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Supplementary Table 3

Supplementary Figure 3. Ectopic overexpression of EWSR1-WT1 +KTS and -KTS in UF5 cells.

Purpose:Desmoplastic small round cell tumor (DSRCT) is a highly lethal intra-abdominal sarcoma of adolescents and young adults. DSRCT harbors a t(11;22)(p13:q12) that generates the EWSR1-WT1 chimeric transcription factor, the key oncogenic driver of DSRCT. EWSR1-WT1 rewires global gene expression networks and activates aberrant expression of targets that together mediate oncogenesis. EWSR1-WT1 also activates a neural gene expression program.Experimental Design:Among these neural markers, we found prominent expression of neurotrophic tyrosine kinase receptor 3 (NTRK3), a druggable receptor tyrosine kinase. We investigated the regulation of NTRK3 by EWSR1-WT1 and its potential as a therapeutic target in vitro and in vivo, the latter using novel patient-derived models of DSRCT.Results:We found that EWSR1-WT1 binds upstream of NTRK3 and activates its transcription. NTRK3 mRNA is highly expressed in DSRCT compared with other major chimeric transcription factor–driven sarcomas and most DSRCTs are strongly immunoreactive for NTRK3 protein. Remarkably, expression of NTRK3 kinase domain mRNA in DSRCT is also higher than in cancers with NTRK3 fusions. Abrogation of NTRK3 expression by RNAi silencing reduces growth of DSRCT cells and pharmacologic targeting of NTRK3 with entrectinib is effective in both in vitro and in vivo models of DSRCT.Conclusions:Our results indicate that EWSR1-WT1 directly activates NTRK3 expression in DSRCT cells, which are dependent on its expression and activity for growth. Pharmacologic inhibition of NTRK3 by entrectinib significantly reduces growth of DSRCT cells both in vitro and in vivo, providing a rationale for clinical evaluation of NTRK3 as a therapeutic target in DSRCT.

Desmoplastic small round cell tumor (DSRCT) is a rare pediatric cancer caused by the EWSR1-WT1 fusion gene. No targeted therapies have been established and multimodal therapy is ineffective with a 5-year survival rate of 15-25%. Many questions about the biology of DSRCT remain unanswered including the critical genes regulated by the EWSR1-WT1 fusion gene, the role of the - and +KTS fusion gene isoforms produced by alternative splicing, and the relationship between EWSR1-WT1 binding and gene expression alterations. To address these questions, we established four doxycycline-inducible DSRCT cell lines that selectively knockdown the expression of EWSR1-WT1. RNA-seq analysis on these cell lines with or without EWSR1-WT1 knockdown identified commonly altered genes and pathways. To illuminate the role of the EWSR1-WT1 -KTS and +KTS isoforms, the -KTS, +KTS, or both isoforms were overexpressed in a mesothelial cell line, a hypothesized cell of origin for DSRCT. Remarkably, different gene expression alterations were observed between the -KTS and +KTS isoforms. While overexpression of the -KTS isoform upregulated 765 genes and downregulated 366 genes, overexpression of the +KTS isoform upregulated 203 genes and downregulated 25 genes. Gene set enrichment analysis showed EWSR1-WT1 regulated gene signatures are recapitulated by overexpression of the -KTS isoform or both +/-KTS isoforms, but not the +KTS isoform alone, suggesting the -KTS isoform predominantly regulates gene expression in DSRCT. To interrogate the influence of direct and indirect gene regulation by EWSR1-WT1, ChIP-seq and CUT&RUN data were integrated into our RNA-seq analysis. Across each of our four DSRCT cell lines, approximately 25% of EWSR1-WT1 bound peaks led to upregulation, 10% led to downregulation, and 65% led to no gene expression alteration. EWSR1-WT1 binding accounted for 33% of EWSR1-WT1 commonly upregulated genes but only 4.2% of commonly downregulated genes. Upregulated EWSR1-WT1 bound genes were more likely to be bound in the promoter or first intron and coincide with Znf263 or Hoxb4 motifs. To evaluate the functional role of EWSR1-WT1 targets in DSRCT biology, a screen of the 24 druggable EWSR1-WT1 targets was conducted and a number of novel and known target genes were identified as important for DSRCT survival. Current work is verifying these targets with gene knockdown and evaluating their function in vivo. Citation Format: Justin W. Magrath, Ilon A. Goldberg, Alifiani B. Hartono, Sean B. Lee. EWSR1-WT1 isoform selectivity, DNA binding, and druggable targets: unpacking the biology of desmoplastic small round cell tumor. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3529.

