Marc Ansari

Background: Childhood and adolescent acute lymphoblastic leukemia (ALL) survival outcomes have improved significantly, but treatment-related toxicities (TRTs) remain a major concern affecting dose intensity and quality of life. Germline pharmacogenetic variations contribute to inter-individual differences in chemotherapy response, yet consistent replication of associations has been limited by differences in treatment protocols, ethnic backgrounds, and toxicity definitions. Methods: This systematic review and meta-analysis (PROSPERO CRD42021229748) included 68 studies in the qualitative synthesis, with 42 high-quality studies undergoing structured synthesis and, where appropriate, quantitative meta-analysis. Studies focused on the toxicities of thiopurines, methotrexate, glucocorticoids, vincristine, and asparaginase. Results: Meta-analyses showed strong evidence linking the NUDT15 rs116855232 variant to thiopurine-induced myelosuppression (OR 19.0, 95% CI 1.6–224; I² = 86.5%) and a significant association between the TYMS enhancer repeat polymorphism and osteonecrosis (OR 6.66, 95% CI 3.67–12.11; I² = 0%). In contrast, MTHFR variants and VDR polymorphisms showed no significant associations with methotrexate-induced myelosuppression or osteonecrosis, respectively. Narrative synthesis highlighted clinically actionable associations: TPMT and NUDT15 with thiopurine toxicity; CEP72 with vincristine neuropathy; and HLA haplotypes with asparaginase hypersensitivity. Population allele frequency comparisons (IndiGenomes, gnomAD, UK Biobank) showed strong concordance (r = 0.919–0.997), supporting the broad generalisability of identified variants, which remains to be evaluated prospectively. The main limitations included heterogeneous toxicity definitions, non-uniform genetic models, evolving treatment protocols, population heterogeneity, and a lack of harmonised reporting. Conclusions: The review supports routine TPMT and NUDT15 genotyping and highlights the need for harmonised definitions, multi-ethnic studies, standardised data representation, and prospective validation. A literature-based candidate gene list for future PGx association studies was generated.

The optimal busulfan exposure window in pediatric patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (HSCT) remains to be defined. We identify this window for patients receiving busulfan within the prospective international, randomized controlled phase 3 ALLSCTped 2012 FORUM trial. We included 145 participants receiving fludarabine-busulfan-thiotepa conditioning, with available busulfan plasma levels. Busulfan exposure was estimated using a validated pediatric population pharmacokinetic model. Primary outcomes were event-free survival (EFS) and graft-versus-host disease-free relapse-free survival (GRFS). Patients were aged between 0.5 and 19.5 years, with a median follow-up of 5.0 years. The optimal busulfan exposure was defined as area under busulfan concentration curve (cAUC) of 73.3 to 98.0 mg.h/L based on EFS and GRFS. Patients with nonoptimal exposure had lower EFS (hazard ratio [HR], 1.93; p = 0.008) and GRFS (HR, 2.01; p = 0.002). Underexposure (cAUC 98.0 mg.h/L) with an increased risk of treatment-related toxicities and graft-versus-host disease. Patients with optimal busulfan exposure showed no differences in EFS, GRFS, overall survival, or relapse with post hoc matched total-body irradiation (TBI) recipients (n = 51 in each group). This study identifies a favorable busulfan exposure window for pediatric patients with ALL undergoing HSCT from an HLA-matched donor. Therapeutic drug monitoring for optimized personalized busulfan dosing improves HSCT outcomes and might be validated for use as an alternative to irradiation. This trial was registered at EudraCT as 2012-003032-22 and on www.ClinicalTrials.gov as NCT01949129.

Fludarabine monophosphate is an antimetabolite and a cornerstone of hematology and oncology treatments, with expanding clinical applications in hematological malignancies, stem cell transplantation conditioning, and chimeric antigen receptor T-cell (CAR-T) therapy. Despite widespread clinical use, there is substantial interpatient pharmacokinetic variability with up to 14.5-fold differences in drug exposure. Suboptimal exposures (both under- and overexposure) correlate directly with both treatment failure and non-relapse mortality, emphasizing the critical need for personalized dosing strategies. The therapeutic efficacy of fludarabine is determined by complex transport and metabolic processes. Cellular uptake is mediated primarily by human equilibrative (hENT1, hENT2) and concentrative nucleoside transporters (hCNT2, hCNT3). Once intracellular, deoxycytidine kinase catalyzes the rate-limiting phosphorylation step, converting fludarabine to its pharmacologically active triphosphate, which inhibits DNA synthesis and repair, ultimately driving cytotoxicity. The elimination mechanisms of fludarabine involve multiple pathways: cytoplasmic 5′-nucleotidase II and CD73-mediated dephosphorylation, while UDP-glucuronosyltransferases (particularly UGT2B17) catalyze glucuronidation-based elimination. The breast cancer resistance protein (BCRP/ ABCG2 ) represents the principal efflux transporter, whereas fludarabine shows minimal interaction with P-glycoprotein and other major multidrug resistance-associated proteins. This review synthesizes current understanding of fludarabine’s cellular pharmacology, providing a framework for identifying biomarkers to guide personalized medicine approaches and to optimize fludarabine therapy and treatment outcomes.

