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LBA10503 Background: Several pediatric precision oncology programs have identified molecular actionable variants. However, the clinical benefit is largely unknown. We here report a target prioritization algorithm and associated clinical outcome. Methods: INFORM is a prospective, non-interventional, multi-center, multi-national, and feasibility registry collecting clinical and molecular data. Patients with refractory/relapsed/progressive malignant disease, including primary diagnosis high-risk entities, can be enrolled. Fresh frozen tumor material (incl. germline DNA) was subjected to WES, lcWGS, RNA-Seq, RNA expression array and DNA-methylation. A weekly interdisciplinary molecular board reviewed and prioritized alterations based on a 7- step scale from ‘very high’ to ‘very low’, depending on the type of alteration and its entity specific relevance (described by Worst et al. Eur J Cancer 2016). Results: To date, more than 1300 patients were enrolled. 525 patients finished follow-up and were included in this analysis. They were enrolled in 72 centers in 8 countries. The median age was 12.0 (range 0 - 40) years. Average turnaround time from submission to report was 25.4 days. Median PFS and OS were 116 (95% CI 105 – 135) and 289 (95% CI 250 – 335) days. The distribution of the highest priority target per patient was: very high 8.0%, high 14.8%, moderate 20.3%, intermediate 23.6%, borderline 14.4%, low 2.5%, very low 1.0% and no actionable target 15.4%. 149 patients received targeted treatment on the basis of identified targets, of which 20 had a very high priority target (mostly ALK, BRAF and NRAS mutations and MET and NTRK-fusions) with a median PFS of 204.5 (95% CI 91.0 – 628.0) compared to 114 (95% CI 103 – 133) days in all other 505 patients (p = 0.0095). OS did not show clinically relevant differences. Explorative analysis of the time to progression (TTP) ratio (before compared to after enrollment) showed that patients treated according to a very high priority target had a higher TTP ratio (1.0) compared to all other patients (0.7). Possible predisposition syndromes were identified in 7.8% of patients, half of which were newly diagnosed. Methylation analysis provided a diagnosis refinement in 8% of CNS tumors. Conclusions: Pediatric precision oncology in a real world, multi-national setting is feasible. The prioritization algorithm identifies subgroups benefitting from molecularly matched targeted treatment. Still, for the patients without a very high priority target further layers of molecular and functional data should be incorporated in future programs.

TPS10065 Background: Immune checkpoint inhibition in children has shown limited success rates until now. This is most likely due to the fact that the vast majority of pediatric cancers are so-called immunologic cold tumors, and that patients have been enrolled in an unselected manner in single agent trials. Recently, it has been shown that the class I selective HDAC inhibitor entinostat has significant immune enhancing activity in vitro and in vivo. This is mediated through multiple mechanisms including depletion of myeloid-derived suppressor cells, activation of neoantigen transcription and increase of MHC expression. Methods: INFORM2 NivEnt is an exploratory nonrandomized, open-label, multinational and multicenter seamless phase I/II basket trial of nivolumab and entinostat in children and adolescents with relapsed, refractory or progressive high-risk solid and CNS tumors. Patients aged 6-21 will be allocated to the following biomarker-defined groups: high mutational load ( > 100 somatic SNVs/exome; group A), high PD-L1 mRNA expression (RPKM > 3; group B), focal MYC(N) amplification (group C), low mutational load and low PD-L1 mRNA expression and no MYC(N) amplification (Biomarker low group D). Phase I determines the recommended phase 2 dose for the combination for the age groups 6-11 and 12-21 years. Patients will receive nivolumab 3mg/kg every 2 weeks. Entinostat has 2 dose levels: 2mg/m2 and 4mg/m2 once per week. Patients can seamlessly enter the phase II which investigates activity (defined as best response during the first 6 cycles) in the 4 biomarker groups A-D. The duration of treatment is 12 cycles, preceded by 1 entinostat priming week. Interim analyses for futility will be performed after every 10 patients in each group. The study will enroll a maximum of 128 patients in Germany, The Netherlands, Sweden, France, Australia and additional countries under discussion. A comprehensive accompanying biomarker program will investigate a series of immune and epigenetic pharmacodynamic biomarkers. Clinical trial information: NCT03838042.

12090Background: Gliomas regularly evade current therapies through primary and acquired resistance and the effect of temozolomide is mainly restricted to the subgroup of methylguanin-O6-methyltrans...

10509 Background: Relapses from high-risk tumors pose a major clinical challenge in pediatric oncology. The German INFORM registry (INdividualized therapy FOr Relapsed Malignancies in children) addresses this problem using integrated next-generation sequencing to rapidly identify patient-specific therapeutic targets. Methods: Whole-exome, low-coverage whole-genome and RNA sequencing is complemented with microarray-based DNA methylation profiling. Identified alterations are discussed and prioritized according to biological significance and potential druggability in a weekly molecular tumor board. Results: To date, 214 tumor samples of high-risk pediatric cancer patients have been profiled from 47 German centers, with 39% being sarcomas, 30% brain tumors, 13% neuroblastoma and 18% hematological or other malignancies. Turnaround time from tissue arrival to molecular results was 21 calendar days on average. In 14/214 patients (7%) we identified an underlying germline predisposition syndrome. In several cases there were discrepancies between the original histological diagnosis and our molecular findings, especially in brain tumors. We detected one or more potentially druggable alterations in 147/214 (69%) cases. Tyrosine kinases, the PI3K/mTOR pathway, MAPK pathway, and cell-cycle as well as transcriptional regulators were commonly affected. Based on these findings, targeted therapeutics were incorporated into the therapy regime in one-third of patients, with anecdotal reports of marked responses, including a patient with a pleomorphic sarcoma, where we detected a previously undescribed RAF-fusion, showing a partial remission upon RAF-inhibition. Conclusions: In summary, real-time comprehensive profiling of pediatric tumors provides valuable diagnostic information and identifies potential therapeutic targets. In parallel, the implementation of a systematic program for reverse-translational evaluation is ongoing. Recently, this nationwide effort has expanded to include patients from other countries. We will also recruit patients to the complementary eSMART and INFORM2 biomarker-driven, phase I/II combination trial series, to provide unprecedented access to targeted therapies in Europe.