Purpose: Desmoplastic small round cell tumor (DSRCT) is a highly lethal intra-abdominal sarcoma of adolescents and young adults. DSRCT harbors a t(11;22)(p13:q12) that generates the EWSR1-WT1 chimeric transcription factor, the key oncogenic driver of DSRCT. EWSR1-WT1 rewires global gene expression networks and activates aberrant expression of targets that together mediate oncogenesis. EWSR1-WT1 also activates a neural gene expression program. Experimental Design: Among these neural markers, we found prominent expression of neurotrophic tyrosine kinase receptor 3 (NTRK3), a druggable receptor tyrosine kinase. We investigated the regulation of NTRK3 by EWSR1-WT1 and its potential as a therapeutic target in vitro and in vivo, the latter using novel patient-derived models of DSRCT. Results: We found that EWSR1-WT1 binds upstream of NTRK3 and activates its transcription. NTRK3 mRNA is highly expressed in DSRCT compared with other major chimeric transcription factor–driven sarcomas and most DSRCTs are strongly immunoreactive for NTRK3 protein. Remarkably, expression of NTRK3 kinase domain mRNA in DSRCT is also higher than in cancers with NTRK3 fusions. Abrogation of NTRK3 expression by RNAi silencing reduces growth of DSRCT cells and pharmacologic targeting of NTRK3 with entrectinib is effective in both in vitro and in vivo models of DSRCT. Conclusions: Our results indicate that EWSR1-WT1 directly activates NTRK3 expression in DSRCT cells, which are dependent on its expression and activity for growth. Pharmacologic inhibition of NTRK3 by entrectinib significantly reduces growth of DSRCT cells both in vitro and in vivo, providing a rationale for clinical evaluation of NTRK3 as a therapeutic target in DSRCT.

Mitogen Activated Protein (MAP) kinases are a category of serine/threonine kinases that have been demonstrated to regulate intracellular events including stress responses, developmental processes, and cancer progression Although many MAP kinases have been extensively studied in various disease processes, MAP3K19 is an understudied kinase whose activities have been linked to lung disease and fibroblast development. In this manuscript, we use bioinformatics databases starBase, GEPIA, and KMPlotter, to establish baseline expressions of MAP3K19 in different tissue types and its correlation with patient survival in different cancers.

Desmoplastic small round cell tumor (DSRCT) is characterized by the t(11;22)(p13;q12) translocation, which fuses the transcriptional regulatory domain of EWSR1 with the DNA-binding domain of WT1, resulting in the oncogenic EWSR1-WT1 fusion protein. The paucity of DSRCT disease models has hampered preclinical therapeutic studies on this aggressive cancer. Here, we developed preclinical disease models and mined DSRCT expression profiles to identify genetic vulnerabilities that could be leveraged for new therapies. We describe four DSRCT cell lines and one patient-derived xenograft model. Transcriptomic, proteomic and biochemical profiling showed evidence of activation of the ERBB pathway. Ectopic expression of EWSR1-WT1 resulted in upregulation of ERRB family ligands. Treatment of DSRCT cell lines with ERBB ligands resulted in activation of EGFR, ERBB2, ERK1/2 and AKT, and stimulation of cell growth. Antagonizing EGFR function with shRNAs, small-molecule inhibitors (afatinib, neratinib) or an anti-EGFR antibody (cetuximab) inhibited proliferation of DSRCT cells. Finally, treatment of mice bearing DSRCT xenografts with a combination of cetuximab and afatinib significantly reduced tumor growth. These data provide a rationale for evaluating EGFR antagonists in patients with DSRCT. This article has an associated First Person interview with the joint first authors of the paper., Summary: Novel models of desmoplastic small round cell tumor (DSRCT) reveal a role for the ERBB pathway in regulating growth of this sarcoma and provide a rationale for evaluating EGFR antagonists in patients with DSRCT.