For fever in neutropenia (FN) during chemotherapy timely start of antibiotics is recommended. We analyzed time to antibiotics (TTA) and sub-timespans between detection of fever and start of antibiotics in children undergoing chemotherapy for cancer with FN. Specifically, we aimed to assess where delays occur, which variables influence TTA, and whether the order of certain process steps affects TTA. We analyzed 349 FN episodes reported prospectively in 155 Swiss patients from April 2016 to August 2018. In outpatients, the median TTA from fever to the start of antibiotics was 165 minutes, and the median duration from fever to hospital arrival was 80 minutes. For inpatients, the median TTA from fever to the start of antibiotics was 75 minutes. The longest delays were identified for the timespans from phone call to arrival (median, 75 min) and from arrival to decision on treatment (60 min). Known blood counts at recognition of fever, decision to treat FN before arrival at the emergency department, and arrival during office hours contributed to shorter TTA. In conclusion, the time before arrival is relevant and should be considered when optimizing TTA and evaluating its influence on outcomes. Support for transportation, using time to arrive for preparations, and regular blood counts could reduce TTA.

Rationale: Childhood cancer survivors (CCS) are at risk for long-term pulmonary complications from treatment-related toxicity. Nitrogen multiple breath washout (N2MBW) may detect small airway dysfunction earlier than standard pulmonary function tests (PFTs), but its value in CCS remains uncertain. Objectives: To determine the prevalence of ventilation inhomogeneity measured by N2MBW in CCS, evaluate whether it detects abnormalities beyond spirometry and diffusion capacity for carbon monoxide (DlCO), and explore associations with treatment exposures. Methods: In this prospective multicenter study (Bern, Basel, and Geneva, Switzerland), we measured lung function in CCS aged 6 to 21 years who were undergoing routine follow-up. We stratified participants into high-risk (pulmotoxic chemotherapy [busulfan, bleomycin, nitrosoureas], thoracic surgery, radiotherapy, or hematopoietic stem cell transplantation [HSCT]) and standard-risk (other systemic anticancer treatments). PFTs included N2MBW (lung clearance index [LCI], acinar [SACIN] and conductive [SCOND] inhomogeneity), spirometry (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC]), and DlCO. Abnormal values were defined as z-score < −1.645 or >1.645, calculated using the Global Lung Initiative references. We quantified the proportion of participants with isolated elevated LCI and analyzed associations with treatment exposures using multivariable linear regression. Results: We included 191 CCS (median 7 years postdiagnosis). Mean LCI was 6.27 (95% CI, 6.17-6.37), with 7% of participants showing abnormal values. N2MBW results did not differ between high- and standard-risk groups, but allogeneic HSCT survivors had the highest mean LCI (7.18 [95% CI, 5.99-8.38]), with 33% abnormal. Survivors had mildly impaired mean FEV1, FVC, and DlCO z-scores (−0.21, −0.34, 0.23), more pronounced in high-risk CCS (−0.67, −0.85, −0.05). Isolated LCI impairment, without abnormalities in spirometry or DlCO, occurred in only 3%. Among treatment exposures, only allogeneic HSCT was associated with higher LCI (1.40 [95% CI, 0.57-2.33]) and SACIN (1.24 [95% CI, 0.20-2.28]). Conclusions: Most pediatric CCS had normal lung function. N2MBW abnormalities were rare, occurring mainly in allogeneic HSCT survivors. Overall, N2MBW added little beyond standard PFTs, suggesting it may not be needed for routine follow-up at this stage, except after allogeneic HSCT. Larger, longitudinal studies should clarify the onset, progression, and prognostic significance of N2MBW abnormalities and their potential role in risk-adapted follow-up care. Clinical Trial Registration: NCT04732273.

