Impact of RB1 gene screening from blood collected on a single day from 411 family members of 113 Retinoblastoma survivors in India.

OBJECTIVES: To analyse the profile and implication of genetic testing in a cohort of retinoblastoma (RB) patients and their families conducted on a single day during World Retinoblastoma Awareness Week 2017. METHODS: Retrospective analysis of blood samples were collected from 411 subjects, including 113 probands at a camp organised for RB awareness and were analysed for RB1 mutations by Sanger sequencing and Multiplex Ligation-dependent Probe Amplification (MLPA). If germline mutations were detected, the parents and siblings of the proband were tested for the same mutation. RESULTS: Germline RB1 mutations were identified in 61/113(54%) probands with a mutation detection rate of 96% (47/49) and 22% (14/64) for bilateral and unilateral RB, respectively. Ten novel pathogenic mutations were identified. Splice mutation was most common (31%) followed by nonsense mutation (26%). The mean age at RB diagnosis was significantly lower in patients having germline RB1 mutation (mean 10.7 months ±2.5) compared to those without (mean 27.2 months ±6.5) (p = <0.0001). Parental transmission of the mutant allele was detected in 15/61(25%) cases of which 11(18%) parents were unaffected indicating incomplete penetrance. The origin of the variant allele was both paternal (n = 7) and maternal (n = 4) wherein 5 were bilateral and 6 unilateral. CONCLUSIONS: The detection of a germline mutation impacts the proband and family members due to its implications on change in prognosis, frequency of subsequent evaluations, screening for ocular and non-ocular cancers, and surveillance of family and future progeny.

MiR-142-5p promotes retinoblastoma cell proliferation, migration and invasion by targeting PTEN.

The study intends to probe the functions of miR-142-5p in retinoblastoma (RB) and the relationship between miR-142-5p and phosphatase and tensin homolog deleted on chromosome ten (PTEN). In our study, miR-142-5p and PTEN mRNA expression in RB tissue, serum of RB patients and RB cell lines were investigated by quantitative real-time polymerase chain reaction (qRT-PCR). The proliferation, migration, invasion and cell apoptosis were measured using MTT assay, BrdU assay, Transwell experiments and flow cytometry analysis, respectively. Binding sites between miR-142-5p and PTEN were predicted by the TargetScan database and were confirmed via qRT-PCR, western blot and dual-luciferase reporter gene assay. It was demonstrated that miR-142-5p expression was elevated in RB tissue, serum of RB patients and RB cell lines. MiR-142-5p overexpression remarkably promoted the proliferation, migration, invasion and inhibited the apoptosis of WERI-RB-1 cells while miR-142-5p knockdown induced opposite effects in Y79 cells. MiR-142-5p decreased PTEN expression in both mRNA and protein expression levels, and PTEN was identified as a target gene of miR-142-5p. Cotransfection of PTEN overexpression plasmids reversed the influences of miR-142-5p on RB cells. In conclusion, miR-142-5p enhances proliferation, migration and invasion of RB cell by targeting PTEN.

Association between Predictors of Vitamin D Serum Levels and Risk of Retinoblastoma in Children: A Case-Control Study.

BACKGROUND: vitamin D (VD) may be a protective factor for retinoblastoma, though no temporal association has been reported during pregnancy or the child's first year of life. Serum VD concentrations are determined by both distal (DF) and proximal factors (PF). OBJECTIVE: To identify if DF and PF can predict VD insufficiency (VDI) and VD deficiency (VDD) in women of childbearing age; and to test whether maternal exposure to DF and PF during pregnancy and a child's exposure during the first 11.9 months postpartum are associated with sporadic retinoblastoma (SRb) in children. METHODS: This is a secondary analysis of data from the Epidemiology of SRb in Mexico (EpiRbMx) study and the National Health and Nutrition Survey 2018-2019 (ENSANUT 2018-2019, for its acronym in Spanish). The association of DF and PF with VDD or VDI was estimated using ENSANUT 2018-2019, and the association of DF and PF with SRb using EpiRbMx. All were estimated using logistic regression, with comparable samples selected from ENSANUT 2018-2019 and EpiRbMx. RESULTS: Altitude, latitude and obesity predicted VDI and VDD in ENSANUT women. In EpiRbMx, residence in a rural location during pregnancy increased the risk of SRb. For children, rural residence and latitude increased the risk of SRb, while the number of days exposed to the spring-summer season during months 6 to 11.9 of life was protective. CONCLUSIONS: risk of VDI and VDD in women (ENSANUT 2018-2019) increased with altitude, urban dwelling, overweight and obesity. The child and mother's place of residence, including altitude, latitude and rural classification were important predictors of SRb in EpiRbMx.

