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Purpose The advances in the treatment of retinoblastoma have enabled salvaging the globe in advanced stages with intra-arterial chemotherapy (IAC). We developed a strategy of alternate application of systemic intravenous chemotherapy (IVC) and IAC (referred to as alternate systemic IVC and IAC; ASIAC) to reduce central nervous metastases during IAC and examined its efficacy and safety in eye globe salvage in this study.Materials and Methods Between January 2010 and February 2021, 43 eyes of 40 patients received ASIAC treatment for retinoblastoma at the Yonsei Cancer Center, Yonsei University Health System. Their medical records were reviewed retrospectively to evaluate the eye salvage rate (ESR), defined from diagnosis to enucleation. High-risk retinoblastoma was defined as group D or E by the International Classification of Retinoblastoma.Results The study enrolled 38 and five cases of high-risk and low-risk retinoblastoma, respectively. In total, 178 IAC and 410 IVC courses were administered, with a median of 4 (interquartile range [IQR], 3.0 to 5.0) IAC and 9 (IQR, 6.0 to 11) IVC courses per eye, respectively. The 5-year ESR was 60.4%±8.7% for the whole cohort, 100% for low-risk retinoblastoma, and 53.6%±9.8% for high-risk retinoblastoma. Among those diagnosed since 2015, the 5-year ESR for high-risk retinoblastoma was 63.5%±14.0%. Fifteen eyes underwent enucleation; no viable tumor was found in three enucleated eyes. There were no deaths in this cohort.Conclusion Primary IAC-IVC (i.e., ASIAC) for patients with retinoblastoma was tolerable and effective in salvaging the eye and maintaining survival.

Purpose In 2017, the Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) system was introduced. We aimed to evaluate the accuracy of Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) System for the prediction of event-free survival in Korean pediatric patients with hepatoblastoma. Materials and methods This two-center retrospective study included consecutive Korean pediatric patients with histopathologically confirmed hepatoblastoma from March 1988 through September 2019. We compared event-free survival (EFS) among four risk groups according to the CHIC-HS system. Discriminatory ability of CHIC-HS system was also evaluated using optimism-corrected C-statistics. Factors associated with EFS were explored using multivariable Cox regression analysis. Results We included 129 patients (mean age, 2.6±3.3 years; female:male, 63:66). The 5-year EFS rates in the very low, low, intermediate, and high-risk groups, according to the CHIC-HS system were 90.0%, 82.8%, 73.5%, and 51.3%, respectively. The CHIC-HS system aligned significantly well with EFS outcomes (p=0.004). The optimism-corrected C index of CHIC-HS was 0.644 (95% CI, 0.561-0.727). Age ≥8 (vs. age ≤2; HR, 2.781; 95% CI, 1.187-6.512; p=0.018), PRE-Treatment EXTent of tumor (PRETEXT) stage IV (vs. PRETEXT I or II; HR, 2.774; 95% CI, 1.228-5.974; p=0.009), and presence of metastasis (HR, 2.886; 95% CI, 1.457-5.719; p=0.002), which are incorporated as the first three nodes in the CHIC-HS system, were independently associated with EFS. Conclusion The CHIC-HS system aligned significantly well with EFS outcomes in Korean pediatric patients with hepatoblastoma. Age group, PRETEXT stage, and presence of metastasis were independently associated with EFS.

Background This multinational study was conducted to report clinical presentations and treatment strategies in patients with intracranial germinomas across selected Asian centers, including failure patterns, risk factors, and outcomes. Methods A retrospective data collection and analysis of these patients, treated between 1995 and 2015 from eight healthcare institutions across four countries was undertaken. Results From the results, 418 patients were analyzed, with a median follow-up of 8.9 years; 79.9% of the patients were M0, and 87.6% had β-human chorionic gonadotropin values Conclusions Survival outcomes of patients with germinoma were excellent. Thus, the focus of treatment for intracranial germinoma should be on survivorship. Further studies are warranted to find the optimal intensity and volume of radiation, including the role of chemotherapy in the survival of patients with intracranial germinomas, considering age, primary tumor location, and extent of disease.

