Blank, Peter M K de

Pediatric central nervous system tumors are the leading cause of cancer-related deaths in children. The five-year survival rate for high-grade glioma in children is less than 20%. The development of new treatments is dependent upon multi-institutional collaborative clinical trials requiring reproducible and accurate centralized response assessment. We present the results of the BraTS-PEDs 2023 challenge, the first Brain Tumor Segmentation (BraTS) challenge focused on pediatric brain tumors. This challenge utilized data acquired from multiple international consortia dedicated to pediatric neuro-oncology and clinical trials. BraTS-PEDs 2023 aimed to evaluate volumetric segmentation algorithms for pediatric brain gliomas from magnetic resonance imaging using standardized quantitative performance evaluation metrics employed across the BraTS 2023 challenges. The top-performing AI approaches for pediatric tumor analysis included ensembles of nnU-Net and Swin UNETR, Auto3DSeg, or nnU-Net with a self-supervised framework. The BraTS-PEDs 2023 challenge fostered collaboration between clinicians (neuro-oncologists, neuroradiologists) and AI/imaging scientists, promoting faster data sharing and the development of automated volumetric analysis techniques. These advancements could significantly benefit clinical trials and improve the care of children with brain tumors.

Abstract BACKGROUND Treatment and clinical management decisions for children with NF1-OPGs remain challenging as most existing data are retrospective and have not included standardized visual outcomes. In this study, we prospectively enrolled newly diagnosed NF1-OPGs and performed standardized neuro-oncology and ophthalmology assessments in order to develop evidence-based guidelines for monitoring and treatment. METHODS Children with NF1-OPG on MRI who were evaluated by both a study ophthalmologist and neuro-oncologist/NF1 expert within 1 month of radiologic diagnosis were eligible for enrollment. All subjects attempted quantitative visual acuity using Teller acuity cards (TAC) as well as ATS-HOTV testing. The neuro-oncologist/NF1 expert provided reasons for obtaining the MRI as well as initiating treatment, if applicable. Descriptive statistics calculated the success rate of acquiring TAC and reasons to obtain the MRI. RESULTS Two-hundred fifty subjects from 22 institutions were enrolled and had at least one visit beyond baseline (Median age 3.1 years, range 0.1–16.8; 53% female). TAC was successfully acquired in both eyes (N=195, 78%) and at least one eye in (N=206, 82%). ATS-HOTV was successfully acquired in both eyes (N=97, 39%) and at least one eye in (N=98, 39%). The two most common reasons to obtain an MRI were screening due to a diagnosis of NF1 (N=99, 39%) and ophthalmologic concern (N=81, 32%). At enrollment, continued observation occurred in a majority of subjects (N=221, 88%) while treatment with chemotherapy was initiated in only 11% (N=29). Twenty-nine (11%) subjects initially observed transitioned to treatment after enrollment (range: 2.5–25 months) thus far. DISCUSSION We present a prospective multicenter study of children with newly diagnosed NF1-OPGs. The ability to acquire quantitative visual acuity was higher than anticipated. The frequency of NF1-OPGs requiring treatment is lower than previously reported. Regression models of clinical and MRI features that prompted immediate treatment with chemotherapy versus observation will be discussed.

Abstract BACKGROUND NF1-OPGs are amorphous tumors involving either single or multiple locations (optic nerve, chiasm, tract) along the anterior visual pathway (AVP). In this prospective study, we investigated how volumetric MRI measures of the AVP as well as other clinical variables are associated with treatment decisions in children with newly diagnosed NF1-OPGs. METHODS Children with newly diagnosed NF1-OPG whose MRI included a T1-weighted volumetric sequence without significant artifact at their enrollment visit were eligible for inclusion. All subjects underwent a quantitative ophthalmic exam to determine if visual acuity (VA) was normal. The neuro-oncologist/NF1 expert determined whether the subject would be observed or undergo treatment at that baseline visit. Volumetric MRI analysis was automatically performed using a deep learning network that measured AVP volume (mm3). Non-parametric group comparisons and multivariable logistic regression models evaluated the impact of age at enrollment, sex, NF1 inheritance type, AVP volume, and VA on the decision for immediate treatment with chemotherapy versus observation. RESULTS One-hundred twenty-three subjects met inclusion criteria. Subjects assigned to observation (N=112, 44% female) and subjects immediately treated with chemotherapy (N=11, 80% female) at enrollment were of similar age (2.7 and 2.8 years, respectively) and inheritance (p > 0.05). Abnormal VA was present more often in the treatment group (46%) compared to the observation group (17%, p <0.001). AVP volume was significantly greater in the treatment group (4,181.1mm3) compared to the observation group (1,819.8mm3, p <0.001). AVP volume, sex, and VA reached significance in univariable regression, however, in the multivariable regression model only the AVP volume (p < 0.001) was significantly associated with treatment initiation. DISCUSSION Children with greater NF1-OPG AVP volumes are treated more often compared with those with lower volumes. Volumetric measures of NF1-OPGs are a valuable metric in understanding treatment patterns and are positioned to help inform clinical decision making.