Molecular diagnosis of retinoblastoma by circulating tumor DNA analysis.

PURPOSE: The analysis of circulating tumor DNA (ctDNA), a fraction of total cell-free DNA (cfDNA), might be of special interest in retinoblastoma patients. Because the accessibility to tumor tissue is very limited in these patients, either for histopathological diagnosis of suspicious intraocular masses (biopsies are proscribed) or for somatic RB1 studies and genetic counseling (due to current successful conservative approaches), we aim to validate the detection of ctDNA in plasma of non-hereditary retinoblastoma patients by molecular analysis of RB1 gene. EXPERIMENTAL DESIGN: In a cohort of 19 intraocular unilateral non-hereditary retinoblastoma patients for whom a plasma sample was available at diagnosis, we performed high-deep next-generation sequencing (NGS) of RB1 in cfDNA. Two different bioinformatics/statistics approaches were applied depending on whether the somatic RB1 status was available or not. RESULTS: Median plasma sample volume was 600 µL [100-1000]; median cfDNA plasma concentration was 119 [38-1980] and 27 [11-653] ng/mL at diagnosis and after complete remission, respectively. In the subgroup of patients with known somatic RB1 alterations (n = 11), seven of nine somatic mutations were detected (median allele fraction: 6.7%). In patients without identified somatic RB1 alterations (n = 8), six candidate variants were identified for seven patients. CONCLUSIONS: Despite small tumor size, blood-ocular barrier, poor ctDNA blood release and limited plasma sample volumes, we confirm that it is possible to detect ctDNA with high-deep NGS in plasma from patients with intraocular non-hereditary retinoblastoma. This may aid in diagnosis of suspicious cases, family genetic counseling or follow-up of residual intraocular disease.

Chimerism involving a RB1 pathogenic variant in monochorionic dizygotic twins with twin-twin transfusion syndrome.

We report the first case of blood chimerism involving a pathogenic RB1 variant in naturally conceived monochorionic-dizygotic twins (MC/DZ) with the twin-twin-transfusion syndrome (TTTS), presumably caused by the exchange of stem-cells. Twin A developed bilateral retinoblastoma at 7 months of age. Initial genetic testing identified a de novo RB1 pathogenic variant, with a 20% allelic ratio in both twins' blood. Subsequent genotyping of blood and skin confirmed dizygosity, with the affected twin harboring the RB1 pathogenic variant in skin and blood, and the unaffected twin carrying the variant only in blood.

Serum exosomal miRNA as biomarkers for Retinoblastoma.

Retinoblastoma (RB) is a childhood eye tumor, caused by RB1 mutation. Though diagnosing RB is easier, prognosticating RB is limited to examining the patient under anesthesia and imaging technique. The aim of the study is to find exosomal miRNA biomarkers to prognosticate RB. Exosomes were isolated from one control - MIO-M1 and two RB cell lines - WERI-Rb-1 and NCC-RbC-51. Small RNA sequencing was performed on exosomal miRNA isolated from the three cell lines. miRNAs specific to each cell line were shortlisted. A total of 243, 606 and 400 miRNAs were identified in MIO-M1, WERI-Rb-1 and NCC-RbC-51 cell lines respectively. Nine miRNAs were shortlisted based on adjusted p value and literature, MIO-M1 specific (n = 1), WERI-RB-1 specific (n = 2), NCC-RbC-51 specific (n = 2) and miRNAs common to both RB cell lines (n = 4) were chosen. Validation was done using specific Taqman miRNA assays.miRNA validation was carried out on cell lines, cell line derived exosomes, primary RB tissues and exosomes isolated from serum of the RB patients. Validation of the miRNAs in cell lines and exosomes derived from the cell lines, confirmed the sequencing data. However, only 2 miRNAs - hsa-miR-301b-3p and hsa-miR-216b-5p were upregulated in the primary RB tissues. None of the miRNAs had significant expression in the serum exosomes of RB patients. Therefore, serum exosomal miRNA may not be ideal for prognosticating RB.Further research on other body fluids like CSF and vitreous could serve as potential source for biomarkers for prognosticating RB.

