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Precision medicine endeavors to match patients to therapies mostly on the basis of the genomic alterations in their tumors. However, it has been shown that ‘genomics only’ approach is often insufficient for best drug selection. Functional precision medicine has been recently emerging as it provides directly translatable information on which drug to choose among available drugs. Traditionally, cancer drugs are tested in cancer cell line models, but cell lines cannot represent individual clinical patients and are too biologically pronounced to be useful for drug screening purposes. Our patient-derived cell (PDC) drug screening system overcomes these points and can generally also correlate with genome changes. AVATAMED and CBmed, together with AimedBio, are collaborating in a Precision Cancer Project, set out next generation drug screening platform to screen Austrian glioma patients for proof-of-concept study. Fresh native tissue from both low- and high-grade glioma are collected. Tumor tissue is used for PDC isolation using mechanical and enzymatic tissue dissociation. To preserve the original tumor similarity, tissue is short term cultured under two weeks, and PDCs are seeded and treated with a panel of clinical- and preclinical drugs followed by viability assessment. We have cultured 65 PDCs from both low- and high-grade glioma. Tissue culture success rate and drug screening success rate was >85% suggesting that specimen logistics and tissue processing are well-established and conducted. PDCs were treated with 79 drugs that are commonly used in clinical setting. In order to evaluate the quality of the results, the screening was conducted at two different sites, AimedBio and CBmed, and the data were compared. Overall, high accuracy and reproducibility were confirmed by low Coefficient of Variation (CV) between replicates and high Z-factor between negative and positive controls. In addition, data generated from both sites showed high correlations. Collectively, our next-generation drug screening platform shows the potential to give the best therapeutic options to glioma patients. To this end, we are moving forward use this platform in clinical study. Citation Format: Nam-Gu Her, Amin El-Heliebi, Gi Ju Lee, San Ha Park, Barbara Prietl, Stephanie S. Ahn, Hong Boon Toh, Thomas R. Pieber, Do-Hyun Nam. Proof of concept study of next generation drug screening platform for glioma patients [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 3411.

Background: FGFR3-TACC3 (F3-T3) fusion leads to FGFR3 kinase activation constitutively and acts as a driver mutation in several solid tumors. AMB302/GR1017 is a novel FGFR3 targeting ADC that was developed using the intelligent Ligase-Dependent Conjugation (iLDC) technologies from GeneQuantum (GQ) that provide high homogeneity, excellent druggability and high linker stability, and contains a topoisomerase 1 inhibitor as a payload. Based on the preclinical characterization, AMB302/GR1017 shows impressive anti-tumor activities against glioblastoma (GBM) and bladder cancer (BC) models with either FGFR3 amplification or F3-T3 fusion, and demonstrates the potential as a first-in-class FGFR3 ADC against FGFR3 active solid tumor indications. Methods: in vitro anti-tumor effects and mechanism of action for AMB302/GR1017 were assessed on patients-derived cells with F3-T3 using a 3D-spheroid high throughput assay. in vivo anti-tumor effect of AMB302/GR1017 were assessed on F3-T3 fusion GBM orthotopic PDX model and several FGFR3+ or F3-T3 fusion BC models Results: AMB302/GR1017 was generated by linking FGFR3 targeting antibody (AimedBio) with TopoIx (GQ), a next generation Topoisomerase 1 inhibitor via a cleavable linker using the iLDC technologies. In a 3D-spheroid high throughput assay system, AMB302/GR1017 showed significant anti-tumor activity against glioblastoma patients-derived cells (PDCs) in F3-T3 dependent manner, which is superior to chemical conjugate applying the same antibody and Dxd payload. Also, AMB302/GR1017 prolonged the survival of GBM orthotopic PDX models with F3-T3 fusion by 200 % and achieved complete tumor regression in RT112 BC model with F3-T3 fusion. AMB302/GR1017 treatments were well-tolerated up to 200 mg/kg in a mouse safety study. Conclusion: AMB302/GR1017 showed robust anti-tumor efficacies in F3-T3 fusion and FGFR3 overexpression models derived from GBM and BC in vitro and in vivo. In addition, AMB302/GR1017 was well tolerated with no adverse effects in rodent model. Our data suggest AMB302/GR1017 has a potential therapeutic option as a first-in-class FGFR3 targeting ADC for GBM, BC, and other solid tumors with FGFR3 overexpression or alterations. Citation Format: Byeongkwi Min, Lily Shi, Hye Jin Kim, Sangwoo Kim, Beibei Fan, Cao Lv, Yajun Sun, Nam-Gu Her, Paul Song, Gang Qin, Do-Hyun Nam. AMB302/GR1017, an antibody-drug conjugate (ADC) with topoisomerase 1 inhibitor shows therapeutic potency in orthotopic glioblastoma PDX and bladder cancer models with FGFR3-TACC3 fusion [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 2634.

Precision medicine refers to the tailoring of individual therapeutics based on each patient’s genetic, phenotypic, and clinical characteristics, therefore seeking the most effective treatment for the patient. With recent advances in genome sequencing technology, it was anticipated that identifying specific genetic alterations would contribute greatly to the realization of precision medicine. However, most cancer patients do not benefit from genomic precision medicine, as shown in recent Next Generation Sequencing (NGS)-driven clinical trials. Functional precision medicine directly uses patient tumor cells to test their ex vivo responses to diverse drugs to predict the most effective drugs. Functional precision medicine is emerging because it provides immediate translatable information to select drugs among clinically available therapeutics. AVATASCAN®, developed by Samsung Medical Center and AimedBio Inc., is a robust and accurate high throughput functional precision medicine platform with more than 1,500 historical sample data. AVATASCAN® has tested more than 1,500 cancer patient samples across 14 different tumor types, including glioblastoma, lung, colorectal, stomach and breast cancers. We achieved a tissue culture success rate and a drug screening success rate of more than 90% in most tumor types. A retrospective analysis of the clinical outcomes of patients given matched drugs demonstrated actual complete/partial response in 85% of AVATASCAN® screening responders. Recognizing its potential for clinical application, AVATASCAN® was selected as one of the datasets referenced by the pediatric tumor board at Seoul National University Hospital for clinical decision-making. Furthermore, AVATASCAN® is now available in Singapore and Thailand as an early-access, premium precision medicine service. Overall, we present compelling evidence that AVATASCAN® is a valuable platform for personalized cancer therapy. Therefore, we are moving forward to adopt and expand this platform in clinical applications. Citation Format: Nam-Gu Her, Gi Ju Lee, Seung Yoon Hyun, San Ha Park, Jae Woo Ahn, Ji Soo Kang, Hong Boon Toh, Do-Hyun Nam. AVATASCAN®, a pioneer of functional precision medicine in guiding clinical decision-making [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 3410.

