Children's Cancer Group Research Articles

Abstract B002: A therapeutically targetable positive feedback loop between long noncoding RNA-HLX-2-7, HLX, and MYC that promotes childhood cancer group 3 medulloblastoma

Abstract Medulloblastoma (MB) is the most common malignant pediatric brain tumor. MB is categorized into four main molecular subgroups: wingless pathway (WNT)-activated, sonic hedgehog pathway (SHH)-activated, group 3 (G3), and group 4 (G4). Although the driver pathways for G3 and G4 MB are unclear, most of these tumors are characterized by c-Myc and MYCN signatures, respectively. Recent studies suggest that long non-coding RNAs (lncRNAs) contribute to medulloblastoma formation and progression. We have identified lncRNA, lnc-HLX-2-7, as an oncogene and a potential therapeutic target in group 3 (G3) medulloblastomas. lnc-HLX-2-7 RNA specifically accumulates in the promoter region of its host coding gene HLX, a sense overlapping gene of lnc-HLX-2-7, which activates HLX expression by recruiting multiple factors, including enhancer elements. RNA sequencing and chromatin immunoprecipitation reveal that HLX binds to and activates the promoters of several oncogenes, including TBX2, LIN9, HOXM1, and MYC. Intravenous treatment with cerium oxide nanoparticle–coated antisense oligonucleotides targeting lnc-HLX-2-7 (CNP-ASO-lnc-HLX-2-7) and lipid nanoparticle-coated HLX (LNP-si-HLX) inhibits tumor growth by 40-50% in an intracranial medulloblastoma xenograft mouse model (p<0.01). Combining nanoparticle-coated lnc-HLX-2-7 and HLX with standard-of-care cisplatin further inhibits tumor growth and significantly prolongs mouse survival compared with monotherapy (p<0.01). Thus, the lnc-HLX-2-7–HLX–MYC axis is important for regulating G3 medulloblastoma progression, providing a strong rationale for using lnc-HLX-2-7 and HLX as therapeutic targets for G3 MBs. Citation Format: Ranjan R Perera. A therapeutically targetable positive feedback loop between long noncoding RNA-HLX-2-7, HLX, and MYC that promotes childhood cancer group 3 medulloblastoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr B002.

Survival and prognostic factors for relapsed childhood acute lymphoblastic leukemia after treatment with the Chinese children's cancer group ALL-2015 protocol: a single center results.

This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University. The study cohort involving 852 evaluable children with ALL reported a total of 146 relapses during a median follow-up period of 53 months. The primary outcomes measured were the second complete remission (CR2) rates, and 5-year event-free survival (EFS) and overall survival (OS) for patients who received re-treatment post-relapse. Patient data were stratified by ALL subtype (B-ALL vs. T-ALL), age at relapse, site of relapse, and timing of relapse. Univariate and multivariate analyses were performed to identify factors significantly associated with EFS and OS. As of March 31, 2023, 146 relapses were observed, including 128 B-ALL and 18 T-ALL cases. The 8-year CIR was (19.8 ± 1.6)%, with no significant difference between B-ALL and T-ALL (P=0.271). Among the 105 patients who underwent re-treatment, 70 achieved CR2, resulting in a CR2 rate of 67.6%. The 5-year EFS and OS rates for re-treated patients were (45.0 ± 5.4)% and (56.9 ± 5.2)%, respectively. Significant differences in 5-year OS and EFS were found between B-ALL and T-ALL relapses (P < 0.001). The 5-year EFS and OS varied significantly with relapse timing and site of relapse. Factors significantly affecting EFS after relapse included the site of relapse, immunophenotyping, CR2 achievement, and hematopoietic stem cell transplantation (HSCT). Immunophenotyping, CR2 achievement, and HSCT were also identified as significant factors affecting OS after relapse. Despite treatment with the CCCG-ALL-2015 protocol, a significant relapse rate was observed, with 72% of children opting for re-treatment post-relapse. The study highlights the importance of considering specific prognostic factors to inform tailored treatment strategies for relapsed childhood ALL. The findings emphasize the need for further research into improving therapeutic approaches for this patient population. This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University.

Survival of Children with Acute Lymphoblastic Leukemia with Risk Group-Based Protocol Changes: A Single Center Experience with 460 Patients over a 20-Year Period.

Recent treatments for pediatric acute lymphoblastic leukemia (ALL) are founded on risk stratification. We examined the survival rates and prognostic factors of patients over a 20-year period at a single institution. This study analyzed patients diagnosed with ALL and treated at the Pediatric Department of Samsung Medical Center (SMC). Patients were categorized into standard-risk (SR), high-risk (HR), and very high-risk (VHR) groups. The SMC protocol for the HR group underwent two changes during the study period: A modified Children's Cancer Group (CCG)-1882 protocol was used from 2000 to 2005, the Korean multicenter HR ALL-0601 protocol from 2006 to 2014, and the Korean multicenter HR ALL-1501 protocol from 2015 to 2019. Of the 460 patients, complete remission was achieved in 436 patients (94.8%). The 10-year overall survival rate (OS) was 83.8±1.9% for all patients. OS according to the SMC risk group was as follows: 95.9±1.4% in the SR group, 83.8±3.6% in the HR group, and 66.2±6.9% in the VHR group. The 5-year OS within the HR group varied according to the treatment protocol: 73.9±7.5%, in the modified CCG-1882 protocol, 83.0±3.9%, in the 0601 protocol, and 96.2±2.6%, in the 1501 protocol. For those aged 15 years and older, the OS was only 56.5±13.1%. Relapse occurred in 71 patients (15.4%), and the OS after relapse was 37.7±6.0%. The treatment outcomes of patients with ALL improved markedly. However, there is a need to further characterize adolescents and young adult patients, as well as those who have experienced relapses.

Treatment of relapsed acute lymphoblastic leukemia in children: an observational study of the Japan Children's Cancer Group.