Purpose Effectiveness and safety of clofarabine (one of the treatment mainstays in pediatric patients with relapsed/refractory acute lymphoblastic leukemia [ALL]) was assessed in Korean pediatric patients with ALL to facilitate conditional coverage with evidence development.Materials and Methods In this multicenter, prospective, observational study, patients receiving clofarabine as mono/combination therapy were followed up every 4-6 weeks for 6 months or until hematopoietic stem cell transplantation (HSCT). Response rates, survival outcomes, and adverse events were assessed.Results Sixty patients (2-26 years old; 65% B-cell ALL, received prior ≥ 2 regimen, 68.3% refractory to previous regimen) were enrolled and treated with at least one dose of clofarabine; of whom 26 (43.3%) completed 6 months of follow-up after the last dose of clofarabine. Fifty-eight patients (96.7%) received clofarabine combination therapy. Overall remission rate (complete remission [CR] or CR without platelet recovery [CRp]) was 45.0% (27/60; 95% confidence interval [CI], 32.4 to 57.6) and the overall response rate (CR, CRp, or partial remission [PR]) was 46.7% (28/60; 95% CI, 34.0 to 59.3), with 11 (18.3%), 16 (26.7%), and one (1.7%) patients achieving CR, CRp, and PR, respectively. The median time to remission was 5.1 weeks (95% CI, 4.7 to 6.1). Median duration of remission was 16.6 weeks (range, 2.0 to 167.6 weeks). Sixteen patients (26.7%) proceeded to HSCT. There were 24 deaths; 14 due to treatment-emergent adverse events.Conclusion Remission with clofarabine was observed in approximately half of the study patients who had overall expected safety profile; however, there was no favorable long-term survival outcome in this study.

Hepatic veno-occlusive disease (VOD) is a serious systemic endothelial complication after stem cell transplantation. Defibrotide is under investigation as a prophylactic agent for VOD; however, high costs limit its utility. We evaluated the prophylactic efficacy of a low-dose defibrotide regimen for VOD. We retrospectively enrolled 147 paediatric patients who underwent autologous haematopoietic stem cell transplantation (HSCT; 69 with defibrotide prophylaxis and 78 historical controls) at the Yonsei Cancer Center in Seoul, Korea, between March 2013 and Feb 2020. Low-dose defibrotide (12.5 mg/kg/day) was administered from D-3 to D+10 after HSCT. The most common diagnosis in the cohort was brain tumour (N = 86). VOD developed in 10 (12.8%) and 3 (4.3%) patients in the control and prophylaxis groups, respectively (P = 0.071). In the second HSCT group, VOD incidence was significantly lower in the prophylaxis group [2.9% (1/35)] than in the control group (28.6%, 6/21, P = 0.005). VOD severity was significantly higher in the control group than in the prophylaxis group (P = 0.006). Three VOD-related mortalities occurred in the control group, whereas no VOD-related mortality occurred in the prophylaxis group. In conclusion, low-dose defibrotide prophylaxis is a promising and economical strategy for preventing VOD, especially in second-round HSCT.

Background : : Approximately 8% of male patients presenting with primary mediastinal germ cell tumors (GCTs) have Klinefelter syndrome (KS), while patients diagnosed with retroperitoneal GCTs also exhibit a range of chromosomal abnormalities. The exact mechanism underlying the development of GCTs in Klinefelter syndrome is unknown, but KS frequently goes underdiagnosed as a result of its varied symptoms and a low general awareness of this condition. Thus, the Children’s Oncology Group recommends screening of Klinefelter syndrome in pediatric and adolescent male subjects who present with GCTs. Methods : : We retrospectively reviewed the medical records of extragonadal germ cell tumor patients treated at Severance hospital, department of pediatrics or division of pediatric hematology-oncology over the last ten years. Results : : A total of 95 patients with extragonadal germ cell tumors were included in this study. Karyotyping was done in eight patients out of 95 patients, three patients with KS and one patient with Down syndrome. Twelve of extragonadal GCT patients presented at mediastinum, with most common histology of mature teratoma, and three patients presented with chromosomal abnormalities, two with KS and one with Down syndrome. A total of nine patients were diagnosed with retroperitoneal GCTs and only one had KS. Conclusion : : We described the characteristics of 95 cases of extragonadal GCTs. Although the mechanism of extragonadal GCTs in KS is not clear, karyotyping in pediatric and adolescent extragonadal GCT patients could be helpful in figuring out chromosomal abnormalities including KS and their roles in GCT pathophysiology, which can contribute to improve one’s health.