Childhood cancers are rare and clinically diverse. They are typically associated with few driver mutational events than adult cancers, constituting potential targets for patient-specific precision therapy approaches. Here, we evaluated the feasibility of using a patient-derived tumor cell (PDC) based drug screening system and integrated multi-omics data to achieve precision oncology for pediatric patients. We established a PDC library derived from a few passage-cultured tumor cells from surgically resected tumor specimens and conducted chemical screening, which composed of various target agents of major oncogenic pathways (e.g. receptor tyrosine kinase inhibitor, proteasome inhibitor and histone deacetylase etc.). Next Generation Sequencing was performed to characterize the genomic and transcriptomic traits of tumors. Overall, success of establishing PDCs of pediatric cancers was high (80.4%) and comparable to adult cancers. The amount of obtained tissue was an important factor for the success of PDC establishment; the estimated optimal weight for PDC establishment was small (1.14g) and it is noteworthy that a small amount of tumor sample is sufficient to identify the potential hit(s) of parental tumors. The platform provided therapeutic options to pediatric tumors regardless of actionable targets. Our PDC approach identified several potential gene-drug associations, including anti-PI3K/Akt agents for neuroblastomas and anti-SHH agents for sarcomas with EWSR1 fusion. Given that a considerable proportion of pediatric tumors still lack actionable targets with matched treatment options, PDC-based drug screening profiles can be an optimal therapeutic strategy for these cases. Collectively, our analysis confirmed the feasibility of PDC-based in vitro drug screening systems to guide the therapeutic strategy for pediatric patients. This approach will accelerate the preclinical research for pediatric tumors to understand their pathophysiology and investigate the potential therapeutic strategies to fulfill the future precision oncology. Citation Format: Gi Ju Lee, Seung-Won Choi, Seung Ah Choi, Hee-Jin Cho, Robyn Gartrell, Ji Won Lee, Joo Whan Kim, Nam-Gu Her, Raul Rabadan, Ki Woong Sung, Do-Hyun Nam, Seung-Ki Kim. Proof of principle for pharmacogenomic-guided precision oncology for pediatric malignancy. [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 4486.

Tumor permeability is a critical determinant of drug delivery and sensitivity, but systematic methods to identify factors that perform permeability barrier functions in the tumor microenvironment are not yet available. Multicellular tumor spheroids have become tractable in vitro models to study the impact of a three-dimensional (3D) environment on cellular behavior. In this study, we characterized the spheroid-forming potential of cancer cells and correlated the resulting spheroid morphologies with genetic information to identify conserved cellular processes associated with spheroid structure. Spheroids generated from 100 different cancer cell lines were classified into four distinct groups based on morphology. In particular, round and compact spheroids exhibited highly hypoxic inner cores and permeability barriers against anticancer drugs. Through systematic and correlative analysis, we reveal JAK–STAT signaling as one of the signature pathways activated in round spheroids. Accordingly, STAT3 inhibition in spheroids generated from the established cancer cells and primary glioblastoma patient–derived cells altered the rounded morphology and increased drug sensitivity. Furthermore, combined administration of the STAT3 inhibitor and 5-fluorouracil to a mouse xenograft model markedly reduced tumor growth compared with monotherapy. Collectively, our findings demonstrate the ability to integrate 3D culture and genetic profiling to determine the factors underlying the integrity of the permeability barrier in the tumor microenvironment, and may help to identify and exploit novel mechanisms of drug resistance. Cancer Res; 76(5); 1044–54. ©2015 AACR.

Malignant glioma (glioblastoma, GBM) is a lethal cancer resistant to multimodality therapeutic approaches. A high burden of tumor-specific mutant peptides (neoantigens) correlates with a more favorable prognosis and response to immunotherapies in selected solid tumors but the role of neoantigens and how they impact clinical outcome in most tumors including GBM remains unclear. Here, we exploited the similarity between tumor neoantigens and infectious disease-derived immune epitopes and applied a neoantigen fitness model for the identification of high quality neoantigens in human GBM. The neoantigen quality fitness model stratified GBM patients with more favorable clinical outcome and, together with tumor infiltration of CD8 T lymphocytes, identified a subgroup of GBM patients with the longest survival, thus exhibiting optimal performance. Conversely, neither tumor neoantigen burden from a quantity model nor the isolated enrichment of CD8 T lymphocytes could predict better survival of GBM patients. The GBM subgroup that emerged from the neoantigen quality model displays distinct genomic and transcriptomic features that should guide patient stratification for immunotherapy and maximal benefit of GBM patients. Citation Format: Jing Zhang, Francesca P. Caruso, Jason K. Sa, Sune Justesen, Do-Hyun Nam, Peter Sims, Michele Ceccarelli, Anna Lasorella, Antonio Iavarone. A high quality neoantigen fitness model cooperates with T lymphocyte infiltrates to identify glioblastoma patients with the longest survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-065.

The RUNX1-RUNX1T1 fusion is a frequent chromosomal alteration in acute myeloid leukemias (AMLs). Although RUNX1-RUNX1T1 fusion protein has pivotal roles in the development of AMLs with the fusion, RUNX1-RUNX1T1 fusion protein is difficult to target since it lacks kinase activities. Here, we used a sophisticated bioinformatic tool to elucidate targetable signaling pathways in AMLs with RUNX1-RUNX1T1 fusion. After analysis of 93 AMLs from the TCGA database, the expressions of 293 genes were significantly correlated with the expression of the RUNX1-RUNX1T1 fusion gene. Based on the 293 genes, the COX, VEGFR, PDGFR, and FGFR pathways are predicted to be specifically activated in AMLs with RUNX1-RUNX1T1 fusion. Compared with the AML cells without the fusion, the specific activations of the AML cell lines with RUNX1-RUNX1T1 fusion were confirmed by the increased phosphorylation of VEGFRs, PDGFRs, and FGFRs. Moreover, the in vitro proliferation of AML cells with RUNX1-RUNX1T1 fusion decreased significantly more than that of AML cells without the fusion when the pathways were inhibited pharmacologically. The results indicate that novel targetable signaling pathways could be identified by the analysis of the gene expression features of AMLs with non-targetable genetic alterations. The elucidation of specific molecular targets for AMLs that have a specific genetic alteration would promote personalized treatment of AMLs and improve treatment outcomes for AML patients in clinic. Note: This abstract was not presented at the meeting. Citation Format: Jae Won Yun, Yoon Kyung Bae, So Yeong Cho, Hee-Jin Kim, Do-Hyun Nam, Sun-Hee Kim, Sejong Chun, Kyeung Min Joo, Hye Won Lee, Woong-Yang Park. Elucidation of novel therapeutic targets for acute myeloid leukemias with RUNX1-RUNX1T1 fusion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1723.