The Japan Children's Cancer Group Relapsed Acute Lymphoblastic Leukemia (ALL) Committee conducted a prospective observational study (ALL-R14) to explore promising reinduction therapy regimens for relapsed ALL to investigate in future trials. In Japan, clofarabine- and bortezomib-based regimens were of interest since they were newly introduced for ALL in the study period (2015-2018). Seventy-five pediatric patients were enrolled in total. The 2-year event-free/overall survival rates in patients with first (n = 59) or second (n = 11) relapse were 40.1% (95% confidence interval [CI]: 25.5-52.3%)/66.3% (95% CI 52.3-77.0%) and 34.1% (95% CI 9.1-61.6%)/62.3% (95% CI 27.7-84.0%), respectively. Clofarabine- or bortezomib-based regimens were used only in patients with high-risk disease. The first reinduction therapy used in the 41 patients with early or multiple relapsed B-cell precursor ALL was clofarabine in 7 patients and bortezomib in 9 patients. The odds ratio for reinduction failure risk with a clofarabine- or bortezomib-based regimen compared with other regimens was 9.0 (95% CI 0.9-86.4, P = 0.057) or 1.9 (95% CI 0.4-8.7, P = 0.42), respectively. Thus, clofarabine- or bortezomib-based regimens had no obvious advantage as reinduction therapy for relapsed ALL in children.

Myeloid sarcoma, spectrum of clinical characteristics, prognostic impact, and treatment outcome

BackgroundAcute leukemia may present with extramedullary (EM) tissues. Myeloid sarcoma (MS) and leukemia cutis (LC) are considered extramedullary diseases. This study aims to evaluate the incidence, clinical characteristics, and prognostic factors affecting the outcome of pediatric patients with myeloid sarcoma at the pediatric oncology center from July 2007 to December 2017. Radiological imaging was used to stage the tumor, biopsy was done for pathological diagnosis, and bone marrow aspirate for morphology, flow cytometry, cytogenetics, and molecular analysis. Patients received chemotherapy protocols based on those used by the Children's Cancer Group for acute myeloid leukemia (AML).ResultThe study included 91 (13.2%) of 687 pediatric patients with acute myeloid leukemia, with a male-to-female ratio of 1.9 to 1. Prognostic factors that improved the patient’s 5-year overall survival (OS) were age > 5 years old, molecular and cytogenetic detection of t (8; 21), inv 16, presence of a single and small size lesion < 5 cm, negative CNS lesion, and achieved radiological response in isolated disease or radiological and marrow complete remission in disseminated disease post induction 1 with significant P value. Relapse, particularly early relapse, worsens the OS and EFS by 10% and 7.7%, respectively.ConclusionPatients over five with low-risk disease based on cytogenetics, a small, single, negative CNS lesion, and a complete response post induction 1 had better outcomes, with no significant difference between those with isolated extramedullary disease and those with marrow dissemination. Early relapse harms the outcome. The study group’s 5-year OS and EFS rates are 51.4% and 49.4%, respectively.

Risk factors for recurrence of childhood acute lymphoblastic leukemia after treatment with the Chinese Children's Cancer Group ALL-2015 protocol

To investigate the cumulative incidence of recurrence (CIR) in children with acute lymphoblastic leukemia (ALL) after treatment with the Chinese Children's Cancer Group ALL-2015 (CCCG-ALL-2015) protocol and the risk factors for recurrence. A retrospective analysis was conducted on the clinical data of 852 children who were treated with the CCCG-ALL-2015 protocol from January 2015 to December 2019. CIR was calculated, and the risk factors for the recurrence of B-lineage acute lymphoblastic leukemia (B-ALL) were analyzed. Among the 852 children with ALL, 146 (17.1%) experienced recurrence, with an 8-year CIR of 19.8%±1.6%. There was no significant difference in 8-year CIR between the B-ALL group and the acute T lymphocyte leukemia group (P>0.05). For the 146 children with recurrence, recurrence was mainly observed in the very early stage (n=62, 42.5%) and the early stage (n=46, 31.5%), and there were 42 children with bone marrow recurrence alone (28.8%) in the very early stage and 27 children with bone marrow recurrence alone (18.5%) in the early stage. The Cox proportional-hazards regression model analysis showed that positive MLLr fusion gene (HR=4.177, 95%CI: 2.086-8.364, P<0.001) and minimal residual disease≥0.01% on day 46 (HR=2.013, 95%CI: 1.163-3.483, P=0.012) were independent risk factors for recurrence in children with B-ALL after treatment with the CCCG-ALL-2015 protocol. There is still a relatively high recurrence rate in children with ALL after treatment with the CCCG-ALL-2015 protocol, mainly bone marrow recurrence alone in the very early stage and the early stage, and minimal residual disease≥0.01% on day 46 and positive MLLr fusion gene are closely associated with the recurrence of B-ALL.

Clinical outcomes and prognostic factors of parameningeal rhabdomyosarcoma in children and adolescents: results of two consecutive protocols.

