The clinical impact of primary granulocyte-colony stimulating factor prophylaxis in children with acute lymphoblastic leukemia who underwent induction chemotherapy.

BACKGROUND: Data describing the risk factors for the occurrence of severe infections in acute lymphoblastic leukemia (ALL) patients following induction chemotherapy and the role of prophylactic granulocyte-colony stimulating factor (G-CSF) in the era of antimicrobials prophylaxis are limited. METHODS: This study enrolled 188 children aged ≤18 years with newly diagnosed ALL who received Taiwan Pediatric Oncology Group ALL-2002 and 2013 treatments between January 1, 2010 and June 30, 2021. Prophylactic G-CSF was administered when a patient continues neutropenia after achieving the first bone marrow remission since June 1, 2015. Clinical factors were assessed for their association with severe infections. RESULTS: From January 2010 to May 2015, 80 children experienced a total of 11 (13.5%) episodes of severe infections; while 10 (9.2%) episodes were reported to occur in 108 patients who received prophylactic G-CSF. Reduction of severe infections occurrence did not achieve statistical significance during prophylactic G-CSF administration in ALL patients. Compared with ALL-high risk (HR) and very high risk patients with no G-CSF prophylaxis, the use of G-CSF prophylaxis significantly reduced episodes of febrile neutropenia. Occurrence of grade III-IV intestinal ileus, grade II-III oral mucositis, prolonged neutropenia, central venous catheter (CVC) placement, or the requirement insulin therapy for hyperglycemia were associated with higher risk of bloodstream infections. CONCLUSIONS: ALL-HR patients with G-CSF prophylaxis were associated with reduction of febrile neutropenia episodes. Occurrence of severe ileus, oral mucositis, hyperglycemia, CVC placement, or prolonged neutropenia were associated with severe infections in ALL patients receiving induction chemotherapy.

Refining risk stratification in paediatric B-acute lymphoblastic leukaemia: Combining IKZF1plus and Day 15 MRD positivity.

This study investigates the potential utility of IKZF1 deletion as an additional high-risk marker for paediatric acute lymphoblastic leukaemia (ALL). The prognostic impact of IKZF1 status, in conjunction with minimal/measurable residual disease (MRD), was evaluated within the MRD-guided TPOG-ALL-2013 protocol using 412 newly diagnosed B-ALL patients aged 1-18. IKZF1 status was determined using multiplex ligation-dependent probe amplification. IKZF1 deletions, when co-occurring with CDKN2A, CDKN2B, PAX5 or PAR1 region deletions in the absence of ERG deletions, were termed IKZF1plus. Both IKZF1 deletion (14.6%) and IKZF1plus (7.8%) independently predicted poorer outcomes in B-ALL. IKZF1plus was observed in 4.1% of Philadelphia-negative ALL, with a significantly lower 5-year event-free survival (53.9%) compared to IKZF1 deletion alone (83.8%) and wild-type IKZF1 (91.3%) (p < 0.0001). Among patients with Day 15 MRD ≥0.01%, provisional high-risk patients with IKZF1plus exhibited the worst outcomes in event-free survival (42.0%), relapse-free survival (48.0%) and overall survival (72.7%) compared to other groups (p < 0.0001). Integration of IKZF1plus and positive Day 15 MRD identified a subgroup of Philadelphia-negative B-ALL with a 50% risk of relapse. This study highlights the importance of assessing IKZF1plus alongside Day 15 MRD positivity to identify patients at increased risk of adverse outcomes, potentially minimizing overtreatment.

Pediatric Cardiac Lymphoblastic Lymphoma: A Case Report and Review of the Literature.

Cardiac lymphoma is rare in children. Treatment typically includes chemotherapy, combination of radiotherapy, or surgery. We report a case of stage IV precursor B lymphoblastic lymphoma with secondary involvement of the heart in an 11-year-old girl who was treated with acute lymphoblastic leukemia-based chemotherapy. Also, we review the literature on this uncommon malignancy.

Application of Drug Testing Platforms in Circulating Tumor Cells and Validation of a Patient-Derived Xenograft Mouse Model in Patient with Primary Intracranial Ependymomas with Extraneural Metastases.