GBM is the most aggressive human primary brain tumor and leads to poor clinical outcomes. According to previous studies, exogenous factors secreted from primary brain tumor cells can change the growth pattern of normal cells. We analyzed the ingredients of cell culture media from two patient glioblastoma cells which can grow without growth factors. As a result, we selected a significant factor for tumor cell growth which is called cytokine A, the Heparin-binding growth factor. Because of the cell viability maintenance ability of cytokine A, we tried to investigate detailed mechanism of cytokine A and applied the result to the combination therapy. Cytokine A is critical for tumorigenesis of GBM by modulating DNA damage signaling and cell cycle through ROS. For that reason, cytokine A is effective therapeutic target and can be used in combination therapy. Citation Format: Suji Han, Kayoung Shin, Kyoungmin Lee, Sungsoo Kim, Hyunju Kang, Jin-Ku Lee, Hyun Nam, Kyeung Min Joo, Do-Hyun Nam. Patient GBM cell originated secretome analysis identifies cytokine A, as a potent therapeutic target [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 2521.

Necrosis is a hallmark of glioblastoma (GBM) and is responsible for poor prognosis and resistance to conventional therapies. However, the molecular mechanisms underlying necrotic microenvironment-induced malignancy of GBM have not been elucidated. Here, we report that transglutaminase 2 (TGM2) is upregulated in the perinecrotic region of GBM and triggered mesenchymal (MES) transdifferentiation of glioma stem cells (GSC) by regulating master transcription factors (TF), such as C/EBPβ, TAZ, and STAT3. TGM2 expression was induced by macrophages/microglia-derived cytokines via NF-κB activation and further degraded DNA damage–inducible transcript 3 (GADD153) to induce C/EBPβ expression, resulting in expression of the MES transcriptome. Downregulation of TGM2 decreased sphere-forming ability, tumor size, and radioresistance and survival in a xenograft mouse model through a loss of the MES signature. A TGM2-specific inhibitor GK921 blocked MES transdifferentiation and showed significant therapeutic efficacy in mouse models of GSC. Moreover, TGM2 expression was significantly increased in recurrent MES patients and inversely correlated with patient prognosis. Collectively, our results indicate that TGM2 is a key molecular switch of necrosis-induced MES transdifferentiation and an important therapeutic target for MES GBM. Cancer Res; 77(18); 4973–84. ©2017 AACR.

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. In United States alone, it was estimated that nearly 137,000 people were diagnosed, and more than 50,000 were dead from the disease each year. CRC primary tumors often metastasize to liver which accounts for most of CRC death. The molecular mechanism of tumor metastasis is complicate and remains poorly understood. In this study, we have collected 79 human CRC samples, and 60 of them are paired primary tumor and liver metastatic surgically resected samples. Molecular characterization of these samples was conducted by exome and RNA sequencing, as well as SNP6.0 analysis. Genetic analysis revealed no significant difference in genetic alterations including common oncogenic mutations, whole genome mutations and copy number variations between primary and their matched liver metastatic tumors. To further characterize the molecular mechanism of metastatic progression, we have assembled gene correlation networks by utilizing a genome-wide interrogation of co-regulated networks based on RNA sequencing data of these CRC samples. Computational analysis of these correlation networks has identified gene signatures of immune-suppression, epithelial-mesenchymal transition (EMT) and angiogenesis as the key events and potentially synergistic drivers associated with CRC metastasis. Further independent cohort validation using published datasets verified that these specific gene networks of tumor microenvironment were progressively up-regulated throughout the carcinogenesis, and represented distinct biological processes. These gene networks were capable of discriminating the previously categorized CRC molecular subclasses. In addition, we also showed an association of type I interferon network with good clinical outcome of CRC, and gene networks of EMT, angiogenesis, immune-suppression and T cell exhaustion are closely associated with the poor patient outcome. We further demonstrated that the networks of EMT and angiogenesis were related to innate anti-PD-1 resistance, and the networks of immunosuppression and T cell exhaustion were associated with resistance to radiation and checkpoint blockade. Overall, we conclude that a genome-wide interrogation of co-regulated networks utilized in this study represents a valuable strategy to identify molecular mechanisms of cancer metastasis, and gene networks of immune-suppression, EMT and angiogenesis are among the key events associated with CRC metastasis. Citation Format: Jiangang Liu, Yong Beom Cho, Hye kyung Hong, Song Wu, Philip J. Ebert, Steven M. Bray, Swee Seong Wong, Jason C. Ting, John N. Calley, Catherine F. Whittington, Shripad Bhagwat, Emma Bowden, Amit Aggarwal, Christoph Reinhard, Robert Wild, Do-Hyun Nam, Woo Yong Lee, Sheng-Bin Peng. Molecular characterization of primary tumor & the paired liver metastatic biopsies of colorectal cancer reveals a critical role of immunosuppression, EMT & angiogenesis in cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 849. doi:10.1158/1538-7445.AM2017-849

Highly metastatic and chemotherapy-resistant properties of malignant melanomas stand as challenging barriers to successful treatment; yet, the mechanisms responsible for their aggressive characteristics are not fully defined. We show that a distinct population expressing CD133 (Prominin-1), which is highly enriched after administration of a chemotherapeutic drug, dacarbazine, has enhanced metastatic potential in vivo. CD133+ tumor cells are located close to tumor-associated lymphatic vessels in metastatic organs such as the regional lymph nodes and lung. Lymphatic endothelial cells promote the migratory activity of a CD133+ subset to target organs and regulation of lymphatic growth efficiently modulates the metastasis of CD133+ tumor cells. We found that lymphatic vessels in metastatic tissues stimulate chemokine receptor 4 (CXCR4)+/CD133+ cell metastasis to target organs by secretion of stromal cell–derived factor-1 (SDF-1). The CXCR4+/CD133+ cells exhibited higher metastatic activity compared with CXCR4−/CD133+ cells and, importantly, blockade of CXCR4 coupled with dacarbazine efficiently inhibited both tumor growth and metastasis; dacarbazine alone could not attenuate tumor metastasis. The current study demonstrates a previously unidentified role of the lymphatic microenvironment in facilitating metastasis of chemoresistant melanoma cells via a specific chemotactic axis, SDF-1/CXCR4. Our findings suggest that targeting the SDF-1/CXCR4 axis in addition to dacarbazine treatment could therapeutically block chemoresistant CD133+ cell metastasis toward a lymphatic metastatic niche. Cancer Res; 70(24); 10411–21. ©2010 AACR.

