Asmann, Yan W.

Age‐related mitochondrial dysfunction is paralleled by reductions in gene transcripts and expression of proteins involved in cellular ATP production. Short‐term endurance exercise has been shown to enhance muscle protein synthesis in the elderly. We determined the impact of long‐term endurance exercise on gene expression and protein abundance of numerous proteins involved in cellular energetics. Vastus lateralis tissue was biopsied from 11 young sedentary (YS), 10 old sedentary (OS), 11 young trained (YT), and 11 old trained (OT) subjects. Trained subjects vigorously exercised ¡Ý 1 hr/d, ¡Ý five d/wk for ¡Ý 4 years. Large‐scale measurement of relative protein abundance was performed using isobaric tags for relative and absolute quantitation (iTRAQ) reagents and tandem mass spectrometry. Gene transcript levels were measured by high‐density oligonucleotide microarrays. Ingenuity Pathway Analysis was used to determine canonical pathways that were altered by age. Of the 33 proteins involved in cellular ATP production 27 were less abundant in OS vs. YS, while only 4 of these proteins were less abundant in OT vs. YT. Genes involved in glycolysis and oxidative phosphorylation were underexpressed in OS vs. YS, with no effects of age in OT vs. YT. CONCLUSIONS: Long‐term vigorous endurance exercise ameliorates the detrimental effects of old age on muscle gene and protein expression in humans.

Leucine (Leu) is the most potent branched‐chain amino acid that selectively enhances protein synthesis via intracellular signaling pathways. Since protein synthesis is an energy consuming process, we hypothesized that Leu may enhance mitochondrial biogenesis and functions. We determined the effect of Leu at mitochondrial mRNA levels, enzyme activities, and ATP production rate (MAPR) in cultured human liver cell line THLE‐3. Cells were pre‐incubated in a low‐Leu (0.1mM), serum‐free media for 24 hours and gene transcript profiles were measured using Affymetrix HG‐U133A GeneChips at 0, 30, 60, 120 and 480 minutes after increasing the Leu concentrations from to 2.0 mM. Thirty mitochondrial gene transcripts, both mitochondrial DNA and nuclear‐encoded, were significantly increased at various time points with treatment of higher concentrations of Leu. The mRNA levels of 6 mitochondrial genes including two ATP synthase, cytochrome P450, cytochrome C oxidase III, and NADH dehydrogenase 4 were confirmed by real‐time PCR measurements. Western blot analysis showed that 8 hours of high concentrations of Leu increased protein levels of key mitochondrial proteins, citrate synthase and cytochrome c oxidase I, by 42% and 20% respectively. In addition, the enzyme activity of citrate synthase was significantly increased by 25%, and MAPR by 30–40% using various substrates after 8 hours of high Leu. In conclusion, Leu stimulated mitochondrial biogenesis and oxidative phosphorylation in liver cells. This work is supported by NIH grants T32 DK7352, and RO1 DK41972.