Abstract Background This study evaluated the safety and pharmacokinetics (PK) of oral ONC201 administered twice-weekly on consecutive days (D1D2) in pediatric patients with newly diagnosed DIPG and/or recurrent/refractory H3 K27M glioma. Methods This phase 1 dose-escalation and expansion study included pediatric patients with H3 K27M-mutant glioma and/or DIPG following ≥1 line of therapy (NCT03416530). ONC201 was administered D1D2 at 3 dose levels (DLs; −1, 1, and 2). The actual administered dose within DLs was dependent on weight. Safety was assessed in all DLs; PK analysis was conducted in DL2. Patients receiving once-weekly ONC201 (D1) served as a PK comparator. Results Twelve patients received D1D2 ONC201 (DL1, n = 3; DL1, n = 3; DL2, n = 6); no dose-limiting toxicities or grade ≥3 treatment-related adverse events occurred. PK analyses at DL2 (D1-250 mg, n = 3; D1-625 mg, n = 3; D1D2-250 mg, n = 2; D1D2-625 mg, n = 2) demonstrated variability in Cmax, AUC0–24, and AUC0–48, with comparable exposures across weight groups. No accumulation occurred with D1D2 dosing; the majority of ONC201 cleared before administration of the second dose. Cmax was variable between groups but did not appear to increase with D1D2 dosing. AUC0–48 was greater with D1D2 than once-weekly. Conclusions ONC201 given D1D2 was well tolerated at all DLs and associated with greater AUC0–48.

Abstract ONC201, an anti-cancer DRD2 antagonist and ClpP agonist, is in Phase II trials for adult H3 K27M-mutant diffuse midline gliomas. The recommended phase 2 dose (RP2D) of 625mg ONC201 once a week has been established as a biologically active dose that is well tolerated in adult and pediatric populations. Radiographic regressions with single agent ONC201 have been reported in recurrent H3 K27M-mutant glioma patients. In another study, twice/week dosing was explored in adult patients and deemed to be safe (no DLTs observed). This warranted exploration of twice/week dosing in pediatric patients and will be discussed in this presentation. This multi-arm, dose-escalation and dose-expansion trial (ONC014; NCT03416530) determined the pediatric RP2D of ONC201 administered once per week and twice per week on two consecutive days. ONC201 was orally administered and scaled by body weight. Dose escalation was performed by a 3 + 3 design beginning with two 125mg capsules less than the adult RP2D equivalent. Twelve children (8 females; 4 males) with H3 K27M-mutant gliomas (pons: 8; thalamus: 2; spinal cord: 2) aged 4-19 years have been treated post-radiation: 3 at dose level -1; 3 at dose level 1; 6 as part of the dose expansion cohort on dose level 2. Median KPS was 90 (range 70-100). One treatment cycle was 21 days (6 doses), which also defined the DLT window. Patients were on-treatment for a median length of 4 cycles (range: 2-11). Twice weekly dosing of ONC201 was tolerated well, as observed with weekly dosing, with no instance of DLT. A total of 4 SAEs were reported, none of which were related to the study drug. The most common AEs (regardless of relatedness) included headache, facial nerve disorder, abducens nerve disorder, nausea, fatigue and ataxia. Additional safety data, PK, and clinical outcomes from this arm will be reported.

Abstract INTRODUCTION Because treatment and clinical management decisions for children with NF1-OPG remain challenging, we sought to establish evidence-based guidelines. We prospectively enrolled children with newly-diagnosed NF1-OPGs, and gathered standardized clinical neuro-oncology and ophthalmology assessments. METHODS Only children with NF1 and newly diagnosed OPGs, confirmed by central review, were eligible. Indications for obtaining the initial MRI, as well as factors associated with the decision to treat with chemotherapy or observe without treatment, were obtained. Quantitative visual acuity (VA), other ophthalmic features, and imaging were captured at standard time points. Goal enrollment is 250 subjects. RESULTS One-hundred thirty-three children (52% female) from 20 institutions met inclusion criteria, and were included in this preliminary analysis. Eighty-six percent of subjects were able to perform quantitative VA testing at enrollment. The most common reasons for the diagnostic MRI included screening related to NF1 diagnosis (36.8%), ophthalmologic concerns (29.3%), and non-ophthalmologic concerns (24.8%), such as headache. To date, twenty subjects have initiated treatment with chemotherapy, twelve (9%) at the time of the initial OPG diagnosis. Median age at OPG diagnosis was 3.1 years. Age and sex distribution were similar in subjects immediately entering the observation and treatment arms (median age 3.0 versus 3.5 years, respectively). CONCLUSION Most children with NF1-OPGs are observed at time of their initial OPG diagnosis, rather than treated. Importantly, a large proportion of children are able to complete quantitative VA testing at enrollment. Once enrollment is complete, these data will help to establish evidence-based guidelines for clinical management of NF1-OPGs.