Cell-free DNA profiling in retinoblastoma patients with advanced intraocular disease: An MSKCC experience.

PURPOSE: The enucleation rate for retinoblastoma has dropped from over 95% to under 10% in the past 10 years as a result of improvements in therapy. This reduces access to tumor tissue for molecular profiling, especially in unilateral retinoblastoma, and hinders the confirmation of somatic RB1 mutations necessary for genetic counseling. Plasma cell-free DNA (cfDNA) has provided a platform for noninvasive molecular profiling in cancer, but its applicability in low tumor burden retinoblastoma has not been shown. We analyzed cfDNA collected from 10 patients with available tumor tissue to determine whether sufficient tumorderived cfDNA is shed in plasma from retinoblastoma tumors to enable noninvasive RB1 mutation detection. METHODS: Tumor tissue was collected from eye enucleations in 10 patients diagnosed with advanced intra-ocular unilateral retinoblastoma, three of which went on to develop metastatic disease. Tumor RB1 mutation status was determined using an FDA-cleared tumor sequencing assay, MSK-IMPACT. Plasma samples were collected before eye enucleation and analyzed with a customized panel targeting all exons of RB1. RESULTS: Tumor-guided genotyping detected 10 of the 13 expected somatic RB1 mutations in plasma cfDNA in 8 of 10 patients (average variant allele frequency 3.78%). Without referring to RB1 status in the tumor, de novo mutation calling identified 7 of the 13 expected RB1 mutations (in 6 of 10 patients) with high confidence. CONCLUSION: Plasma cfDNA can detect somatic RB1 mutations in patients with unilateral retinoblastoma. Since intraocular biopsies are avoided in these patients because of concern about spreading tumor, cfDNA can potentially offer a noninvasive platform to guide clinical decisions about treatment, follow-up schemes, and risk of metastasis.

Intra-arterial chemotherapy combined with VEC intravenous chemotherapy in the treatment of advanced retinoblastoma.

PURPOSE: To explore the efficacy and safety of intra-arterial chemotherapy (IAC) combined with vincristine + etoposide + carboplatin (VEC) intravenous chemotherapy (IVC) in the treatment of advanced retinoblastoma (RB). METHODS: A total of 86 child patients (98 eyes) newly diagnosed with advanced RB (stage D and E), among whom 42 cases (49 eyes) underwent IVC and IAC combined with local ocular treatment (IVC+IAC group), and 44 cases (49 eyes) were treated with IAC combined with local ocular treatment (IAC group). At 4 weeks after treatment, the maximum diameter and thickness of the tumor were evaluated, the expression levels of serum markers [vascular endothelial growth factor (VEGF), neurone specific enolase (NSE), Livin and Survivin] were assessed. RESULTS: The maximum diameter and thickness of the tumor significantly declined in patients after treatment compared with those before treatment. The maximum diameter and thickness of the tumor in IVC+IAC group were significantly smaller than those in IAC group after treatment. In the two groups, the eye salvage rate was 85.7% (42/49) and 79.6% (39/49), respectively. The recurrence rate was 12.2% and 18.4%, respectively, and the metastasis and mortality rate were all 2.0%. The levels of serum VEGF, NSE, Livin and Survivin were obviously decreased in both groups after treatment compared with those before treatment, while they were significantly lower in IVC+IAC group than those in IAC group after treatment.

Analysis of the p53 pathway in peripheral blood of retinoblastoma patients; potential biomarkers.

Loss of retinoblastoma (RB) function in the cone cells during retina development is necessary but not sufficient for retinoblastoma development. It has been reported that in the absence of RB activity, a retinoma is generated, and the onset of retina cancer occurs until the p53 pathway is altered. Unlike other types of cancer, in retinoblastoma the p53 tumour suppressor is mostly wild type, although its two primary regulators, MDMX and MDM2, are commonly dysregulated. A mutated RB form is inherited in around 35% of the cases, but normally two, somatic mutations are needed to alter the RB function. Here we investigated the mRNA levels of RB, p53, MDMX and MDM2 in peripheral blood samples of retinoblastoma patients to monitor the pathway status of p53 in somatic cells. We sought to investigate the involvement of these genes in the development of retina cancer, with the aim of identifying biomarkers for early diagnosis of this disease.