Abstract Background: Although risk of late relapse in hormone receptor-positive (HR+) breast cancer is well established, most existing data pertain to the HR+ HER2-negative (HER2-) subgroup. CTS5 is one of the models for predicting risk of late relapse in HR+ HER2- breast cancer. However, the value of this model in HR+ HER2+ disease is less known, particularly in the context of adjuvant trastuzumab. Here, we evaluated CTS5 in patients with early stage HR+ HER2+ breast cancer treated in the NCCTG N9831 (Alliance for Clinical Trials in Oncology) and NSABP B-31 (NRG) trials. Methods: Stage I-III HR+ (ER+ and/or PR+) HER2+ breast cancer patients who were free of recurrence after 5 years in N9831 and B-31 trials were included. The online CTS5 calculator was used to determine CTS5 score and risk group (low, intermediate, and high) based on age, tumor size, grade, and number of involved nodes. Kaplan-Meier (KM) estimates, Cox regression models, and C index were used for analysis. N9831 and B-31 trials were analyzed separately. Results: 1,204 patients in N9831 and 658 patients in B-31 met the entry criteria. Baseline characteristics were similar between both trials, including median age, tumor size, and follow up. Similar distribution within CTS5 risk group was observed in both trials; 68.2% and 70.1% patients were high risk, 24% and 21.9% as intermediate risk, as well as 7.8% and 8.1% as low risk classified in N9831 and B-31, respectively. Using univariate Cox regression analysis, CTS5 score as a continuous variable was associated with recurrence-free survival (RFS) in the entire study cohort, including patients who received chemotherapy alone or in combination with trastuzumab, (HR 1.37, 95%CI 1.03-1.81, p=0.03, C index 0.57 in N9831 and HR 1.36, 95%CI 1.06-1.76, p=0.02, C index 0.54 in B-31), but not in patients who received concurrent trastuzumab (HR 1.19, 95%CI 0.73-1.2, p=0.49, C index 0.54 in N9831 and HR 1.35, 95%CI 0.96-1.9, p=0.08, C index 0.54 in B-31). As categorical variable in the entire study cohort, CTS5 risk group was not significantly associated with RFS among patients with intermediate vs. low (HR 0.47, 95%CI 0.18-1.22, p=0.12 and HR 1.61, 95%CI 0.66-3.92, p=0.29) and high vs. low (HR 1.23, 95%CI 0.57-2.67, p=0.6 and HR 1.93, 95%CI 0.85-4.41, p=0.12) with the C index of 0.58 and 0.53 in N9831 and B-31 respectively. There was also no significant difference in RFS among 3 CTS5 risk groups with Kaplan-Meier estimates. Among patients who received concurrent trastuzumab, similar trends were observed with no statistical difference in RFS between high vs. low (HR 0.68, 95%CI 0.24-1.97, p=0.48 and HR 1.44, 95%CI 0.52-3.96, 0.49) with the C index of 0.55 and 0.51 in N9831 and B-31, respectively. Paradoxically, patients with intermediate risk had better RFS than low risk (HR 0.18, 95%CI 0.03-0.97, p=0.05) in N9831 but no significant difference in B-31 (HR 1.31, 95%CI 0.44-3.95, p=0.63). Conclusions: While CTS5 score as a continuous variable was associated with outcome in overall HR+ HER2+ population, this model was not prognostic in patients receiving adjuvant trastuzumab in both N9831 and B-31 trials. Furthermore, the correlation (C index) was modest and CTS5 risk group as a categorical variable could not stratify outcome in this group of patients. This study underlines the need to develop a new prognostic model to better delineate the risk of late relapse in HR+ HER2+ breast cancer patients receiving trastuzumab as this model can facilitate clinical decision for extended adjuvant endocrine therapy. Support: BCRF-19-161, U10CA180821, U10CA180868 and U10CA180822 (NRG), Genentech. https://acknowledgments.alliancefound.org Citation Format: Tanyami Pai, Angelica Gil, Yaohua Ma, Zhuo Li, Pooja Advani, Moreno Moreno-Aspitia, Gerardo Colon-Otero, Edith A. Perez, Yan Asmann, Katherine Pogue-Geile, E. A. Thompson, Saranya Chumsri. Prognostic value of clinical treatment score post-5 years (CTS5) and late relapse risk in hormone receptor-positive HER2-positive breast cancer in the North Central Cancer Treatment Group (NCCTG) N9831 (Alliance) and NSABP B-31 (NRG) trials [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-03.