Parameningeal rhabdomyosarcoma (PM-RMS) accounts for about 20% of all rhabdomyosarcoma (RMS) cases. At present, most research on PM-RMS has been conducted in Europe and the United States of America, and research in China has been very limited. This study sought to analyze the clinical outcomes and prognostic factors of PM-RMS in children and adolescents from two consecutive protocols at Beijing Children's Hospital (BCH). A total of 80 patients aged up to 18 years with previously untreated PM-RMS who had received treatment under two consecutive protocols [i.e., either the BCH-RMS-2006 protocol or the Chinese Children Cancer Group (CCCG)-RMS-2016 protocol] were included in the statistical analysis. The Kaplan-Meier method was used for the survival analysis, and Cox regression was used for the univariate and multivariate analyses. Of the 80 patients enrolled in the study, 69 (86.2%) had meningeal invasion (MI). Of these 69 MI patients, 18 (22.5%) had cranial nerve palsy (CNP), 64 (80.0%) had cranial base bone erosion (CBBE), 25 (31.3%) had intracranial extension (ICE), and 2 (2.5%) had positive cerebrospinal fluid (CSF) tumor cells. The median follow-up time was 20.5 months (range, 5-100 months). The 5-year overall survival (OS) and progression-free survival (PFS) rates for the entire cohort were 51.7% and 45.6%, respectively. The 5-year OS rates of the patients who received the BCH-RMS-2006 protocol (18/80, 22.5%) and the CCCG-RMS-2016 protocol (62/80, 77.5%) were 33.3% and 57.0%, respectively (P<0.05), while the PFS rates of these patients were 22.2% and 53.6%, respectively (P<0.05). In relation to the PM-RMS patients with MI, the 5-year OS rates were 21.4% and 52.7%, and the 5-year PFS rates were 14.3% and 51.1% for the patients who received the old and new regimens, respectively (P<0.05). The extent of surgical resection had no significant effect on survival. The multivariate analysis showed that the coexistence of CBBE and ICE, no radiotherapy, a poor response to induction chemotherapy, and the BCH-RMS-2006 protocol were risk factors affecting PFS and OS. Of the patients examined in this study, those with PM-RMS with CBBE accompanied by ICE had the worst prognosis. The patients with MI benefited from intensive chemotherapy combined with radiation therapy, but the effect of surgery was very limited.

The correlation of asparaginase enzyme activity levels after PEG-asparaginase administration with clinical characteristics and adverse effects in Chinese paediatric patients with acute lymphoblastic leukaemia.

Studies on asparaginase enzyme activity (AEA) monitoring in Chinese patients receiving PEG-asparaginase remain limited. We monitored AEA in paediatric patients diagnosed with acute lymphoblastic leukaemia (ALL) and treated according to the Chinese Children's Cancer Group study protocols, CCCG-ALL-2015/CCCG-ALL-2020 protocols. We measured the AEA at days 7 ± 1 and 14 ± 1 and analysed their association with patient characteristics and PEG-asparaginase-related adverse effects (AEs). We measured 2147 samples from 329 patients. Mean AEA levels (interquartile range) were 931 iu/L (654-1174 iu/L) at day 7 ± 1 and 664 iu/L (463-860 iu/L) at day 14 ± 1. The AEA levels were higher in younger children and increased with the cumulative dose numbers. PEG-asparaginase inactivation rate was 19.1%, and the silent inactivation (SI) rate was 12.5%. Nine patients were identified with allergic-like reactions. Hypofibrinogenaemia, hypertriglyceridaemia, pancreatitis and thrombosis were associated with older age, whereas hypoglycaemia was associated with younger age. The risk of hypertriglyceridaemia and hypoglycaemia increased with cumulative dose numbers of PEG-asparaginase. Except for hypofibrinogenaemia, elevated AEA levels did not increase the risk of PEG-asparaginase-related AEs. Drug monitoring can be utilized as guidance for treatment decision-making. Individualizing asparaginase doses do not reduce toxicities. The treatment target of PEG-asparaginase remains to achieve sustained and adequate activity.

Trends in incidence and survival of childhood cancers in Khon Kaen, Thailand (2000–2019): a population-based Khon Kaen Cancer Registry study

BackgroundIn Thailand, the national health care system and nationwide standard treatment protocols have evolved over time, potentially influencing the trends in the incidence and survival rates of childhood cancers. However, further investigations are required to comprehensively study these trends in Khon Kaen, Thailand.MethodsChildhood cancer patients aged 0–14 years (n = 541) who were diagnosed with one of the five most common cancers between 2000 and 2019 from the population-based Khon Kaen Cancer Registry were enrolled. Descriptive statistics were used to analyse the demographic data, which are presented as numbers, percentages, means, and standard deviations. The trends in incidence between 2000 and 2019, including age-standardized incidence rates (ASRs) and annual percent changes (APCs), were analysed using the Joinpoint regression model. Survival analysis was performed for 5-year relative survival rates (RSRs) according to the Pohar Perme estimator and Kaplan–Meier survival curves.ResultsThe ASRs of the overall top 5 childhood cancer groups were 67.96 and 106.12 per million person-years in 2000 and 2019, respectively. Overall, the APC significantly increased by 2.37% each year for both sexes. The overall 5-year RSRs were 60.5% for both sexes, 58.2% for males, and 63.9% for females. The highest 5-year RSR was for germ cell tumours (84.3%), whereas the lowest 5-year RSR was for neuroblastoma (29.1%).ConclusionsThe incidence and survival rates of childhood cancers in Khon Kaen, Thailand, varied according to sex. The incidence trends increased over time, meanwhile, the relative survival rates rose to satisfactory levels and were comparable to those of other nations with similar financial status. The implementation of national health policies and adherence to national treatment guidelines have improved cancer diagnosis and treatment outcomes.

Antineoplastic therapy is an independent risk factor for dental caries in childhood cancer patients: a retrospective cohort study.

To evaluate the antineoplastic therapy (AT) as a risk factor for dental caries lesions independent of other risk factors such as income, family education, stimulated salivary flow rate, hygiene habits, frequency of sugar intake, and microbiota in childhood cancer (CC) patients. 72 individuals were divided into CC patients (n=36) and healthy individuals (control group - CT n=36). Demographic data, hygiene habits, frequency of sugar intake, CC type, and AT were collected. Stimulated salivary flow rate was measured and the presence and concentration of Streptococcus mutans were assessed using a real-time polymerase chain reaction (qPCR) technique. Clinical evaluations included plaque index (PI) and decayed-missing-filled-teeth index (dmft/DMFT). Descriptive statistics, T-test, Mann-Whitney test, chi-square test, Fisher's exact test, and two-way analysis of variance were used for data analysis (p<0.05). At the time of oral evaluation, both groups exhibited similar ages with means of 12.0±3.9 years old for CC and 12.0±4.0 years old for CT patients. All CC patients underwent chemotherapy with nine also undergoing radiotherapy. Significant differences were observed between the groups in terms of color/race, income, family education, and hygiene habits. However, no statistically significant differences were found between groups regarding the frequency of sugar intake, stimulated salivary flow rate, or the concentration of Streptococcus mutans (qPCR technique). For clinical parameters, the DMF (CC:1.80, CT: 0.75), decayed (CC: 0.88, CT: 0.19), missing (CC: 0.25, CT:0), and PI (CC: 30.5%, CT: 22.6%) were higher in the CC group (p<0.05). Childhood cancer (CC) patients undergoing antineoplastic therapy (AT) exhibit a higher prevalence of dental caries, regardless of income/education, frequency of sugar intake, stimulated salivary flow rate, and microbiota.