LncRNA NKILA Inhibits Retinoblastoma by Downregulating lncRNA XIST.

Purpose: Although retinoblastoma is rare but can be deadly in some severe cases. To find novel therapeutic targets for retinoblastoma, we explored the potential role of lncRNA NKILA in retinoblastoma. Results: We found that, comparing to healthy controls, NKILA was downregulated, while lncRNA XIST was upregulated in plasma of retinoblastoma patients and they were inversely correlated. Downregulation of NKILA distinguished early-stage patients from healthy controls. Overexpression of lncRNA NKILA mediated the downregulation of XIST in retinoblastoma cells, while XIST overexpression failed to significantly affect NKILA. Overexpression of NKILA resulted in decreased, while XIST overexpression resulted in increased proliferation, migration and invasion rates of retinoblastoma cells. In addition, rescue experiment showed that XIST overexpression attenuated the effects of NKILA overexpression on cancer cell behaviors. Conclusions: Therefore, NKILA inhibits retinoblastoma possibly by downregulating XIST, but the causality has not been fully validated.

Mutational analysis of the RB1 gene and the inheritance patterns of retinoblastoma in Jordan.

Retinoblastoma (RB) is a childhood cancer developing in the retina due to RB1 pathologic variant. Herein we are evaluating the oncogenic mutations in the RB1 gene and the inheritance patterns of RB in the Jordanian patients. In this prospective study, the peripheral blood of 50 retinoblastoma patients was collected, genomic DNA was extracted, mutations were identified using Quantitative multiplex PCR (QM-PCR), Allele-specific PCR, Next Generation Sequencing analysis, and Sanger sequencing. In this cohort of 50 patients, 20(40%) patients had unilateral RB and 30(60%) were males. Overall, 36(72%) patients had germline disease, 17(47%) of whom had the same RB1 pathologic variant detected in one of the parents (inherited disease). In the bilateral group, all (100%) patients had germline disease; 13(43%) of them had inherited mutation. In the unilateral group, 6(30%) had germline disease, 4(20%) of them had inherited mutation. Nonsense mutation generating a stop codon and producing a truncated non-functional protein was the most frequent detected type of mutations (n = 15/36, 42%). Only one (2%) of the patients had mosaic mutation, and of the 17 inherited cases, 16(94%) had an unaffected carrier parent. In conclusion, in addition to all bilateral RB patients in our cohort, 30% of unilateral cases showed germline mutation. Almost half (47%) of germline cases had inherited disease from affected (6%) parent or unaffected carrier (94%). Therefore molecular screening is critical for the genetic counseling regarding the risk for inherited RB in both unilateral and bilateral cases including those with no family history.

MicroRNAs in retinoblastoma: Potential diagnostic and therapeutic biomarkers.

Retinoblastoma (Rb) is known as one of important childhood malignancies which due to inactivation of the RB gene (tumor suppressor gene in various patients). The early detection of Rb could provide better treatment for Rb patients. Imaging techniques (e.g., MRI and CT) are known as one of effective diagnosis approaches for detection of patients with Rb. It has been shown that utilization of imaging techniques is associated with some limitations. Hence, identification of new diagnosis approaches might provide a better treatment for Rb patients. Identification of new biomarkers could contribute to better understanding of pathogenesis events involved in Rb and provide new insights into design better treatment approaches for these patients. Among the various biomarkers, microRNAs (miRNAs) have emerged as attractive tools for Rb detection. miRNAs are one classes of small non-coding RNAs which could anticipate in a variety of biological process via targeting sequence of cellular and molecular pathways. Deregulations of these molecules are associated with cancerous condition. Multiple lines of evidence indicated that deregulation of various miRNAs involved in various stages of Rb. Here, we summarized a variety of tissue-specific and circulating miRNAs involved in Rb pathogenesis which could be used as diagnostic, prognostic, and therapeutic biomarkers in Rb patients.

[Value of serum miR-17-92 cluster in diagnosis of retinoblastoma].