Obesity is a worldwide epidemic associated with increased risk and progression of colon cancer. Here, we aimed to determine the role of adipose triglyceride lipase (ATGL), responsible for intracellular lipid droplet (LD) utilization, in obesity-driven colonic tumorigenesis. In local colon cancer patients, significantly increased ATGL levels in tumor tissue, compared to controls, were augmented in obese individuals. Elevated ATGL levels in human colon cancer cells (CCC) relative to non-transformed were augmented by an obesity mediator, oleic acid (OA). In CCC and colonospheres, enriched in colon cancer stem cells (CCSC), inhibition of ATGL prevented LDs utilization and inhibited OA-stimulated growth through retinoblastoma-mediated cell cycle arrest. Further, transcriptomic analysis of CCC, with inhibited ATGL, revealed targeted pathways driving tumorigenesis, and high-fat-diet obesity facilitated tumorigenic pathways. Inhibition of ATGL in colonospheres revealed targeted pathways in human colonic tumor crypt base cells (enriched in CCSC) derived from colon cancer patients. In CCC and colonospheres, we validated selected transcripts targeted by ATGL inhibition, some with emerging roles in colonic tumorigeneses (ATG2B, PCK2, PGAM1, SPTLC2, IGFBP1, and ABCC3) and others with established roles (MYC and MUC2). These findings demonstrate obesity-promoted, ATGL-mediated colonic tumorigenesis and establish the therapeutic significance of ATGL in obesity-reinforced colon cancer progression.

Background & Aims: Diminished forkhead box O3 (FOXO3) function drives inflammation and cancer growth; however, mechanisms fostering these pathobiologies are unclear. Here, we aimed to identify in colon loss of FOXO3-dependent cellular and molecular changes that facilitate inflammation-mediated tumor growth. Methods: FOXO3 knockout (KO) and wild-type (WT) mice were used in the AOM/DSS model of inflammation-mediated colon cancer. Bioinformatics were used for profiling of mRNA sequencing data from human and mouse colon and tumors; specific targets were validated in human colon cancer cells (shFOXO3). Results: In mice, FOXO3 deficiency led to significantly elevated colonic tumor burden (incidence and size) compared with WT (P < .05). In FOXO3 KO colon, activated molecular pathways overlapped with those associated with mouse and human colonic inflammation and cancer, especially human colonic tumors with inflammatory microsatellite instability (false discovery rate < 0.05). FOXO3 KO colon, similar to tumors, had increased neutrophils, macrophages, B cells, T cells, and decreased natural killer cells (false discovery rate < 0.05). Moreover, in KO colon differentially expressed transcripts were linked to activation of inflammatory nuclear factor kappa B, tumorigenic cMyc, and bacterial Toll-like receptor signaling. Among differentially expressed transcripts, we validated altered expression of integrin subunit alpha 2 (ITGA2), ADAM metallopeptidase with thrombospondin type 1 motif 12, and ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 5 in mouse WT and FOXO3 KO colon and tumors (P < .05). Similarly, their altered expression was found in human inflammatory bowel disease and colon cancer tissues and linked to poor patient survival. Ultimately, in human colon cancer cells, FOXO3 knockdown (shFOXO3) led to significantly increased ITGA2, and silencing ITGA2 (siRNA) alone diminished cell growth. Conclusions: We identified the loss of FOXO3-mediated immune landscape, pathways, and transcripts that could serve as biomarkers and new targets for inflammatory colon cancer treatment. Keywords: Colon Cancer, Inflammation, FOXO3, RNAseq

