Homozygous variant in TKFC abolishing triokinase activities is associated with isolated immunodeficiency.

BACKGROUND: Triokinase and FMN cyclase (TKFC) is a bifunctional enzyme involved in fructose metabolism. Triokinase catalyses the phosphorylation of fructose-derived glyceraldehyde (GA) and exogenous dihydroxyacetone (DHA), while FMN cyclase generates cyclic FMN. TKFC regulates the antiviral immune response by interacting with IFIH1 (MDA5). Previously reported pathogenic variants in TKFC are associated with either a multisystemic disease or isolated hypotrichosis with loose anagen hairs. METHODS: Whole-exome sequencing identified a homozygous novel variant in TKFC (c.1624G>A; p.Gly542Arg) in an individual with a complex primary immunodeficiency disorder. The variant was characterised using enzymatic assays and yeast studies of mutant recombinant proteins. RESULTS: The individual presented with chronic active Epstein-Barr virus disease and multiple bacterial and viral infections. Clinical investigations revealed hypogammaglobulinaemia, near absent natural killer cells and decreased memory B cells. Enzymatic assays showed that this variant displayed defective DHA and GA kinase activity while maintaining FMN cyclase activity. An allogenic bone marrow transplantation corrected the patient's immunodeficiency. CONCLUSION: Our report suggests that TKFC may have a role in the immunological system. The pathological features associated with this variant are possibly linked with DHA/GA kinase inactivation through a yet an unknown mechanism. This report thus adds a possible new pathway of immunometabolism to explore further.

Cancer-related fatigue: scoping review to synthesize a definition for childhood cancer survivors.

CONTEXT: There is no universal definition of cancer-related fatigue (CRF) specific to childhood cancer survivors, despite this population facing unique long-term side effects from their cancer. We aimed to synthesize and combine existing definitions of CRF specific to this context to inform on the necessity of a panel of experts to formulate a new definition of CRF for childhood cancer survivors. METHODS: The literature search was performed in various databases. Titles, abstracts, and keywords were screened by two researchers to confirm eligibility. The data extraction process was performed by two researchers. Our search was conducted in various databases. RESULTS: Thirty articles were included in the qualitative analysis. Two coders reached consensus on 14 codes. The thematization process produced 4 themes: frequency, context, attributes, and consequences of CRF. These themes were used to synthesize a definition of CRF, as follows: "In childhood cancer survivors, cancer-related fatigue is a common late effect of cancer and cancer treatments. It is characterized by a subjective, persistent, and multidimensional experience that differs from normal fatigue in the physical, emotional, and/or cognitive spheres. Cancer-related fatigue may have a variety of negative consequences including a reduced quality of life and level of functioning, a lack of vigor, work difficulties, relationship issues, and emotional distress." CONCLUSION: A definition of CRF applicable to childhood cancer survivors is timely to organize research efforts and design appropriate interventions. The proposed definition is a first step towards the formulation of a new definition of CRF specific to childhood cancer survivors by experts.

Quality of life in childhood advanced cancer: from conceptualization to assessment with the Advance QoL tool.

BACKGROUND: Advanced childhood cancer, a condition with no available cancer-focused treatment options, greatly impacts Quality of Life (QoL). We need appropriate assessment strategies to select adapted treatment targets, improve care and optimize communication. Our first goal was to identify the domains of patients' QoL by combining for the first time the perspectives of patients and parents with previously collected reports in professionals. Our second goal was to develop a simple QoL assessment tool and optimize its format and content for use in the childhood advanced cancer population. METHODS: To identify QoL domains, we conducted qualitative interviews with 7 young patients (4 girls, 3 boys, aged 13 ± 4 yrs) and 9 parents (7 mothers, 2 fathers) from our treatment centre. We used inductive thematic content analysis to code and categorize respondents' viewpoints. The first version of the tool (Advance QoL) was then drafted, and structured feedback was collected through interviews and a survey with 15 experts. We computed content validity indices. RESULTS: Apart from the physical, psychological, and social domains, participants insisted on four original themes: autonomy, pleasure, the pursuit of achievement, and the sense of feeling heard. This was in line with the categories found in a preliminary study involving professionals (PMID: 28137343). Experts evaluated the tool as clear, relevant, acceptable, and usable. They formulated recommendations on instructions, timeframe, and item formulations, which we implemented in the refined version. CONCLUSIONS: Advance QoL is an innovative tool targeting key life domains in childhood advanced cancer. It is focused on preserved abilities and targets of care. The refined version is appropriate for adult respondents within families and professionals. Future studies will develop versions for young ages to collect the experience of patients themselves. This will open on future reliability, validity, sensitivity, and implementation studies.