Glioblastoma multiforme (GBM) is the most aggressive and common form of brain cancer in adults. There are currently no effective therapies for GBM. Even with standard of care treatments, such as surgery, radiation, and chemotherapy, ∼90% of adult patients die within 2 years of diagnosis. To identify therapeutic targets for Glioblastoma (GBM), we performed genome-wide CRISPR-Cas9 “knockout” (KO) screens in patient-derived GBM stem-like cells (GSCs) and human neural stem/progenitors (NSCs), non-neoplastic stem cell controls, for genes required for their in vitro growth. Surprisingly, the vast majority GSC-lethal hits were found outside of molecular networks commonly altered in GBM and GSCs (e.g., oncogenic drivers). In vitro and in vivo validation of GSC-specific targets revealed several strong hits, including the wee1-like kinase, PKMYT1/Myt1. Mechanistic studies demonstrated that PKMYT1 acts redundantly with WEE1 to inhibit Cyclin B-CDK1 activity via CDK1-Y15 phosphorylation and to promote timely completion of mitosis in NSCs. However, in GSCs, this redundancy is lost, likely as a result of oncogenic signaling, causing GBM-specific lethality. From a biological standpoint, our results help re-discover PKMYT1 function in human cells. From a cancer standpoint, these results suggest that targeting PKMYT1 is a glioma-lethal gene and that tandem or sequential use of PKMYT1 and WEE1 inhibitors may illicit therapeutic responses in GBM. In addition to these results we will also present retest data for other candidate glioma-lethal genes and networks in multiple patient samples. Citation Format: Chad Toledo, Ding Yu, Pia Hoellerbauer, Ryan Davis, Ryan Basom, Emily Girard, Philip Corrin, Hamid Bolouri, Jerry Davison, Qing Zhang, Do-Hyun Nam, Jeongwu Lee, Steven Pollard, Jeffery Delrow, Bruce Clurman, James Olson, Patrick Paddison. Genome-wide CRISPR-Cas9 screens reveal loss of redundancy between PKMYT1 and WEE1 in patient-derived glioblastoma stem-like cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4370.

Metastatic renal cell carcinoma (mRCC) evolves from primary RCC (pRCC) and harbors multiple subpopulations with distinct molecular and phenotypic features. Such underlying intratumoral heterogeneity (ITH) imposes difficulties in designing marker-based clinical trials because targeted mono-therapy eliminates a specific subpopulation of tumor cells while leaving others unharmed. Accordingly, a rational combination strategy that minimizes the survival of the drug-resistant subpopulation in a given heterogeneous tumor is essential for long-term therapeutic efficacy. Here, we examined the ITH of a paired mRCC and pRCC using single-cell mRNA sequencing (scRNA-seq) to identify specific tumor cell populations with drug target pathway activation. From the single cell expression profiles, we found the highly activated status of the EGFR and Src signaling pathways in the mRCC compared to the pRCC, with supporting in vitro high-throughput drug screening results. Distinct features of intratumoral expression variability across mRCC single cells that were masked in the bulk measurement prompted us to test the co-targeting strategy for the EGFR and Src pathways with increased likelihood for complete response. This combinatorial strategy showed significantly better treatment effects on mRCC-derived xenograft platforms in vitro and in vivo than monotherapies. Taken together, our findings show clinical implications of scRNA-seq in designing effective treatment regimens for overcoming treatment failure to conventional monotherapies, and also provide novel insights to the unmet clinical needs in effective personalized treatments. Citation Format: Kyu-Tae Kim, Hye Won Lee, Hae-Ock Lee, Hye Jin Song, Da Eun Jeong, Sang Shin, Hyunho Kim, Yoojin Shin, Do-Hyun Nam, Byong Chang Jeong, David G. Kirsch, Kyeung Min Joo, Woong-Yang Park. Single-cell transcriptome analysis guides tailored combinatorial therapeutics in refractory kidney cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 165.

We studied growth factors and their receptors in tumor cells and tumor-associated endothelial cells as the therapeutic targets in colon cancer. Immunohistochemical analysis of 13 surgical specimens of human colon adenocarcinoma revealed that both tumor cells and tumor-associated endothelial cells in 11 of the 13 specimens expressed the epidermal growth factor (EGF), transforming growth factor α (TGF-α), EGF receptor (EGFR), phosphorylated EGFR (pEGFR), vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and phosphorylated VEGFR (pVEGFR). HT29 human colon cancer cells growing orthotopically in the cecum of nude mice expressed a high level of EGF, EGFR, pEGFR, VEGF, VEGFR, and pVEGFR. Double-immunofluorescence staining found that tumor-associated mouse endothelial cells also expressed pEGFR and pVEGFR. Tumors in mice treated for 5 weeks with oral AEE788 (an inhibitor of EGFR and VEGFR tyrosine kinase) as a single agent or with CPT-11 alone were smaller (>50%) than those in control mice. Mice treated with the combination of AEE788 and CPT-11 had significantly smaller tumors (P < 0.01) and complete inhibition of lymph node metastasis. AEE788 alone or in combination with CPT-11 inhibited pEGFR, pVEGFR, and phosphorylated Akt expression on tumor-associated endothelial cells as well as on tumor cells. The combination therapy also significantly decreased microvessel density and tumor cell proliferation and increased the level of apoptosis in both tumor cells and tumor-associated endothelial cells. Collectively, these data suggest that the dual inhibition of EGFR and VEGFR signaling pathways in tumor cells and tumor-associated endothelial cells in combination with chemotherapy can provide a new approach to the treatment of colon cancer.

Glioblastoma multiforme (GBM) is the most aggressive and common form of brain cancer in adults. There are currently no effective therapies for GBM. Even with standard of care treatments, such as surgery, radiation, and chemotherapy, ∼90% of adult patients die within 2 years of diagnosis. Our inability to develop new more effective therapies may arise from pre-clinical models that inadequately predict therapeutic window and the fact that many new GBM drugs are “hand-me-downs” from other cancers, not specifically developed for treating brain tumors. To identify patient-tailored drug targets for GBM, our group has performed a series of functional genetic screens in patient derived GBM stem-like cells (GSCs) and also non-transformed human neural stem cells (NSCs). GSCs retain tumor-initiating potential and tumor-specific genetic and epigenetic signatures, even during extended outgrowth in serum-free culture. NSCs represent non-transformed candidate cell of origin controls, which share similar gene expression signatures and identical in vitro growth conditions. Using these systems along with RNAi or CRISPR/Cas9 platforms, we have identified multiple molecular vulnerabilities specific to GSCs, which appear to be largely driven by oncogenic transformation, in processes ranging from kinetochore regulation to 3′ pre-mRNA splice site recognition. At this meeting, we present our latest findings from genome-wide CRISPR-Cas9 gene knockout screens in multiple GSC and NSC isolates. These include validation studies of patient tumor-lethal genes using gene knockout rather than gene knockdown technology. In addition, we will present validation studies of gene products growth limiting for NSC expansion/self-renewal from these screens, a subset of which are candidate tumor suppressors for glioma. Strengths and weaknesses of using gene editing technology and GSC isolates for identification of therapeutic targets will be discussed. Citation Format: Yu Ding, Chad Toledo, Pia Hoellerbauer, Ryan Basom, Emily Girad, Eunjee Lee, Philip Corrin, Qi Lin, Xiao-Nan Li, Do-Hyun Nam, Jeongwu Lee, Jun Zhu, Steven Pollard, Jeffery Delrow, Jim Olson, Patrick J. Paddison. Genome-wide CRISPR-Cas9 screens reveal candidate therapeutic targets and tumor suppressor genes for human glioma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1106. doi:10.1158/1538-7445.AM2015-1106

