bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A46: INCB018424 induces apoptotic cell death through the suppression of pJAK1 in human colon cancer cells
Authors: Eunkyoung Choi , Hana Jung , Hojung Ahn , Seung-Woo Hong , Jai-Hee Moon , Jae-Sik Shin , Kyu-Pyo Kim , Sang Hong Yong , Jae-Lyun Lee , Kyung Choi Eun , Shin Lee Jung , Dong-Hoon Jin , Won Kim Tae
Published: May 2015

Janus kinase (JAK) is one of the main upstream activators of signal transducers and activators of transcription (STAT) that are constitutively activated in various malignancies and are associated with cell growth, survival, and carcinogenesis. Here, we investigated to role of JAKs in colorectal cancer in order to develop effective therapeutic targets for INCB018424, which is the first JAK1/2 inhibitor to be approved by FDA. After examining the basal expression levels of phospho-JAK1 and phospho-JAK2, we measured the effects of INCB018424 on the phosphorylation of JAK1/2 using western blot analysis. Cell viability was determined using the trypan blue exclusion assay. The cell death mechanism was identified by the activation of caspase 3 using western blot and annexin V staining. The basal levels of phospho-JAK1 and phospho-JAK2 were cancer cell type dependent. Colorectal cancer cell lines that phosphorylate both JAK1 and JAK2 include DLD-1 and RKO. INCB018424 inactivates both JAK1 and JAK2 in DLD-1 cells but inactivates only JAK1 in RKO cells. Cell death was proportional to the inactivation of JAK1 but not JAK2. INCB018424 causes caspase-dependent cell death, which is prevented by treatment with z-VAD. The inhibition of JAK1 phosphorylation seemed sufficient to allow INCB018424-mediated apoptosis. JAK1 is a key molecule that is involved in colon cancer cell survival and the inhibition of JAK1 by INCB01424 results in caspase-dependent apoptosis in colorectal cancer cells. The use of selective JAK1 inhibitors could be an attractive therapy against colorectal cancer, but further clinical investigations are needed to test this possibility.

Citation Format: Choi Eunkyoung, Jung Hana, Ahn Hojung, Hong Seung-Woo, Moon Jai-Hee, Shin Jae-Sik, Kim Kyu-Pyo, Hong Yong Sang, Lee Jae-Lyun, Choi Eun Kyung, Lee Jung Shin, Jin Dong-Hoon, Kim Tae Won. INCB018424 induces apoptotic cell death through the suppression of pJAK1 in human colon cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A46.
Abstract B19: Functional translation of total RNA packaged in microparticles shed from multidrug resistant cancer cells
Authors: Lu Jamie Fung , Pokharel Deep , Luk Frederick , Bebawy Mary
Published: May 2015

Microparticles (MPs) are submicron (0.1 -1 µM) membrane vesicles released from various cell types including malignant cells. Long considered to be inert cellular debris, MPs have recently been identified to play a crucial role in cellular cross-talk. MPs represent a heterogeneous mixture of surface antigens, proteins, lipids and cytoplasmic components resembling its parental cell. Our previous studies have identified the packaging and transfer of the transcripts, regulatory nucleic acids and proteins which are associated with the acquirement of multidrug resistance (MDR) between cancer cells. In this study we verify the functionality of packaged transcripts via in vitro translation of extracted total RNA from MPs isolated from cancer cells. We confirm the translation of exogenous RNA in a rabbit reticulocyte translation system via Western Blot analysis, 2-D SDS and mass spectrometry. These findings have significance in understanding the impact of MPs on cancer cell biology and reiterate their potential as a target in clinical oncology.

