Phase II Trial of Dabrafenib Plus Trametinib in Relapsed/Refractory BRAF V600-Mutant Pediatric High-Grade Glioma.

PURPOSE: BRAF V600 mutation is detected in 5%-10% of pediatric high-grade gliomas (pHGGs), and effective treatments are limited. In previous trials, dabrafenib as monotherapy or in combination with trametinib demonstrated activity in children and adults with relapsed/refractory BRAF V600-mutant HGG. METHODS: This phase II study evaluated dabrafenib plus trametinib in patients with relapsed/refractory BRAF V600-mutant pHGG. The primary objective was overall response rate (ORR) by independent review by Response Assessment in Neuro-Oncology criteria. Secondary objectives included ORR by investigator determination, duration of response (DOR), progression-free survival, overall survival (OS), and safety. RESULTS: A total of 41 pediatric patients with previously treated BRAF V600-mutant HGG were enrolled. At primary analysis, median follow-up was 25.1 months, and 51% of patients remained on treatment. Sixteen of 20 discontinuations were due to progressive disease in this relapsed/refractory pHGG population. Independently assessed ORR was 56% (95% CI, 40 to 72). Median DOR was 22.2 months (95% CI, 7.6 months to not reached [NR]). Fourteen deaths were reported. Median OS was 32.8 months (95% CI, 19.2 months to NR). The most common all-cause adverse events (AEs) were pyrexia (51%), headache (34%), and dry skin (32%). Two patients (5%) had AEs (both rash) leading to discontinuation. CONCLUSION: In relapsed/refractory BRAF V600-mutant pHGG, dabrafenib plus trametinib improved ORR versus previous trials of chemotherapy in molecularly unselected patients with pHGG and was associated with durable responses and encouraging survival. These findings suggest that dabrafenib plus trametinib is a promising targeted therapy option for children and adolescents with relapsed/refractory BRAF V600-mutant HGG.

Clinical outcome of pediatric medulloblastoma patients with Li-Fraumeni syndrome.

BACKGROUND: The prognosis for Li-Fraumeni syndrome (LFS) patients with medulloblastoma (MB) is poor. Comprehensive clinical data for this patient group is lacking, challenging the development of novel therapeutic strategies. Here, we present clinical and molecular data on a retrospective cohort of pediatric LFS MB patients. METHODS: In this multinational, multicenter retrospective cohort study, LFS patients under 21 years with MB and class 5 or class 4 constitutional TP53 variants were included. TP53 mutation status, methylation subgroup, treatment, progression free- (PFS) and overall survival (OS), recurrence patterns, and incidence of subsequent neoplasms were evaluated. RESULTS: The study evaluated 47 LFS individuals diagnosed with MB, mainly classified as DNA methylation subgroup "SHH_3" (86%). The majority (74%) of constitutional TP53 variants represented missense variants. The 2- and 5-year (y-) PFS were 36% and 20%, and 2- and 5y-OS were 53% and 23%, respectively. Patients who received postoperative radiotherapy (RT) (2y-PFS: 44%, 2y-OS: 60%) or chemotherapy before RT (2y-PFS: 32%, 2y-OS: 48%) had significantly better clinical outcome then patients who were not treated with RT (2y-PFS: 0%, 2y-OS: 25%). Patients treated according to protocols including high-intensity chemotherapy and patients who received only maintenance-type chemotherapy showed similar outcomes (2y-PFS: 42% and 35%, 2y-OS: 68% and 53%, respectively). CONCLUSIONS: LFS MB patients have a dismal prognosis. In the presented cohort use of RT significantly increased survival rates, whereas chemotherapy intensity did not influence their clinical outcome. Prospective collection of clinical data and development of novel treatments are required to improve the outcome of LFS MB patients.

Germ Cell Maintenance and Sustained Testosterone and Precursor Hormone Production in Human Prepubertal Testis Organ Culture with Tissues from Boys 7 Years+ under Conditions from Adult Testicular Tissue.

Human prepubertal testicular tissues are rare, but organ culture conditions to develop a system for human in vitro-spermatogenesis are an essential option for fertility preservation in prepubertal boys subjected to gonadotoxic therapy. To avoid animal testing in line with the 3Rs principle, organ culture conditions initially tested on human adult testis tissue were applied to prepubertal samples (n = 3; patient ages 7, 9, and 12 years). Tissues were investigated by immunostaining and transmission electron microscopy (TEM), and the collected culture medium was profiled for steroid hormones by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Culture conditions proved suitable for prepubertal organ culture since SSCs and germ cell proliferation could be maintained until the end of the 3-week-culture. Leydig cells (LCs) were shown to be competent for steroid hormone production. Three additional testis tissues from boys of the same age were examined for the number of germ cells and undifferentiated spermatogonia (SPG). Using TEM micrographs, eight tissues from patients aged 1.5 to 13 years were examined, with respect to the sizes of mitochondria (MT) in undifferentiated SPG and compared with those from two adult testicular tissues. Mitochondrial sizes were shown to be comparable between adults and prepubertal boys from approximately 7 years of age, which suggests the transition of SSCs from normoxic to hypoxic metabolism at about or before this time period.

Final results of the Choroid Plexus Tumor study CPT-SIOP-2000.

INTRODUCTION: Standards for chemotherapy against choroid plexus tumors (CPT) have not yet been established. METHODS: CPT-SIOP-2000 (NCT00500890) was an international registry for all CPT nesting a chemotherapy randomization for high-risk CPT with Carboplatin/Etoposide/Vincristine (CarbEV) versus Cyclophosphamide/Etoposide/Vincristine (CycEV). Patients older than three years were recommended to receive irradiation: focal fields for non-metastatic CPC, incompletely resected atypical choroid plexus papilloma (APP) or metastatic choroid plexus papilloma (CPP); craniospinal fields for metastatic CPC/APP and non-responsive CPC. High risk was defined as choroid plexus carcinoma (CPC), incompletely resected APP, and all metastatic CPT. From 2000 until 2010, 158 CPT patients from 23 countries were enrolled. RESULTS: For randomized CPC, the 5/10 year progression free survival (PFS) of patients on CarbEV (n = 20) were 62%/47%, respectively, compared to 27%/18%, on CycEV (n = 15), (intention-to-treat, HR 2.6, p = 0.032). Within the registry, histological grading was the most influential prognostic factor: for CPP (n = 55) the 5/10 year overall survival (OS) and the event free survival (EFS) probabilities were 100%/97% and 92%/92%, respectively; for APP (n = 49) 96%/96% and 76%/76%, respectively; and for CPC (n = 54) 65%/51% and 41%/39%, respectively. Without irradiation, 12 out of 33 patients with CPC younger than three years were alive for a median of 8.52 years. Extent of surgery and metastases were not independent prognosticators. CONCLUSIONS: Chemotherapy for Choroid Plexus Carcinoma is feasible and effective. CarbEV is superior to CycEV. A subset of CPC can be cured without irradiation.