A nationwide phase II study of delayed local treatment for children with high-risk neuroblastoma: The Japan Children's Cancer Group Neuroblastoma Committee Trial JN-H-11.

Survival rates of patients with high-risk neuroblastoma are unacceptable. A time-intensified treatment strategy with delayed local treatment to control systemic diseases has been developed in Japan. We conducted a nationwide, prospective, single-arm clinical trial with delayed local treatment. This study evaluated the safety and efficacy of delayed surgery to increase treatment intensity. Seventy-five patients with high-risk neuroblastoma were enrolled in this study between May 2011 and September 2015. Delayed local treatment consisted of five courses of induction chemotherapy (cisplatin, pirarubicin, vincristine, and cyclophosphamide) and myeloablative high-dose chemotherapy (melphalan, etoposide, and carboplatin), followed by local tumor extirpation with surgery and irradiation. The primary endpoint was progression-free survival (PFS). The secondary endpoints were overall survival (OS), response rate, adverse events, and surgical complications. Seventy-five patients were enrolled, and 64 were evaluable (stage 3, n=8; stage 4, n=56). The estimated 3-year PFS and OS rates (95% confidence interval [CI]) were 44.4% [31.8%-56.3%] and 80.7% [68.5%-88.5%], resspectively. The response rate of INRC after completion of the treatment protocol was 66% (42/64; 95% CI: 53%-77%; 23 CR [complete response], 10 VGPR [very good partial response], and nine PR [partial response]). None of the patients died during the protocol treatment or within 30days of completion. Grade 4 adverse effects, excluding hematological adverse effects, occurred in 48% of patients [31/64; 95% CI: 36%-61%]. Major Surgical complications were observed in 25% of patients [13/51; 95% CI: 14%-40%]. This study indicates that delayed local treatment is feasible and shows promising efficacy, suggesting that this treatment should be considered further in a comparative study of high-risk neuroblastoma.

Effect of rituximab on immune status in children with aggressive mature B-cell lymphoma/leukemia–a prospective study from CCCG-BNHL-2015

BackgroundLimited research has been conducted on the impact of rituximab on immune function and the incidence of side effects in children undergoing combination chemotherapy for aggressive mature B-cell lymphoma/leukemia. MethodsClinical data from 85 patients with primary pediatric aggressive mature B-cell lymphoma/leukemia, treated according to the Chinese Children's Cancer Group (CCCG)-mature B-cell non-Hodgkin lymphoma (BNHL)-2015 protocol from June 1, 2015, to December 1, 2022, were collected from three tertiary medical centers in China. Patients with pre-existing malignancies or primary immune deficiencies (PIDs) were excluded. ResultsBetween June 1, 2015, and December 1, 2022, 85 patients (65 [76.5%] boys and 20[23.5%] girls; mean age, 6.95 years) were enrolled, and immune data at baseline during follow-up were analyzed. At the end of chemotherapy, a higher proportion of patients in the R4 group exhibited a decrease in peripheral blood CD3− CD19+ B cells (20[100%] of 20 vs 13[47.8%] of 18, p = 0.04), CD3+ T cells (21[91.3%] of 23 vs 14[60.9%] of 23, p = 0.016), and serum IgM (14[60.9%] of 23 vs 4[17.4%] of 23, p = 0.003) compared to the R3 group. However, these differences were no longer statistically significant six months after chemotherapy administration. The combination of rituximab with AA was associated with a higher incidence of significant thrombocytopenia (49[81.7%] of 60 vs 29[52.7%] of 55, p = 0.001) and infection (35[58.3%] of 60 vs 17[30.9%] of 55, p = 0.003) compared to AA alone. Furthermore, the combination of rituximab with BB was linked to a higher incidence of significant thrombocytopenia (32[52.5%] of 61 vs 31[31.0%] of 100, p = 0.007) compared to BB alone. ConclusionsWhile the effects of rituximab in combination with intense chemotherapy for childhood aggressive mature B-cell lymphoma/leukemia on children's immune function generally recovers within six months it may still prolong the recovery from immunoglobulinemia, posing a risk of secondary infections. Further studies are required to identify children with potential primary immunodeficiencies.

Epidemiology of childhood acute leukemias

Abstract Acute leukemias are the largest group of childhood cancers. According to the latest WHO data 80,491 leukemias were diagnosed in 2020 alone. In the coming years the incidence worldwide will continue at a similar level. The morbidity correlates with biological determinants such age, gender and race. The etiology of leukemia formation is complex and depends on genetic, physiological, environmental and even prior treatment-related factors. Both the incidence and curability are also influenced by age, gender, and race. The peak of incidence of leukemia occurs between the ages of 1–4 years and 9–19. The etiology of leukemia formation is complex and depends on genetic, physiological, environmental and even prior treatment-related factors. Boys suffer from leukemia more often than girls. In 2020 58.2% of diagnoses were for boys. Numerous factors contribute to the development of acute leukemia. In the case of young children, a notable association exists between acute leukemia and infections caused by viruses such as EBV or HHV-6. Furthermore, the risk of leukemia can be elevated by allergies, which involve Th1/Th2 lymphocyte-dependent mechanisms. A familial predisposition to tumorigenesis in children is observed in Li-Fraumeni Syndrome. Also, genetic diseases such as Down syndrome and Fanconi anemia are associated with an increased risk of acute leukemia. Previous exposure to radiation therapy or the use of anti-cancer drugs can also lead to the development of secondary cancers, including leukemia. The analysis of risk factors can be used to support efforts aimed to reduce potentially harmful exposure and to decrease the risk of disease.