Background Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma subtype with a 5-year survival of ~64%. While DLBCL is treated using immunochemotherapy (IC) with curative intent, 20%-40% of patients do not reach remission or relapse post IC. Clonal somatic mutations have been associated with aging, hematologic malignancies (predominately myeloid), and reduced OS in the general population. The objective of this study was to evaluate the association of clonal somatic mutations with event-free survival (EFS) and overall survival (OS). Methods We studied newly diagnosed DLBCL cases treated with IC who were enrolled in the Molecular Epidemiology Resource (MER) of the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence (SPORE). Clinical and treatment data were abstracted from medical records and all patients were systematically followed for disease outcomes. Pre-treatment DNA was extracted from matched peripheral blood and paraffin-embedded tumor tissue, and whole exome sequencing was conducted at 100x coverage. From the peripheral blood, allele counts from GVCF files produced by HaplotypeCaller in GATK were extracted for 42 genes commonly associated with clonal hematopoiesis (e.g. DNMT3A, TET2, and ASXL1). Mutations were deemed clonal somatic if the population minor allele frequency was <0.5% in ExAC and had a variant allele fraction (VAF) that deviated from 0.5 using a binomial distribution test at p<0.001. Furthermore, mutations had to have a minimum alternate read count of at least 5 reads, a VAF greater than or equal to 10%, and met at least one of the following criteria: CAVA impact of "HIGH"; pathogenic/likely pathogenic per ClinVar; or reported in COSMIC at least 10 times. EFS was defined as time from diagnosis to disease progression, relapse, retreatment, or death due to any cause. The association of clonal somatic mutations with prognosis was estimated using Kaplan-Meier curves, and hazard ratios (HR) and 95% confidence intervals (CI) from Cox regression. Associations were adjusted for age at diagnosis, sex, and the International Prognostic Index (IPI). Results The study consisted of 261 DLBCL patients treated with IC. The median age at diagnosis was 65 years (range 20-90) and 56% were male. With a median follow-up time of 5.1 years (range 0.1-15.0), there were 100 events and 80 deaths. A total of 17 (6.5%) patients had clonal somatic mutations, and16 patients were over the age of 60. A total of 8 (of 42) genes had clonal somatic mutations, with SF3B1, ASXL1, and TET2, being the most frequent (4 individuals per gene). VAFs ranged from 0.10 to 0.28 and none of the patients had multiple mutations. Additionally, the clonal somatic variants found in the peripheral blood were abscent in the tumor sample. Of the 17 patients with clonal somatic mutations, 12 had an event while 88 patients without a mutation had an event. In a univariate analysis, clonal somatic mutations were associated with inferior EFS (HR=2.55, 95% CI 1.39-4.68, p=0.002; Figure 1A). After adjusting for age, sex, and IPI, clonal somatic mutations remained associated with inferior EFS (HR=2.02, 95% CI 1.09-3.74, p=0.026). Clonal somatic mutations were also associated with inferior OS in the univariate analysis (HR=2.06, 95% CI 0.99-4.29, p=0.053), which attenuated after multivariate adjustment (HR=1.59, 95% CI: 0.76-3.34, p=0.22, Figure 1B). Although based on small numbers, mutations in SF3B1 were associated with inferior EFS (HR=3.25, 95% CI 1.16-9.12, p=0.025), but did not reach significance for OS (HR=2.56, 95% CI 0.78-8.38, p=0.120). Conclusions In this novel study of newly diagnosed DLBCL patients, clonal somatic mutations were identified in 6.5% of patients and were associated with inferior outcomes. Additional research is required at deeper sequencing to validate these findings and integration with tumor genomics is required to understand the prognosis of DLBCL patients with smaller clonal populations. Disclosures Shah: Dren Bio: Consultancy. Maurer:Celgene / BMS: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Nanostring: Research Funding. Martin:Celgene: Consultancy; Karyopharm: Consultancy, Research Funding; Morphosys: Consultancy; Regeneron: Consultancy; Incyte: Consultancy; Kite: Consultancy; Cellectar: Consultancy; Bayer: Consultancy; Beigene: Consultancy; Sandoz: Consultancy; I-MAB: Consultancy; Janssen: Consultancy; Teneobio: Consultancy. Witzig:AbbVie: Consultancy; Incyte: Consultancy; Acerta: Research Funding; Karyopharm Therapeutics: Research Funding; Immune Design: Research Funding; Spectrum: Consultancy; Celgene: Consultancy, Research Funding; MorphSys: Consultancy. Nowakowski:NanoString: Research Funding; Seattle Genetics: Consultancy; Curis: Consultancy; Kymera: Consultancy; Kite: Consultancy; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees; MorphoSys: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding. Novak:Celgene/BMS: Research Funding. Cerhan:NanoString: Research Funding; BMS/Celgene: Research Funding.

