Abstract BACKGROUND Metastatic infant medulloblastoma (MB) is a major challenge given the devastating long-term effects of craniospinal irradiation to the developing brain. However large cohorts of ...metastatic infant medulloblastoma have not been analysed to date. METHODS A multicentre molecularly informed international cohort of children <6 years old with metastatic medulloblastoma was assembled and analysed. RESULTS Eighty-four patients with a median age of 2.95 (0.66-6.58) years were identified. 48.8% were Group3-MB, 23.8% Group4-MB and 27.4% SHH-MB. 78% of Group3-MB were subtype II (40.4%) and IV (38.1%), 50% of Group 4 were subtype VII, and within SHH, SHHß and SHHγ were 52.2% and 43.5% respectively. 28.5% of all Group3-MB harboured MYC amplification. A multivariable analysis incorporating subgroup, MYC amplification and upfront craniospinal irradiation revealed that survival was superior for SHH patients compared to Group 3 irrespective of MYC status (Group3-veMYCamp: HR 3.05 95%-CI 1.05-8.87 p=0.04, Group3+veMYCamp HR 7.87 95%-CI 2.49-24.87 p=0.00044). Group 4 had a trend to a poor outcome (HR 2.63 95%-CI 0.82-8.39 p=0.1). SHH subjects had a superior outcome with 5-year PFS of 0.657 (95%-CI 0.47-0.92), without a significant difference between SHHß and SHHγ. High-dose chemotherapy regimens portended to a superior outcome for both subtypes of SHH-MB. 5-year PFS for non-radiated SHH-MB was 61% (95%-CI 40.8-91.4), compared to non-radiated Group3-MB (18.5%; 95%-CI 5.4-62.8) and Group4-MB (20%; 95%-CI 3.4-100). SHH-MB patients had more local than metastatic relapses compared to non-SHH-MB (p=0.01). CONCLUSIONS In the largest study dedicated to metastatic infant medulloblastoma assembled to date, outcomes for infants with Group 3- and 4-MB with metastatic disease treated with radiation sparing approaches is dismal despite intensified regimens. MYC amplification portends to a near uniformly fatal prognosis with current treatment irrespective of upfront radiotherapy. Novel radiation sparing approaches are urgently needed for this group. Infants with both metastatic SHHß and SHHγ benefit from intensified therapy.
Abstract BACKGROUND Advanced pediatric solid tumors, including central nervous system (CNS) tumors with PDGFRA and/or KIT mutations/amplifications are aggressive diseases with limited treatment ...options. KIT alterations occur in germ cell tumors and high-grade glioma (HGG); platelet-derived growth factor receptor alpha (PDGFRA) alterations are common in sarcoma and HGG. No KIT-/PDGFRA-targeted therapies are currently approved for pediatric patients. The selective KIT and PDGFRA inhibitor avapritinib has demonstrated potent activity against KIT activation-loop (exon 17) and juxtamembrane (exon 11) mutants (IC50<2 nM), and PDGFRA activation-loop (D842V) mutants (half-maximal inhibitory concentration IC50=0.24 nM). Cellular IC50 of wild-type PDGFRA was 95 nM. CNS penetration in preclinical models (steady-state brain-to-plasma ratios, 0.74–1.00) indicates potential for CNS antitumor activity. Avapritinib is approved in the USA and Europe to treat adults with indolent systemic mastocytosis, in the USA for adults with advanced systemic mastocytosis (AdvSM), and in Europe for adults with AdvSM after ≥1 prior systemic therapy. Avapritinib is also approved to treat adults with unresectable/metastatic gastrointestinal stromal tumors harboring PDGFRA exon 18 mutations (including D842V) in the USA and PDGFRA D842V mutations in Europe. METHODS ROVER, a 2-part phase 1/2, multicenter, open-label study (NCT04773782), is investigating avapritinib (once daily, administered in continuous 28-day cycles) in pediatric patients aged 2 to <18 years with relapsed/refractory solid tumors that harbor PDGFRA and/or KIT mutations/amplifications or patients with diffuse midline glioma H3K27-altered (DMG-H3K27a). Objectives include safety, efficacy, and pharmacokinetics. Part 1 will enroll ≥12 patients; primary endpoint is to determine the recommended Part 2 dose (RP2D). Part 2 will enroll ≥25 patients at the RP2D; primary endpoint is objective response rate per RECIST v1.1 for solid tumors and Response Assessment in Neuro-Oncology for CNS tumors. Study enrollment is planned at 26 sites in 9 countries, including North America, Europe, and Asia/Pacific.