Pediatric cancer patients undergoing chemotherapy or radiation therapy generally require a central venous catheter (CVC). However, serum drawn from CVCs has several drawbacks for use in routine chemistry tests. Biochemical analytes were evaluated using heparin plasma instead of serum to maintain turnaround time and to prevent problems caused by micro-clot formation or delayed clotting time.Venous blood samples from 52 pediatric oncology patients with chemoports or Hickman catheters were collected in serum separating tubes (SSTs) and lithium heparin tubes (LHTs). A total of 29 parameters were analyzed on a Cobas c702 (Roche Diagnostics, Mannheim, Germany). Passing-Bablok regression and Bland-Altman difference plots were used for statistical analyses.When the mean value of each analyte measured from LHT was compared with those from SST, percentage bias was within the desirable bias limit in most of the analytes. However, albumin, potassium, and inorganic phosphorus showed a negative constant bias of -3.0%, -5.3%, and -1.6%, respectively, and total protein showed a positive constant bias of + 3.8%.The use of LHTs for sample collection from pediatric patients with CVCs could be helpful for routine chemistry analyses. The results of potassium and total protein should be interpreted with consideration of the difference between serum and plasma samples.

Renal tumors account for approximately 7% of all childhood cancers. These include Wilms tumor (WT), clear cell sarcoma of the kidney (CCSK), malignant rhabdoid tumor (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea.From January 2001 to December 2015, data of pediatric patients (0-18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed.Among 439 patients (male, 240), the most common tumor was WT (n=342, 77.9%), followed by RCC (n=36, 8.2%), CCSK (n=24, 5.5%), MRTK (n=16, 3.6%), CMN (n=12, 2.7%), and others (n=9, 2.1%). Median age at diagnosis was 27.1 months (range 0-225.5) and median follow-up duration was 88.5 months (range 0-211.6). Overall, 32 patients died, of whom 17, 11, 1, and 3 died of relapse, progressive disease, second malignant neoplasm, and treatment-related mortality. Five-year overall survival and event free survival were 97.2% and 84.8% in WT, 90.6% and 82.1% in RCC, 81.1% and 63.6% in CCSK, 60.3% and 56.2% in MRTK, and 100% and 91.7% in CMN, respectively (p0.001).The pediatric renal tumor types in Korea are similar to those previously reported in other countries. WT accounted for a large proportion and survival was excellent. Non-Wilms renal tumors included a variety of tumors and showed inferior outcome, especially MRTK. Further efforts are necessary to optimize the treatment and analyze the genetic characteristics of pediatric renal tumors in Korea.

Purpose Fertility preservation (FP) discussion is a crucial step for adolescent and young adult (AYA) cancer patients; however, it is relatively new to Asian countries. This study highlights the quality of communication during FP discussions in Korea. Methods Participants were AYA patients (n = 34) and their guardians (n = 34). We described clinical pathways for FP and surveyed details on the discussion characteristics and satisfaction scales during the FP discussions in Yonsei Cancer Center, Seoul, Korea. Quality of FP discussions and the degree of satisfaction with the discussions were measured on a scale of 1–7. Results Of the participants, two guardians did not answer the survey. All respondents reported high overall satisfaction; however, several factors were related to low satisfaction or information quality. Regarding the type of counselors, both respondent groups reported high overall satisfaction when their counselors were physicians rather than other types of care providers. Regarding information quality, guardians who were provided with both verbal and non-verbal communication tools (pamphlets, internet resources, or others) were more satisfied with the information quality than those who were provided with only verbal communication tools. Regarding the number of discussion sessions, more than one discussion session indicated improved understanding of the FP concept, higher communication, and information quality. Conclusion To improve the FP process for AYA cancer patients, we need to adjust the type of counselors, number of discussion sessions, and types of information. This will be the cornerstone of effective FP communications in Korea.