AbstractBackgroundUsing an objective mathematical algorithm to assess corticolimbic involvement of neurofibrillary tangle pathology, we identified three AD subtypes: hippocampal sparing (HpSp) AD, typical AD, and limbic predominant AD. Typical AD brains were representative of the expected patterns of hippocampal and cortical involvement as outlined by Braak tangle stage. In contrast, we discovered an extreme phenotype that exists outside of the Braakian‐concept of neurofibrillary tangle patterns. Hippocampal sparing AD cases demonstrate unexpected sparing of the hippocampus relative to severely involved association cortices and limbic predominant AD cases demonstrate inundation of the hippocampus relative to mildly involved association cortices. Using these AD subtypes, our objective was to leverage our understanding of disease spectrum to uncover transcriptomic changes that underlie selective vulnerability of the hippocampus in AD.MethodWe performed RNA‐sequencing in 40 neuropathologically diagnosed AD cases (10 HpSp, 20 Typical and 10 Limbic) and 15 controls to uncover gene expression changes associated with phenotype differences allowing us to prioritize 44 genes for further exploration. Validation with NanoString and quantification with digital pathology were performed in an expanded cohort of 158 AD cases (36 HpSp, 79 Typical and 35 Limbic) and 32 controls. We quantified digital pathology measures of early tangle pathology (CP13), mature tangle pathology (Ab39), amyloid‐β (33.1.1). In addition, we measured cellular markers for microglia (CD68), endothelia (CD34), and astroglia (GFAP). Deep learning based prediction models were employed, which nominated the SLC38A2 gene as a predictor of AD.ResultThe SLC38A2 gene was originally prioritized in our RNA‐sequencing data based upon differential expression between controls and typical AD. We observed upregulation of SLC38A2 in all AD subtypes. RNA‐seq gene expression measures validated well with NanoString for SLC38A2 (R=0.97, p<0.001). Regression analysis identified early tangle (p=0.011) and late tangle measures (p=0.026) as significant predictors of gene expression, but not amyloid measures (p=0.74). Microgliosis approached significance (p=0.052), but with no contribution from endothelial cell burden (p=0.17) or astrogliosis (p=0.58). Age approached significance (p=0.06), but not sex (p=0.88) or APOE‐ε4 status (p=0.10).ConclusionOur data supports consideration of intra‐disease divergence with regard to case stratification and may reveal genes previously masked by heterogeneity of cohorts.

Abstract Background Glioblastomas (GBMs) are the main primary brain tumors in adults with almost 100% recurrence rate. Patients with lateral ventricle proximal GBMs (LV-GBMs) exhibit worse survival compared to distal locations for unknown reasons. One hypothesis is the proximity of these tumors to the cerebrospinal fluid (CSF) and its chemical cues that can regulate cellular phenotype. We therefore investigated the role of CSF on GBM gene expression and the role of a CSF-induced gene, SERPINA3, in GBM malignancy in vitro and in vivo. Methods We utilized human CSF and GBM brain tumor-initiating cells (BTICs). We determined the impact of SERPINA3 expression in glioma patients using The Cancer Genome Atlas (TCGA) database. SERPINA3 expression changes were evaluated at mRNA and protein levels. The effects of knockdown (KD) and overexpression (OE) of SERPINA3 on cell migration, viability and cell proliferation were evaluated. Stem cell characteristics on KD cells were evaluated by differentiation and colony formation experiments. Tumor growth was studied by intracranial and flank injections. Results GBM-CSF increased BTIC migration accompanied by upregulation of the SERPINA3 gene. In patient samples and TCGA data, we observed SERPINA3 to correlate directly with brain tumor grade and indirectly with GBM patient survival. SERPINA3 KD induced a decrease in cell proliferation, migration, invasion, and stem cell characteristics, while SERPINA3 OE increased cell migration. In vivo, SERPINA3 KD BTICs showed increased survival in a murine model. Conclusions SERPINA3 plays a key role in GBM malignancy and its inhibition results in a better outcome using GBM preclinical models.