Abstract BACKGROUND The utility of precision-guided therapeutic approaches to H3K27-altered diffused midline glioma (DMG) remains uncertain. The Australian Zero Childhood Cancer (ZERO) program ...combines molecular profiling (whole-genome sequencing (WGS), whole-transcriptome sequencing (RNAseq), and DNA methylation profiling), with in vitro high-throughput drug screening (HTS) and patient-derived xenograft (PDX) drug-efficacy testing in patients with high-risk cancer. METHODS We report on the cohort of patients enrolled with a DMG in the ZERO clinical trial between 2017 and 2023. RESULTS 68 patients were enrolled, predominantly at diagnosis (87%), with pontine lesions (66%) at a mean age of 8.7 years. 59 (87%) patients had WGS + RNAseq successfully performed. Most tumors harbored an H3F3A mutation (n=50), followed by HIST1H3B (n=11), HIST1H3C (n=2), HIST2H3C (n=1) and EZHIP overexpression (n=4). 37 samples were suitable for cell culture, with HTS successfully performed in 25 cases, and PDXs established in 7. Precision-guided therapy (PGT) was recommended by the ZERO multidisciplinary tumor board for 53 patients (78%), including 5 recommendations guided by HTS. PI3K/mTOR inhibitors and MEK inhibitors were the most recommended PGTs. 21 patients (31%), receiving 24 PGTs, were eligible for survival analysis. The clinical benefit rate (per RAPNO) was 52% for patients receiving PGT, with 5 patients exhibiting PR and 6 patients SD >6 months. Notably, the 5 PR included: a PR in a patient with BRAFV600E mutation to dabrafenib/trametinib, a near-CR in a patient with germline BRCA2 mutation to olaparib/durvalumab, a sustained PR in a patient with FGFR1 mutation to trametinib/bevacizumab and 2 patients with PIK3CA mutations who received PGT in the context of recent radiotherapy. Median overall survival of the PGT group was 21.2 months versus 11.8 months for the rest of the cohort (hazard ratio 0.67 95%CI 0.39-1.1). CONCLUSIONS These results, for the first time, highlight the potential clinical benefit of PGT in H3K27-altered DMG.
Abstract BACKGROUND Pediatric low-grade gliomas (pLGG) exhibit dramatic objective response to treatment with MEKi (Mitogen-Activated Protein Kinase inhibitors). Although the initial response to MEKi ...is promising, it is unknown whether it is safe to stop MEKi therapy and if the response to re-initiating MEKi would have the same impact. The study objective was to compare the first and second response to MEKi in patients with pLGG who stopped therapy and had further tumor progression. METHODS PLGG identified at neurooncology centers in Canada, Australia, and US, which were treated twice with MEKi were included. Second therapy was defined as MEKi upon progression for tumors where treatment was stopped. Response to MEKi between 2 treatments (MEKi1, MEKi2) were analyzed by using RANO criteria. RESULTS Mature data on 19 patients reveals a median patient age of 13 years (range 7–24), and the most common tumor location is hypothalamic/chiasmatic (89%). PLGG alterations include KIAA1549:BRAF fusion in 69%, NF1 in 21%, and other alterations in 10%. The overall response (minor and partial) to MEKi1 was 63% compared to 26% in MEKi2 (p=0.04). Furthermore, upon restarting MEKi2, 11% had further growth on therapy in contrast to none at MEKi1. MEKi1 resulted in average of 37% size decrease (range, 3%-98%), including 6 PLGG with over 50% response. In contrast, the average decrease to MEKi2 was 10% (range, 6%-40%, p=0.005), and none had >50% size reduction. Comparing each patient MEKi1 to MEKi2 revealed that initial response was superior to the second one in all PLGG. CONCLUSION These data suggest that the second response to MEKi is inferior when compared to initial therapy. Expansion of this cohort and biomarker correlates are ongoing. Biological insights are required for this observation, and careful consideration should be made for stopping MEKi, especially in strategic locations such as the optic pathway.
