Purpose: Chronic myeloid leukemia (CML) in children, adolescents, and young adults is rare and differs from older adults. This study evaluated the outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) in young Korean CML patients during the tyrosine kinase inhibitor (TKI) era. Materials and Methods: A retrospective analysis of 35 CML patients aged < 40 years who underwent allogeneic HSCT from 2009 to 2019 was conducted using Korean Blood and Marrow Transplantation Registry data. Patients were grouped by age < 20 years at HSCT (group 1, n=15) and 20-40 years at HSCT (group 2, n=20). Survival outcomes including overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS) were analyzed using the Kaplan-Meier method. Results: The median time between diagnosis and HSCT was 8.9 months. All the patients achieved engraftment but platelet recovery was significantly slower in group 1 (p=0.034). Acute and chronic graft-versus-host disease occurred in 54.3% and 34.3%, respectively. Five-year OS, RFS, and EFS rates of total patients were 66.8%, 50.8%, and 47.6%, with better OS was observed in group 1 by multivariable analysis (p=0.048). Disease status at HSCT was a significant predictor of OS (p=0.028), RFS (p=0.003), and EFS (p=0.004). Disease progression occurred in 13 out of 35 patients (37.1%); treatment-related mortality accounted for 63.6% of deaths (7 out of 11). Conclusion When performed at a younger age, allogeneic HSCT result in superior outcome in CML. Achieving remission before HSCT is critical for improved outcomes, highlighting the importance of pretransplant remission via optimal TKI strategies and minimal residual disease monitoring.

Purpose: The Korean Society of Pediatric Neuro-Oncology (KSPNO) conducted treatment strategies for children with medulloblastoma (MB) by using alkylating agents for maintenance chemotherapy or tandem high-dose chemotherapy (HDC) with autologous stem cell rescue (ASCR) according to the risk stratification. The purpose of the study was to assess treatment outcomes and complications based on risk-adapted treatment and HDC. Materials and Methods: Fifty-nine patients diagnosed with MB were enrolled in this study. Patients in the standard-risk (SR) group received radiotherapy (RT) after surgery and chemotherapy using the KSPNO M051 regimen. Patients in the high-risk (HR) group received two and four chemotherapy cycles according to the KSPNO S081 protocol before and after reduced RT for age following surgery and two cycles of tandem HDC with ASCR consolidation treatment. Results: In the SR group, 24 patients showed 5-year event-free survival (EFS) and overall survival (OS) estimates of 86.7% (95% confidence interval [CI], 73.6 to 100) and 95.8% (95% CI, 88.2 to 100), respectively. In the HR group, more infectious complications and mortality occurred during the second HDC than during the first. In the HR group, the 5-year EFS and OS estimates were 65.5% (95% CI, 51.4 to 83.4) and 72.3% (95% CI, 58.4 to 89.6), respectively. Conclusion High intensity of alkylating agents for SR resulted in similar outcomes but with a high incidence of hematologic toxicity. Tandem HDC with ASCR for HR induced favorable EFS and OS estimates compared to those reported previously. However, infectious complications and treatment-related mortalities suggest that a reduced chemotherapy dose is necessary, especially for the second HDC.

Purpose: Hemophilia A is a genetic disorder characterized by a lack of factor VIII (FVIII). Emicizumab, a recombinant humanized bispecific monoclonal antibody, mimics the function of FVIII. In this article, we present data on an initial real-world evaluation of emicizumab use in Korean children with severe hemophilia A without inhibitors. Methods: This study was conducted from June 2020 to March 2024 at 4 centers in Korea. The participants were pediatric patients with severe hemophilia A without inhibitors who had received emicizumab treatment for over 6 months. The mean and median annualized bleeding rates (ABRs) and mean and median annual joint bleeding rates (AJBRs) were compared. Results: Each of the 21 patients in the study received an emicizumab loading regimen of 3 mg/kg weekly for 4 weeks, followed by a modified maintenance regimen of which 2 patients (9.5%) received a 1.5 mg/kg weekly dose, 3 patients (14.3%) received a 6 mg/kg dose every 4 weeks, and the remaining 16 patients (76.2%) received a 3 mg/kg dose every 2 weeks. Before emicizumab prophylaxis initiation, the mean and median ABRs for all patients were 7.04 (SD ± 5.83) and 6.52 (range 0–21.74), respectively. After receiving emicizumab treatment, the mean and mediam ABRs decreased to 0.41 and zero, respectively. Additionally, 85.7% of the patients achieved no bleeding events within 6 months of starting the treatment. Conclusion These first real-world data in Korea indicate that emicizumab is effective and safe for pediatric patients with severe hemophilia A without inhibitors.