Purpose: Breast cancer remains a prominent global disease affecting women worldwide despite the emergence of novel therapeutic regimens. Metastasis is responsible for most cancer-related deaths, and acquisition of a mesenchymal and migratory cancer cell phenotypes contributes to this devastating disease. The utilization of kinase targets in drug discovery have revolutionized the field of cancer research but despite impressive advancements in kinase-targeting drugs, a large portion of the human kinome remains under-studied in cancer. NEK5, a member of the Never-in-mitosis kinase family, is an example of such an understudied kinase. Here, we characterized the function of NEK5 in breast cancer. Methods: Stably overexpressing NEK5 cell lines (MCF-7) and shRNA knockdown cell lines (MDA-MB-231, TU-BcX-4IC) were utilized. Cell morphology changes were evaluated using immunofluorescence and quantification of cytoskeletal components. Cell proliferation was assessed by Ki-67 staining and transwell migration assays tested cell migration capabilities. In vivo experiments with murine models were necessary to demonstrate NEK5 function in breast cancer tumor growth and metastasis. Results: NEK5 activation altered breast cancer cell morphology and promoted cell migration independent of effects on cell proliferation. NEK5 overexpression or knockdown does not alter tumor growth kinetics but promotes or suppresses metastatic potential in a cell type specific manner, respectively. Conclusion: While NEK5 activity modulated cytoskeletal changes and cell motility, NEK5 activity affected cell seeding capabilities but not metastatic colonization or proliferation in vivo. Here we characterized NEK5 function in breast cancer systems and we implicate NEK5 in regulating specific steps of metastatic progression.

Desmoplastic Small Round Cell Tumor (DSRCT) is a rare and aggressive form of pediatric cancer caused by a translocation between chromosomes 11 and 22, creating the novel EWSR1-WT1 fusion gene. Current therapy including surgery and the P6 chemotherapy regimen is insufficient, leading to a 5-year survival rate of only 15-25%. One potential explanation for this poor prognosis is the existence of a cancer stem cell (CSC) population with the ability to resist chemotherapy and cause both tumor recurrence and metastasis. While a CSC population has been identified in the closely related Ewing Sarcoma, most commonly caused by the EWSR1-FLI1 fusion gene, no CSC population has yet been identified in DSRCT. In this study, novel culture conditions were developed that enabled the formation of tumorspheres in vitro in the two commonly available DSRCT cell lines: JN-DSRCT-1 and BER-DSRCT. These novel culture conditions led to upregulation of stemness genes at the RNA and protein level including NANOG and SOX2, two genes that are associated with poor survival outcomes in TCGA sarcomas data. CCK-8 assay demonstrated an increased chemoresistance for tumorspheres versus normal adherent culture especially for doxorubicin, which was confirmed by reduction in PARP cleavage. This chemoresistance may be partially explained by a more quiescent CSC state as shown by reduced cell proliferation and a lower percentage of cells in the S and G2/M phases. However, cells grown in tumorspheres still robustly formed tumors in vivo, thus demonstrating the two hallmark CSC traits of chemoresistance and tumor formation. RNA-seq was performed to elucidate key differences between the adherent and sphere culture conditions and identify potential targets for the therapeutically important CSC-like population. Overrepresentation analysis and gene set enrichment analysis both showed upregulation of pathways related to chromatin assembly and disassembly, suggesting epigenetic changes as DSRCT cells move to a more stem-like state. RNA-seq further revealed kinases upregulated in tumorspheres including B-lymphocyte kinase (BLK) which previous studies have demonstrated is oncogenic, regulated by EWSR1-WT1, and not necessary for normal survival. BLK knockdown reduced CSC-like properties including abrogation of tumorsphere formation and reduction in the levels of SOX2 and NANOG. Together, this work for the first time identifies a CSC-like population in DSRCT and BLK as a potential DSRCT CSC target. Citation Format: Justin W. Magrath, Alifiani B. Hartono, Sean B. Lee. Identification, characterization, and targeting of desmoplastic small round cell tumor cancer stem cell-like cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 902.