A Portrait of Self-Reported Health and Distress in Parents Whose Child Died of Cancer.

Grieving a child following cancer is a substantially difficult task. The objectives of this research were: 1) to describe current quality of life (QoL), psychological distress and symptoms of grief of bereaved parents, and 2) to explore the role of possible contributors of QoL and psychological distress. Forty-six parents (32 mothers) of children who died of cancer were surveyed on their QoL, distress, and complicated grief. Data were analyzed using multiple linear regression. Parents had a high frequency of grieving symptoms (58%). Mothers reported more retrospective grief symptoms than fathers when describing the year after child death. Current lower mental well-being was associated with experiencing higher retrospective grief symptoms, a shorter period since child death, and being a father. Hence, parents experienced disturbances even long after child death. Mothers and fathers may present specificities that should be considered when developing supportive activities for this vulnerable population.

Transfusion-related Epstein-Barr virus (EBV) infection: A multicenter prospective cohort study among pediatric recipients of hematopoietic stem cell transplants (TREASuRE study).

BACKGROUND: Epstein-Barr virus (EBV) is carried in the blood of most adults, and transfusion-related infections have been reported. EBV is particularly deleterious in immunosuppressed transplant patients. The aim was to determine if EBV transmission occurred through leukodepleted blood product transfusion in pediatric recipients of hematopoietic stem cell transplants (HSCT). STUDY DESIGN AND METHODS: This prospective Canadian multi-center cohort study includes 156 allogeneic HSCT pediatric recipients. The association between EBV and transfusion was analyzed using Cox regressions. EBV infection, defined by a PCR+ test in the blood of seronegative recipients of an EBV-negative graft, was monitored in order to correlate the recipient EBV strain with that of the blood donors. EBV genotypes were determined by PCR amplification followed by DNA sequencing at two loci (EBNA3b and LMP1). RESULTS: No statistically significant associations were found between transfusions and EBV. One case of post-transplant EBV infection was identified among the 21 EBV-seronegative recipients receiving an EBV-negative graft. A total of 22 blood donors were retraced to determine whether the recipient's EBV strain matched that of a donor. One donor strain showed 100% sequence homology at the EBNA3b locus, but differed by one or two point mutations and by a 132-bp deletion at the LMP1 locus. The blood donor in question was alone among the 22 donors to show amplifiable virus in plasma. Blood from this donor readily produced an immortalized lymphoblastoid cell line in culture. CONCLUSION: While considered a rare event, EBV transmission through transfusion may occur in the context of severe immunosuppression.

Risk factors for post-transplant Epstein-Barr virus events in pediatric recipients of hematopoietic stem cell transplants.