Citation Format: Jamie Fung Lu, Deep Pokharel, Frederick Luk, Mary Bebawy. Functional translation of total RNA packaged in microparticles shed from multidrug resistant cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B19.
Abstract B21: Chemoresistant bladder cancer cells induces epithelial mesenchymal transition
Authors: Liu Jingchun , Martin Darryl T. , Wheeler Marcia A. , Weiss Robert M.
Published: May 2015

Although chemotherapeutic treatments are efficacious in a number of cancers, some cancer cells ultimately will become resistant to chemotherapy. It has been suggested that chronic chemotherapy-resistance is linked to the induction of epithelial mesenchymal transition (EMT). EMT is associated with increased tumor invasiveness, development of angiogenesis, and the development of drug resistance and is linked to more aggressive cancer. The objective of this study is to determine if a link exists between mitomycin C (MMC)-resistant RT-4 bladder cancer cells and the induction of EMT. EMT is a process where cells acquire molecular alterations characterized by loss of cell-cell adhesion, repression of E-cadherin expression, and increased cell mobility. Clinical studies have shown that as bladder cancer grade increases, tumors typically exhibit a decreased expression of E-cadherin, a cell-cell adhesion molecule. In addition, there is an increase in N-cadherin expression in muscle invasive bladder tumors.

We have shown that MMC-resistant human RT-4 bladder cancer cells demonstrate a decrease in cell-cell adhesion, a higher invasion potential, and a higher CD44(+)/CD24(-) ratio (96.4%) compared to parental human RT-4 bladder cancer cells. In addition, the invasion capacity of MMC-resistant RT-4 bladder cancer cells was higher than that of parental cells. The MMC-resistant RT-4 bladder cancer cells expressed higher levels of N-cadherin and numerous apoptotic related proteins including pSTAT3, RAD17, Bcl-X and catalase. Using an exon array we showed that the MMC-resistant RT-4 bladder cancer cells up-regulate several EMT markers including vimentin (77 times), transforming growth factor -beta (27 times), and Zinc finger E-box-binding homeobox 1 (33 times) and down-regulate E-cadherin (71 times).

In summary, in our MMC-resistant RT4 bladder cancer cells, EMT was activated, and there was an increase in apoptotic related proteins as well as an increase N-cadherin expression. Our data suggest a link between chemotherapy-resistant bladder cancer cells and EMT. Deactivating EMT and down-regulating apoptotic related proteins may offer a novel strategy for overcoming bladder cancer drug resistance.

Citation Format: Jingchun Liu, Darryl T. Martin, Marcia A. Wheeler, Robert M. Weiss. Chemoresistant bladder cancer cells induces epithelial mesenchymal transition. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B21.
Abstract B35: The strength of drug selection determines the maximum fitness cost of resistance mutations in culture and xenografts
Authors: Albacker Lee A. , Kohler Rainer , Weissleder Ralph , Sorger Peter K.
Published: May 2015

This abstract is being presented as a short talk. A full abstract is printed in the Proffered Abstracts section (PR07) of the Conference Proceedings.

Citation Format: Lee A. Albacker, Rainer Kohler, Ralph Weissleder, Peter K. Sorger. The strength of drug selection determines the maximum fitness cost of resistance mutations in culture and xenografts. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B35.
Abstract B36: Modeling genetic mechanisms of resistance in melanoma primary tumor xenografts
Authors: Balbin Alejandro , Singh Angad , Korn Joshua , Gao Hui , Stuart Darrin , Green John , Crenshaw Andrew , Mahan Scott , Houde Nathan , Raza Alina , Leary Rebecca , Chiang Derek , Morrissey Michael , Winckler Wendy , William Sellers
Published: May 2015

Melanoma is the most lethal skin cancer and approximately 50% of the cases harbor mutations in the BRAF oncogene, with the mutation V600E representing 80-90% of all BRAF mutations in this indication. BRAF inhibitors as Vemurafenib and Dabrafenib have shown improved overall and progression free survival; however, the long term efficacy of these compounds is limited by the emergence of resistance. Several mechanisms of resistance to BRAF inhibitors have been already described, such as BRAF overexpression, increased ERBB3 signaling, expression of BRAF alternative isoforms, secondary mutations in BRAF or MEK1 and recently BRAF amplifications, among others. A fundamental aspect on devising optimal therapeutic regimes that overcome resistance is to develop preclinical models that resemble the genetic makeup of clinical patients who become resistance during the course of treatment to BRAF inhibitors. To this end, melanoma primary tumor xenografts (PTX) harboring BRAF V600E mutations were subject to treatment with BRAF inhibitors and response data was collected for a maximum of 180 days. Vehicle and treated samples were then sequenced using a targeted next generation sequencing approach in order to characterize their mutational landscape. Raw sequencing data was aligned to the human genome and potential mouse contamination was filter out before downstream analysis. Comparing SNV and copy number calls between treated and control samples revealed that focal amplifications of BRAF and de-novo mutations in the MEK1 gene were frequent genetic aberrations found in the PTX models that developed resistance. In summary, our results indicate that the genetic mechanisms of resistance observed in primary tumor xenograft models closely resemble what is observed in the clinical setting, making these models a valuable research tool for designing optimal therapeutic strategies.