Desmoplastic small round cell tumor (DSRCT) is characterized by the t(11;22)(p13;q12) chromosomal translocation, which fuses the transcriptional regulatory domain of EWSR1 with the zinc finger DNA-binding domain of WT1, resulting in the oncogenic transcription factor EWS-WT1. DSRCT primarily affects young males and has a 5-year overall survival of about 15%. Typical treatment approaches for patients with DSRCT involve a multi-modal combination of surgery, chemotherapy and radiation. The paucity of DSRCT disease models has hampered functional and pre-clinical therapeutic studies in this aggressive cancer. Here, we developed robust preclinical disease models and mined DSRCT expression profiling data to identify genetic vulnerabilities that could be leveraged for the identification of rational therapies. Specifically, we developed four new DSRCT cell lines and one patient-derived xenograft (PDX) model. Transcriptomic and proteomic profiling showed evidence of activation of the ERBB pathway. Ectopic expression of EWSR1-WT1 resulted in upregulation of ERRB family ligands and downstream signaling. Treatment of DSRCT cell lines with ERBB ligands resulted in activation of EGFR, ERBB2, ERK1/2 and AKT, and stimulation of cell growth. Conversely, targeting of EGFR using shRNA, small molecule inhibitors (afatinib, neratinib) or an anti-EGFR antibody (cetuximab) inhibited growth and induced apoptosis in DSRCT cells. Finally, treatment of mice bearing DSRCT xenografts with a combination of cetuximab and afatinib significantly reduced tumor growth. These data provide a rationale for the clinical evaluation of EGFR antagonists in patients with DSRCT.

Obesity is associated with poorer responses to chemo- and radiation therapy for breast cancer, which leads to higher mortality rates for obese women who develop breast cancer. Adipose stem cells (ASCs) are an integral stromal component of the tumor microenvironment (TME). In this study, the effects of obesity-altered ASCs (obASCs) on estrogen receptor positive breast cancer cell&rsquo, s (ER+BCCs) response to radiotherapy (RT) were evaluated. We determined that BCCs had a decreased apoptotic index and increased surviving fraction following RT when co-cultured with obASCs compared to lnASCs or non-co-cultured cells. Further, obASCs reduced oxidative stress and induced IL-6 expression in co-cultured BCCs after radiation. obASCs produce increased levels of leptin relative to ASCs from normal-weight individuals (lnASCs). obASCs upregulate the expression of IL-6 compared to non-co-cultured BCCs, but BCCs co-cultured with leptin knockdown obASCs did not upregulate IL-6. The impact of shLeptin obASCs on radiation resistance of ER+BCCs demonstrate a decreased radioprotective ability compared to shControl obASCs. Key NOTCH signaling players were enhanced in ER+BBCs following co-culture with shCtrl obASCs but not shLep obASCs. This work demonstrates that obesity-altered ASCs, via enhanced secretion of leptin, promote IL-6 and NOTCH signaling pathways in ER+BCCs leading to radiation resistance.

Desmoplastic Small Round Cell Tumor (DSRCT) is a rare and aggressive malignant cancer caused by the chromosomal translocation of t(11;22)(p13;q12) that produces a novel, aberrant transcription factor, EWS-WT1. EWS-WT1 is essential in the formation of DSRCT as well as for maintaining DSRCT cell growth. However, current research has not elucidated how EWS-WT1 leads to the oncogenesis of DSRCT. Through our integrative gene expression data, we identified Salt Inducible Kinase 1 (SIK1) as one of direct target genes of EWS-WT1 in JN-DSRCT-1 cell line. SIK1 is a member of the AMPK related kinases and is involved in gluconeogenesis and lipogenesis regulation, skeletal myocytes development, p53 dependent anoikis, and cell cycle regulation. Through our ChIP analysis, we showed that EWS-WT1 directly binds to a 2kb proximal promoter region of SIK1. Following SIK1 depletion, JN-DSRCT-1 cell proliferation sharply decreased, similar to the growth inhibition observed when EWS-WT1 is depleted. We further showed that cells do not transit to S phase when SIK1 is depleted, suggesting a critical role of SIK1 in cell cycle regulation in DSRCT. Taken together, we have established that EWS-WT1 directly activates SIK1 expression and promotes cell proliferation through SIK1. Therefore, our work identified SIK1 as a new potential therapeutic target in DSRCT. Citation Format: Alifiani B. Hartono, Sean B. Lee. Identification of SIK1 as a potential therapeutic target for desmoplastic small round cell tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2386.