Primary intracranial ependymoma is a challenging tumor to treat despite the availability of multidisciplinary therapeutic modalities, including surgical resection, radiotherapy, and adjuvant chemotherapy. After the completion of initial treatment, when resistant tumor cells recur, salvage therapy needs to be carried out with a more precise strategy. Circulating tumor cells (CTCs) have specifically been detected and validated for patients with primary or recurrent diffused glioma. The CTC drug screening platform can be used to perform a mini-invasive liquid biopsy for potential drug selection. The validation of potential drugs in a patient-derived xenograft (PDX) mouse model based on the same patient can serve as a preclinical testing platform. Here, we present the application of a drug testing model in a six-year-old girl with primary ependymoma on the posterior fossa, type A (EPN-PFA). She suffered from tumor recurrence with intracranial and spinal seeding at 2 years after her first operation and extraneural metastases in the pleura, lung, mediastinum, and distant femoral bone at 4 years after initial treatment. The CTC screening platform results showed that everolimus and entrectinib could be used to decrease CTC viability. The therapeutic efficacy of these two therapeutic agents has also been validated in a PDX mouse model from the same patient, and the results showed that these two therapeutic agents significantly decreased tumor growth. After precise drug screening and the combination of focal radiation on the femoral bone with everolimus chemotherapy, the whole-body bone scan showed significant shrinkage of the metastatic tumor on the right femoral bone. This novel approach can combine liquid biopsy, CTC drug testing platforms, and PDX model validation to achieve precision medicine in rare and challenging tumors with extraneural metastases.

Pediatric Extracranial Germ Cell Tumors: Review of Clinics and Perspectives in Application of Autologous Stem Cell Transplantation.

Pediatric extracranial germ cell tumors (GCTs) are rare, accounting for approximately 3.5% of childhood cancers. Since the introduction of platinum-based chemotherapy, the survival rate of patients has improved to more than 80%. However, poor-risk subtypes of pediatric extracranial GCTs do not respond well to chemotherapy, leading to refractory or relapsed (R/R) diseases. For example, long-term survival rates of mediastinal GCTs or choriocarcinoma are less than 50%. According to reports in recent years for adult patients with R/R GCTs, the use of high-dose chemotherapy (HDCT) combined with autologous stem cell transplantation (ASCT) has clinical advantages; however, HDCT combined with ASCT has rarely been reported in pediatric GCTs. The R/R and poor-risk groups of pediatric GCTs could benefit from HDCT and ASCT.

Rare presentation in a rare case of pancreatic extraosseous Ewing's sarcoma: A case report.

RATIONALE: Extraosseous Ewing's sarcoma is a rare tumor which is aggressive with poor prognosis; it can occur anywhere in the body, but scantily in the pancreas. Pancreatic Ewing's sarcoma is not reported commonly, with inconsistent clinical manifestations. In this regard, early recognition of this disease is very important for the patient's sake. PATIENT CONCERNS: A 16-year-old boy presented with left lower quadrant abdominal pain for 2 months, and left flank pain with dysuria for 1 month. DIAGNOSIS: Abdominal and renal ultrasonography found a mass between the spleen and left kidney as well as left renal pelvic dilatation. Abdominal computed tomography found a heterogenous mass derived from the tail of the pancreas. Serial examinations revealed that the mass was a pancreatic Ewing's sarcoma. Furthermore, no metastasis was documented. INTERVENTIONS: The tumor was totally excised after 6 months of chemotherapy, which included 10 courses of neoadjuvant chemotherapy with vincristine, epirubicin, and cyclophosphamide, alternating with ifosfamide and etoposide. The patient completed consolidation chemotherapy with vincristine, epirubicin, and cyclophosphamide, alternating with ifosfamide and etoposide for 5 courses. Radiotherapy was applied to the tumor-involved region and tumor bed. OUTCOMES: To date, the malignancy has not recurred since the treatment was completed 4 years ago. There are no complications from the treatment for the patient. LESSONS: The pancreas is a very rare extraosseous location for Ewing's sarcoma. Pancreatic extraosseous Ewing's sarcoma should be regarded as a differential diagnosis of non-urinary originated left flank pain with dysuria in adolescents.

Surgical treatment confers prognostic significance in pediatric malignant mediastinal germ cell tumors.