Introduction: Population studies have identified genes with germline polymorphisms associated with acute myeloid leukemia (AML) risk and outcome. However, somatic mutations in these genes have not been reported in an AML clinical population and whether they are associated with epidemiologic exposures, clinical AML phenotypes and outcome after therapy. Methods: We systemically interrogated PubMed database (1998-2018), to identify genes with germline polymorphisms associated with AML risk, response to chemotherapy or outcome. To determine the prevalence and relevance of somatic mutations in these genes in an unselected AML population, we performed an analysis using Whole-Exome Sequencing (WES) on remnant diagnostic cytogenetic pellets from 98 patients from the Mayo Clinic AML Epidemiology Cohort, a detailed and highly-annotated cohort of 295 consecutive AML patients treated at Mayo Clinic Florida & Arizona between October, 2000 and December, 2011. Patient characteristics are shown in Table 1. Samples were sequenced at a depth of ~100 million paired-end 100bp reads using Agilent SureSelectXT Human All Exon V5 + UTRs target enrichment kit. Sequencing reads were aligned to human reference genome, and somatic mutations including non-synonymous and truncating single nucleotide variants and small INDELs were identified and filtered using Exome Sequencing Project, 1000 genome, HapMap, & Mayo Clinic internal biobank genetic variants database. Copy number aberrations were identified & filtered using public copy number polymorphism databases. The association analyses were performed at the gene level, with a primary endpoint of whether a given patient harbored a somatic mutation in any genes linked to AML risk or outcome in literature, and to determine the associations of these mutations with epidemiologic exposures, AML phenotype and clinical outcomes. Results: From the literature search, we identified 77 unique genes with known germline polymorphisms associated with AML risk, response to chemotherapy or outcome. Fifty-eight of these were found to be somatically mutated in our WES dataset, with subsequent analysis focusing on the 11 genes (ABCB1, CYP1A1, CYP2B6, EPHX1, ERCC1, ERCC2, ERCC5, JAK2, MEFV, MTRR, and TERT) that had greater than 5 patients with nonsynonymous somatic mutations in the given gene. Significant associations with epidemiologic exposures and outcomes were noted in patients with somatic mutations in ERCC2, CYP1A1 and ERCC5 genes. Table 2 shows a comparison of patient characteristics and associations according to the presence of somatic mutations in these genes. Patients with mutations in CYP1A1 had a significantly younger age at AML diagnosis (Median: 51.7 vs. 71.0 years, P=.02) and significantly shorter OS in age-adjusted analysis (HR=4.45, P=.003). The former is a novel finding, whereas the latter is consistent with previous reports. Patients with mutations in ERCC2 more commonly used statins (66.7% vs. 21.7%, P=.03). Patients with ERCC5 mutations had a lower rate of tobacco use (20.0% vs. 54.5%, P=.049). In unadjusted analysis, there was a significant association between presence of somatic mutations in JAK2 and poorer survival after AML diagnosis (HR=2.83, P=.017), but this attenuated and did not retain significance when adjusting for age at AML diagnosis (HR=2.22, P=.067). Conclusion: Our exploratory study describes a novel association of CYP1A1 somatic nonsynonymous mutations with age of AML onset, as well as novel associations of ERCC2 and ERCC5 mutations with epidemiologic exposures in an unselect cohort of patients with AML. We confirm the association of CYP1A1 with inferior overall survival after AML diagnosis. These findings suggest that some genes associated with AML risk may also harbor somatic mutations that are clinically relevant. These results will guide a planned confirmatory prospective study to determine frequency and impact of both germline and somatic mutations of risk genes in AML patients, and may contribute to a better understanding leukemia risk assessment and potentially to prevention strategies. Disclosures Finn: Jazz Pharmaceuticals: Speakers Bureau; Celgene: Speakers Bureau; Seattle Genetics: Speakers Bureau. Cerhan:BMS/Celgene: Research Funding; NanoString: Research Funding. Foran:Revolution Medicine: Consultancy; Servier: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Research Funding; H3Biosciences: Research Funding; Xencor: Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Agios: Honoraria, Research Funding.