Background We report dose-escalation results from an open-label, phase 1/2 trial evaluating avelumab (anti-PD-L1) in paediatric patients with refractory/relapsed solid tumours. Methods In phase 1, patients aged Results At data cut-off (27 July 2021), 21 patients aged 3–17 years had received avelumab 10 mg/kg (n = 6) or 20 mg/kg (n = 15). One patient had three events that were classified as a DLT (fatigue with hemiparesis and muscular weakness associated with pseudoprogression; 20 mg/kg cohort). Grade ≥ 3 AEs occurred in five (83%) and 11 (73%) patients in the 10 and 20 mg/kg cohorts, respectively, and were treatment-related in one patient (7%; grade 3 [DLT]) in the 20 mg/kg cohort. Avelumab exposure in paediatric patients receiving 20 mg/kg dosing, but not 10 mg/kg, was comparable or higher compared with approved adult dosing (10 mg/kg or 800 mg flat dose). No objective responses were observed. Four patients with CNS tumours (20 mg/kg cohort) achieved stable disease, which was ongoing in two patients with astrocytoma at cut-off (for 24.7 and 30.3 months). Conclusion In paediatric patients with refractory/relapsed solid tumours, avelumab monotherapy showed a safety profile consistent with previous adult studies, but clinical benefits were limited.

(1) Background: To analyze changes in treatment patterns for advanced retinoblastoma over time and differences in globe salvage rates, (2) Methods: Retrospective, observational case-control study of 97 eyes of 91 patients with advanced retinoblastoma (Group D and E)., (3) Results: Patients were divided into two groups based on whether they were treated before or after intraarterial chemotherapy (IAC) was introduced in our center in 2010. Before 2010, primary treatment pattern was enucleation, which was performed in 57.6% of cases, whereas primary treatment pattern after 2010 was IAC combined with intravenous chemotherapy (IVC), which was performed in 78.1%. Intravitreal chemotherapy (IVitC) has been performed to treat vitreous and subretinal seeding since 2015. The 5-year globe salvage rate of IVC alone was 24.0% for Group D and 0% for Group E, whereas that of IVC–IAC was 50.4% for Group D and 49.7% for Group E. Whether IVitC was performed or not did not significantly contribute to globe salvage rate. There was one metastatic death in the IVC alone group., (4) Conclusions: Primary treatment pattern changed from enucleation to IAC-based treatment, which can now save nearly half of eyes with advanced retinoblastoma with excellent safety profile and survival rate.

Purpose This study aimed to identify the attributes of social adjustment among adolescent cancer survivors using concept analysis and to propose a definition of the concept. Methods In accordance with the hybrid model of concept analysis, this study employed a three-phase circular process comprising theoretical, fieldwork, and final analysis phases. A thorough literature review was conducted using MEDLINE, Embase, and Korean databases, followed by qualitative fieldwork with seven participants. The results derived from the theoretical and fieldwork phases were integrated into the final analysis phase. Results Four attributes of social adjustment were found in adolescent cancer survivors: having harmonious relationships with friends, having harmonious relationships with boy/girlfriends, fulfilling their present roles, and planning for and expecting future roles. The following definition of social adjustment of adolescent cancer survivors is proposed: “the conquering of difficulties arising from the continuum of childhood cancer and the achievement of the developmental tasks of typical adolescents.” Conclusion Social adjustment of childhood cancer survivors is crucial for integrating them into society. The findings of this study provide a basis for developing an instrument to measure the social adjustment of adolescent cancer survivors and for developing of interventions that target this group.

To develop and validate the Distress Screening Tool (DST) for child and adolescent cancer survivors. In part 1, items of the DST were generated through literature search and group interviews. Initially, the DST was tested on pediatric cancer survivors and their caregivers. In part 2, the modified version of the DST was retested with a different set of participants. Lastly, the psychometric properties and cutoff scores of the DST were evaluated on a separate set of survivors and caregivers. In part 1, six items of the DST self- and caregiver-report versions were generated. The initial 6 DST items of both versions showed acceptable internal consistency, but low inter-item correlation. Following the item modification, both versions of the DST showed improved inter-item correlation. In part 2, the modified DST had acceptable internal consistency and convergent validity, with acceptable psychometric properties. Cutoff scores were also generated. The DST could be a useful tool for pediatric cancer survivors.