BACKGROUND: Primary malignant mediastinal germ cell tumors (GCTs) are rare pediatric tumors that have a poorer prognosis compared to GCTs occurring elsewhere in the body. The current study aimed to assess the prognostic factors and treatment outcomes of children with primary malignant mediastinal GCT in Taiwan. METHODS: The authors retrospectively reviewed children 0-18 years old who were newly diagnosed with primary malignant mediastinal GCT between January 1, 2005 and December 31, 2019 and were registered in the Taiwan Pediatric Oncology Group patient registry. The impact of presenting characteristics, including sex, age, tumor stage, histology subtype, surgical treatment, and chemotherapy regimens of the patients were analyzed. RESULTS: This study enrolled 52 children with malignant mediastinal GCT who had a median age of 16.0 (range, 6.0-17.9) years at diagnosis. The most common histological subtypes were mixed GCTs (n = 20) and yolk sac tumors (n = 15). Advanced disease stage and choriocarcinoma histology subtype were associated inferior outcomes. Children who received surgical treatment exhibited better outcomes compared to those who did not (5-year overall survival, 78% vs. 7%, p < .001). After comparing patients who received first-line cisplatin- and carboplatin-based chemotherapy, no difference in treatment outcomes was observed. Multivariate analysis showed that surgical management was the only independent predictor for superior OS. CONCLUSIONS: Surgical treatment is recommended for mediastinal GCT. Cisplatin-based chemotherapy was not superior to carboplatin-based chemotherapy as first-line treatment and may be avoided due to toxicity concerns.

Influence of blood group and von Willebrand factor on population pharmacokinetics and dose individualization of recombinant factor VIII in Taiwanese patients with haemophilia A.

INTRODUCTION: The large interpatient variability in the pharmacokinetic (PK) parameters of recombinant Factor VIII (rFVIII) observed in haemophilia A hinders efficient and cost-beneficial prophylactic regimen initiation. Identification of factors influencing the PK of rFVIII may shed more light on personalised treatment. AIM: This study aimed to develop a population PK model in the Taiwanese haemophilia A and evaluate the current national health insurance (NHI) reimbursement guidelines of Taiwan for haemophilia treatment. METHODS: A population PK analysis was established based on 69 Taiwanese with moderate or severe haemophilia A. A nonlinear mixed-effects modelling (NONMEM® ) was used to estimate PK parameters and their variabilities. A Monte Carlo simulation was performed to evaluate different prophylactic regimens. RESULTS: A two-compartment model with first-order elimination best described the rFVIII data. Weight-based allometric scaling was related to clearance and central volume of distribution. Blood type and baseline von Willebrand factor (VWF) were significant covariates for clearance. For single dose simulations, a time achieving target level (> 1 IU/dL) was associated with increasing rFVIII dose and VWF level. The multiple dose simulations showed that > 96.4% of patients with high VWF level (> 200%) had predicted trough level > 1 IU/dL for all dosing regimens (15-40 IU/kg, two to three times weekly). However, for twice weekly dosing, lower percentage (47.62-62.20%) of patients with blood group O and low VWF level (< 50%) achieved a predicted trough level > 1 IU/dL. CONCLUSION: The population PK of rFVIII was successfully developed. Dose adjustment based on blood type and VWF level should be considered.

Characteristics and outcomes of second cancers in patients with childhood cancer: A report from the Taiwan Pediatric Oncology Group.

BACKGROUND: Patients with childhood cancer are at increased risk for the development of second cancers. METHODS: A national multicenter survey of second cancers conducted by the Taiwan Pediatric Oncology Group retrieved retrospective data from the database at the Children Cancer Foundation in Taiwan beginning in 1995. The characteristics of second cancers and associations of patient demographic and clinical characteristics with time to death due to a second cancer were analyzed. RESULTS: We examined the records of 8782 patients with a primary cancer diagnosed between January 1, 1995 and December 31, 2013, and a total of 99 patients with a second cancer were identified. The most common type of second cancer was acute myeloid leukemia (n = 35), followed by acute lymphoblastic leukemia (n = 15), central nervous system (CNS) tumors (n = 15), and sarcomas (n = 10). Secondary hematological malignancies occurred earlier than other secondary cancers. The frequencies of second CNS tumors and second bone cancers and sarcomas were notably increased when prior radiation doses increased from zero, low dose to high dose. The overall 5-year survival of patients with a second cancer was poor (33.7%). Multivariate survival analysis revealed that the year of primary diagnosis ≤2002, secondary hematological malignancies, and age at second cancer diagnosis ≤9.3 years or >26.8 years increased the risk of death following second cancer. CONCLUSION: Children who develop a second cancer have an unfavorable outcome. Early detection and improved treatment for second cancers are needed.

Effectiveness and antimicrobial susceptibility profiles during primary antimicrobial prophylaxis for pediatric acute myeloid leukemia.