Objectives: This exploratory study assessed psychological distress of grandparents of children recently diagnosed with cancer within 2 years post‐diagnosis. We examined changes over time, identified associated factors, and compared distress levels with a comparison group (grandparents of survivors). Methods: Grandparents were recruited via parents of children recently diagnosed with cancer (within 3 months). Survivors (3–10 years post‐diagnosis) were asked to provide contact information of their grandparents (comparison group). Grandparents completed surveys at 3 (T1), 6 (T2), 12 (T3), and 24 months (T4) post‐diagnosis. The comparison group completed a questionnaire once. Psychological distress was assessed using the Brief Symptom Inventory‐18, with three subscales (depression, anxiety, somatization), and an overall score (Global Severity Index; GSI). Scores were T‐standardized. We used linear mixed models to compare distress across time points and linear regressions for between‐group differences (grandparents versus comparison group). Results: Forty‐one grandparents (mean age = 68 years, 59% female) of 20 patients participated. In the comparison group 133 grandparents (mean age = 72 years, 60% female) of 66 survivors (mean years post‐diagnosis = 6.7, SD = 2.3) participated. GSI scores were all below normative values. Increases in GSI were observed from T1 to T2 (24%) and T3 to T4 (26%). Greater distance from the child's hospital was associated with lower GSI ( β : −13.27, p = 0.033) and anxiety scores ( β : −5.50, p = 0.017). Grandfathers reported higher levels of somatization than grandmothers ( β : 4.00, p = 0.071). Older age was associated with lower anxiety ( β : −9.86, p = 0.042). Conclusion: Although most grandparents reported psychological distress within normative ranges, distress levels increased in some. Targeted interventions might help support grandparents of children with cancer.

Background: Resilience, or the ability to adapt, recover, and thrive under stress, is crucial for mental health, but remains understudied in parents of childhood cancer survivors (CCS‐parents). We aimed to: (a) describe the resilience of CCS‐parents, comparison parents (parents from general population), and the Swiss general population (SGP), (b) compare resilience of CCS‐parents and comparison‐parents, and (c) identify characteristics associated with resilience in CCS‐parents. Methods: This is a cross‐sectional population‐based study including CCS‐parents who were identified through the Swiss Childhood Cancer Registry, and comparison‐parents from a representative sample of the general population. Resilience was measured using the Connor‐Davidson Resilience Scale (CD‐RISC). Linear regression was used to estimate differences between CCS‐parents and comparison parents, adjusting for confounders. Characteristics associated with resilience in CCS‐parents were identified through multilevel linear regression with parent couples clustered at the family level. Results: Data from 468 CCS‐parents (mean age = 62.2 years; 58.5% female), 473 comparison parents (mean age = 62.1 years; 57.5% female) and 1246 individuals from the SGP (mean age = 48.9 years; 58.2% female) were analyzed. Mean resilience in the SGP was 72.2 (SD = 13.3). CCS‐parents had lower resilience (mean = 69.5; SD = 12.4) than in comparison parents (mean = 73.9; SD = 13.6; p < 0.001). Among CCS‐parents, better general health was associated with higher resilience ( p < 0.001), while living in French‐ or Italian‐speaking regions (vs. German‐speaking; p = 0.044) and higher levels of depression ( p = 0.001) were associated with lower resilience. Conclusion: Our study supports the need to enhance resilience in parents of survivors, which may help to improve overall mental health and wellbeing of this population.

Background: Understanding interindividual variability in treatment response and toxicity is essential for optimizing outcomes in pediatric acute lymphoblastic leukemia (ALL). Molecular and pharmacogenetic markers hold promise in predicting treatment efficacy and adverse effects, particularly in genetically diverse populations. This protocol outlines the methodology for a prospective, nonrandomized observational cohort designed to evaluate molecular and pharmacogenetic factors associated with treatment response and toxicity in Indian children diagnosed with ALL. Objective: The primary objective is to identify genetic markers associated with treatment-related toxicity and therapeutic response. Secondary objectives include evaluating associations between the occurrence of early toxicities and quality of life during active ALL treatment, specific pharmacogenetic variants, and survival outcomes along with generating data to support the future implementation of personalized treatment strategies in Indian children with ALL. Methods: In this prospective, observational cohort, 556 children (≤18 years of age) with newly diagnosed ALL treated under the Indian Childhood Collaborative Leukemia–Acute Lymphoblastic Leukemia 2014 (ICiCLe-ALL-14) protocol at two Indian centers will be enrolled, aiming for a minimum of 500 evaluable children. Eligible participants will be enrolled prior to the initiation of chemotherapy and followed longitudinally throughout treatment. Clinical and laboratory data (demographics, nutritional assessment, quality of life, comorbidities, treatment regimen, toxicity graded by Common Terminology Criteria for Adverse Events v5.0, remission status, and survival) will be collected at predefined intervals up to day 100 of the maintenance phase. Germline and somatic DNA will be sampled at diagnosis and remission. The first phase will use whole-exome sequencing to discover candidate variants by implementing a candidate gene prioritization strategy. The second phase will genotype the top candidates in the full cohort using array technology. Associations with early treatment–related toxicities, steroid response, and survival will be tested by multivariable regression and Cox models. A machine learning approach with pharmacogenetic predictors as classifiers will be implemented further with cross-validation and sensitivity analyses. Results: Ethical committees approved the protocol version 1.0 in 2020: IEC-1167/06.11.2020 (All India Institute of Medical Sciences, New Delhi), JIP/IEC/2020/201 (Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry), and AO_2021-00048 (UNIGE, Geneva). Funding was received from Swiss National Science Foundation, Switzerland; Department of Biotechnology, India; and CANSEARCH Foundation, Switzerland. Recruitment began in December 2022 and is likely to conclude by 2027. A comprehensive analysis of the complete study cohort is anticipated to be completed by 2027. Conclusions: The MPGx-INDALL (Molecular and Pharmacogenetic Marker Evaluation in Relation to the Toxicity and Clinical Response of Acute Lymphoblastic Leukemia Treatment in Indian Children) study will generate actionable insights for individualized ALL therapy in India via systematically evaluating germline and somatic markers in a large ethnically distinct cohort.