Purpose The purpose of the current study was to explore physical activity (PA) levels, exercise preferences, and perceived barriers to PA in childhood cancer survivors. Methods This cross-sectional study surveyed 120 childhood cancer survivors aged 8-18 years from the pediatric oncology center in South Korea between March and August 2017. The modified Exercise & Quality of Life questionnaire, Korea Youth Risk Behavior Web-based Survey, and Godin Leisure-Time Questionnaire were used to assess PA levels, preferences, and exercise barriers. Results Among 120 participants (72 boys, 48 girls) whose average age at the time of the survey was 14.57 ± 3.00 years and the average age at diagnosis was 8.22 years, the three most common diagnoses were acute leukemia (43.3%), brain tumor (13.3%), and malignant lymphoma (10.8%). Only 16 participants (5%) met the PA recommendations for children (at least 60 min of moderate PA per day). The most preferred sporting activities included soccer, basketball, strengthening exercises, badminton, dance, and taekwondo. They generally had positive attitudes toward exercise, and more than 63% of participants intended to exercise the following month. The five most prevalent perceived barriers to exercise were lack of time, poor health, reluctance to sweat, lack of exercise skills, and no exercise partners. Conclusions While most childhood cancer survivors did not meet the PA recommendation, most of them agreed that exercise was beneficial, and they intended to participate in the exercise. Exercise and PA programs should be tailored to the personal health and preferences of childhood cancer survivors.

Background Hodgkin's lymphoma (HL) constitutes 10%–20% of all malignant lymphomas and has a high cure rate (5-year survival, around 90%). Recently, interest has increased concerning preventing secondary complications (secondary cancer, endocrine disorders) in long-term survivors. We aimed to study the epidemiologic features and therapeutic outcomes of HL in children, adolescents, and young adults in Korea. Methods We performed a multicenter, retrospective study of 224 patients aged < 25 years diagnosed with HL at 22 participating institutes in Korea from January 2007 to August 2016. Results A higher percentage of males was diagnosed at a younger age. Nodular sclerosis histopathological HL subtype was most common, followed by mixed cellularity subtype. Eighty-one (36.2%), 101 (45.1%), and 42 (18.8%) patients were classified into low, intermediate, and high-risk groups, respectively. Doxorubicin, bleomycin, vinblastine, dacarbazine was the most common protocol (n = 102, 45.5%). Event-free survival rate was 86.0% ± 2.4%, while five-year overall survival (OS) rate was 96.1% ± 1.4%: 98.7% ± 1.3%, 97.7% ± 1.6%, and 86.5% ± 5.6% in the low, intermediate, and high-risk groups, respectively (P = 0.021). Five-year OS was worse in patients with B-symptoms, stage IV disease, high-risk, splenic involvement, extra-nodal lymphoma, and elevated lactate dehydrogenase level. In multivariate analysis, B-symptoms and extra-nodal involvement were prognostic factors for poor OS. Late complications of endocrine disorders and secondary malignancy were observed in 17 and 6 patients, respectively. Conclusion This is the first study on the epidemiology and treatment outcomes of HL in children, adolescents, and young adults in Korea. Future prospective studies are indicated to develop therapies that minimize treatment toxicity while maximizing cure rates in children, adolescents, and young adults with HL., Graphical Abstract

PURPOSE Pediatric cancer impacts all family members, including parents and siblings, who strive to adjust to a multitude of changes brought about by the illness. Family resilience is an important factor in the successful adaptation of families of children with cancer. Therefore, we aimed to identify risk and protective factors for family resilience at the child, family, and community levels that affect the adaptation of families of children with cancer. METHOD This study employed a descriptive survey design, and data were collected from 111 parents of children undergoing treatment for cancer between April and May 2020 at a university hospital in South Korea. Based on Patterson's family resilience model, risk factors-severity of child's condition, parental depression, and stigma and discrimination-and protective factors-the child's temperament, family communication skills, and supportive health services-for family adaptation were analyzed using multiple regression analyses. RESULTS Among family resilience factors affecting the adaptation of families of children with cancer, parental depression (s = -0.290, p = 0.004) and family communication skills (s = 0.403, p