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Background: Pediatric patients with relapsed or refractory high-risk solid and CNS tumors have dismal survival. To date treatment with immune checkpoint inhibitors in this population has been ...disappointing. This study exploits the immune enhancing effects of entinostat on nivolumab in biomarker enriched subpopulations. The study aims to determine the pediatric recommended phase II dose (pRP2D) and to evaluate activity and safety. Methods: This is an exploratory non-randomized, open-label, multinational seamless phase I/II trial in children and adolescents with relapsed / refractory or progressive high-risk solid and CNS tumors. The phase I is divided in 2 age cohorts: 12–21 years (y) and 6–11y and follows a 3 + 3 design with two dose levels for entinostat (dose level 1: 2 mg/m
2
and dose level 2: 4 mg/m
2
once per week) and fixed dose nivolumab (3 mg/kg every 2 weeks). Patients entering the trial on pRP2D can seamlessly enter phase II which consists of a biomarker defined four group basket trial: high mutational load (group A), high PD-L1 mRNA expression (group B), focal MYC(N) amplification (group C), low mutational load and low PD-L1 mRNA expression and no MYC(N) amplification (group D). Results: The first patient was enrolled in May 2020 and at the time of the data cut (21-JAN-2022), 19 patients were treated. The median age at enrollment was 14 y. In the 12 – 21y cohort 15 patients were enrolled and four patients in the 6 – 11y cohort. The most frequent treatment-related AEs to date were thrombocytopenia in six (32%), nausea and vomiting both in four (21%), and neutropenia in three patients (16%). Five patients (26%) experienced grade 3/4 mostly reversible treatment-related AEs, e.g. neutropenia/leukopenia. No treatment related deaths were reported. In the 6 – 11y cohort dose escalation is ongoing. In the 12 – 21y cohort, one DLT (CTCAE grade 3 thrombocytopenia) was observed in six patients on dose level two, which was determined as the pRP2D of the combination. At the time of the data cut, 10 patients (six in arm D and four patients in which the biomarker group was not yet determined) had received at least one RECIST/RANO response evaluation by central review in phase II. One patient (17%) in arm D with metastatic relapsed renal cell carcinoma (RCC) harboring a typical PRCC-TFE3 fusion showed a PR after two cycles and finally achieved an ongoing CR. Extensive explorative analyses of immune signatures derived from INFORM RNA-Seq and WES data revealed that both the primary diagnosis and the current relapse samples harbored a remarkable high immune cell infiltration, especially CD8+ T-cells. Conclusions: The first and ongoing global INFORM2 trial has identified the pRP2D for the nivolumab and entinostat combination in the older age cohort with good tolerability. A patient with metastasized relapsed RCC experienced a CR. The role of immune infiltration as a potential predictive biomarker is currently being explored. Clinical trial information: NCT03838042.
Abstract
BACKGROUND
Pediatric low-grade glioma (pLGG) is the most common childhood brain tumor. Genomic alterations of RAF are common oncogenic drivers in pLGG. Tovorafenib is an investigational, ...selective, CNS-penetrant, type II RAF inhibitor.
METHODS
FIREFLY-1 (NCT04775485) is a phase 2 study evaluating tovorafenib monotherapy. Registrational arm 1 enrolled patients aged 6 months–25 years of age with recurrent or progressive LGG harboring an activating BRAF alteration. Tovorafenib 420 mg/m2 (600 mg max) was administered weekly (tablet or liquid suspension). Independently assessed overall response rate (ORR), as defined by RANO-HGG and RANO-LGG criteria, are primary and exploratory endpoints.
