g/m2 doses. Terminal half-life (t0.5) of treosulfan was in the range of 1.71–2.15 h, but the mean percent of parent drug eliminated with urine was 30%, range 16.3–45.4% of the total dose eliminated during the first 12 h after administration. The results of this study confirmed the linear pharmacokinetics of treosulfan, as used in children. However, variability of pharmacokinetic results observed in children studied demonstrates the need for pharmacokinetic evaluation in each paediatric patient undergoing the treosulfan-based preparative regimen, including those using different doses. This approach could enable further reduction of the risk of early and late organ toxicity related to high-dose treosulfan in paediatric patients.

Risk of complications during hematopoietic stem cell collection in pediatric sibling donors: a prospective European Group for Blood and Marrow Transplantation Pediatric Diseases Working Party study.

We investigated prospectively factors influencing the safety of hematopoietic stem cell (HSC) collection in 453 pediatric donors. The children in the study donated either BM or peripheral blood stem cells (PBSCs) according to center policy. A large variability in approach to donor issues was observed between the participating centers. Significant differences were observed between BM and PBSC donors regarding pain, blood allotransfusion, duration of hospital stay, and iron supplementation; however, differences between the groups undergoing BM vs PBSC donation preclude direct risk comparisons between the 2 procedures. The most common adverse event was pain, reported mainly by older children after BM harvest, but also observed after central venous catheter (CVC) placement for PBSC collection. With regard to severe adverse events, one patient (0.7%) developed a pneumothorax with hydrothorax after CVC placement for PBSC collection. The risk of allotransfusion after BM harvest was associated with a donor age of < 4 years and a BM harvest volume of > 20 mL/kg. Children < 4 years were at higher risk than older children for allotransfusion after BM harvest and there was a higher risk of complications from CVC placement before apheresis. We conclude that PBSC and BM collection are safe procedures in children.

High-resolution human leukocyte antigen allele and haplotype frequencies of the Polish population based on 20,653 stem cell donors

We present high-resolution allele and haplotype frequency (HF) estimations of the Polish population based on more than 20,000 registered stem cell donors. Sequencing-based donor human leukocyte antigen (HLA) typing led to unambiguous typing results in most cases (between 94.3% for HLA-DRB1 and 96.9% for HLA-B). HF estimations were carried out with a new, validated implementation of the expectation-maximization algorithm that allowed processing of data with ambiguities. Our results confirm several earlier results, for example, the relative commonness of the haplotype A*25:01 g, B*18:01 g, C*12:03, DRB1*04:01 in the Polish population. Because of the large sample size, we were able to obtain results of unprecedented accuracy. The estimated population-specific HFs were then used to analyze questions of strategic donor registry planning. Simulated matching probabilities by donor file size suggest that there is a need for intense donor recruitment efforts in Poland despite the large German donor registry and the genetic relatedness of both populations. Based on the current German registry size of approximately 4 million donors, the recruitment of 100,000 Polish donors would produce a stronger increase in matching probabilities for Polish patients than the recruitment of 3.3 million additional German donors.

Treosulfan-based conditioning for allogeneic HSCT in children with chronic granulomatous disease: a multicenter experience.

Chronic granulomatous disease (CGD) can be cured by allogeneic hemopoietic stem cell transplantation (HSCT). Complications include graft failure, graft-versus-host disease (GVHD), infection, and transplant-related mortality; therefore, reduced-intensity conditioning regimens are being used to improve outcomes. In this retrospective study, the aim was to determine the outcome of treosulfan-based conditioning in HSCT for pediatric patients with CGD. The following data were collected: risk features pre-HSCT, additional conditioning agents, donor type and stem cell source, toxicity, engraftment, GVHD, chimerism, viral reactivation, post-HSCT complications, length of follow-up, and outcome. Seventy patients (median age, 107 months; interquartile range [IQR], 46-232 months) from 16 centers worldwide were transplanted between 2006 and 2015. Ninety-one percent had high-risk features. Fifty-seven HLA-matched donors, 12 HLA-mismatched donors, and 1 CD3(+)TCR αβ/CD19 depleted parental haploidentical transplants were performed. No major toxicity was reported. Median times to neutrophil and platelet engraftment were 17 (IQR, 15-35) and 16 (IQR, 13-50) days. At a median follow-up of 34 months (IQR, 13-102 months), the overall survival was 91.4%, and event-free survival was 81.4%. The cumulative incidence of acute grade III-IV GVHD was 12%. Nine patients developed chronic GVHD. When split cell chimerism was available, 95% or more myeloid donor chimerism was documented in 80% of surviving patients. Secondary graft failure occurred in 12% of patients. Treosulfan-containing conditioning regimens can be used safely in HSCT for children with CGD and high-risk clinical features, achieving excellent survival with high myeloid chimerism. Further studies are needed to compare with other regimens and evaluate the long-term outcome, particularly on fertility.