Childhood and Adolescent Central Nervous System Tumours in Spain: Incidence and Survival over 20 Years: A Historical Baseline for Current Assessment.

Central nervous system (CNS) neoplasms are highly frequent solid tumours in children and adolescents. While some studies have shown a rise in their incidence in Europe, others have not. Survival remains limited. We addressed two questions about these tumours in Spain: (1) Is incidence increasing? and (2) Has survival improved? This population-based study included 1635 children and 328 adolescents from 11 population-based cancer registries with International Classification of Childhood Cancer Group III tumours, incident in 1983-2007. Age-specific and age-standardised (world population) incidence rates (ASRws) were calculated. Incidence time trends were characterised using annual percent change (APC) obtained with Joinpoint. Cases from 1991 to 2005 (1171) were included in Kaplan-Meier survival analyses, and the results were evaluated with log-rank and log-rank for trend tests. Children's survival was age-standardised using: (1) the age distribution of cases and the corresponding trends assessed with Joinpoint; and (2) European weights for comparison with Europe. ASRw 1983-2007: children: 32.7 cases/106; adolescents: 23.5 cases/106. The overall incidence of all tumours increased across 1983-2007 in children and adolescents. Considering change points, the APCs were: (1) children: 1983-1993, 4.3%^ (1.1; 7.7); 1993-2007, -0.2% (-1.9; 1.6); (2) adolescents: 1983-2004: 2.9%^ (0.9; 4.9); 2004-2007: -7.7% (-40; 41.9). For malignant tumours, the trends were not significant. 5-year survival was 65% (1991-2005), with no significant trends (except for non-malignant tumours). CNS tumour incidence in Spain was found to be similar to that in Europe. Rises in incidence may be mostly attributable to changes in the registration of non-malignant tumours. The overall malignant CNS tumour trend was compatible with reports for Southern Europe. Survival was lower than in Europe, without improvement over time. We provide a baseline for assessing current paediatric oncology achievements and incidence in respect of childhood and adolescent CNS tumours.

10121-BT-8 CLINICOPATHOLOGICAL ANALYSIS OF CENTRAL NERVOUS SYSTEM GERM CELL TUMORS -387CASES IN THE JCCG COHORT AND THE IGCT CONSORTIUM COHORT

Abstract BACKGROUND Central nervous system germ cell tumors (CNS GCTs) are rare primary tumors that tend to occur in East Asian boys. In Japan, the Japan Children's Cancer Group (JCCG) and the CNS GCT Genome Analysis Consortium (iGCT Consortium) have been accumulating clinical and pathological data on CNS-GCT cases. METHODS Statistical analyses were performed on 178 cases in the JCCG's Solid Tumor Observational Study (2016-2022) and 209 cases in the iGCT Consortium (2011-2021) for age, gender, site of origin, and pathological diagnosis. RESULTS There were 306 primary cases and 44 recurrent cases, 296 (77%) males and 90 (23%) females, with a median age of 13 years, 11 years for JCCG and 16 years for iGCT Consortium, with differences between these two cohorts. The most common pathological diagnosis was germinoma in 200 cases (52%). Non-germinomatous germ cell tumors (NGGCTs) in 167 cases (43%), of which 69 cases (18%) were mixed GCT with germinoma, 34 cases were immature teratoma, mature teratoma in 32 cases (8%), yolk sac tumor in 20 cases (5%), mixed GCT without germinoma in 5 cases (1%), choriocarcinoma in 5 cases (1%), embryonal carcinoma in 2 cases (0.5%). The median age of patients with germinoma was 15 years, while with other histological types was 12 years. The pineal gland was the most common site (208 cases, 56%) and 114 cases (31%) occurred in the neurohypophysis. 38 cases of them were bifocal. Tumor development in the basal ganglia occurred in 40 cases (11%), and multiple lesions were seen in 37 cases (10%). In the neurohypophysis, the male-to-female ratio was 1:1, while in the pineal region was 11:1. In the neurohypophysis, 67% had germinoma and 9% had teratoma, whereas, in the pineal regions, 50% had germinoma and 19% had teratoma. CONCLUSIONS CNS GCT is closely correlated with age, sex, site of origin, and histology.

A Nationwide Clinical Trial ALL-B12: An Optimized Therapy for Pediatric B-Precursor Acute Lymphoblastic Leukemia with Excellent Overall Survival and Minimal Non-Relapse Mortality: A Report from the Japan Children's Cancer Group