BACKGROUND: Tumor progression within a brain is the process of acquiring malignant genetic mutations from glial progenitor cells, dodging their original developmental fate and deteriorating functional connectivity of CNS. In order to devise effective targeted therapeutic strategies, understanding distinct molecular and phenotypic evolutionary features of cancer clones is eminent. METHODS: To examine molecular signatures associated with malignant glioma progression, we analyzed transcriptome dynamics of 311 single-cells derived from 3 patients showing distinct disease patterns. Combined with single-cell level signatures, clonal architecture of tumors was reconstructed based on Bayesian-model clustering with integrated information of SSNVs and SCNAs identified from bulk population-level using aCGH and WES. RESULTS: We found evidence of branched evolutionary patterns within and across two histopathological separated tumor regions. Both tumors have high clonal probable somatic mutations, and evolutionary inference showed clonal lineage between two tumor regions was divided at early time during tumor progression. For all patients, the gene expression signatures within a tumor were heterogeneous but converged towards mesenchymal phenotype in the aggressive region. In the first case, the left tumor was self-limiting and showed mixed proneural and classical gene expression signatures whereas the right side tumor has expanded to the corpus callosum with EGFR overexpression and mesenchymal gene expression. In a case of a monocentric tumor with PDGFRA amplification, cancer cells disseminated from the core mass with massive immune cell infiltration underwent transcriptome switching from proneural to mesenchymal gene expression, with a concomitant FGFR1 copy number gain and mutation. Lastly, in a secondary glioblastoma with IDH1 mutation, GLIOLAN positive glioblastoma was surrounded by grade III oligodendroglioma. The two tumor areas showed intermingled heterogeneous gene expression signatures, with upregulation of astrocytic/mesenchymal genes in the GLIOLAN positive tumor cells. CONCLUSIONS: Our results show distinct genetic patterns of clonal expansion across patients undergoing malignant glioma progression. We also provide the transcriptome-wide view of gene expression signatures directed by genomic alterations. Overall our study reveals heterogeneity of individual tumor but elucidates common genomic features of glioblastoma progression. Citation Format: Kyu-Tae Kim, Jin-Ku Lee, Dong-Hyun Park, Do-Hyun Nam, Hae-Ock Lee, Woong-Yang Park. Transcriptome landscape of brain tumor progression at single-cell resolution. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3748. doi:10.1158/1538-7445.AM2015-3748

Distinct genomic signature of a patient's cancer could provide a clue to design and predict accurate therapeutic responses to targeted medicine. Current approaches regarding heterogeneous cancer cells en masse as a pooled population, however, hardly reflect complete genomic landscape of tumor diversity, missing potentially important minor clones' implications regarding metastasis and drug resistance. Here we report a comprehensive analysis to discover different patterns of subclonal behaviors in functional modalities and signaling pathways out of heterogeneous population derived from a patient with lung squamous cell carcinoma, using single-cell mRNA sequencing. As a result of nonnegative matrix factorization as a clustering, we identified discrete 4 subgroups with a major group in accordance with overall expression profile of a pooled population of cells, and the other 3 minor groups that were masked in a pooled sample. Genomic variants were also reliably identified and compared across single cells. We integrated these genomic signatures from single cells to address the different responses in drug screening. Together, our approach provides insights into the more accurate strategy to identify minor but potentially important subclones that are relevant to drug resistance. Citation Format: Kyu-Tae Kim, Hye-Won Lee, Kyeung Min Joo, Sang-Chul Kim, Jin-Ku Lee, Nakho Chang, Jason K. Sa, Yu Jin Cho, Do-Hyun Nam, Hae-Ock Lee, Woong-Yang Park. Single-cell transcriptome analysis on lung squamous cell carcinoma derived from a patient. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4664. doi:10.1158/1538-7445.AM2014-4664

Glioblastomas multiforme (GBM) contain highly tumorigenic, self-renewing populations of stem/initiating cells [glioblastoma stem cells (GSC)] that contribute to tumor propagation and treatment resistance. However, our knowledge of the specific signaling pathways that regulate GSCs is limited. The MET tyrosine kinase is known to stimulate the survival, proliferation, and invasion of various cancers including GBM. Here, we identified a distinct fraction of cells expressing a high level of MET in human primary GBM specimens that were preferentially localized in perivascular regions of human GBM biopsy tissues and were found to be highly clonogenic, tumorigenic, and resistant to radiation. Inhibition of MET signaling in GSCs disrupted tumor growth and invasiveness both in vitro and in vivo, suggesting that MET activation is required for GSCs. Together, our findings indicate that MET activation in GBM is a functional requisite for the cancer stem cell phenotype and a promising therapeutic target. Cancer Res; 72(15); 3828–38. ©2012 AACR.

Aberrant activation of receptor tyrosine kinases (RTK) is causally linked to the pathobiological traits of glioblastoma and genesis of glioma stem-like cells (GSC), but the underlying mechanism is still unknown. Here, we show that epidermal growth factor receptor (EGFR) signaling regulates the proliferation, angiogenesis, and acquisition of GSC characteristics by inducing inhibitor of differentiation 3 (ID3) and ID3-regulated cytokines [GRO1 and interleukins (IL)-6 and 8] induction. We found that EGFR-mediated ID3 expression was regulated by Smad5, which was directly phosphorylated by AKT. Furthermore, ID3 alone imparted GSC features to primary astrocytes derived from Ink4a/Arf-deficient mouse, and EGFR–ID3–IL-6 signaling axis gave rise to tumor cell heterogeneity. Conversely, EGFR inhibitors suppressed EGFR-AKT-Smad5–driven induction of ID3, which led to a decrease in the tumorsphere forming ability of GSCs and U87MG cells that possess an active mutant EGFR, EGFRvIII, without obvious cytotoxic effects. However, these cells seemed to regain colonogenic ability after removal of the EGFR inhibitors. Together, the results delineate a novel integrative molecular mechanism in which the RTK-ID signaling pathway governs genesis and maintenance of GBM histopathologic features, such as GSCs-based tumor initiation, progression, and angiogenesis. Cancer Res; 71(22); 7125–34. ©2011 AACR.