Background: Multiple myeloma (MM) is an incurable plasma cell malignancy and genetic abnormalities contribute to disease heterogeneity and outcome. Primary abnormalities, namely recurrent immunoglobulin (Ig) heavy chain translocations and hyperdiploidy, occur early in disease course. Secondary events, such as MYC abnormalities occur upon progression. Earlier studies showed MYC abnormalities detected by FISH or by capture sequencing were independently associated with poor outcome (Walker, et al., BCJ, 2014), while recent studies using WGS did not support this finding (excluding MYC/IGL) (Mikulasova, et al. Haematologica, 2020; Misund, et al. Leukemia, 2020). We hypothesize these discrepancies are due to differences in methods and sensitivities of detection of MYC abnormalities by FISH vs. WGS. Given that MYC abnormalities often display remarkable genomic heterogeneity with numerous gene partners, reduced detection of MYC abnormalities by FISH is not unexpected. This hypothesis is supported by lower frequencies of MYC abnormalities found by FISH (15%) vs. NGS (30-35%) consistent with ~50% false-negative rate of the MYC FISH probe (Smadbeck, et al. BCJ, 2019). To better understand the role of MYC in myeloma disease outcome, we compared the MYC abnormality subtype identified by FISH or NGS vs. MYC gene expression levels and overall survival. Methods: We performed a retrospective study of newly diagnosed MM patients seen at Mayo Clinic or enrolled in the MMRF CoMMpass trial. For Mayo cases, MYC FISH results (breakapart probe, Abbott) were obtained from the Mayo Clinic Genomics database (N=1342) and mate pair sequencing (MPseq) was performed on 140 cases. For CoMMpass cases, we obtained tumor long-insert whole genome sequencing (WGS), RNA sequencing (RNAseq) for gene expression and clinical outcome data. Overall survival (OS) was defined as time from diagnosis to death from any cause or to last follow up. Survival curves were estimated using Kaplan Meier and compared using the Log-Rank test. Statistical analyses performed using SPSS and JMP with significance determined when P &lt;0.05. Results: We first evaluated the impact of MYC abnormalities on OS when detected by FISH or NGS. In Mayo cases, OS was significantly shorter in patients with MYC abnormalities compared to patients without MYC abnormalities using FISH (5.3 vs. 8.0 years, P&lt;0.001, N=1342). In contrast, there was no significant difference in OS between patients with or without MYC or abnormalities using MPseq or WGS in both the Mayo and CoMMpass cohorts (Mayo: 6.4 vs. and 6.9 years P=0.78, N=140; CoMMpass: 4.9 vs. and 5.1 years P=0.74, N=546). Since FISH-detected MYC abnormalities were associated with poor outcome, we evaluated differences in the types of MYC abnormalities identified FISH and genome sequencing; 270 of 658 CoMMpass cases had a MYC abnormality and 12 abnormality subgroups were identified. In the Mayo cases, FISH preferentially detected translocations and complex abnormalities and missed insertions with flanking duplicating sequences or terminal tandem duplications (TTD) that occur telomeric to MYC. Since the level of MYC expression should be a consequence of the various genomic abnormalities altering the MYC gene region, we compared MYC expression levels in relation to MYC abnormality subgroups. Highest expression was seen with MYC amplification, followed by Ig abnormalities, non-Ig abnormalities, complex deletion/duplications, proximal deletions, non-Ig insertions, terminal deletions, TTD, trisomy 8, no MYC structural variation, monosomy 8 and cases with MAX mutations had the lowest expression. Abnormalities identified by FISH had higher MYC expression (83.5 TPM) compared to cases predicted to be missed by FISH (63.2 TPM). We tested if high MYC expression, irrespective of MYC structural abnormality, was associated with differences in OS. Boxplot analysis was used to categorize MYC expression in 631 CoMMpass patients as top quartile/high MYC expression (Q4≥ 75 TPM, n=159) and bottom quartile/low MYC expression (Q1≤ 16.5 TPM, n= 158) (see Figure). OS was significantly shorter in patients with high MYC expression compared to patients with low MYC expression (4.6 vs. 5.3 years, P &lt;0.038). Conclusion: We show that FISH detects only a subset of the MYC abnormalities detected by genome sequencing, and that FISH-detected MYC abnormalities are associated with higher MYC gene expression and decreased survival. Figure 1 Disclosures Kumar: Kite Pharma: Consultancy, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Dr. Reddy's Laboratories: Honoraria; Cellectar: Other; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Tenebio: Other, Research Funding; Carsgen: Other, Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Genecentrix: Consultancy; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Sanofi: Research Funding; MedImmune: Research Funding; Adaptive Biotechnologies: Consultancy.