Background: Advancements in treatment have significantly improved therapeutic outcomes for pediatric acute lymphoblastic leukemia (ALL) and relapsed ALL. However, there remains a need for therapies that minimize relapse in high-risk groups and avoid long-term complications. To address this gap. we conducted the nationwide clinical trial ALL-B12, aimed at newly diagnosed B-precursor ALL aged 1-18 years. Methods: ALL-B12 enrolled participants from November 2012 to November 2017. Patients were stratified based on the NCI classification (age and WBC count at diagnosis). Those with NCI-SR and NCI-HR were assigned to the standard risk group (SR) and the intermediate group (IR), respectively. Poor steroid responders and those with high-risk genomic abnormalities were assigned to the high risk group (HR). A treatment regimen, including 4-drug remission induction, early consolidation, HD-MTX-containing intensification, re-induction, and maintenance, was implemented. Anthracycline dose in the induction therapy was reduced in SR patients. In contrast, early consolidation was intensified with L-ASP for a part (randomized) of the IR and the entire HR. Patients classified as CNS3 were treated as high risk, receiving 12 Gy cranial irradiation; prophylactic cranial irradiation was avoided in non-CNS3 groups. Allogeneic hematopoietic cell transplantation (allo-HCT) during the first remission was restricted to those in the very high-risk group with specific genomic abnormalities (e.g., hypodiploid &amp;lt;44 and TCF3-HLF) and residual MRD above 10^-3 at the end of early consolidation. A randomized comparison was carried out within each risk group to identify the optimal treatment. We assessed the effectiveness of intensification with VCR/DEX pulses for the SR, the impact of L-ASP intensification for the IR, and compared block-type treatment and HD-MTX intensified with VCR and L-ASP (HD-MTX/VL) for the HR. The primary outcome measure was the 5-year event-free survival (EFS) rate. Results: In total, 1,936 patients were enrolled, with 1,804 patients receiving protocol treatment after excluding ineligible patients such as those with BCR-ABL1 positivity. The percentage of patients achieving remission at the end of early consolidation was 98.9%. The overall 5-year EFS and OS probability were 85.2% (95%CI 83.5-86.8%) and 94.3% (95%CI 93.1-95.3%), respectively. Only 1.7% of patients underwent allo-HCT during the first remission. The mortality rate during induction was just 0.6%, with non-relapse mortality (NRM) after remission at 0.6%. The overall relapse incidence was 13.2%, and the overall CNS relapse rate was 1.9%. Among patients assigned to risk groups, 1,107 (62.7%) were assigned to the SR, 459 (26.0%) to the IR, and 200 (11.3%) to the HR. The 5yEFS for the SR was 89.9%. The post-randomization EFS rates for those with and without VCR/DEX intensification were 90.7% and 90.1%, respectively, indicating nearly identical survival curves (p = 0.73). The EFS for the IR was 79.7%, but L-ASP intensification was expected to be effective, the EFS for groups with and without ASP intensification was 82.1% and 77.9%, respectively, failing to reach statistical significance (p = 0.31). The EFS for the HR was 75.5%, with overlapping survival curves for block treatment (75.7%) and HD-MTX/VL (74.2%) (p = 0.92). MRD dynamics were associated with prognosis, and early consolidation therapy enhanced by ASP resulted in better MRD clearance. MRD of 10^-4 was associated with poor prognosis at both the end of induction and the end of early consolidation. Conclusion: In our multi-center clinical trial, we observed excellent outcomes in a diverse group of patients nationwide. Using the NCI criteria for stratification, a significant number of patients were categorized into the SR. Additionally, introducing L-ASP during early consolidation decreased the number of MRD-positive patients, which subsequently reduced the subset needing allo-HCT. This strategic adjustment in treatment intensity resulted in both high EFS rates and low NRM. Given the rise of immunotherapy and its promising results for recovery even post-relapse, there's a pressing need to enhance overall outcomes while minimizing non-relapse mortality. We anticipate refining our stratification further and integrating immunotherapy and other innovative treatments into our approach.

Outcome of Newly Diagnosed Children and Adolescents with Localized Lymphoblastic Lymphoma Treated on JPLSG-LLB-NHL03 Trial: A Report from the Japan Children's Cancer Group

Background: Localized lymphoblastic lymphoma (LL) is rare in pediatric patients and have a favorable outcome. Although the Berlin-Frankfurt-Münster (BFM) 90/95 protocol has been considered standard therapy, this regimen is too intense for patients with localized disease and the total doses of anthracycline and alkylating agents are high. To resolve these problems, we planned a clinical trial to examine the efficacy and safety of a modified BFM regimen for patients with localized LL. We report the 3-year event-free survival (EFS) and overall survival (OS) rate for children and adolescents with localized LL treated on JPLSG-LLB-NHL03 trial. Procedure: From November 2004 to October 2019, 41 newly diagnosed patients up to 18 years of age enrolled on LLB-NHL03 with localized LL (Murphy stages I and II) and with either T- or B- cell immunophenotype. Staging procedures included: bilateral bone marrow aspirates and biopsies, lumbar puncture, CT or MRI of abdomen, chest X-ray, and bone scintigraphy or whole body bone X-ray. Central pathology review consisted of examination of morphology and immunophenotypic and any available genetic data from the original diagnostic biopsy to confirm the submission diagnosis and assign phenotypic lineage. Treatment consisted of 5 phases: induction (prednisolone 60mg/m 2, day 0-27; vincristine 1.5mg/m 2, day0,7,14,21; cyclophosphamide 1g/m 2, day 0; daunorubicin 30mg/m 2, day 0,7; E.coli L-asparaginase 6,000 units/m 2, 9 total doses, and intrathecal methotrexate and hydrocortisone, day 0,14), consolidation (mercaptopurine 60mg/m 2, day 0-27; cyclophosphamide 500mg/m 2, day0,14; cytarabine 75mg/m 2, 12 total doses and intrathecal therapy methotrexate and hydrocortisone, day 0,14) , CNS prophylaxis (high dose methotrexate 3g/m 2, day0,7,14; and intrathecal methotrexate and hydrocortison, day 0. Standard leucovorin dosing, 15mg/m 2 intravenous every 6h, is delivered 36h after the start of the methotrexate infusion and is continued until methotrexate levels are less than 0.1 μmol/L.), delayed intensification (prednisolone 60mg/m2, day 0-13; vincristine 1.5mg/m 2, day 0,7,14; cyclophosphamide 1g/m 2, day0; daunorubicin 30mg/m 2, day 0,7; L-asparaginase 6,000 units/m 2, 6 total doses and intrathecal methotrexate and hydrocortison, day 0,14), and maintenance (mercaptopurine 60mg/m 2 daily and methotrexate 20mg/m 2 weekly). Total duration of therapy was 24 months from diagnosis. Patients received 120mg/m 2 of anthracycline (daunorubicin) , 3 g/m 2 of cyclophosphamide and 7 doses of intrathecal therapy. Results: Of the 41 patients enrolled in the study, 35 were included in the primary efficacy and safety analysis, excluding 6 patients because they did not meet the eligibility criteria: three with diffuse large B-cell lymphoma, one with extranodal NK/T lymphoma, one with mixed phenotype LL, and one with stage III disease. Themedian [range] age at enrollment was 9.0 [2.1-16.1] years. Twenty-three (65.7%) were male. Twenty-nine had pre-B and 6 had pre-T immunophenotype. Fifteen (42.9%) were Stage I and 20 (57.1%) were Stage II. Thirty-four (97%) patients achieved complete remission at the end of induction. The median follow-up for EFS was 10.1 [0.0-15.2] years, and the primary endpoint of 3-year EFS rate [95% confidence interval: 95% CI] (n=35) was 97.1% [81.4-99.6%]. (Fig.1) The median follow-up for OS was 10.6 [2.9-16.1] years, and the 3-year OS rate (n=35) was 100%. One pre-T immunophenotype patient with stage II disease failed to achieve complete remission after induction therapy. Overall, patients tolerated therapy well and no treatment-related deaths were observed. There was only one unanticipated adverse event (retinal detachment), and a causal relationship to study treatment was ruled out. Conclusion: This is the largest trial ever conducted in the treatment of pediatric patients with newly diagnosed localized lymphoblastic lymphoma using an individual protocol. Outcomes of pediatric patients with localized LL treated with 2 years of less-intensive BFM-like therapy was excellent. The number of children diagnosed with localized LL limits the possibility of randomized trials focusing on therapeutic questions. Future studies should identify the biologic or clinical difference between LL and lymphoblastic leukemia, explore less intensive treatment for patients with localized disease, and explore novel targeted therapies.