RESULTS
As of December 22 2022, 69 (RANO-HGG) and 76 (RANO-LGG) of 77 patients in arm 1 were evaluable at baseline and had ≥9 months of follow-up. Median age at enrollment was 8 years (range 2–21), and 60% (n = 46) patients had received prior MAPK inhibitor (MAPKi) therapy. Among the evaluable patients, the ORR was 62% (RANO-HGG, n = 69) and 45% (RANO-LGG, n = 76), respectively. The ORR in patients previously treated with MAPKis (n = 41 RANO-HGG; n = 45 RANO-LGG) was 68% (4 CRs; 24 PRs) (RANO-HGG) and 44% (5 PRs; 15 MRs) (RANO-LGG). In MAPKi-naïve patients (28 RANO-HGG; 31 RANO-LGG), the ORR was 54% (15 PRs) (RANO-HGG) and 45% (7 PRs; 7 MRs) (RANO-LGG). Among 136 patients in arms 1 and 2 of FIREFLY-1, the most common treatment-related adverse events (TRAEs) of any grade were hair color changes (71%), fatigue (40%) and maculopapular rash (38%). Tovorafenib dose modifications occurred in 39 (29%) and discontinuations in 4 (3%) patients due to TRAEs.
CONCLUSIONS
Tovorafenib provided clinically meaningful tumor responses, including those with a best response reported of SD or PD using another MAPKi, in patients with BRAF-altered pLGG regardless of prior MAPKi therapy, and has a manageable safety profile.
Abstract
INTRODUCTION
SJMB12 is a phase 2 clinical trial led by the St. Jude Children’s Research Hospital (St. Jude) that enrolls patients with medulloblastoma based on their biological subgroup. The ...large cell/anaplastic (LCA) histologic variant has been identified as an important independent risk factor associated with poor outcome. However, the histologic criteria for LCA is subjective, making the distinction between anaplastic and non-anaplastic medulloblastoma difficult in some cases.
METHODS
Pathological central review was performed at St. Jude. For all patients enrolled in the study to date, concordance was assessed between the initial and central review diagnosis and histologic variant calls made at the Royal Children’s Hospital Melbourne (RCH) and at St. Jude, respectively.
RESULTS
Since the SJMB12 clinical trial opened locally in 2014, 34 patients were enrolled, and 31 were eligible for this retrospective study. A total of 12 (39%) cases with discordance were identified. The most frequent disagreement was between the designation of LCA (10 cases, 32%). In five cases the tumour was not designated as LCA variant locally. In five cases the initial designation of LCA was refuted centrally. Overall, this led to a change of treatment stratum for four patients (13%).
CONCLUSION
A high discordance rate exists between neuropathologists in the designation of LCA variant. Differences in interpretation of the subjective histologic criteria and inconsistencies in the material submitted for central review contributed to the discordance. Incorporation of more objective histologic criteria and implementation of unbiased diagnostic tools may improve the generalisability of future risk stratification.
Abstract
Genomic alterations of BRAF are common oncogenic drivers in pediatric low-grade glioma (pLGG). Tovorafenib is an investigational, oral, selective, brain-penetrant, small molecule, type II ...panRAF inhibitor. FIREFLY-1 (NCT04775485) is a multicenter phase 2 study evaluating the efficacy and safety of tovorafenib monotherapy in patients with BRAF-altered cancers. Registrational arm 1 includes patients 6 months-25 years of age with recurrent or progressive LGG previously treated with ≥1 prior line of systemic therapy. Tovorafenib 420 mg/m2 (≤600 mg) is administered weekly, in 28-day cycles, (tablet or liquid suspension formulation) until progression. The primary endpoint of arm 1 is ORR, as defined by RANO criteria and determined by blinded independent review. As of September 28, 2022, arm 1 had enrolled 77 patients and is fully accrued. All patients had ≥6 months of follow-up. Median age at enrollment was 8 years (range 2-21). Patients had received a median of 3 prior lines of systemic therapy (range: 1-9); 60% had received prior MAPK pathway-targeted agents. The most common tumor site was optic pathway (51%). Sixty-four patients harbored a tumor BRAF fusion/rearrangement (83%) and 13 (17%) a V600E mutation. Median duration of tovorafenib treatment is 8.4 months (range 0.7-16.8); 59 patients (77%) remained on treatment at data cutoff. ORR in 69 RANO-evaluable patients was 64%, 3 CR, 41 PR (10 unconfirmed) and 19 SD with a clinical benefit rate of 91%. The most common treatment-related adverse events (TRAEs) of any grade were hair color changes (75%), increased creatine phosphokinase (64%), anemia (46%), fatigue (42%) and maculopapular rash (42%). Two patients (3%) discontinued tovorafenib due to TRAEs. Updates from a longer follow-up on the 77 patients in arm 1 will be presented. Tovorafenib was generally well tolerated and showed encouraging evidence of antitumor activity in children and young adults with refractory BRAF-altered LGG.
Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare and aggressive cancer predisposition syndrome. Because a scarcity of data on this condition contributes to management challenges ...and poor outcomes, we aimed to describe the clinical spectrum, cancer biology, and impact of genetics on patient survival in CMMRD.
In this cohort study, we collected cross-sectional and longitudinal data on all patients with CMMRD, with no age limits, registered with the International Replication Repair Deficiency Consortium (IRRDC) across more than 50 countries. Clinical data were extracted from the IRRDC database, medical records, and physician-completed case record forms. The primary objective was to describe the clinical features, cancer spectrum, and biology of the condition. Secondary objectives included estimations of cancer incidence and of the impact of the specific mismatch-repair gene and genotype on cancer onset and survival, including after cancer surveillance and immunotherapy interventions.
We analysed data from 201 patients (103 males, 98 females) enrolled between June 5, 2007 and Sept 9, 2022. Median age at diagnosis of CMMRD or a related cancer was 8·9 years (IQR 5·9–12·6), and median follow-up from diagnosis was 7·2 years (3·6–14·8). Endogamy among minorities and closed communities contributed to high homozygosity within countries with low consanguinity. Frequent dermatological manifestations (117 93% of 126 patients with complete data) led to a clinical overlap with neurofibromatosis type 1 (35 28% of 126). 339 cancers were reported in 194 (97%) of 201 patients. The cumulative cancer incidence by age 18 years was 90% (95% CI 80–99). Median time between cancer diagnoses for patients with more than one cancer was 1·9 years (IQR 0·8–3·9). Neoplasms developed in 15 organs and included early-onset adult cancers. CNS tumours were the most frequent (173 51% cancers), followed by gastrointestinal (75 22%), haematological (61 18%), and other cancer types (30 9%). Patients with CNS tumours had the poorest overall survival rates (39% 95% CI 30–52 at 10 years from diagnosis; log-rank p<0·0001 across four cancer types), followed by those with haematological cancers (67% 55–82), gastrointestinal cancers (89% 81–97), and other solid tumours (96% 88–100). All cancers showed high mutation and microsatellite indel burdens, and pathognomonic mutational signatures. MLH1 or MSH2 variants caused earlier cancer onset than PMS2 or MSH6 variants, and inferior survival (overall survival at age 15 years 63% 95% CI 55–73 for PMS2, 49% 35–68 for MSH6, 19% 6–66 for MLH1, and 0% for MSH2; p<0·0001). Frameshift or truncating variants within the same gene caused earlier cancers and inferior outcomes compared with missense variants (p<0·0001). The greater deleterious effects of MLH1 and MSH2 variants as compared with PMS2 and MSH6 variants persisted despite overall improvements in survival after surveillance or immune checkpoint inhibitor interventions.
The very high cancer burden and unique genomic landscape of CMMRD highlight the benefit of comprehensive assays in timely diagnosis and precision approaches toward surveillance and immunotherapy. These data will guide the clinical management of children and patients who survive into adulthood with CMMRD.
The Canadian Institutes for Health Research, Stand Up to Cancer, Children's Oncology Group National Cancer Institute Community Oncology Research Program, Canadian Cancer Society, Brain Canada, The V Foundation for Cancer Research, BioCanRx, Harry and Agnieszka Hall, Meagan's Walk, BRAINchild Canada, The LivWise Foundation, St Baldrick Foundation, Hold'em for Life, and Garron Family Cancer Center.
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