Background: To investigate the clinical treatment status, such as treatment regimen, bleeding events, and drug dose, in patients with hemophilia B in South Korea. Methods: In this retrospective chart review, data of patients with hemophilia B from eight university hospitals were collected. Demographic and clinical data, treatment data, such as regimen and number of injections, dose of factor IX concentrate, and bleeding data were reviewed. Descriptive analyses were performed with annual data for 2019, 2020, and 2021, as well as the three years consecutively. Results: The medical records of 150 patients with hemophilia B between January 1, 2019, and December 31, 2021, were collected. Among these, 72 (48.0%) were severe, 47 (31.3%) were moderate, and 28 (18.7%) were mild. The results showed approximately two times more patients receiving prophylaxis as those receiving on-demand therapy, with 66.1% of patients receiving prophylaxis in 2019, 64.9% in 2020, and 72.1% in 2021. Annualized bleeding rates were 2.2% (± 3.1) in 2019, 1.8% (± 3.0) in 2020, and 1.8% (± 2.9) in 2021 among patients receiving prophylaxis.For the doses of factor IX concentrate, patients receiving prophylaxis received an average of 41.6 (± 11.9) IU/Kg/Injection in 2019, 45.7 (± 12.9) IU/Kg/Injection in 2020, and 60.1 (± 24.0) IU/Kg/Injection in 2021. Conclusions Clinically, prophylaxis is more prevalent than reported. Based on insights gained from current clinical evidence, it is expected that the unmet medical needs of patients can be identified, and physicians can evaluate the status of patients and actively manage hemophilia B using more effective treatment strategies.

Purpose: Hemophilia A is a genetic disorder characterized by a lack of factor VIII (FVIII). Emicizumab, a recombinant humanized bispecific monoclonal antibody, mimics the function of FVIII. In this article, we present data on an initial real-world evaluation of emicizumab use in Korean children with severe hemophilia A without inhibitors. Methods: This study was conducted from June 2020 to March 2024 at 4 centers in Korea. The participants were pediatric patients with severe hemophilia A without inhibitors who had received emicizumab treatment for over 6 months. The mean and median annualized bleeding rates (ABRs) and mean and median annual joint bleeding rates (AJBRs) were compared. Results: Each of the 21 patients in the study received an emicizumab loading regimen of 3 mg/kg weekly for 4 weeks, followed by a modified maintenance regimen of which 2 patients (9.5%) received a 1.5 mg/kg weekly dose, 3 patients (14.3%) received a 6 mg/kg dose every 4 weeks, and the remaining 16 patients (76.2%) received a 3 mg/kg dose every 2 weeks. Before emicizumab prophylaxis initiation, the mean and median ABRs for all patients were 7.04 (SD ± 5.83) and 6.52 (range 0–21.74), respectively. After receiving emicizumab treatment, the mean and mediam ABRs decreased to 0.41 and zero, respectively. Additionally, 85.7% of the patients achieved no bleeding events within 6 months of starting the treatment. Conclusion These first real-world data in Korea indicate that emicizumab is effective and safe for pediatric patients with severe hemophilia A without inhibitors.