Citation Format: Alejandro Balbin, Angad Singh, Joshua Korn, Hui Gao, Darrin Stuart, John Green, Andrew Crenshaw, Scott Mahan, Nathan Houde, Alina Raza, Rebecca Leary, Derek Chiang, Michael Morrissey, Wendy Winckler, Sellers William. Modeling genetic mechanisms of resistance in melanoma primary tumor xenografts. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B36.
Abstract B38: Trastuzumab-induced recruitment of Csk-homologous kinase (CHK) to ErbB2 receptor is associated with ErbB2-Y1248 phosphorylation and ErbB2 degradation to mediate cell growth inhibition
Authors: Dokmanovic Milos , Wu Yun , Shen Yi , Chen Jieqing , Hirsch Dianne S. , Wu Wen Jin
Published: May 2015

Trastuzumab is a humanized recombinant monoclonal antibody directed against extracellular region of ErbB2 and used for the treatment of different ErbB2-positive cancers. Based on literature reports and our clinical data from trastuzumab neoadjuvant studies, increased ErbB2-Y1248 phosphorylation is associated with a better response to trastuzumab in patient samples. Also, in trastuzumab-sensitive cell lines (SKBR3 and BT474), increased basal level and trastuzumab-mediated increase in ErbB2-Y1248 phosphorylation was readily detectable compared to trastuzumab-resistant cell line model (JIMT1). The mechanisms of trastuzumab-induced ErbB2-Y1248 phosphorylation and the role of ErbB2-Y1248 phosphorylation in trastuzumab sensitivity/resistance are still incompletely understood. We demonstrate that trastuzumab activates ErbB2 kinase activity in trastuzumab-sensitive cells, which may further contribute to trastuzumab-mediated ErbB2-Y1248 phosphorylation. However, blocking ErbB1/ErbB2 kinase activity with Lapatinib, a small molecule tyrosine kinase inhibitor only partially reduced trastuzumab-mediated ErbB2-Y1248 phosphorylation. This led to the discovery of a previously unappreciated relationship between trastuzumab and Csk-homologous kinase (CHK), a non-receptor tyrosine kinase also known as MATK. We establish that trastuzumab treatment promotes interaction between ErbB2 and CHK in trastuzumab-sensitive but not in trastuzumab-resistant cells despite similar CHK expression levels in both types of cells. Mimicking trastuzumab, CHK overexpression also induces ErbB2-Y1248 phosphorylation, Akt downregulation and cell growth inhibition and further stimulated trastuzumab-mediated reduction in total ErbB2 levels in trastuzumab sensitive cells. Also, CHK overexpression combined with trastuzumab exerts an additive effect on cell growth inhibition in trastuzumab-sensitive but not in trastuzumab-resistant cells. Understanding of the molecular mechanisms of trastuzumab mediated ErbB2 phosphorylation changes may suggest novel therapeutic approaches in the treatment of trastuzumab resistant cancers.

Disclaimer: The information presented in this article reflects the views of the authors and does not represent the policy of the U.S. Food and Drug Administration.