High-dose treosulfan in conditioning prior to hematopoietic stem cell transplantation.

Importance of the field: Despite the marked development in the field of preparative regimens prior to hematopoietic stem cell transplantation (HSCT) over the last decade, the search for a superior conditioning agent is still continuing. In view of the literature reports, treosulfan (TREO), a structural analog of busulfan (BU), appears to be a promising candidate in terms of myeloablative, immunosuppressive and antimalignancy effects as well as low organ toxicity. Areas covered in this review: The article focuses on pharmacological activity, pharmacokinetics and toxicity of TREO. Compressed description of the drug-based conditioning prior to HSCT is also presented. Finally, TREO and BU characteristics are compared. Specific information of TREO concerning pediatric and adult patients is provided throughout the whole paper. The data refer predominantly to the publications, in majority from the last 10 years. What the reader will gain: According to our best knowledge, the paper is the first such comprehensive review on TREO, especially in terms of its application in pediatric HSCT. Take home message: TREO offers a great potential as a conditioning agent prior to HSCT but further investigations of the drug are warranted to clearly verify its advantages. However, we expect TREO to be registered as a novel conditioning agent in the near future.

Intrathecal therapy with rituximab in central nervous system involvement of post-transplant lymphoproliferative disorder

Abstract Post-transplant lymphoproliferative disorder (PTLD) caused by Epstein–Barr virus (EBV) is a severe complication in high-risk allogeneic hematopoietic stem cell transplant (HSCT) recipients. Central nervous system (CNS) involvement of PTLD is a very rare event in patients with HSCT. As no established standard therapy in CNS-EBV-PTLD is available, the aim of this study was analysis of the safety and efficacy of intrathecal rituximab therapy in a group of eight children and adolescents with CNS-EBV-PTLD. Seven patients responded to therapy: all clinical symptoms and EBV-DNA viral load resolved after a median 2 (range: 1–7) doses of rituximab. However, some magnetic resonance imaging (MRI) changes in brain scan persisted in two patients. In all patients, except one, no adverse events of the therapy were observed. In conclusion, intrathecal rituximab administration seems to be an effective and safe method of treatment of CNS-EBV-PTLD in pediatric stem cell recipients. We recommend this treatment modality for further investigation.

European Society for Blood and Marrow Transplantation Analysis of Treosulfan Conditioning Before Hematopoietic Stem Cell Transplantation in Children and Adolescents With Hematological Malignancies

Standard myeloablative conditioning regimens for children with hematological malignancies undergoing allogeneic HSCT are based mainly on total body irradiation or busulfan. Their serious short‐ and long‐term side effects warranted the exploration of less toxic alternatives. Treosulfan is increasingly used for adults and children before HSCT due to its potent immunosuppressive and cytotoxic effects combined with low organ toxicity.

Haematopoietic stem cell transplantation in children in eastern European countries 1985-2004 : development, recent activity and role of the EBMT/ESH Outreach Programme