Limited data are available on antimicrobials exposure and microbiology evolution in pediatric acute myeloid leukemia (AML) patients underwent antimicrobials prophylaxis. To assess the effectiveness of antimicrobials prophylaxis, antibiotic susceptibilities of bacteria, and exposure of antimicrobials during intensive chemotherapy for AML patients, 90 consecutive de novo AML patients aged 0-18 years between January 1, 1997 and March 31, 2018 were enrolled. Vancomycin, ciprofloxacin and voriconazole prophylaxis was administered from January 1, 2010. During the preprophylaxis period, January 1997 to December 2009, 62 patients experienced a total of 87 episodes of bloodstream infection (BSI) and 17 episodes of invasive fungal infection (IFI) among 502 courses of chemotherapy. In contrast, 16 episodes of BSI occurred and no IFIs were reported to occur in 28 patients who received 247 courses of chemotherapy in the prophylaxis period. Patients who received antimicrobial prophylaxis had a significant reduction of BSI, IFI, and febrile neutropenia in comparison with patients without prophylaxis. Exposure to amikacin, carbapenem, amphotericin B was reduced in the prophylaxis period. Imipenem susceptibility of Enterobacter cloacae as well as vancomycin susceptibility of Enterococcus species were reduced in the prophylaxis period. At the time of the last follow up, patients with prophylaxis had a better subsequent 5-year overall survival rate than those without prophylaxis. Prophylactic antimicrobials administration in children with AML who undergo chemotherapy can significantly reduce the rates of life-threatening infection, exposure to antimicrobials, and might result in a better outcome.

A retrospective study of clinical features and outcome in patients with refractory or recurrent hepatoblastoma: A single institution experience.

BACKGROUND: Hepatoblastoma (HB) is the most common childhood primary hepatic malignancy. The overall survival rate in patients with HB has reached more than 80% over the past decades. The poor prognostic and high-risk HB have been defined, but the treatment and cure of refractory or relapsed HB is still an arduous task. METHODS: The complete records of HB in patients under the age of 18 at the MacKay Memorial Hospital between 1990 and 2019 were examined. RESULTS: The treatment results for 11 patients with refractory or relapsed HB are presented. The multi-modality treatment records were reviewed and the clinical characteristics associated with poor outcome included multifocal lesions, low α-fetoprotein, great vessel invasion and metastases. Delayed liver tumor surgery was carried out in eight cases. The median duration of follow-up for the 11 patients was 48.6 months (range 1.9 to 316.8 months). The 5-year and 10-year overall survival rate were 62.3% ± 15% (SE) and 49.9% ± 16.4% (SE), respectively. Most treatment-related toxicities were tolerable. The major concern during long term follow-up was irreversible high-frequency hearing loss. CONCLUSION: Patients with refractory/relapsed HB are still a thorny issue and more research is needed to improve the outcome.

Treatment outcomes of pediatric acute myeloid leukemia: a retrospective analysis from 1996 to 2019 in Taiwan.

Improvement in outcomes of children with acute myeloid leukemia (AML) is attributed to several refinements in clinical management. We evaluated treatment outcomes of Taiwanese pediatric AML patients in the past 20 years. Overall, 860 de novo AML patients aged 0-18 years and registered in the Childhood Cancer Foundation of R.O.C during January 1996-December 2019 were included. Survival analysis was performed to identify factors that improved treatment outcomes. Regardless of treatment modalities used, patients during 2008-2019 had better 5-year event-free survival (EFS) and overall survival (OS) rates than patients during 1996-2007. For patients received the TPOG-AML-97A treatment, only 5-year OS rates were significantly different between patients diagnosed before and after 2008. Patients with RUNX1-RUNX1T1 had similar relapse-free survival rates, but 5-year OS rates were better during 2008-2019. However, the survival of patients who received hematopoietic stem-cell transplantations (HSCT) did not differ significantly before and after 2008. For patients without relapse, the 5-year OS improved during 2008-2019. Non-relapse mortality decreased annually, and cumulative relapse rates were similar. In conclusion, 5-year EFS and OS rates improved during 2008-2019, though intensities of chemotherapy treatments were similar before and after 2008. Non-relapse mortality decreased gradually. Further treatment strategies including more intensive chemotherapy, novel agents' use, identification of high-risk patients using genotyping and minimal residual disease, early intervention of HSCT, and antibiotic prophylaxis can be considered for future clinical protocol designs in Taiwan.

RAS pathway mutation is an added-value biomarker in pediatric Philadelphia-negative B-cell acute lymphoblastic leukemia with IKZF1 deletions.