Citation Format: Milos Dokmanovic, Yun Wu, Yi Shen, Jieqing Chen, Dianne S. Hirsch, Wen Jin Wu. Trastuzumab-induced recruitment of Csk-homologous kinase (CHK) to ErbB2 receptor is associated with ErbB2-Y1248 phosphorylation and ErbB2 degradation to mediate cell growth inhibition. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B38.
Abstract B45: A search for ideal siRNA targets involved in pathway cross-talks for combinational silencing in human cancer cells
Authors: Aliabadi Hamidreza Montazeri , Mahdipoor Parvin , Uludag Hasan
Published: May 2015

The heterogeneity in the pathways involved in enhanced cell proliferation and survival mechanisms, as well as the mechanisms playing a major role in development of drug resistance, is an important obstacle in cancer treatment. Signaling axes such as PI3K-AKT, Ras-Raf, MEK-ERK, and JAK-STAT pathways have not only been established as major processes involved in enhanced proliferation and activation of the transcription of multiple anti-apoptosis proteins, but are also shown to be interconnected in forming a vast intracellular signaling network. RNA interference, and more specifically, small interfering RNA (siRNA), is a post-transcriptional down-regulation of the expression of a specific protein, and has been studied extensively in the last decade as not only an investigational tool, but also as a therapeutic approach especially in cancer treatment. In the present study, we undertook a systematic approach to simultaneous silencing of two proteins involved in intracellular signaling network in order to inhibit more than one pathway involved in proliferation and survival of cancer cells. After carefully selecting the proteins with pivotal roles in cell survival through diverse pathways, we studied silencing each protein individually and in all possible dual combinations, and evaluated the cell response as the mRNA level of the selected proteins as well as the viable cell number. Our studies reveled that silencing JAK2, STAT3, and JUN have a significant effect on the expression level of anti-apoptotic proteins, e.g., Mcl-1 and survivin, and could negatively impact the survival of MDA435 cells. These results indicate a promising potential for combinational siRNA silencing as an effective anticancer strategy.

Citation Format: Hamidreza Montazeri Aliabadi, Parvin Mahdipoor, Hasan Uludag. A search for ideal siRNA targets involved in pathway cross-talks for combinational silencing in human cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B45.
Abstract B47: The role of ZNF217 in the development of breast cancer chemoresistance
Authors: Suarez Christopher , Badve Sunil S. , Littlepage Laurie E.
Published: May 2015

Breast cancer is the second leading cause of cancer related deaths with an estimated 232,340 new cases and 39,620 deaths in 2013. Despite 93% of patients being diagnosed with local or regional stage disease, most patient deaths result from metastasis as a result of recurrent disease after the development of therapeutic resistance. Developing a better understanding of the molecular mechanisms of therapeutic resistance is critical to help identify novel therapeutics that overcome metastasis, resistance, and death.

We previously identified the transcription factor ZNF217 as a prognostic indicator for breast cancer patients. ZNF217 is overexpressed in breast cancer and numerous other cancers, and this overexpression promotes reduced survival, increased metastasis, and reduced response to therapy. We found that Znf217 overexpression promotes an increase in cancer phenotypes, including self-renewal capacity, invasion, and metastasis. We next determined if Znf217 overexpression in vivo contributed to chemotherapy resistance. We treated mice overexpressing Znf217 or vector with a combination therapy of microtubule inhibitor epothilone B, adriamycin, and cyclophosphamide (EAC). The mice that overexpressed Znf217 had increased tumor volume and decreased survival compared to control mice. Mice overexpressing Znf217, that were treated with EAC, developed a significant increase in tumor volume over control mice within 21 days of EAC treatment. This confirmed that mice overexpressing Znf217 developed resistance to the EAC chemotherapy.

To overcome breast cancer chemoresistance caused by ZNF217 overexpression, we identified triciribine as a drug that kills cells that overexpress ZNF217. We found that triciribine treatment inhibited tumor burden in vivo in tumors that overexpressed Znf217 and also had synergy with doxorubicin in human xenografts. We now are confirming these results using patient-derived tumor xenografts to compare therapeutic response of human tumors with high versus low levels of ZNF217 expression. Utilizing animal models that overexpress ZNF217 will allow us to identify combination therapies that are able to overcome resistance. In addition, these studies will provide an ideal model system to search for mechanistic insight into the process of developing therapeutic resistance.