OBJECTIVE: To investigate the value of serum miR-17-92 cluster in the diagnosis of retinoblastoma (RB). METHODS: Serum samples were collected from 20 children with RB and 20 healthy controls. Quantitative real-time PCR was used to measure the expression of miR-17-92 cluster. The expression of miR-17-92 cluster was compared between children with different stages of RB and the changes in the expression of miR-17-92 cluster after multimodality therapy were analyzed. The receiver operating characteristic (ROC) curve was used to investigate the value of serum miR-17-92 cluster in the diagnosis of RB. RESULTS: Compared with the healthy controls, the children with RB had significantly higher relative expression of miR-17-3P, miR-17-5P, miR-18a, and miR-20a in serum (P<0.05), and miR-18a showed the greatest increase. There were no significant differences in the relative expression of miR-19a, miR-19b-1, and miR-92a-1 between children with RB and healthy controls (P>0.05). There were no significant differences in the expression of miR-17-5P, miR-17-3P, miR-18a, and miR-20a between the children with early-to-moderate stage of RB and those with advanced stage of RB (P>0.05), but there were significant reductions after multimodality therapy (P<0.05). In the diagnosis of RB, the areas under the ROC curve (AUCs) for serum miR-17-3P, miR-17-5P, miR-18a, and miR-20a were 0.770, 0.755, 0.828, and 0.665 respectively, and miR-18a had the largest AUC, with a sensitivity of 90% and a specificity of 65%. CONCLUSIONS: miR-17-3P, miR-17-5P, miR-18a, and miR-20a are highly expressed in the serum of children with RB, and miR-18a may be used as a new marker for the diagnosis of RB.

[A preliminary study of retinoblastoma-related serum tumor markers].

OBJECTIVE: To screen out retinoblastoma (RB)-related serum tumor markers by measuring the levels of serum alpha fetoprotein (AFP), carcino-embryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigen 125 (CA125), carbohydrate antigen 153 (CA153), carbohydrate antigen 199 (CA199), and carbohydrate antigen 724 (CA724) in children with RB. METHODS: The levels of seven serum tumor markers (AFP, CEA, NSE, CA125, CA153, CA199, and CA724) were determined in 20 children with RB and 20 healthy children (control) using a chemiluminescent immunoassay. RESULTS: The serum levels and positive rates of NSE, CA153, and CA199 in the RB group were significantly higher than those in the control group (P<0.05). However, there were no significant differences in the levels of AFP, CEA, CA125, and CA724 between the two groups (P>0.05). NSE had the highest sensitivity, but a relatively low specificity for the diagnosis of RB. CA153 and CA199 had a relatively high specificity, but a relatively low sensitivity for the diagnosis of RB. CONCLUSIONS: The serum levels and positive rates of NSE, CA153, and CA199 are high in children with RB. Combined measurement of these three serum tumor markers may have an important diagnostic value for RB.

Clinical significance of high levels of survivin and transforming growth factor beta-1 proteins in aqueous humor and serum of retinoblastoma patients.

PURPOSE: To evaluate the diagnostic and prognostic values of survivin and transforming growth factor beta-1 (TGF-B1) expression in aqueous humor and serum of retinoblastoma (RB) in comparison to the conventional RB marker lactate dehydrogenase (LDH) and to elucidate a possible correlation between them and the clinicopathological features of the disease. METHODS: This prospective, comparative study included 88 newly diagnosed children with RB and 80 age-matched controls with ophthalmic conditions other than tumors prepared for intraocular surgeries. Concentrations of survivin, TGF-B1, and LDH were measured in serum and aqueous humor before and 6 months after completion of therapy. RESULTS: High serum and aqueous humor concentrations of the three proteins were detected in RB patients before treatment compared to the control group (P < 0.01), with a significant reduction of serum concentrations after treatment (P < 0.01). For the highest sensitivity and specificity, the optimal cutoff values of serum and aqueous survivin were 12.9 pg/ml and 25.2 pg/mg, with a significant positive correlation between aqueous survivin and RB staging and presence of optic nerve infiltration (r = 0.43, P = 0.04); the best cutoff values of serum and aqueous TGF-B1, 370.7 pg/ml and 39.8 pg/mg, with a significant positive correlation between aqueous TGF-B1 and poor differentiation of the tumor (r = 0.69, P = 0.001). CONCLUSIONS: The high sensitivity, specificity, and accuracy of serum and aqueous humor survivin and TGF-B1 proteins make them promising markers for early detection and follow-up of RB patients.

Molecular diagnosis in patients with retinoblastoma: Report of a series of cases. / Diagnóstico molecular en pacientes con retinoblastoma: reporte de una serie de casos.

