Tumor molecular profiling is a fundamental component of precision oncology, enabling the identification of genomic alterations in genes and pathways that can be targeted therapeutically. The existence of recurrent targetable alterations across distinct histologically-defined tumor types, coupled with an expanding portfolio of molecularly-targeted therapies, demands flexible and comprehensive approaches to profile clinically significant genes across the full spectrum of cancers. We established a large-scale, prospective clinical sequencing initiative utilizing a comprehensive assay, MSK-IMPACT, through which we have compiled matched tumor and normal sequence data from a unique cohort of more than 10,000 patients with advanced cancer and available pathological and clinical annotations. Using these data, we identified clinically relevant somatic mutations, novel non-coding alterations, and mutational signatures that were shared among common and rare tumor types. Patients were enrolled on genomically matched clinical trials at a rate of 11%. To enable discovery of novel biomarkers and deeper investigation into rare alterations and tumor types, all results are publicly accessible.

Executive Summary PURPOSE With prospective clinical sequencing of tumors emerging as a mainstay in cancer care, there is an urgent need for a clinical support tool that distills the clinical implications associated with specific mutation events into a standardized and easily interpretable format. To this end, we developed OncoKB, an expert-guided precision oncology knowledge base. METHODS OncoKB annotates the biological and oncogenic effect and the prognostic and predictive significance of somatic molecular alterations. Potential treatment implications are stratified by the level of evidence that a specific molecular alteration is predictive of drug response based on US Food and Drug Administration (FDA) labeling, National Comprehensive Cancer Network (NCCN) guidelines, disease-focused expert group recommendations and the scientific literature. RESULTS To date, over 3000 unique mutations, fusions, and copy number alterations in 418 cancer-associated genes have been annotated. To test the utility of OncoKB, we annotated all genomic events in 5983 primary tumor samples in 19 cancer types. Forty-one percent of samples harbored at least one potentially actionable alteration, of which 7.5% were predictive of clinical benefit from a standard treatment. OncoKB annotations are available through a public web resource (http://oncokb.org/) and are also incorporated into the cBioPortal for Cancer Genomics to facilitate the interpretation of genomic alterations by physicians and researchers. CONCLUSION OncoKB, a comprehensive and curated precision oncology knowledge base, offers oncologists detailed, evidence-based information about individual somatic mutations and structural alterations present in patient tumors with the goal of supporting optimal treatment decisions.

PurposeCancer spread to the central nervous system (CNS) often is diagnosed late and is unresponsive to therapy. Mechanisms of tumor dissemination and evolution within the CNS are largely unknown because of limited access to tumor tissue.Materials and MethodsWe sequenced 341 cancer-associated genes in cell-free DNA from cerebrospinal fluid (CSF) obtained through routine lumbar puncture in 53 patients with suspected or known CNS involvement by cancer.ResultsWe detected high-confidence somatic alterations in 63% (20 of 32) of patients with CNS metastases of solid tumors, 50% (six of 12) of patients with primary brain tumors, and 0% (zero of nine) of patients without CNS involvement by cancer. Several patients with tumor progression in the CNS during therapy with inhibitors of oncogenic kinases harbored mutations in the kinase target or kinase bypass pathways. In patients with glioma, the most common malignant primary brain tumor in adults, examination of cell-free DNA uncovered patterns of tumor evolution, including temozolomide-associated mutations.ConclusionThe study shows that CSF harbors clinically relevant genomic alterations in patients with CNS cancers and should be considered for liquid biopsies to monitor tumor evolution in the CNS.

Abstracts iii21NEURO-ONCOLOGY • MAY 2017 characterized, potential paracrine effects influencing antitumor immunity remain enigmatic. However, they are important to decipher, as immunotherapies targeting IDH1-mutant gliomas are emerging. AIM: This study aimed at characterizing a potential cell-specific modulatory role of the oncometabolite R-2-HG in shaping the immune microenvironment of IDH1-mutant gliomas. METHODS AND RESULTS: By means of expression dataset analyses, syngeneic murine tumor models and human glioma tissue, as well as a novel astrocyte-specific IDH1R132H-knock in model, we demonstrate that R-2-HG impairs endogenous and IDH1(R132H)-specific antitumor T cell immunity. This is underlined by functional and transcriptomic analyses of myeloid cells indicating a R-2-HG-driven induction of tolerogenicity and compromised antigen presentation. Metabolomic profiling was complemented by mitochondrial respiration assays, calcium measurements and pathway analyses in primary human and mouse immune cells to delineate key molecular mechanisms by which tumor-derived R-2-HG corrupts the glioma immunoenvironment. The functional relevance of R-2-HG-mediated impairment of antitumor immunity was demonstrated in vivo and potential pharmacological strategies abrogating its effects were assessed. CONCLU-SION: Glioma-derived R-2-HG impairs antitumor immunity by affecting both infiltrating T-cells and the associated myeloid compartment, thus contributing to tumorigenesis and resistance to therapy. Immunotherapeutic strategies against IDH-mutant gliomas may benefit from approaches to prevent excess R-2-HG production or its uptake by immune cells. BACKGROUND: Despite available treatment options for patients (pts) with recurrent glioblastoma (GBM), < 5% of pts survive 5 years beyond initial diagnosis, and no single-agent therapy has demonstrated a survival benefit in the second-line setting, including bevacizumab (bev), which is approved for the treatment of recurrent disease. Nivolumab (nivo), a fully human IgG4 monoclonal antibody that inhibits the programmed death 1 receptor, has provided clinical benefit in multiple cancer types. In cohort 2 of the open-label, phase 3 CheckMate 143 study (NCT02017717), the efficacy and safety of nivo was compared with that of bev in pts with GBM experiencing their first recurrence after prior radiotherapy (RT) and temozolomide (TMZ). METHODS: Pts with no prior VEGF therapy were randomized 1:1 to receive nivo 3 mg/kg Q2W or bev 10 mg/kg Q2W until confirmed disease progression; pts were stratified by the presence/absence of measurable disease. The primary endpoint was overall survival (OS); secondary endpoints were 12-mo OS rate and investigator-assessed progression-free survival (PFS) and objective response rate (ORR) per Response Assessment in Neuro-Oncology criteria. RESULTS: At the time of final analyses (Jan 20, 2017), 369 pts were randomized to the nivo (n = 184) or bev (n = 185) treatment arms; of these pts, 182 received nivo and 165 received bev. At baseline, most pts in the nivo (...