Citation Format: Christopher Suarez, Sunil S. Badve, Laurie E. Littlepage. The role of ZNF217 in the development of breast cancer chemoresistance. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B47.
Abstract B57: miR-34 mimics synergize with small molecule inhibitors targeting the EGFR and Raf kinase pathways
Authors: Zhao Jane , Kelnar Kevin , Daige Chris , Wiggins Jason , Priddy Leslie , Muenzer Terri , Tran Julie , Brown David , Bader Andreas G.
Published: May 2015

Sorafenib (Nexavar®) and erlotinib (Tarceva®) are FDA-approved therapies for patients with hepatocellular carcinoma (HCC) and non-small cell lung cancer (NSCLC), respectively. Sorafenib is a multi-kinase inhibitor targeting the Raf/Mek/Erk pathway, and erlotinib is a tyrosine kinase inhibitor antagonizing epidermal growth factor receptor (EGFR). Due to their selective inhibitory action and observed toxicities, current treatment options for liver and lung cancer are limited and many cancers develop resistance. Naturally occurring tumor suppressor microRNAs inhibit tumor growth by regulating multiple oncogenes at once and, therefore, microRNA mimics, which are copies of the naturally occurring microRNAs, may be used in combination with the respective standard of care drugs to bring this tumor suppressor activity back into tumor cells and thereby augment drug sensitivity. Here, we investigated the relationship of a mimic of the tumor suppressor microRNA miR-34 in combination with erlotinib or sorafenib and determined the therapeutic activity of the combination in lung and liver cancer cells. Data derived from isobolograms, combination index plots and curve shift analyses indicate synergy in all cancer cell lines tested. Synergy was observed at multiple microRNA and drug ratios and at drug concentrations that induce 50% or greater cancer cell inhibition. Data from cell and animal studies will be presented.

Citation Format: Jane Zhao, Kevin Kelnar, Chris Daige, Jason Wiggins, Leslie Priddy, Terri Muenzer, Julie Tran, David Brown, Andreas G. Bader. miR-34 mimics synergize with small molecule inhibitors targeting the EGFR and Raf kinase pathways. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B57.
Abstract IA01: Immunologic heterogeneity of cancer: Determinants of response and resistance to immunotherapy
Authors: Topalian Suzanne L.
Published: May 2015

Complex interactions between the immune system and cancer influencing tumor invasion, metastasis, and treatment outcomes are poorly understood. Similar to the influence of intra- and inter-tumoral genetic heterogeneity on response and resistance to molecularly targeted therapies, immunologic heterogeneity may explain the outgrowth of resistant tumor clones under the selection pressure of immunotherapy. Evidence for this phenomenon emerged from the results of high-dose IL-2 therapy, with responding metastases showing brisk CD8+ T cell infiltration, while non-responding lesions in the same patients were lymphocyte-poor. It has also been shown in patients receiving adoptive cell transfer therapies (TILs, CARs), with initial tumor regression followed by the outgrowth of tumors that have down-regulated target antigens. More recently, clinical experience with drugs blocking immune checkpoint molecules such as CTLA-4, PD-1 and PD-L1 has revealed unconventional response patterns in 5-10% of patients, including mixed tumor regressions (simultaneous progression/regression at different metastatic sites in an individual patient). Our investigations of the immunosuppressive ligand PD-L1, expressed by many human tumors, as a potential biomarker of response to anti-PD-1 therapy have revealed intra-tumoral as well as inter-tumoral heterogeneity of expression. Within individual tumor lesions, PD-L1 protein expression (IHC) can be patchy or focal, co-localizing with lymphoid infiltrates. Further study on a molecular level revealed expression of IFN-g in the same microenvironment as PD-L1, along with PD-1 and other immunosuppressive molecules, generating the adaptive immune resistance hypothesis. Examination of PD-L1 protein expression in multiple tumor lesions from individual patients showed variability over time and at distinct anatomic sites, consistent with the dynamic and context-dependent nature of immune responses, suggesting that inter-lesional variability could influence susceptibility to anti-PD-1 or PD-L1 therapy. Innovative approaches such as neoadjuvant immunotherapy trials or rapid autopsy analysis are needed to gain a deeper knowledge of tumor immunologic heterogeneity and potential intersections with genetic heterogeneity. This will be critical to understanding the evolution of anti-tumor immunity and developing more effective immune-based and combinatorial therapies.