OBJECTIVES: To report the benefits of genetic diagnosis in patients with retinoblastoma. METHOD: Observational study. Patients with retinoblastoma and their families were included. Demographic and clinical data were recorded. Blood and tumour samples were obtained. Next generation sequencing was performed on the samples. When deletion 13 q syndrome was suspected, cytogenetics microarray was performed (Cytoscan® HD, Affymetrix, Santa Clara, CA, USA), with a high density chip of 1.9 million of non-polymorphic probes and 750 thousand SNP probes. RESULTS: Of the 7 cases were analysed 4 were male. The mean age at diagnosis was 21 months (range 5-36). Three cases had bilateral retinoblastoma, and 4 unilateral. None had family history. In all patients, blood was analysed, and a study was performed on the tissue from 2 unilateral enucleated tumours, in which 6 mutations were identified, all de novo. Just one was novel (c.164delC; case 1). One case of unilateral tumour revealed blood mosaicism, showing that his condition was inheritable, and that there is a high risk of developing retinoblastoma in the unaffected eye. The patient also has an increased risk of presenting with other primary tumours. CONCLUSION: Molecular diagnosis of RB1 in patients with retinoblastoma impacts on the decision process, costs, treatment, and prognosis of patients, as well as their families.

Genetic analysis in retinoblastoma and peripheral blood correlation.

OBJECTIVE: To determine the importance of intratumoral genetic analysis in the diagnosis of germ-line mutations in patients with retinoblastoma. To underline the importance of performing these genetic tests in every case of retinoblastoma. METHOD: Intratumoral genetic analysis of RB1 mutation was performed on 17 enucleated eyes that were non-responsive to conservative treatment. Patients had no family history of retinoblastoma, and lesions were always single. The identified mutations were then also studied in peripheral blood analysis. RESULTS: There were 12 (70.6%) cases with positive results in intratumoral analysis. In 8 cases (47.1%) mutation of both RB1 alelli were detected, and in 4 (23.5%) cases only one allele was found mutated. In 5 patients (29.4%) no mutation was identified. In the first hit, mutations comprised 7 frameshift or nonsense and 2 splice, whereas in the second hit, one splice mutation, 2 nonsense and 8 loss of heterozygosity were identified. Among 6 patients where intratumoral analysis detected a single mutation associated with a loss of heterozygosity, the peripheral blood analysis was able to detect the same mutation in 3 cases (50%). CONCLUSIONS: Intratumoral genetic analysis of sporadic retinoblastoma can detect germ-line mutations. These patients are at higher risk of bilateralization and development of second tumors or trilateral retinoblastoma. Genetic screening is recommended in every patient diagnosed with retinoblastoma.

Carboplatin therapeutic monitoring in preterm and full-term neonates.

INTRODUCTION: Administration of the most appropriate dose of chemotherapy to neonates is particularly challenging and frequently not standardised based on any scientific rationale. We report the clinical utility of carboplatin therapeutic drug monitoring in preterm and full-term neonates within the first month of life. METHODS: Carboplatin therapeutic monitoring was performed to achieve target drug exposures area under the plasma concentration-time curve (AUC values) in nine preterm and full-term neonates diagnosed with retinoblastoma or neuroblastoma treated over an 8 year period. Carboplatin was administered over 3 days with therapeutic drug monitoring utilised to target cumulative AUC values of 5.2-7.8 mg/ml min. RESULTS: AUC values achieved were within 15% of target values for the individual courses of treatment in all but one patient (12/13 courses of treatment), with dose modifications of up to 215% required to achieve target AUC values, based on initial mg/kg dosing schedules. Carboplatin clearance determined across three consecutive chemotherapy courses in two patients increased from 3.4 to 7.1 ml/min and from 7.2 to 16.5 ml/min, representing increases of 210-230% over several weeks of treatment. Complete remission was observed in 8/9 patients, with no renal toxicity reported and only one patient experiencing ototoxicity. CONCLUSION: The study highlights the benefits of utilising therapeutic drug monitoring to achieve target carboplatin AUC values in preterm and full-term neonates treated within the first few weeks of life, particularly in view of marked increases in drug clearance observed over consecutive chemotherapy courses. In the absence of therapeutic drug monitoring, body-weight based dosing is recommended, with dosing guidance provided for both approaches to inform future treatment.