BACKGROUND: IKZF1deletion is an unfavorable factor in Philadelphia negative (Ph -) B-cell acute lymphoblastic leukemia. However, the effects of IKZF1 deletions co-existing genetic alterations in Ph (-) ALL have not been extensively studied. METHODS: Bone marrow samples from 368 children with Ph (-) ALL were analyzed by using multiplex ligation-dependent probe amplification kit for detection of gene deletions and Sanger sequencing for mutational analysis of RAS pathway genes. The outcome was analyzed on 215 patients treated with Taiwan Pediatric Oncology Group-ALL-2002 protocol. RESULTS: IKZF1 deletions were present in 12.8% and IKZF1plus in 6.3% of patients. Mutations of RAS pathway genes were detected in 25.0% of IKZF1-deleted patients. The 10-year event-free survival (EFS) of IKZF1-undeleted patients was significantly better compared with IKZF1-deleted patients (80.0% vs. 47.8%, p = 0.001). Compared with outcome of patients harboring IKZF1 deletion alone, no difference in EFS was observed in patients with IKZF1plus , whereas three patients carried both IKZF1 and ERG deletions had a superior 10-year EFS (100%). The 10-year EFS of patients with any gene mutation of RAS pathway was worse than that of patients with wild-type genes (79.1% vs. 61.6%, p = 0.033). In multivariate analysis, RAS pathway mutations and IKZF1 deletion were independent predictors of inferior EFS. Co-existence of IKZF1 deletion with RAS pathway mutations had a worst 10-year EFS (11.1 ± 10.5%) and 10-year OS (53.3 ± 17.6%). CONCLUSIONS: Our results showed that RAS pathway mutation is an added-value biomarker in pediatric IKZF1-deleted Ph (-) ALL patients.

Efficacy and safety of denosumab therapy for low bone mineral density in childhood cancer survivors: A report of preliminary experience.

BACKGROUND: In childhood cancer survivors, low bone mineral density (BMD) is a bone-related consequence. Efficacy of denosumab, an effective therapy for adult patients with osteoporosis, remains unclear in children. This study aimed to investigate denosumab therapy efficacy for low BMD in childhood cancer survivors. PROCEDURE: Between January 2014 and January 2018, we monitored lumbar BMD of children with cancer using dual-energy X-ray absorptiometry after completing chemotherapy with a 6-month interval. For patients with low BMD, defined as height-adjusted Z-scores of BMD < -1.5 in this study, calcium carbonate and vitamin D supplements were initially administered. When low BMD continued for at least 6 months, denosumab therapy was introduced. Calcium and vitamin D supplementation were continued in patients on denosumab. We investigated BMD change and adverse effects during denosumab therapy. RESULTS: During the study period, 20 patients received denosumab treatment. Mean height-adjusted Z-score of BMD before denosumab treatment was -2.68 but increased to -2, -1.96, and -1.33 at 0.5, 1, and 1.5 years after denosumab treatment, respectively (P = .012). In addition, hypocalcemia occurred in 40% (8/20) of patients; three patients had hypocalcemic symptoms with numbness in all four limbs. All hypocalcemic patients, except one patient who died due to relapsed leukemia, recovered well after continuous calcium supplementation. CONCLUSIONS: Denosumab is an effective treatment for low BMD in childhood cancer survivors. However, the complication of hypocalcemia might develop posttreatment.

Clinical and biological relevance of genetic alterations in pediatric T-cell acute lymphoblastic leukemia in Taiwan.

BACKGROUND: The leukemogenesis of T-cell acute lymphoblastic leukemia (T-ALL) involves multistep processes of genetic alterations. We aimed to determine the genetic alterations including common fusion transcripts, overexpression of T-cell transcription factor oncogenes, and deletion or mutation of targeted genes in pediatric T-ALL in Taiwan as well as their impact on outcomes in those treated with the Taiwan Pediatric Oncology Group-ALL-2002 protocol. PROCEDURE: Between 1995 and 2015, bone marrow samples obtained from 102 children aged <18 years consecutively diagnosed with T-ALL were examined. Thirty-two genetic alterations were examined by reverse transcription polymerase chain reaction (PCR) assays-PCR-based assays-followed by direct sequencing, real time quantitative PCR with TaqMan assays, or multiplex ligase probe amplification. RESULTS: TAL1 overexpression, CDKN2A/2B deletions, and NOTCH1 mutation were the most frequent aberrations while none had NF1, SUZ12 deletion, JAK1 or JAK2 mutations, or NUP214-ABL1 fusion in our cohort. The most frequent cooperating occurrence of genetic alterations included CDKN2A/2B and MTAP, MTAP and CDKN2B, LEF1 and PTPN2, and HOX11L2 and PHF6 mutation/deletion. NOTCH1 mutations conferred a favorable overall survival, whereas SIL-TAL1 fusion, TAL overexpression, LEF1 deletion, and PHF6 deletion/mutation were associated with an inferior outcome. By multivariate analysis, PHF6 mutation/deletion was the only independent predictor for inferior overall survival. CONCLUSIONS: The present study showed that the frequencies of genetic alterations in Taiwanese children with T-ALL differed considerably from those reported in Western countries. PHF6 mutation/deletion was an independently adverse predictor.