Purpose Histiocytic and dendritic cell neoplasms are rare hematologic tumors. This study aimed to describe the epidemiologic features of the entire spectrum of histiocytic and dendritic cell neoplasms, including clinicopathological variables and patient outcomes. Materials and methods We comprehensively reviewed 274 patients who were diagnosed with histiocytic and dendritic neoplasms at Severance Hospital, Seoul, South Korea between 1995 and 2018. Results The most common neoplasm was Langerhans cell histiocytosis (LCH), followed by dermal xanthogranuloma. Among non-LCH sarcomas, histiocytic sarcoma (HS) showed a relatively high prevalence, followed by follicular dendritic cell sarcoma (FDCS). Disseminated juvenile xanthogranuloma (DJG), Erdheim-Chester disease (ECD), indeterminate dendritic cell tumor (IDCT), and interdigitating dendritic cell sarcoma (IDCS) rarely occurred. Generally, these tumors presented in childhood, although the non-LCH sarcoma (HS/FDCS/IDCS/IDCT) group of tumors and ECD occurred in late adulthood. Multiorgan involvement and advanced Ann-Arbor stage, as well as recurrence and death of disease, were not uncommon. The non-LCH sarcoma group had the worst overall survival, compared to the DJG, ECD, and LCH groups. Conclusion Our findings indicate that histiocytic and dendritic cell neoplasms exhibit heterogeneous epidemiologic characteristics and that some patients may have unfavorable outcomes, especially those with non-LCH sarcoma.

Purpose We investigated optimal management for intracranial germinoma, including target volume and dose of radiation therapy (RT) and the combination of RT and chemotherapy (CTx). Methods and Materials We retrospectively evaluated 213 patients with intracranial germinoma treated between 1971 and 2017. Treatment policies changed as diagnostic techniques and clinical experience improved. In the 1980s, trial RT and tumor marker study were performed, and craniospinal irradiation was performed to treat patients with presumed germinoma. CTx was introduced in 1991, and RT volume was reduced in patients showing a complete response. In 2012, the policy was changed to a “reduced volume/dose RT alone” approach, involving a smaller target volume (the whole ventricle/whole brain for localized disease) without CTx. RT doses were gradually reduced to 36 Gy for primary tumors and 18 Gy for neuraxis. Results The median age was 16 years. In total, 118 and 95 patients had pathologically proven and presumed germinoma, respectively, and 151 and 62 patients had localized and multifocal or metastatic diseases, respectively. With a median follow-up of 141 months, the 10-year disease-free and overall survival rates were 91.6% and 95.6%, respectively. Recurrence rates were similar for patients receiving RT-only (9 of 137, 6.6%) and those receiving CTx + RT (4 of 73, 5.5%); all patients receiving CTx-only experienced recurrences (3 of 3, 100%). Rates were the highest in the focal RT group (10 of 29, 34.5%) but were relatively low in the whole ventricle/whole brain RT (3 of 51, 5.9%) and craniospinal irradiation groups (0 of 130, 0%). Infield failure occurred in 3 patients. Fourteen patients died of recurrence (n = 4), secondary malignancy (n = 4), CTx-related toxicity (n = 2), and others (n = 4). Among the 33 patients who received “reduced volume/dose RT alone” treatment, 2 (6.1%) experienced recurrence in the spinal cord and biopsy tract, respectively. Conclusions The additional benefit of CTx in the treatment of intracranial germinoma seems minimal. An RT-only approach with reduced target volume and dose seems reasonable.

Nineteen patients 1 month to

Retinoblastoma is a childhood malignancy of the retina. To increase the exposures of systemic chemotherapy, high-dose cyclosporine, as a P-glycoprotein modulating agent, has been combined with a standard chemotherapy. However, the effective and safe dose of cyclosporine has not been well evaluated. This study is to optimize cyclosporine dose using population pharmacokinetic modeling.Clinical data were obtained from 161 systemic chemotherapy cycles of 34 pediatric retinoblastoma patients between December 2006 and April 2015. Total 15 scenarios were simulated by 5 different doses (12, 14, 15, 17, and 20 mg/kg) of cyclosporine in 3 different weight groups (5-10, 10-15, and 15-20 kg). Numerical success ratio was obtained after assessing the simulated target cyclosporine concentration in the range of 2,000-2,500 ng/mL using NONMEM version 7.3 software.A final model was built based on a 1-compartment model with weight-normalized allometric scaling to minimize the variability of pediatric size. In simulations, numeric success ratio with 15 mg/kg/day and the above were higher than that of traditional doses in all of the scenario groups. No significant adverse responses were reported. Conclusion and Relevance: High-dose cyclosporine regimen as a P-gp modulator is required to improve the efficacy of systemic chemotherapy with caution in pediatric patients with retinoblastoma. Clearance, volume of distribution, and body weight are important parameters to consider in selecting adequate dosing regimen.