Purpose: The genomic landscape of gliomas has been characterized and now contributes to disease classification, yet the relationship between molecular profile and disease progression and treatment response remain poorly understood. Experimental Design: We integrated prospective clinical sequencing of 1,004 primary and recurrent tumors from 923 glioma patients with clinical and treatment phenotypes. Results: Thirteen percent of glioma patients harbored a pathogenic germline variant, including a subset associated with heritable genetic syndromes and variants mediating DNA repair dysfunctions (29% of the total) that were associated with somatic biallelic inactivation and mechanism-specific somatic phenotypes. In astrocytomas, genomic alterations in effectors of cell-cycle progression correlated with aggressive disease independent of IDH mutation status, arose preferentially in enhancing tumors (44% vs. 8%, P < 0.001), were associated with rapid disease progression following tumor recurrence (HR ¼ 2.6, P ¼ 0.02), and likely preceded the acquisition of alkylating therapyassociated somatic hypermutation. Thirty-two percent of patients harbored a potentially therapeutically actionable lesion, of whom 11% received targeted therapies. In BRAFmutant gliomas, response to agents targeting the RAF/MEK/ ERK signaling axis was influenced by the type of mutation, its clonality, and its cellular and genomic context. Conclusions: These data reveal genomic correlates of disease progression and treatment response in diverse types of glioma and highlight the potential utility of incorporating genomic information into the clinical decision-making for patients with glioma.

Purpose The CellSearch® system has been used to identify circulating tumor cells (CTCs) in cerebrospinal fluid (CSF) to diagnose leptomeningeal metastasis (LM) in patients with epithelial cancers. Using this system, we prospectively explored sequential CSF CTC enumeration in patients with LM from HER2+ cancers receiving intrathecal (IT) trastuzumab to capture dynamic changes in CSF CTC enumeration. Methods CSF from patients enrolled in an IRB-approved phase I/II dose escalation trial of IT trastuzumab for LM in HER2+ cancer (NCT01325207) was obtained on day 1 of each cycle and was evaluated by the CellSearch® platform for CTC enumeration. The results were correlated with CSF cytology from the same sample, along with clinical and radiographic response. Results Fifteen out of 34 patients with HER2+ LM were enrolled in CSF CTC analysis; 14 were women. Radiographic LM was documented in 14 (93%) patients; CSF cytology was positive in 6 (40%) and CSF CTCs were identified in 13 (87%). Median CSF CTC was 22 CTCs (range 0-200 +) per 3 ml. HER2/neu expression analysis of CTCs was performed in 8 patients; 75% had confirmed expression of HER2/neu positivity in CSF and HER2/neu expression was absent in 25%. Four of 10 patients received 7 or more cycles of IT trastuzumab; in 3 of these patients, increase in CSF CTCs enumeration from baseline was detected 2-3 months prior to changes seen on MRI, and while CSF cytology remained negative. Conclusion Our study demonstrates that enumeration of CSF CTCs may provide dynamic, quantitative assessment of tumor burden in the central nervous system compartment during treatment for LM and prior to changes on MRI or CSF cytology. Trial Registration: Clinicaltrials.gov: NCT01325207; registered March 29th, 2011.

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In nearly every US state, a large mismatch exists between the need for neurologists and neurologic services and the availability of neurologists to provide these services. Patients with neurologic disorders are rising in prevalence and require access to high-level care to reduce disability. The current neurology mismatch reduces access to care, worsens patient outcomes, and erodes career satisfaction and quality of life for neurologists as they face increasingly insurmountable demands. As a community, we must address this mismatch in the demand and supply of neurologic care in an aggressive and sustained manner to ensure the future health of our patients and our specialty. The American Academy of Neurology has multiple ongoing initiatives to help reduce and resolve the existing mismatch. With the intent of raising awareness and widening the debate nationally, we present a strategic plan that the Academy could implement to coordinate and expand existing efforts. We characterize the suggested strategies as shaping the demand, enhancing the workforce, and advocating for neurologist value. The proposed framework is based on available data and expert opinion when data were lacking. Prioritization of strategies will vary by geography, practice setting, and local resources. The time to act is now to allow concerted effort and targeted interventions to avert this looming public health crisis.