This work was supported by grants from Bristol-Myers Squibb, the National Cancer Institute (R01 CA142779), the Melanoma Research Alliance, the Barney Family Foundation, the Dermatology Foundation, and Stand Up To Cancer.

Citation Format: Suzanne L. Topalian. Immunologic heterogeneity of cancer: Determinants of response and resistance to immunotherapy. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA01.
Abstract IA03: Mutations, drugs, and breast cancer: How are we going to figure it out?
Authors: Ellis Matthew J.
Published: May 2015

Massively parallel DNA and RNA sequencing approaches have generated high dimensional data on thousands of breast cancer genomes. Broad-based conclusions include challenges to the multistep model of breast carcinogenesis and the monoclonality of cancer, a link between leukemogenesis and luminal breast cancer and the discovery of new mutagenesis mechanisms. Unfortunately novel and immediately applicable therapeutic insights have been somewhat sparse. Many of the processes that are disrupted by newly discovered somatic mutations include genes with roles in splicing, histone methylation and long non-coding RNA function. Drugs targeting these processes are in the earliest stages of development, emphasizing a pressing unmet need to move drug discovery efforts beyond our current intense focus on kinase inhibitors. Despite the evident complexity, promising examples are emerging including new efforts to target mutations in two well-established drivers in breast cancer: HER2 in HER2 mutant breast cancer and mutant ESR1 in ESR1 endocrine refractory luminal-type breast cancer. A case for the importance of genome-annotated patient-derived breast cancer xenografts (PDX) will also be made. PDX models are potentially more reliable preclinical setting than cell lines and are a setting in which the biological rules for genome driven therapeutic planning could be developed. A call is also made for a new generation of prospective clinical trials that are fully focused on exploring interactions between cancer genomics and drug outcomes as a primary objective. Finally the integration of DNA and RNA based sequencing studies with mass-spectrometry-based peptide sequencing promises a more complete view of the biochemistry of breast cancer cells and represents a new discovery horizon in efforts to drug the pathophysiology of complex epithelial malignancies.

Citation Format: Matthew J. Ellis. Mutations, drugs, and breast cancer: How are we going to figure it out? [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA03.
Abstract IA10: Kinase-impaired BRAF mutations as predictors of resistance and sensitivity
Authors: Johnson Faye , Sen Banibrata , Mazumdar Tuhina , Peng Shaohua , Kadara Humam , Diao Lixia , Byers Lauren
Published: May 2015

Non-small cell lung cancer (NSCLC) is a common and rapidly fatal cancer for which targeted therapies have been markedly effective in only about 15% of patients - specifically those with EGFR mutations or EML4-ALK translocations. During a clinical trial of the multi-targeted tyrosine kinase inhibitor dasatinib we identified a patient with stage IV NSCLC who harbored a novel BRAF mutation (Y472C), had a near complete radiographic response to the multitargeted kinase inhibitor dasatinib as sole therapy and remained without active cancer 7 years following treatment. We discovered that Y472CBRAF is a kinase-inactivating BRAF mutation (KIBRAF). BRAF mutations can result in increased or decreased BRAF kinase activity, as well as kinase-neutral mutations, and occur in 8% of NSCLC and many other tumor types. We found that NSCLC cells that harbor KIBRAF undergo senescence when exposed to the dasatinib whereas NSCLC patients and cell lines with wild type BRAF are resistant to dasatinib. Transfection of other NSCLC cells with KIBRAF mutations also increased their dasatinib sensitivity, whereas transfection with an activating BRAF mutation led to their increased dasatinib resistance. NSCLC cells transfected with Y472CBRAF exhibited CRAF, MEK, and ERK activation. Currently there are no well-defined, canonical pathways that explain the observed dasatinib-induced senescence in NSCLC cells with KIBRAF. Dasatinib inhibits the activity of 40 distinct kinase targets and can induce BRAF-CRAF dimerization and CRAF activation in cells with activated RAS or KIBRAF mutations. To investigate the mechanism leading to senescence we performed reverse phase protein arrays to simultaneously examine the expression of 137 proteins and phosphoproteins and gene expression arrays. This approach was limited by the existence of only two NSCLC cell lines with KIBRAF but nonetheless we determined that dasatinib induced DNA damage and subsequently activated DNA repair pathways and the HIPPO signaling pathway only in NSCLC cells with KIBRAF. We are currently conducting a clinical trial for NSCLC patients with KIBRAF mutations to determine the efficacy of dasatinib in these patients prospectively.