One of the most detrimental hallmarks of glioblastoma multiforme (GBM) is cellular invasiveness, which is considered a potential cause of tumor recurrence. Infiltrated GBM cells are difficult to completely eradicate surgically and with local therapeutic modalities. Although much effort has focused on understanding the various mechanisms controlling GBM invasiveness, its nature remains poorly understood. In this study, we established highly serial intracranial transplantation. U87R4 cells were highly invasive and displayed stem cell-like properties, as compared to noninvasive but proliferative U87L4 cells. Microarray analysis during serial transplantation revealed that apoptosis-inducing genes (caspase3 and PDCD4) were downregulated whereas several cancer stem cell–relevant genes [Frizzled 4 (FZD4) and CD44] were upregulated in more invasive cells. U87R4 cells were resistant to anticancer drug–induced cell death, partly due to downregulation of caspase3 and PDCD4, and they retained activated Wnt/β-catenin signaling due to upregulation of Frizzled 4, which was sufficient to control neurosphere formation. We also found that FZD4 promoted expression of the epithelial to mesenchymal transition regulator SNAI1, along with acquisition of a mesenchymal phenotype. Taken together, our results argue that Frizzled 4 is a member of the Wnt signaling family that governs both stemness and invasiveness of glioma stem cells, and that it may be a major cause of GBM recurrence and poor prognosis. Cancer Res; 71(8); 3066–75. ©2011 AACR.

The ErbB3 binding protein Ebp1 has been implicated in a number of human cancers. Ebp1 includes 2 isoforms, p48 and p42, that exhibit different cellular activities. Here we show that the larger p48 isoform is transforming and that it promotes cell growth, clonogenicity, and invasion in human glioblastoma (GBM). P48 overexpression in GBM cells facilitated tumorigenesis and enhanced tumor growth in mouse xenograft models. Human GBM tissues displayed elevated levels of p48 compared with surrounding normal tissues or low-grade tumors. Notably, p48 levels were inversely correlated with poor prognosis in GBM patients. We determined that p48 binds to the p53 E3 ligase HDM2, enhancing HDM2-p53 association and thereby promoting p53 polyubiquitination and degradation to reduce steady-state p53 levels and activity. Together, our findings suggest that p48 functions as an oncogene by promoting glioma tumorigenicity via interactions with HDM2 that contribute to p53 downregulation. Cancer Res; 70(23); 9730–41. ©2010 AACR.

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumor, yet with no targeted therapy with substantial survival benefit. Recent studies on many types of solid tumors showed that fusion genes often play driver roles and are promising targets for pharmaceutical intervention. To survey potential fusion genes in GBM, we analysed RNA-Seq data from 162 GBM patients available through The Cancer Genome Atlas (TCGA). From the analysis, we identified recurrent fusion of neurotrophic tyrosine kinase receptor type 1 (NTRK1, also called TrkA) to the genes highly expressed in neuronal tissues, neurofascin (NFASC) and brevican (BCAN). NTRK1 is a mediator of the pro-survival signaling of nerve growth factor (NGF) and is a known oncogene, found commonly altered in human cancer. While GBMs largely lack NTRK1 expression, the fusion-positive GBMs express fusion transcripts in high abundance that retain NTRK1 kinase domain in frame. Analyses of the matching Exome-Seq data indicated that NFASC-NTRK1 fusion occurred through DNA-level rearrangement, whereas BCAN-NTRK1 fusion presumably occurred at RNA-level. As analogous NTRK1-fusions with thyroid-expressed genes were previously shown to drive thyroid cancer, NTRK1-fusion in GBM might have a similar role. Consistent with this hypothesis, the GBMs that harbor the NTRK1-fusion showed elevated NGF/NTRK1 pathway activity. About 1% of GBM patients are estimated to have NTRK1-fusion; these patients might benefit from potential NTRK1 inhibition therapies. Citation Format: Jinkuk Kim, Hee-Jin Cho, Gye-Hyun Cho, Young-Hyeh Ko, Soonmyung Paik, Do-Hyun Nam. Recurrent fusion of NTRK1 in glioblastoma multiforme. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1765. doi:10.1158/1538-7445.AM2013-1765 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Glioblastoma multiforme (GBM) is the most common and lethal primary brain tumor. GBM cells are highly resistant to standard-of-care therapies including radiation and chemotherapy, indicating an urgent need for the development of novel therapeutics. Recent evidence suggests that deubiquitinating enzymes are overexpressed or activated in various cancers, and they contribute to tumor progression and recurrence. Here, we report that the deubiquitinating enzyme ubiquitin-specific peptidase 1 (USP1) is highly expressed in GBMs and the targeting USP1 decreases cell survival and tumor growth. Targeting USP1 by RNA interference or treatment with a chemical USP1 inhibitor attenuated self-renewal and survival of GSCs. As one of the molecular mechanism that link USP1 to pro-tumorigenic roles, we found that the USP1 stabilized the inhibitor of DNA binding protein1 (ID1) and checkpoint kinase 1 (CHEK1), both of which are positive GSC regulators and implicated in radioresistance. Inhibition of USP1 in GBM cells leads to hypersensitivity to ionizing radiation through the decrease in DNA damage repair capacity. Finally, USP1 inhibition in orthotopic GBM xenografts significantly reduced tumor growth and prolonged the survival of tumor bearing mice. Together, our findings suggest that USP1 is a promising therapeutic target for GBMs and provide a rationale for positioning USP1 inhibitor as a GBM radiosensitizer. Citation Format: Young Taek M. Oh, Eunhee Kim, Jeongwu Lee, Do-Hyun Nam. Targeting USP1 decreases glioblastoma stem cell survival and tumor growth. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-270. doi:10.1158/1538-7445.AM2013-LB-270