Prognostic Features of CD9 in Childhood Acute Lymphoblastic Leukemia - a Retrospective Analysis of a Nation-Wide Multicenter Study in China

Background and objectives: The outcomes of children with acute lymphoblastic leukemia (ALL) have been incrementally improved with risk-directed chemotherapy but therapy responses remain heterogeneous in clinically defined risk groups. Parameters with added prognostic values are therefore warranted to refine the current risk stratification system and inform appropriate management. CD9, a cell surface protein presented on malignant lymphoblasts, may have such predictive characteristics as shown by our previous single-center study conducted in Hong Kong (Leung et al, Leukemia, 2020). This study aims to determine the precise prognostic features of CD9 in a nation-wide, multicenter childhood ALL cohort in China, and deliver algorithms for identification of patients who may benefit from early interventions. Study design and outcome measures: This multicenter cohort study included childhood ALL patients (aged &amp;lt;18 years) enrolled into the Chinese Children Cancer Group (CCCG)-ALL-2015 study from January 2015 to December 2019, with 7,640 patients from 20 tertiary hospitals in China treated with a uniform protocol. A total of 3,781 subjects (49.5%) from 16 sites had flow cytometry data on lymphoblast CD9 at diagnosis. The final study cohort comprised 3,395 B-ALL and 386 T-ALL patients with a median follow-up of 53.9 months. The primary outcomes were 5-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) for patients with CD9 + or CD9 - phenotypes (positivity defined by the presence of ≥20% CD9 + blasts evaluated through a univariate analysis demonstrating the highest odds for adverse events or relapse at this cut-off). The secondary outcomes were 5-year OS, EFS, and CIR rates of CD9 + and CD9 - patients after inclusion of known prognostic factors, including risk assignment, cytogenetic anomalies, and minimal residual disease (MRD) status. Survival benefits of CD9 + subjects from treatment intensification or hematopoietic stem cell transplantation (HSCT) were analyzed. Results: CD9 was expressed in 88.5% of B-ALL and 27.9% of T-ALL cases. It conferred a dismal EFS (82.1% vs. 89.3%, P=0.001) and a higher CIR (15.5% vs. 7.8%, P&amp;lt;0.001) in B-ALL but not T-ALL patients. The prognostic impact of CD9 is much more prominent in subjects with adverse presenting features or poor early treatment responses, as best exemplified in those assigned to the intermediate/high-risk arms (EFS: 72.8% vs. 83.2%, P=0.028; CIR: 23.1% vs. 10.2%, P=0.003) or those with positive MRD at day 19 (EFS: 65.2% vs. 82.0%, P=0.053; CIR: 30.3% vs. 9.7%, P=0.007). The adverse impact of CD9 is confined to specific cytogenetics, including BCR-ABL1 (CIR: 39.5% vs. 0%, P=0.019) and normal karyotype (CIR: 15.0% vs. 6.8%, P=0.034). In multivariate analyses, CD9 remains an independent factor predicting event-free survival (HR=1.917, P=0.001) and relapse (HR=2.208, P&amp;lt;0.001). The time to and site of relapse did not differ between CD9 + and CD9 - patients. For CD9 + patients with MRD at the end of induction, treatment upstaging only benefited initial low-risk subjects. HSCT at first remission did not improve the outcomes of high-risk subjects with a CD9 + phenotype. Conclusions: This is the largest study to evaluate the significance of CD9 in childhood ALL. We confirmed the results of our previous single-center study with this multicenter national study. CD9 positivity is definitively associated with a higher relapse probability particularly for patients with intermediate/high risk diseases, MRD positivity or specific cytogenetic background. BCR-ABL1 + patients with a CD9 - phenotype had excellent outcomes and HSCT may not be required. Whereas MRD + patients who were CD9 + had poor outcomes, and therefore should have early interventions with innovative treatments to reduce the risk of relapse. With these, we propose to incorporate CD9 into the diagnostic immunophenotyping panel to inform risk stratification and management of childhood ALL.