Treatment of childhood acute lymphoblastic leukemia with delayed first intrathecal therapy and omission of prophylactic cranial irradiation: Results of the TPOG-ALL-2002 study.

BACKGROUND: To eliminate cranial irradiation (CrRT)-related sequelae and to minimize the adverse impact of traumatic lumbar puncture (TLP) with blasts, the Taiwan Pediatric Oncology Group (TPOG) introduced a modified central nervous system (CNS)-directed regimen characterized by delayed triple intrathecal therapy (TIT) and the omission of CrRT for all children with newly diagnosed acute lymphoblastic leukemia (ALL). METHODS: This study compared the treatment outcomes of patients overall and patients with a non-CNS-1 status (CNS-2, CNS-3, or TLP with blasts) in 2 treatment eras, one before and another after the revision of the TPOG-ALL-2002 protocol by the introduction of the modification (era 1 [2002-2008] with CrRT and era 2 [2009-2012] with delayed first TIT and no CrRT). RESULTS: There were no statistically significant differences in major outcomes between the 903 patients treated in era 1 and the 444 patients treated in era 2: the 5-year event-free survival (EFS) rates were 75.7% ± 1.4% and 72.1% ± 2.4%, respectively (P = .260), and the cumulative risks of isolated CNS relapse were 4.0% ± 0.7% and 4.1% ± 1.0%, respectively (P = .960). There were also no differences between non-CNS-1 patients treated in era 1 (n = 76) and era 2 (n =28): the 5-year EFS rates were 52.3% ± 5.8% and 62.9% ± 9.4%, respectively (P = .199), and the cumulative risks of isolated CNS relapse were 6.3% ± 3.1% and 3.6% ± 3.5%, respectively (P = .639). Notably, TLP with blasts was completely eliminated after the first TIT was delayed in era 2. CONCLUSIONS: The delay of the first TIT until the clearance of circulating blasts and the total omission of CrRT did not compromise survival or CNS control in patients with childhood ALL, including those with a non-CNS-1 status.

Mutational status of NRAS, KRAS, and PTPN11 genes is associated with genetic/cytogenetic features in children with B-precursor acute lymphoblastic leukemia.

BACKGROUND: We aimed to investigate the frequencies and the association with genetic/cytogenetic abnormalities as well as prognostic relevance of RAS pathway mutations in Taiwanese children with B-precursor acute lymphoblastic leukemia (ALL), the largest cohort in Asians. PROCEDURE: Between 1995 and 2012, marrow samples at diagnosis from 535 children were studied for NRAS, KRAS, and PTPN11 mutations. The mutational status of each gene was correlated with the clinico-hematological features, recurrent genetic abnormalities, and outcomes for those treated with TPOG-ALL-2002 protocol (n = 346). RESULTS: The frequencies of NRAS, KRAS, and PTPN11 mutations were 10.8% (57/530), 10.2% (54/530), and 3.0% (16/526), respectively. NRAS mutations were associated with a higher frequency of hyperdiploidy (P = 0.01) and lower frequency of ETV6-RUNX1 (P < 0.01), whereas KRAS mutations were associated with younger age (P < 0.01), a higher frequency of KMT2A rearranged (P < 0.01) but no significant difference if infants with ALL were excluded, and inferior event-free survival (66.6% vs. 80.5%, P = 0.04). None of patients with TCF3-PBX1 had KRAS mutation (P = 0.02). CONCLUSIONS: Our study showed that the frequency of KRAS mutations in Taiwan was significantly higher than that reported in Caucasians. The occurrence of RAS pathway mutations was associated with recurrent genetic/cytogenetic abnormalities in pediatric B-precursor ALL.