BACKGROUND: Epstein-Barr virus (EBV) can cause severe disease following hematopoietic stem cell transplant (HSCT), including post-transplant lymphoproliferative disorder (PTLD). The objective was to analyze risk factors associated with post-transplant EBV outcomes among pediatric allogeneic HSCT recipients. METHODS: We used data from 156 pediatric allogeneic HSCT recipients enrolled in the Canadian multicenter TREASuRE study. Cox and Prentice-Williams-Petersen models were used to analyze risk factors for post-transplant EBV events including occurrence and recurrence of EBV DNAemia, increase in EBV viral load (EBV-VL), and preemptive use of rituximab, an effective therapy against PTLD. RESULTS: Females were at higher risk for increasing EBV-VL (adjusted hazard ratio (HR) = 2.83 [95% confidence intervals (CI): 1.33-6.03]) and rituximab use (HR = 3.08 [1.14-8.30]), but had the same EBV DNAemia occurrence (HR = 1.21 [0.74-1.99]) and recurrence risks (HR=1.05 [0.70-1.58]) compared to males. EBV DNAemia was associated with recipient pre-transplant EBV seropositivity (HR = 2.47 [1.17-5.21]) and with graft from an EBV-positive donor (HR = 3.53 [1.95-6.38]). Anti-thymocyte globulin (ATG) was strongly associated with all EBV outcomes, including the use of rituximab (HR = 5.33 [1.47-19.40]). Mycophenolate mofetil (MMF) significantly decreased the risk of all EBV events including the rituximab use (HR = 0.13 [0.03-0.63]). CONCLUSION: This study in pediatric allogeneic HSCT patients reveals a reduced risk of all EBV outcomes with the use of MMF. Risk factors for EBV events such as EBV-VL occurrence and recurrence include EBV positivity in the donor and recipient, and use of ATG, whereas risk factors for the most severe forms of EBV outcome (EBV-VL and the use of rituximab) include female sex and ATG use.

Decision-Making in the Era of New Medical Technologies in Pediatric Hematology-Oncology: The Death of Palliative Care?

BACKGROUND: Recent advances in immunology, genomics, and cellular therapy have opened numerous therapeutic possibilities in pediatric hematology-oncology, generating new hope in poor prognosis situations. How decisions are made when it comes to treatments and aims needs to be explored in this new technologic context. In particular, their impact on the gold standard of early referral to palliative care must be assessed. MATERIALS AND METHODS: Stemming from an ethnographic study combining semistructured interviews and observations carried out in a hematopoietic stem cell transplant unit in a Montréal Pediatric Hospital, we discuss the decision-making process when a patient faces poor prognosis. RESULTS AND DISCUSSION: Although health care providers individually envisioned that palliative care may be the best course of action for patients receiving emergent therapy, they remained collectively in the curative mode. The intricate relationship between science, hope, caregiver, and care receiver sustains this perspective even when (near) death is the probable outcome. When proven treatment fails, emerging therapeutic possibilities offer new hope that can delay the referral to the palliative care team.

Patients' NK cell stimulation with activated plasmacytoid dendritic cells increases dinutuximab-induced neuroblastoma killing.

Targeted immunotherapy has improved the outcome of patients with high-risk neuroblastoma (NB). However, immune escape of tumor cells still occurs and about 40% of NB patients relapse and die from their disease. We previously showed that natural killer (NK) cell stimulation by Toll-like receptor (TLR)-activated plasmacytoid dendritic cells (pDC) increases the efficacy of dinutuximab-based immunotherapy against NB cell lines via the TRAIL death-receptor pathway. With the aim to translate our findings into a novel adoptive therapy of TLR-activated pDC, we investigated the pDC/NK cell axis in NB patients undergoing dinutuximab-based immunotherapy. We show that pDC counts were low at the beginning of immunotherapy but reached normal levels over time. Blood NK cell counts were normal in all patients, although a high proportion of CD56bright CD16low/- cells was observed. The stimulation of patient's blood cells with a TLR9 ligand led to IFN-α production by pDC, and TRAIL expression on NK cell surface. Patient's NK cells expressed high levels of CD69 and TRAIL after stimulation with activated pDC. Both CD56bright CD16low/- and CD56dim CD16+ NK cells degranulated against autologous target cells in the presence of dinutuximab. Importantly, pDC-induced NK cell activation increased the dinutuximab mediated autologous killing of patient-derived NB cells. Altogether, our study demonstrates that TLR-activated pDC strongly increase the cytotoxic functions of NK cells in high-risk NB patients undergoing immunotherapy. These results, therefore, support pDC adoptive immunotherapy as a novel approach to decrease the risk of relapse in patients with high-risk NB.

Asymmetric polymer mixtures in good solvents: A light scattering study.