Clinical Features and Therapeutic Evaluation of Central Nervous System Involvement in Pediatric Anaplastic Large Cell Lymphoma

Objective：To analyze the clinical features of central nervous system involvement (CNS3) in pediatric anaplastic large cell lymphoma (ALCL) and evaluate the efficacy of CNCL-ALCL-2017 protocol for the treatment of CNS3. Methods：The clinical data of 215 pediatric ALCL patients ≤18 years old enrolled in the Chinese Children's Cancer Group (CNCL) between April 2017 and March 2023 were collected sequentially. All enrolled patients staging and CNS layering were according to the IPNHLSS staging system and treated with CNCL-ALCL-2017 protocol (modified BFM-ALCL99 protocol). The clinical features at diagnosis and treatment outcomes of CNS3 patients were analyzed. All patients were followed up until June 30, 2023. Data were collected using a unified information platform. Associations between patient characteristics were analyzed with Chi-squared or Fisher's exact tests. Eventfree survival (EFS) and overall survival (OS) curves were estimated according to the KaplanMeier method and compared by Logrank test. Furthermore, statistical analysis was performed using SPSS 22.0 software. P&amp;lt;0.05 was considered statistically significant. Results: Among the 215 ALCL pediatric patients, 17 (7.9%) had CNS3, including 13 males and 4 females with median age of 8.0 (range 1.0-14.0) years. In this patients, brain parenchyma and spinal cord involvement were found in 58.8% (10/17) patients on imaging, with space-occupying lesions in 7 cases and abnormal signals on MRI in 4 cases. Concurrent space-occupying lesions and abnormal signals on MRI was detected in 1 case. Cerebrospinal fluid (CSF) positivity was detected in 35.3% (6/17) patients, including 2 cases with positive ALK gene and 5 cases with positive flow cytometry, with 1 case positive for both. Cranial nerve deficits such as facial nerve palsy, visual or hearing impairment were observed in 23.5% (4/17) patients. Concurrent CSF, imaging and cranial nerve abnormalities were present in 5.9% (1/17), while two of this were present in 29.4% (5/17). Isolated CSF positivity without other abnormalities was detected in 23.5% (4/17). Pathological subtypes included common type (76.5%, 13/17), histiocyte-rich variant (5.9%, 1/17), small cell variant (5.9%, 1/17), others (11.8%, 2/17). Immunohistochemistry showed ALK + in 94.1% (16/17) and CD3 + in 76.5% (13/17). Concurrent ALK gene positivity in both peripheral blood and bone marrow was detected in 64.7% (11/17), with 58.8% (10/17) positive in both samples. The median follow-up of all patients was 35.4 months (range 0.5-74.9). All CNS3 patients had stage IV disease and were treated with regimen D (with 5 g/m 2 methotrexate). The 3-year OS was 94.3%, 98.2% and 93.3% for CNS1 (144, 67.0%), CNS2 (54, 25.1%) and CNS3 (17, 7.9%) patients, respectively; the 3-year EFS was 85.6%, 90.3% and 86.7%, respectively. No significant differences were found among the three groups. The 3-year OS and EFS for the whole cohort were 95.1% and 84.7%, respectively, also with no significant differences from the CNS3 group. Of the CNS3 patients, 1 was lost to follow-up after the first course, 1 died during treatment, and the interim CR rate was 75.0% (12/16). CSF conversion was achieved in 3/6 (50%) CSF-positive patients. 6.25% (1/16) patient had CSF ALK gene re-positivity during maintenance and persistent positivity despite additional ALK inhibitor alectinib and intrathecal therapy. In the CNS1 group, 2 cases were lost to follow-up and 4 cases died. The relapse rate was 11.4% (16/140), and the rate of central nervous system relapse was 2.1% (3/140). Additionally, the rate of CNS1 relapse was slightly higher but not statistically significantly different for CNS2. Conclusions: CNS involvement is relatively rare in pediatric ALCL. Detection rate of CNS3 can be improved by CSF flow cytometry and gene screening. The prognosis of CNS3 was significantly improved with CNCL-ALCL-2017 protocol, which may be related to the increased dose of methotrexate in the protocol. The short follow-up time and the small number of cases in this group may affect the results. Furthermore, CNS relapse rate of CNS2 was not markedly higher compared to CNS1. Keywords: Anaplastic large cell lymphoma; Pediatric; Central nervous system; Clinical features; Prognosis

Minimal Residual Disease Detected by the 7NB-mRNAs ddPCR Assay Is Associated with Disease Progression in High-Risk Neuroblastoma Patients: A Prospective Multicenter Observational Study in Japan.

High-risk neuroblastoma (HR-NB) patients remain far from obtaining optimal outcomes, with more than 50% relapse/regrowth rate despite current intensive multimodal therapy. This originated from the activation/proliferation of chemoresistant minimal residual disease (MRD). MRD with a significant prognostic was reported by several quantitative PCR (qPCR) or droplet digital PCR (ddPCR) assays quantitating different sets of NB-associated mRNAs (NB-mRNAs). The 7NB-mRNAs ddPCR assay quantitating CRMP1, DBH, DDC, GAP43, ISL1, PHOX2B, and TH mRNAs was reported to outperform other qPCR assays by a retrospective in-house observational study. In the present study, the Japan Children's Cancer Group (JCCG) Neuroblastoma Committee conducted a prospective multicenter observational study aimed at evaluating a prognostic value of MRD in bone marrow (BM-MRD) and peripheral blood (PB-MRD) detected by 7NB-mRNAs ddPCR assay. Between August 2018 and August 2022, 7 HR-NB patients who registered for JCCG clinical trials (JN-H-11 and JN-H-15) were enrolled. A total of 19 BM and 19 PB samples were collected, and 4/15 BM and 4/15 PB samples were classified as progressive disease (PD)/non-PD samples. BM-MRD and PB-MRD estimated area under curve (AUC) of 0.767 and 0.800 with a significant accuracy (AUC > 0.7). The present study validated a prognostic value of BM-MRD obtained by a previous study (AUC 0.723) and revealed the significant accuracy of PB-MRD as well as BM-MRD.