Overall, triple negative breast cancers (TNBCs) constitute 12% of all breast cancers, and is approximately twice more prevalent in African-American populations. Louisiana has a high proportion of African-American residents (32.5% in 2015), and thus hosts a higher population of TNBC patients. TNBCs have an aggressive phenotype that is elusive to the targeted therapeutics used to treat other breast cancer subtypes. Certain kinase families have been extensively studied as regulators of epithelial-mesenchymal transition (EMT), a process involved in the initiation of cancer metastasis. Discovery of novel kinase targets within the subset of uncharacterized kinases could provide important insight into future targeted therapies. However, current models utilized in target discovery research are limited by the inability to accurately recapitulate the complex stromal architecture and heterogenous genetic and molecular composition of breast cancer. Furthermore, immortalized cell lines are limited to a 2D environment and over time acquire mutations that may not reflect the primary tumor. Recently, our laboratory has successfully established two TNBC patient-derived xenograft (PDX) models derived from African-American patients, and generated cell lines (TU-BCx-2K1, TU-BCx-2O0) and mammospheres. One of these models, 2O0, presents tumor architecture, cellular composition, genomic (qRT-PCR) and protein (western blot) expressions that are concordant with a claudin-low subtype, which has higher rates of metastasis and recurrence. Furthermore, we show that both TNBC models metastasize to the lungs, and exhibit molecular characteristics consistent with mesenchymal phenotypes. We utilized these translational PDX models to screen a library of small molecule inhibitors that represent a variety of kinase pathways to identify novel therapeutic targets and/or pathways that are specific to TNBC subtypes. We found in a preliminary cell morphology screen using three TNBC cell lines (MDA-MB-231, BT549, MDA-MB-157), two small molecule inhibitors that increased epithelial marker (CDH1) gene expression, suppressed mesenchymal (VIM, c-FOS, SNAI1, ZEB1) expression and/or suppressed cellular motility in transwell migration assays. We observed after ex vivo treatments with our PDX tumors the two compounds increase the epithelial marker CDH1 expression, and suppress mesenchymal markers (VIM, MMP2, c-FOS, SNAI1, ZEB1) expressions. We confirm these findings in the TU-BCx-2K1 cell line. Kinase array data revealed candidate kinases responsible for the observed EMT changes in the two compounds of interest (NEK5, NEK9, NEK1 potentially affect cell motility; SRC-family kinases, TAOK2, STK10 potentially affect EMT gene changes); we plan to utilize the PDX cell lines to characterize these kinases in EMT. We aim to ultimately discover novel therapeutic targets specific to different TNBC molecular subtypes. Citation Format: Matossian M, Burks H, Bowles A, Sabol R, Hoang V, Elliott S, Bunnell B, Zuercher W, Drewry D, Wells C, Alfortish A, Lee S, Hartono A, Jones S, Moroz K, Zea A, Burow M, Collins-Burow B. Patient-derived triple negative breast cancer xenografts as a translational model to screen for novel kinase pathways [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-05.

Desmoplastic small round cell tumor (DSRCT) is a soft-tissue sarcoma that predominantly affects adolescent and young adult males and has a dismal prognosis, despite aggressive treatment. It is characterized by the t(11;22)(p13:q12) translocation that generates the EWSR1-WT1 chimeric transcription factor, a powerful oncogene and the main molecular driver of DSRCT. EWSR1-WT1 rewires global gene expression networks and activates aberrant expression of targets that contribute to an oncogenic expression program. It has been previously described that EWSR1-WT1 can activate neural gene expression (1), supporting the hypothesis that targeting neural differentiation markers might offer a novel therapeutic approach to treat DSRCT. Among those markers, our analysis of DSRCT tumors demonstrated prominent expression of neurotrophic tyrosine kinase receptor 3 (NTRK3; TrkC), a druggable receptor tyrosine kinase, specifically expressed in DSRCT compared to other translocation-driven sarcomas. We show that EWSR1-WT1 directly activates its expression, and that abrogation of NTRK3 reduces growth of DSRCT cells. Conversely, we show that pharmacologic targeting of NTRK3 is effective both in in vitro and in vivo models of DSRCT, suggesting that NTRK3 is a viable therapeutic target, especially in light of the recent clinical development of highly specific and effective NTRK inhibitors. Reference 1. Kang et al., Cancer Res 2014;15;74(16):4526-35. Citation Format: Lee Spraggon, Julija Hmeljak, Heather Magnan, Romel Somwar, Marina Asher, Alifiani B. Hartono, Sean Bong Lee, Marc Ladanyi. Therapeutic potential of NTRK3 in desmoplastic small round cell tumor [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr B12.