Dilute solutions of asymmetric polystyrene/poly(methyl methacrylate) (PS/PMMA) mixtures in toluene and tetrahydrofuran (THF) are investigated by static and dynamic light scattering (SLS and DLS). Both solvents are good solvents for each of the two polymers. In toluene, the PMMA refractive index increment is close to zero and SLS provides a direct measurement of the PS static scattering functions. DLS correlatively leads to a single relaxation mode connected with these PS chains. Contrarily, two modes well separated in time are observed for identical PS/PMMA mixtures in THF. Scattering from the PMMA chains is no longer negligible and partial static scattering functions can only be obtained through SLS-DLS combination. For identical polymer concentration and PS/PMMA mixture composition, PS scattering functions are then found to be different in both solvents. The difference increases with concentration and is only partly due to distinct thermodynamic parameters according to the solvent. PMMA scattering functions lead to similar conclusions. The Random Phase Approximation (RPA) describes all scattering functions. However, the SLS-DLS combination affords a reasonable approximation for extracting the partial static scattering functions only for the lowest concentrations, i.e. provided the cross polymer correlation term remains negligible.

NUP98-BPTF gene fusion identified in primary refractory acute megakaryoblastic leukemia of infancy.

The advent of large scale genomic sequencing technologies significantly improved the molecular classification of acute megakaryoblastic leukaemia (AMKL). AMKL represents a subset (∼10%) of high fatality pediatric acute myeloid leukemia (AML). Recurrent and mutually exclusive chimeric gene fusions associated with pediatric AMKL are found in 60%-70% of cases and include RBM15-MKL1, CBFA2T3-GLIS2, NUP98-KDM5A and MLL rearrangements. In addition, another 4% of AMKL harbor NUP98 rearrangements (NUP98r), with yet undetermined fusion partners. We report a novel NUP98-BPTF fusion in an infant presenting with primary refractory AMKL. In this NUP98r, the C-terminal chromatin recognition modules of BPTF, a core subunit of the NURF (nucleosome remodeling factor) ATP-dependent chromatin-remodeling complex, are fused to the N-terminal moiety of NUP98, creating an in frame NUP98-BPTF fusion, with structural homology to NUP98-KDM5A. The leukemic blasts expressed two NUP98-BPTF splicing variants, containing one or two tandemly spaced PHD chromatin reader domains. Our study also identified an unreported wild type BPTF splicing variant encoding for 2 PHD domains, detected both in normal cord blood CD34+ cells and in leukemic blasts, as with the fly BPTF homolog, Nurf301. Disease course was marked by rapid progression and primary chemoresistance, with ultimately significant tumor burden reduction following treatment with a clofarabine containing regimen. In sum, we report 2 novel NUP98-BPTF fusion isoforms that contribute to refine the NUP98r subgroup of pediatric AMKL. Multicenter clinical trials are critically required to determine the frequency of this fusion in AMKL patients and explore innovative treatment strategies for a disease still plagued with poor outcomes.

Incorporation of GSTA1 genetic variations into a population pharmacokinetic model for IV busulfan in paediatric hematopoietic stem cell transplantation.

AIMS: The aim of this study is to develop a population pharmacokinetic (PopPK) model for intravenous busulfan in children that incorporates variants of GSTA1, gene coding for the main enzyme in busulfan metabolism. METHODS: Busulfan concentration-time data was collected from 112 children and adolescents (median 5.4 years old, range: 0.1-20) who received intravenous busulfan during the conditioning regimen prior to stem cell transplantation. Weight, sex, baseline disease (malignant vs. non-malignant), age, conditioning regimen and GSTA1 diplotypes were evaluated as covariates of pharmacokinetic parameters by using nonlinear mixed effects analysis. The ability to achieve the target AUC24h (3600-6000 µM min-1 ) was assessed by estimating the first dose based on the present PopPK model and by comparing the results with other available models in children. RESULTS: A one-compartment model with first-order elimination best described the data. Allometric scaling of weight and a factor of busulfan metabolism maturation were included in the base model. GSTA1 diplotypes were found to be a significant covariate of busulfan clearance, which was 7% faster in rapid metabolizers and 12% slower in poor metabolizers, in comparison with normal ones. Busulfan doses calculated using the parameters of the proposed PopPK model were estimated to achieve the target AUC in 85.2% of the cases (95% CI 78.7-91.7%). CONCLUSION: This is the first PopPK for busulfan that successfully incorporated GSTA1 genotype in a paediatric population. Its use may contribute to better prediction of busulfan exposure in children and adolescents since the first dose, by tailoring the dose according to the individual metabolic capacity.