The paediatric population of 19 eastern European countries amounts to approximately 80 million children. Between 1985 and 2004, the number of centres performing haematopoietic stem cell transplantation (HSCT) in children increased from 1 in 1985 to 24 in 2004 and the yearly number of paediatric HSCTs rose from 1 in 1985 to 291 in 2004. Altogether, 2342 transplants were reported to the EBMT Registry during this time (Poland 953, Czech Republic 501, Hungary 269, Russia 217, Croatia 129, Slovakia 71, Bulgaria 45, Serbia and Montenegro 36, Slovenia 35, Belarus 33, Estonia 26, Lithuania 19 and Romania 8). Out of the 2342 transplants, 1487 (63.5%) transplants were performed in paediatric centres, 453 (19.3%) in centres for adults and 402 (17.2%) in combined centres. The number of children who underwent autologous HSCT (auto-HSCT) was 1053 (45%), whereas 1289 (55%) underwent allogeneic HSCT (allo-HSCT). Peripheral blood (PB) was the source of HSC in 751 (71.3%) out of 1053 auto-transplants, BM in 246 (23.4%) and PB+BM in 52 (4.9%) (missing data in 4, that is, 0.4%). Among the 1289 allo-transplants, BM was the source of HSC in 827 (64.3%), PB in 416 (32.3%), CB in 23 (1.8%) and BM+PB in 14 (1.1%) (missing data in 9, that is, 0.7%). Among them, 728 (57.4%) obtained HSC from MSD, 322 (25.4%) from UD, 195 (15.4%) from MMFD, 14 (1.1%) from CB family donor and 9 (0.7%) from CB unrelated donor (missing data in 21, that is, 1.6%). The number of children who underwent allo-HSCT for malignant diseases was 945 (73.4%), including ALL 376 (29.2%), AML 234 (18.2%), CML 177 (13.8%), MDS 97 (7.5%), NHL 35 (2.7%) and other malignancy 31 (2.4%), while 339 (26.9%) for non-malignant disorders, including SAA 202 (15.7%), immunodeficiencies 61 (4.7%), inborn errors of metabolism 40 (3.1%), Fanconi anaemia 19 (1.5%) and others 17 (1.3%). Out of 1053 recipients of auto-HSCT, 168 (16%) were transplanted for neuroblastoma, 129 (12.2%) for NHL, 124 (11.7%) for AML, 114 (10.8%) for ALL, 109 (10.4%) for Hodgkins disease, 62 (5.9%) for Ewings sarcoma, 16 (1.5%) for CNS tumour, 15 (1.4%) for Wilms tumour and 316 (30%) for other tumours. In 2001, the EBMT in collaboration with the European School of Haematology (ESH) developed the Outreach Programme, that is a programme supporting emerging HSCT projects and transplant centres in countries with limited resources and/or experience.

Regional HLA Differences in Poland and Their Effect on Stem Cell Donor Registry Planning

Regional HLA frequency differences are of potential relevance for the optimization of stem cell donor recruitment. We analyzed a very large sample (n = 123,749) of registered Polish stem cell donors. Donor figures by 1-digit postal code regions ranged from n = 5,243 (region 9) to n = 19,661 (region 8). Simulations based on region-specific haplotype frequencies showed that donor recruitment in regions 0, 2, 3 and 4 (mainly located in the south-eastern part of Poland) resulted in an above-average increase of matching probabilities for Polish patients. Regions 1, 7, 8, 9 (mainly located in the northern part of Poland) showed an opposite behavior. However, HLA frequency differences between regions were generally small. A strong indication for regionally focused donor recruitment efforts can, therefore, not be derived from our analyses. Results of haplotype frequency estimations showed sample size effects even for sizes between n≈5,000 and n≈20,000. This observation deserves further attention as most published haplotype frequency estimations are based on much smaller samples.

Topotecan exposure estimation in pediatric acute myeloid leukemia supported by LC-MS-based drug monitoring and pharmacokinetic analysis.

Individualization of the topotecan dosing can reduce inter-patient variability, toxicity, and at the same time increases chemotherapy efficacy. Topotecan dosing based on simultaneous drug monitoring and pharmacokinetic analysis can yield more accurate and precise estimation of the topotecan systemic exposure than that attainable with the fixed dosing approach. Therefore, a combined approach could provide a tool assisting the clinicians in individualization of the topotecan dosing. The aim of the study was to estimate the topotecan exposure in pediatric patients with acute myeloid leukemia (AML) based on the plasma concentration-time data and using the pharmacokinetic analysis. The primary goal was achieve the correct estimation of the target plasma area against the topotecan concentration-time curve (AUC) in a 5 day course of cladribine followed by monitored topotecan in pediatric patients with recurrent/refractory AML. A sensitive and selective reversed-phase liquid chromatographic-mass spectrometry (LC-MS) assay was developed to quantify total topotecan in the human plasma samples. This method, with its lower quantification limit of 1 ng/ml, was validated over a linear range of 1-150 ng/ml. Under the proposed approach, the topotecan dosing was selected so as to achieve the final AUC value of 140±20 ng/ml h. The presented analytical and pharmacokinetic data demonstrate that the proposed approach can be a practical, useful, efficient, and accurate tool for individualizing the topotecan dosing in children with AML.