At least one-third of renal cell carcinoma (RCC) patients are diagnosed with metastases and an additional 20 to 40% of patients develop metastases after radical nephrectomy with curative intent. Although the treatment of advanced RCC has recently evolved to the use of VEGF-targeted antiangiogenic therapies, there have been no significant improvements in the mortality rate of RCC, most likely because currently available therapies are relatively ineffective. A full understanding of the molecular pathogenesis involved in the progression of RCC is important for the development of innovative treatment options. Tumor Progression Locus 2 (Tpl2/MAP3K8), is a serine-threonine kinase with an important physiological role in tumor necrosis factor, interleukin-1, CD40, Toll-like receptor and G protein-coupled receptor-mediated extracellular signal-regulated kinases (ERK1/ERK2), c-Jun NH2-terminal kinases (JNK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and p38MAPK pathways. Previously identified as an oncogene, its overexpression is reported in many types of cancer and associated with metastatic potential. Inspection of transcriptome profiles registered in the oncomine database indicates that Tpl2 expression is differentially expressed in RCC compared to normal tissue. However, the relevance of Tpl2 in tumor growth and metastasis of RCC and the underlying mechanisms remain to be explored. To investigate a functional role of Tpl2 in the progression of RCC, the molecular effects of Tpl2 inhibition were examined in human RCC preclinical model using Caki-1 cells. In this study, we report a functional role for Tpl2 in RCC tumorigenesis and metastasis. Gene silencing with Tpl2 short hairpin RNA and treatment with a Tpl2 kinase inhibitor remarkably suppressed proliferation, focus formation potential, anoikis-resistance and cell-adhesion as well as in vitro cell migration/invasion capabilities in Caki-1 cells. Cell cycle assay showed that the anti-proliferation effect of Tpl2 shRNA was mediated by arresting cells in the G0/G1 phase. We found that interleukin 1β-induced phosphorylation of ERK or JNK was markedly suppressed by Tpl2 shRNA or Tpl2 kinase inhibitor. Furthermore, the orthotopically xenografted tumor growth of Caki-1 cells was significantly suppressed by Tpl2 knockdown with Tpl2 shRNA. An experimental metastasis assay also shows that Tpl2 inhibition suppressed the ability of Caki-1 cells to form lung metastases in a murine tail vein injection model. In clinical specimens of RCC, immunohistochemistry showed that Tpl2 expression levels in RCC specimens were significantly higher than those in normal renal tissues. These data suggest that Tpl2 may function as an oncogene linked to RCC and potential target for novel therapeutic modalities for advanced RCC. Citation Format: Hye Won Lee, Se Jeong Lee, Mi Young Song, Kyeung Min Joo, Byong Chang Jeong, Do-Hyun Nam. Tumor progression locus 2 (Tpl2) protein kinase contributes tumor growth and metastasis of renal cell carcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C53.

Frequent early development of systemic metastasis leads unfavourable clinical prognosis of the non-small cell lung cancer (NSCLC). Although the brain metastasis (BM) contributes significantly to the morbidity and mortality of NSCLC, relevant driver mechanisms are largely unknown. To elucidate genetic alterations and prognostic markers associated with early BM of NSCLC, we retrospectively collected 18 NSCLC patients with BM (12 adenocarcinomas (ADC) and 6 squamous cell carcinomas (SQCC)) whose surgical tissues of primary and/or metastatic tumors were preserved as formaldehyde fixed and paraffin embedded (FFPE) pathologic samples. When chromosomal copy number alterations (CNAs) of those FFPE samples were analysed by the Molecular Inversion Probe (MIP) technology, the most frequent CNAs detected in primary ADCs were gains of 3q, 5p, 5q, 6p, 8q, 9p, 11p, 15q, 17q and losses of 10q and 22q whereas primary SQCCs revealed gains in 4q and 12q and loss in 9q. Moreover, comparative MIP analysis on 11 matched cases demonstrated the fact that the BM carried the majority of genetic alterations present in the corresponding primary tumor but with a slightly higher frequency including gain of 9p11 and loss of 2p11 in ADCs. Especially, when primary 12 ADCs were analyzed depending on the pattern of BM to uncover predetermining signatures that can predict the risk of BM, selectively amplified regions of primary lung ADCs (5q35, 10q23 and 17q23-24) were identified as significantly associated with the development of early BM within 3 months after first diagnosis of primary tumor. Small interfering RNA silencing of ACTA2, which is one of several candidate genes revealed in this study, reduced the in vitro migratory and invasive potential of human ADC cell line PC14PE6-GFP tagged cells without affecting on proliferation. Although more validation is needed, the genetic signatures elucidated in this study shed light on the molecular mechanisms involved in BM and help to identify prognostic markers stratifying the subgroup at high risk of developing recurrence or distant metastasis within heterogeneous NSCLC patients. Citation Format: Hye Won Lee, Se Jeong Lee, Mi Young Song, Kyeung Min Joo, Do-Hyun Nam. Genomic copy number alterations associated with the early brain metastasis of non-small cell lung cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B100.

Glioblastoma (GBM) patients have dismal median survival even with the most rigorous treatments currently available. Radiotherapy is the most effective non-surgical therapy for GBM patients; however, patients succumb due to tumor recurrence within a year. To develop a curative therapeutic approach, we need to better understand the underlying molecular mechanism of radiation resistance in GBM. Towards this goal, we developed an in vivo orthotopic GBM model system that mimics the radiation response of human GBM, using both established-GBM cell line and patient-derived freshly dissociated GBM specimen. In-vivo ionizing radiation (IR) treatment prolonged the survival of mice with intracranical tumor derived from U373MG, but failed to prevent tumor recurrence. U373MG and GBM578 cells isolated after in-vivo IR (U373-IR and 578-IR) were more clonogenic and enriched with stem cell-like characteristics, compared with mock-treated control tumor cells. Transcriptomic analyses and quantitative real-time reverse-transcription PCR analyses using these matched GBM cells before and after radiation treatment revealed that Wnt pathways were preferentially activated in post-IR GBM cells. U373-IR cells and 578-IR were enriched with cells positive for both active b-catenin (ABC) and Sox2 population, and this subpopulation was further increased after additional in-vitro radiation treatment, suggesting that radiation resistance of GBM is mediated due, in part, to the activation of stem cell-associated pathways including Wnt. Finally, pharmacological and siRNA inhibition of Wnt pathway significantly decreased the survival and clonogenicity of GBM cells and reduced their ABCþ/Sox2þ population. Together, these data suggest that Wnt activation is a molecular mechanism to confer GBM radioresistance and an important therapeutic target. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3458. doi:1538-7445.AM2012-3458

Ionizing radiation (IR) is a critical component in the treatments of breast cancer patients with all stages of the disease and a gold standard modality in patients with multiple brain metastasis, demonstrating improved overall survival (OS) in recent meta-analysis. However, the problem of recurrent or persistent disease exists due to tumor radio-resistance, and the development of distant metastasis after IR has presented a major obstacle to treatment. We investigated which molecule could be targeted for radio-sensitization. We found that c-Met over-expression and activation of downstream-signaling were induced in response to IR in a panel of human breast cancer cells by q-PCR, FACS, and Western blot analysis. The radio-sensitizing effect of c-Met silencing in vitro showed that increased c-Met activity is required for radio-resistance. In addition, c-Met inhibition combined with IR showed synergistic antitumor response including improved tumor regression and lengthened overall survival in breast cancer orthotopic and experimental brain metastasis xenograft models. Our preclinical findings establish a basis for a novel strategy to target the HGF/c-Met pathway with radiation when treating primary and brain metastatic breast cancer and possibly other c-Met pathway dependent cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3460. doi:1538-7445.AM2012-3460