Survey highlights the need for specific interventions to reduce frequent conflicts between healthcare professionals providing paediatric end-of-life care.

AIMS: This study explored how paediatric healthcare professionals experienced and coped with end-of-life conflicts and identified how to improve coping strategies. METHODS: A questionnaire was distributed to all 2300 professionals at a paediatric university hospital, covering the frequency of end-of-life conflicts, participants, contributing factors, resolution strategies, outcomes and the usefulness of specific institutional coping strategies. RESULTS: Of the 946 professionals (41%) who responded, 466 had witnessed or participated in paediatric end-of-life discussions: 73% said these had led to conflict, more frequently between professionals (58%) than between professionals and parents (33%). Frequent factors included professionals' rotations, unprepared parents, emotional load, unrealistic parental expectations, differences in values and beliefs, parents' fear of hastening death, precipitated situations and uncertain prognosis. Discussions with patients and parents and between professionals were the most frequently used coping strategies. Conflicts were frequently resolved by the time of death. Professionals mainly supported designating one principal physician and nurse for each patient, two-step interdisciplinary meetings - between professionals then with parents - postdeath ethics meetings, bereavement follow-up protocols and early consultations with paediatric palliative care and clinical ethics services. CONCLUSION: End-of-life conflicts were frequent and predominantly occurred between healthcare professionals. Specific interventions could target most of the contributing factors.

Activation of innate immunity in primary human cells using a plant virus derived nanoparticle TLR7/8 agonist.

Rod-shaped virus-like nanoparticles (VLNP) made of papaya mosaic virus (PapMV) coat proteins (CP) self-assembled around a single stranded RNA (ssRNA) were showed to be a TLR7 agonist. Their utilization as an immune modulator in cancer immunotherapy was shown to be promising. To establish a clinical relevance in human for PapMV VLNP, we showed that stimulation of human peripheral blood mononuclear cells (PBMC) with VLNP induces the secretion of interferon alpha (IFNα) and other pro-inflammatory cytokines and chemokines. Plasmacytoid dendritic cells (pDCs) were activated and secreted IFN-α upon VLNP exposure. Monocyte-derived dendritic cells upregulate maturation markers and produce IL-6 in response to PapMV VLNP stimulation, which suggests the activation of TLR8. Finally, when co-cultured with NK cells, PapMV induced pDCs promoted the NK cytolytic activity against cancer cells. These data obtained with primary human immune cells further strengthen the clinical relevance of PapMV VLNPs as a cancer immunotherapy agent.

How do professionals assess the quality of life of children with advanced cancer receiving palliative care, and what are their recommendations for improvement?

BACKGROUND: It is known that information regarding the quality of life of a patient is central to pediatric palliative care. This information allows professionals to adapt the care and support provided to children and their families. Previous studies have documented the major areas to be investigated in order to assess the quality of life, although it is not yet known what operational criteria or piece of information should be used in the context of pediatric palliative care. The present study aims to: 1) Identify signs of quality of life and evaluation methods currently used by professionals to assess the quality of life of children with cancer receiving palliative care. 2) Collect recommendations from professionals to improve the evaluation of quality of life in this context. METHODS: We selected a qualitative research design and applied an inductive thematic content analysis to the verbal material. Participants included 20 members of the Department of Hematology-Oncology at CHU Sainte-Justine from various professions (e.g. physicians, nurses, psychosocial staff) who had cared for at least one child with cancer receiving palliative care in the last year. RESULTS: Professionals did not have access to pre-established criteria or to a defined procedure to assess the quality of life of children they followed in the context of PPC. They reported basing their assessment on the child's non-verbal cues, relational availability and elements of his/her environment. These cues are typically collected through observation, interpretation and by asking the child, his/her parents, and other members of the care. To improve the assessment of quality of life professionals recommended optimizing interdisciplinary communication, involving the child and the family in the evaluation process, increasing training to palliative care in hematology/oncology, and developing formalized measurement tools. CONCLUSION: The formulation of explicit criteria to assess the quality of life in this context, along with detailed recommendations provided by professionals, support the development of systematic measurement strategy. Such a strategy would contribute to the development of common care goals and further facilitate communication between professionals and with the family.