Background: To investigate the clinical treatment status, such as treatment regimen, bleeding events, and drug dose, in patients with hemophilia B in South Korea. Methods: In this retrospective chart review, data of patients with hemophilia B from eight university hospitals were collected. Demographic and clinical data, treatment data, such as regimen and number of injections, dose of factor IX concentrate, and bleeding data were reviewed. Descriptive analyses were performed with annual data for 2019, 2020, and 2021, as well as the three years consecutively. Results: The medical records of 150 patients with hemophilia B between January 1, 2019, and December 31, 2021, were collected. Among these, 72 (48.0%) were severe, 47 (31.3%) were moderate, and 28 (18.7%) were mild. The results showed approximately two times more patients receiving prophylaxis as those receiving on-demand therapy, with 66.1% of patients receiving prophylaxis in 2019, 64.9% in 2020, and 72.1% in 2021. Annualized bleeding rates were 2.2% (± 3.1) in 2019, 1.8% (± 3.0) in 2020, and 1.8% (± 2.9) in 2021 among patients receiving prophylaxis.For the doses of factor IX concentrate, patients receiving prophylaxis received an average of 41.6 (± 11.9) IU/Kg/Injection in 2019, 45.7 (± 12.9) IU/Kg/Injection in 2020, and 60.1 (± 24.0) IU/Kg/Injection in 2021. Conclusions Clinically, prophylaxis is more prevalent than reported. Based on insights gained from current clinical evidence, it is expected that the unmet medical needs of patients can be identified, and physicians can evaluate the status of patients and actively manage hemophilia B using more effective treatment strategies.

Purpose: Hemophilia A is a genetic disorder characterized by a lack of factor VIII (FVIII). Emicizumab, a recombinant humanized bispecific monoclonal antibody, mimics the function of FVIII. In this article, we present data on an initial real-world evaluation of emicizumab use in Korean children with severe hemophilia A without inhibitors. Methods: This study was conducted from June 2020 to March 2024 at 4 centers in Korea. The participants were pediatric patients with severe hemophilia A without inhibitors who had received emicizumab treatment for over 6 months. The mean and median annualized bleeding rates (ABRs) and mean and median annual joint bleeding rates (AJBRs) were compared. Results: Each of the 21 patients in the study received an emicizumab loading regimen of 3 mg/kg weekly for 4 weeks, followed by a modified maintenance regimen of which 2 patients (9.5%) received a 1.5 mg/kg weekly dose, 3 patients (14.3%) received a 6 mg/kg dose every 4 weeks, and the remaining 16 patients (76.2%) received a 3 mg/kg dose every 2 weeks. Before emicizumab prophylaxis initiation, the mean and median ABRs for all patients were 7.04 (SD ± 5.83) and 6.52 (range 0–21.74), respectively. After receiving emicizumab treatment, the mean and mediam ABRs decreased to 0.41 and zero, respectively. Additionally, 85.7% of the patients achieved no bleeding events within 6 months of starting the treatment. Conclusion These first real-world data in Korea indicate that emicizumab is effective and safe for pediatric patients with severe hemophilia A without inhibitors.

Background: To investigate the clinical treatment status, such as treatment regimen, bleeding events, and drug dose, in patients with hemophilia B in South Korea. Methods: In this retrospective chart review, data of patients with hemophilia B from eight university hospitals were collected. Demographic and clinical data, treatment data, such as regimen and number of injections, dose of factor IX concentrate, and bleeding data were reviewed. Descriptive analyses were performed with annual data for 2019, 2020, and 2021, as well as the three years consecutively. Results: The medical records of 150 patients with hemophilia B between January 1, 2019, and December 31, 2021, were collected. Among these, 72 (48.0%) were severe, 47 (31.3%) were moderate, and 28 (18.7%) were mild. The results showed approximately two times more patients receiving prophylaxis as those receiving on-demand therapy, with 66.1% of patients receiving prophylaxis in 2019, 64.9% in 2020, and 72.1% in 2021. Annualized bleeding rates were 2.2% (± 3.1) in 2019, 1.8% (± 3.0) in 2020, and 1.8% (± 2.9) in 2021 among patients receiving prophylaxis.For the doses of factor IX concentrate, patients receiving prophylaxis received an average of 41.6 (± 11.9) IU/Kg/Injection in 2019, 45.7 (± 12.9) IU/Kg/Injection in 2020, and 60.1 (± 24.0) IU/Kg/Injection in 2021. Conclusions Clinically, prophylaxis is more prevalent than reported. Based on insights gained from current clinical evidence, it is expected that the unmet medical needs of patients can be identified, and physicians can evaluate the status of patients and actively manage hemophilia B using more effective treatment strategies.

Purpose: 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 of the kidney (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea. Materials and Methods: From January 2001 to December 2015, data of pediatric patients (0–18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed. Results: 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 (p < 0.001). Conclusion 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.