Background: Understanding drug interactions in hematopoietic stem cell transplantation (HSCT) is crucial given the narrow therapeutic index of busulfan (BU), which is a key conditioning agent. In this study, we investigate the potential impacts of fludarabine (Flu) as a frequently co-administered agent in HSCT on BU pharmacokinetics (PK). Specifically, we examine whether Flu can alter BU metabolism by affecting the predominantly expressed cytosolic glutathione-S-transferases (GSTs), particularly GSTA1, GSTM1, and GSTP1, which are essential for BU detoxification. Methods: We conducted molecular docking and atomistic molecular dynamics simulations using the crystal structures of GSTA1, GSTM1, and GSTP1 to study the estimated binding affinity of Flu as well as its metabolites to these target enzymes. We then performed in vitro assays on human recombinant GST enzymes and HepaRG hepatocyte cells by focusing on enzymatic inhibition, GST expression analysis, and glutathione level measurements. Enzymatic assays were conducted using 1-chloro-2,4-dinitrobenzene as a substrate alongside Western blotting and cell-viability-corrected glutathione (GSH) assays to determine the influences of Flu on the enzymatic activities and expression of GSTs. Results: In silico analysis predicted the binding affinities of Flu to the GST isoforms, with estimated Ki values of 0.2 µM, 5.2 µM, and 23.9 µM for GSTA1, GSTM1, and GSTP1, respectively; although these are micromolar (µM) inhibition values that indicate relatively weak or moderate inhibition, they are still insightful for understanding the potential interactions. However, the in vitro assays revealed no significant inhibition of the GST enzymes by Flu, even at concentrations up to ten times the clinical peak (C _max ). Further, Flu did not notably alter GSTA1 expression or affect cellular glutathione levels in the HepaRG cells. These experimental findings suggest that Flu may have minimal influence on the GST-mediated detoxifying pathway in the context of cancer treatment. Conclusion: The present study underscores the importance of empirically validating in silico observations in pharmacological research by emphasizing the minimal effect of Flu on GST activity and its implications in clinical oncology. Moreover, the findings suggest that Flu is not likely to alter BU pharmacokinetics via the GSH-conjugation pathway.

Fludarabine (Flu), administered as a prodrug Flu monophosphate, is a lymphodepleting agent used prior to hematopoietic stem cell transplantation (HSCT) which exhibits substantial pharmacokinetics (PK) variability, contributing to suboptimal outcomes. This study developed and validated a physiologically based pharmacokinetic (PBPK) model using literature‐based data and a middle‐out approach for Flu and its two main metabolites in adults and children, and evaluated its performance to predict individual Flu exposures in 28 pediatric HSCT patients using a virtual twin (VT) approach using PK‐Sim software. Different informed models with individual demographic and biological characteristics were assessed by comparing predicted and observed plasma exposures (AUC _0➔24h ) via fold error metrics and regression analyses. The PBPK model accurately reproduced observed Flu and metabolites concentrations in both adults and children. In the VT cohort, informing the model with plasma protein scaling factor and nuclear GFR improved drug exposure predictions in total (mean fold error (MFE) = 0.91) and unbound (MFE = 0.88) compartments with minimal bias in both Deming and Bland–Altman analyses. This model provided superior agreement between observed and predicted exposures, achieving improved agreement across statistical and regression approaches compared to the model with estimated GFR. PBPK‐based VT modeling enables accurate, individualized prediction of Flu PK in pediatric HSCT patients. These results support the implementation of model‐informed precision dosing to achieve personalized pediatric dosing of Flu in HSCT.