GSTA1 Genetic Variants and Conditioning Regimen: Missing Key Factors in Dosing Guidelines of Busulfan in Pediatric Hematopoietic Stem Cell Transplantation.

Busulfan (Bu) is a key component of conditioning regimens used before hematopoietic stem cell transplantation (SCT) in children. Different predictive methods have been used to calculate the first dose of Bu. To evaluate the necessity of further improvements, we retrospectively analyzed the currently available weight- and age-based guidelines to calculate the first doses in 101 children who underwent allogenic SCT in CHU Sainte-Justine, Montreal, after an intravenous Bu-containing conditioning regimen according to genetic and clinical factors. The measured areas under the curve (AUCs) were within target (900 to 1500 µM/min) in 38.7% of patients after the administration of the first dose calculated based on age and weight, as locally recommended. GSTA1 diplotypes linked to poor Bu metabolism (G3) and fludarabine-containing regimens were the only factors associated with AUC within target (OR, 4.7 [95% CI, 1.1 to 19.8, P = .04]; and OR, 9.9 [95% CI, 1.6 to 61.7, P = .01], respectively). From the 11 methods selected for dose calculation, the percentage of AUCs within the target varied between 16% and 74%. In some models G3 was associated with AUCs within the therapeutic and the toxic range, whereas rapid metabolizers (G1) were correlated with subtherapeutic AUCs when different methods were used. These associations were confirmed by clearance-prediction analysis, in which GSTA1 diplotypes consistently influenced the prediction errors of the methods. These findings suggest that these factors should be considered in Bu dose prediction in addition to the anthropometric data from patients. Furthermore, our data indicated that GSTA1 diplotypes was a factor that should be included in future population pharmacokinetic models, including similar conditioning regiments, to improve the prediction of Bu exposure after its initial dose.

In vitro differentiated plasmacytoid dendritic cells as a tool to induce anti-leukemia activity of natural killer cells.

Acute lymphoblastic leukemia (ALL) is believed to be resistant to NK cell-mediated killing. To overcome this resistance, we developed an innovative approach based on NK cell stimulation with Toll-like receptor (TLR)-activated plasmacytoid dendritic cells (pDC). The translation of this approach into the clinic requires the production of high numbers of human pDC. Herein, we show that in vitro differentiation of cord blood CD34+ progenitors in the presence of aryl hydrocarbon receptor antagonists gives rise to clinically relevant numbers of pDC, as about 108 pDC can be produced from a typical cord blood unit. Blocking the aryl hydrocarbon receptor (AHR) pathway significantly increased the yield of pDC. When compared to pDC isolated from peripheral blood, in vitro differentiated pDC (ivD-pDC) exhibited an increased capacity to induce NK cell-mediated killing of ALL. Although ivD-pDC produced lower amounts of IFN-α than peripheral blood pDC upon TLR activation, they produced more IFN-λ2, known to play a critical role in the induction of anti-tumoral NK cell functions. Both TLR-9 and TLR-7 ligands triggered pDC-induced NK cell activation, offering the possibility to use any clinical-grade TLR-7 or TLR-9 ligands in future clinical trials. Finally, adoptive transfer of ivD-pDC cultured in the presence of an AHR antagonist cured humanized mice with minimal ALL disease. Collectively, our results pave the way to clinical-grade production of sufficient numbers of human pDC for innate immunotherapy against ALL and other refractory malignancies.

Identifying domains of quality of life in children with cancer undergoing palliative care: A qualitative study with professionals.