Abstract Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults with a median survival of 14 months despite multimodal treatment. Patients with GBM tumors exhibit a post-resection recurrence rate of almost 100%. The tumor recurrence and treatment resistance properties of GBM reside in a stem-like cell population called Brain Tumor Initiating Cells (BTIC). Among primary GBMs, periventricular tumors exhibit worse survival than tumors distal to the lateral ventricles (LV), the cause for this worse outcome is not known. A potential explanation is the proximity of these tumors to the cerebrospinal fluid (CSF) and the neurogenic niche in the sub-ventricular zone (SVZ). Chemotactic signals present in the cerebrospinal fluid (CSF) regulate neural progenitor cells migratory response and differentiation profile. Our preliminary data show that cancer-derived CSF induces an increase in the migration and proliferation of GBM cells when compared to non-cancer CSF. We evaluated the transcriptome of human GBM cells in response to cancer and non-cancer CSF and identified alpha-1-antichymotrypsin (SERPINA3) as one of the genes that show higher over expression upon cancer CSF-stimulation. SERPINA3 is a circulating anti-protease that is produced and released in different tissues such as liver, prostate, lungs, endometrium and brain that is over-expressed in multiple cancers. We hypothesize that the overexpression of SERPINA3 in response to CSF is a contributing factor to the increase malignancy of periventricular GBM tumors. We tested this hypothesis in silico, in vitro and in vivo. Using TCGA and Rembrandt databases we observed a higher expression of SERPINA3 in brain tumor tissue compared to controls with no differences among GBM subtypes. In GBM patients, expression of SERPINA3 negatively affects survival expectancy. In vitro, Using intraoperative samples, we confirmed that SERPINA3 is overexpressed in brain cancer tissue by western-blot and qRT-PCR. Interestingly, we observed a higher nuclear localization of SERPINA3 in cancer tissue and cells. To determine if SERPINA3 has an effect on the malignancy of GBM cells, we silenced its expression using shRNA. SERPINA3 silencing induced a decrease in cell proliferation (p&lt;0.05), as well as migration (p&lt;0.05), and invasion (p&lt;0.05). Remarkably CD133 expression and stem cell markers were decreased when SERPINA3 is silenced. In contrast, the addition of recombinant SERPINA3 induced an increase in cell migration (p&lt;0.05) of GBM cells. Moreover, cancer CSF is no longer able to induce an increase in GBM cell migration in SERPINA3-KD cells (p&lt;0.05). In vivo, mice orthotopically-injected with SERPINA3-KD cells showed a prolonged overall survival (p&lt;0.05). In summary, our results support the hypothesis that SERPINA3 plays a key role in GBM malignancy in response to CSF and its inhibition results in a better outcome using GBM preclinical models. Targeting the CSF-GBM interaction is a potential therapeutic approach that remains to be explored. Citation Format: Montserrat A. Lara Velazquez, Natanael Zarco, Anna Carrano, Jordan Phillips, Paula Schiapparelli, Emily S. Norton, Stephanie Jeanneret, Teresita Corona, Jose Segovia, Kaisorn Chaichana, Yan Asmann, Alfredo Quinones Hinojosa, Hugo Guerrero-Cazares. Cerebrospinal fluid-responsive factor SERPINA3 induces an increase in the malignancy of glioblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3780.