We aimed at generating a clinically meaningful in vivo platform for preclinical drug screening in colorectal cancer. Surgical specimens were collected from 143 patients, and 97 carcinomas were engrafted in immunodeficient mouse (tumor take rate 67%). To develop in vivo platform suitable for drug screening, 39 of xenografted carcinomas were selected and expanded satisfactorily in mice with a mean time to reach a size of 1000-1500 mm3 of 90 ± 20 days. In order to validate the similarity of molecular characters between the patient tumor and carcinomas obtained from xenografts, we conducted the mutation status, an expression array, arrayCGH, and other molecular profiling in colon cancer to look at the molecular progression and transition along with primary tumor, metastatic tumor and xenograft model. Histological analysis and the molecular profiles of tumors revealed a high degree of similarity between the patient tumor and xenografted carcinomas. The xenografted tumors maintain their genotypic features of original tumors, suggest that the in vivo platform can be useful for the personalized drug development in colorectal cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1315. doi:1538-7445.AM2012-1315

Tumor angiogenesis is the process that leads to the formation of blood vessels in a tumor and a prognostic indicator in various cancers. Vascular endothelial growth factor (VEGF) and its receptors are considered to be primary regulators of tumor-induced angiogenesis and activation of VEGFR2/KDR is the major signaling pathway for tumor growth. In addition, VEGFR2/KDR is also expressed in many cancer cells, and regulates cell growth and survival through autocrine pathway. In this study, we evaluated the therapeutic potential of TTAC-0001, fully human antibody against VEGFR2/KDR, for the inhibition of tumor growth. In the tube formation assay using HUVEC, TTAC-0001 exhibited a potent anti-angiogenic activity in vitro. In U-87 MG glioblastoma cells, TTAC-0001 significantly inhibited the phosphorylation of VEGFR2/KDR mediated by VEGF. To reveal in vivo efficacy, we have tested TTAC-0001 in glioblastoma and colorectal xenograft models. We demonstrated that antitumor activity of TTAC-0001 in preclinical models correlated with induction of growth arrest and apoptosis as well as the inhibition of angiogenesis. Currently, we are evaluating the combination of TTAC-0001 with chemotherapeutic agents in xenograft models. A single dose study performed in mouse allowed us to establish the relationship between the pharmacokinetics (PK) and efficacy of TTAC-0001. Taken together, our data suggest that targeting VEGFR2 pathway by TTAC-0001 would be a promising candidate for the treatment of cancer. (This study was supported by grants of the Korea Healthcare technology R&D Project, Ministry for Health & Welfare Affairs (A092255 and A040016) and Advanced Medi-cluster R&D Project, DaejeonTechnoPark, Republic of Korea. Seol HJ and Nam DH are co-corresponding authors for this manuscript.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 647. doi:10.1158/1538-7445.AM2011-647

The malignant glioma is the most common primary human brain tumor, and its migration and invasiveness away from the primary tumor mass is considered a leading cause of tumor recurrence and treatment failure. Recently, gene expression profiling revealed CD99, which is a transmembrane glycoprotein, is more expressed in malignant glioma than in normal brain. It has been implicated in cell adhesion and migration in various cells, even if the function of this gene is not understood clearly. This gene has two isoforms of wild-type and splicing variant. We revealed that only wild-type CD99 is expressed in human glioma cells and tissues. Through MTS, colony-forming, and anoikis assays, we found that wild-type CD99 in glioma cells has enough resistance for anoikis and ability to survive and grow in anchorage independence, as is opposed to previous reports in other tumors. Using tissue microarray, we validated that CD99 demonstrates higher expression in gliomas compared to non-neoplastic brain. We inhibited CD99 expression by siRNA and demonstrated decreased glioma cell migration and invasion. In contrast, when CD99 was over-expressed in glioma cells, we observed enhancement of cell migration and invasiveness. Orthotopic brain tumor model with nude mice harboring CD99 overexpressing glioma cells results in significant decreased survival rate, compared to control mice. Moreover, higher invasiveness is observed in overexpressing mice by pathological review. Taken together, our findings suggest that CD99 play an important role in the migration and invasion of human gliomas. CD99 could be a target to inhibit migration and invasion especially in CD99-expressing gliomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2355. doi:10.1158/1538-7445.AM2011-2355

Objective: Ionizing irradiation causes cell death but also birth and migration of new neurons within sites of cerebral damage. The cellular environment that induces neuronal regeneration and migration after irradiation has not been defined yet. The aim of this study was to evaluate the neuronal response after irradiation injury induced by gamma knife radiosurgery. Methods: We used a model of long-distance migration of newly transplanted neural stem cells from the subependymal zone on the other hemisphere to that on the ipsilateral side after irradiation using gamma knife radiosurgery for the purpose of defining the cellular cues that induce neuronal regeneration after CNS injury. Results: In vitro and in vivo studies showed that irradiation induced neurogenesis from transplanted GFP-tagged neural stem cells and migration of newly born neurons into a unique neurovascular niche. Within this neurovascular niche, newly born, immature neurons were closely associated with the remodeling vasculature. The relationship between neurogenesis and angiogenesis is causally linked through vascular production of CD31 and VEGF receptor-2. Conclusions: These experiments defined a novel brain environment for neuronal regeneration after irradiation using gamma knife radiosurgery and identified molecular mechanisms that are shared between angiogenesis and neurogenesis during functional recovery from brain injury. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3317.

The presence of active immunity within the brain supports the possibility of effective immunotherapy for glioblastoma (GBM). To provide a clinically-relevant adoptive immunotherapy for GBM using ex vivo expanded cytokine-induced killer (CIK) cells, the treatment capability of CIK cells, either alone or in combination with temozolomide (TMZ) were evaluated. Human CIK (hCIK) cells were cultured from PBMC using activating anti-CD3 antibody and IL-2, which were 99% CD3+, 91% CD3+CD8+ and 29% CD3+CD56+. In vitro, hCIK cells showed tumor-specific cytotoxicity against U-87MG human GBM cells. When hCIK cells were injected into tail veins of immune-compromised mice bearing U-87MG tumors in their brains, numerous CIK cells infiltrated into the brain tumors. CIK treatments (1 × 105, 1 × 106 or 1 × 107, once a week for four weeks) inhibited the tumor growth significantly in a dose-dependent manner; 44%, 54% and 72% tumor volume reduction, respectively, compared with the control group (P < 0.05). Moreover, hCIK cells (1 × 107, once a week for four weeks) and TMZ (2.5 mg/kg, daily for 5 days) combination treatment further increased tumor cell apoptosis and decreased tumor cell proliferation and vessel density (P < 0.05), creating a more potent therapeutic effect (95% reduction in tumor volume) compared with either hCIK cells or TMZ single therapy (72% for both, P < 0.05). Taken together, CIK cell-immunotherapy and TMZ chemotherapy have synergistic therapeutic effects and could be combined for a successful treatment of GBM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-326.