OBJECTIVE: The goal of pediatric palliative care (PPC) is to maintain the quality of life (QoL) of children whose lives are threatened. However, there are sparse scientific data on the domains of QoL in this particular context, and no measurement strategies are available. The present study aims to describe the domains of QoL in the context of PPC in oncology, according to the perceptions of professional caregivers. METHOD: Semistructured interviews were conducted with a random sample of 20 professional caregivers from the Division of Hematology/Oncology at Le Centre Hospitalier Universitaire Sainte-Justine (Montréal, Canada). The caregivers were asked about their perceptions about the QoL of the children they have cared for in this context. The data were analyzed using inductive thematic content analysis. RESULTS: The analysis allowed us to identify seven domains of QoL: "physical comfort," "alleviation of psychological suffering," "fun and the present moment," "sense of control," "feeling valued and appreciated," "feeling that life goes on," and "meaningful social relationships." SIGNIFICANCE OF RESULTS: Caregivers recount the regard that should be accorded to maintaining well-being and a sense of fun, as well as fostering the child's abilities, taking account of the progression of the disease, and to fulfilling his or her needs, especially social ones. Our results also demonstrate that all domains were positively referred to by professional caregivers. The data from our study will lead to better assessment of QoL according to the trajectory of a child with advanced cancer while undergoing PPC.

Limited sampling strategies for estimating intravenous and oral cyclosporine area under the curve in pediatric hematopoietic stem cell transplantation.

BACKGROUND: The optimal monitoring strategy for cyclosporine (CsA) in pediatric hematopoietic stem cell transplantation (HSCT) patients remains unclear. Although there is a growing interest in the use of the area under the concentration-time curve (AUC), measurement of AUC in clinical settings is often impractical. The objective of this study was to identify and validate limited sampling strategies (LSSs) for the prediction of CsA AUC after intravenous (IV) and oral (PO) administration in this population. METHODS: Sixty-eight pediatric patients who underwent HSCT and received CsA were investigated. Twelve-hour pharmacokinetic profiles (n = 138) performed per standard of care were collected. Weighted multiple linear regression was used to investigate all possible LSSs consisting of 4 or less concentration-time points. Their predictive performance was evaluated by leave one out cross validation and external validation by measuring the root mean squared relative error (RMSE%) and the 95th percentile of the absolute relative error (AE%). Values less than 20% were considered clinically acceptable. RESULTS: Nine LSSs (4 IV and 5 PO) convenient for clinical application proved to have clinically acceptable performance. Notably, LSS based on C0, C2, and C4 was found to be accurate for estimation of CsA exposure after both IV and PO administration with the 95th percentile of AE% of 19.7% and 17.5%, respectively. CONCLUSIONS: LSSs using 3 or 4 concentration-time points obtained within 4 hours postdose provide a convenient and reliable method to estimate CsA exposure in this population. These LSSs may facilitate future research aiming at better defining the relationship between AUC and clinical outcomes.

Impaired interferon-alpha production by plasmacytoid dendritic cells after cord blood transplantation in children: implication for post-transplantation toll-like receptor ligand-based immunotherapy.

Plasmacytoid dendritic cells (pDCs) initiate both innate and adaptive immune responses, making them attractive targets for post-transplantation immunotherapy, particularly after cord blood transplantation (CBT). Toll-like receptor (TLR) agonists are currently studied for pDC stimulation in various clinical settings. Their efficacy depends on pDC number and functionality, which are unknown after CBT. We performed a longitudinal study of pDC reconstitution in children who underwent bone marrow transplantation (BMT) and single-unit CBT. Both CBT and unrelated BMT patients received antithymocyte globulin as part of their graft-versus-host disease prophylaxis regimen. pDC blood counts were higher in CBT patients than in healthy volunteers from 2 to 9 months after transplantation, whereas they remained lower in BMT patients. We showed that cord blood progenitors gave rise in vitro to a 500-fold increase in functional pDCs over bone marrow counterparts. Upon stimulation with a TLR agonist, pDCs from both CBT and BMT recipients upregulated T cell costimulatory molecules, whereas interferon-alpha (IFN-α) production was impaired for 9 months after CBT. TLR agonist treatment is thus not expected to induce IFN-α production by pDCs after CBT, limiting its immunotherapeutic potential. Fortunately, in vitro production of large amounts of functional pDCs from cord blood progenitors paves the way for the post-transplantation adoptive transfer of pDCs.