Citation Format: Faye Johnson, Banibrata Sen, Tuhina Mazumdar, Shaohua Peng, Humam Kadara, Lixia Diao, Lauren Byers. Kinase-impaired BRAF mutations as predictors of resistance and sensitivity. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA10.
Abstract IA12: Correlating cancer heterogeneity to treatment response and relapse
Authors: Papaemmanuil Elli
Published: May 2015

Systematic sequencing screens of hundreds of cancer genomes has delivered a near complete catalogue of somatic mutations in the coding genome that drive oncogenic transformation across a diverse range of tumor types. The picture that is emerging is one of extensive genomic diversity and clonal complexity.

Our recent work in MDS has shown that the underlying genomic architecture is predominantly characterized by infrequently mutated genes (<5% of patient samples), specific gene-gene interactions and a structured order of mutation acquisition, implicating mutations in RNA splicing as early initiating events followed by secondary mutations in epigenetic modifiers and transcriptional regulators. The enrichment for infrequently mutated genes and complex secondary interactions impose significant challenges in defining prognostic and predictive biomarkers of patient outcome and therapeutic response. Single gene studies are not entirely representative of the disease pathophysiology and certainly do not account for the epistatic or modifying effects conferred by the composite underlying genetic architecture. Detailed investigations on well-annotated patient cohorts pre-, during and post- treatment support the definition of predictive signatures of response and studies investigating changes in clonal dynamics using sequential samples during therapy are offering important new avenues in understanding the underlying biology of chemo sensitivity as well as resistance.

Citation Format: Elli Papaemmanuil. Correlating cancer heterogeneity to treatment response and relapse. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA12.
Abstract IA18: ERK activity in mutant BRAF melanoma – A live report
Authors: Aplin Andrew E.
Published: May 2015

The response of BRAF V600E/K melanoma patients to either RAF inhibitors or the RAF/MEK inhibitor combination is heterogeneous and short-term responses are associated with acquired resistance. Our previous studies have implicated compensatory FOXD3-ERBB3-AKT signaling as an adaptive response to targeted inhibition of the ERK1/2 pathway. While adaptive responses likely modulate the initial tumor response to targeted inhibitors, stable changes drive acquired resistance leading to the re-growth of tumors that initially responded to RAF inhibitors. Outgrowth of resistant cells may be due to the acquisition of a secondary mutation and/or selection of pre-existing cells harboring genetic alterations that negate the effect of RAF inhibitors. To model acquired resistance to RAF inhibitors, we developed mutant BRAF melanoma ERK1/2 activity reporter xenograft models. This system enables quantitative analysis of ERK1/2 activity in response to pathway inhibitors across the whole tumor in a temporal manner. We have utilized this system to analyze the initial response to RAF inhibitors in vivo, as well as re-activation of the ERK1/2 pathway associated with acquired resistance. Furthermore, we are utilizing this model to analyze response and resistance to RAF/MEK inhibitor combinations and next-generation RAF inhibitors.

Citation Format: Andrew E. Aplin. ERK activity in mutant BRAF melanoma – A live report. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA18.
Abstract PR02: Identification of ERK1/2 mutations that confer resistance to MAPK pathway inhibitors
Authors: Goetz Eva M. , Ghandi Mahmoud , Treacy Daniel , Wagle Nikhil , Garraway Levi A.
Published: May 2015

Recent treatment advances in metastatic BRAF mutant melanoma using targeted therapy have increased progression free survival by many months. However, resistance to these targeted agents is a common occurrence, with relapse occurring in almost every case. Many of the alterations that confer clinical resistance to RAF and MEK inhibitors in BRAF mutant melanoma reactivate the MAPK pathway, but remain sensitive to ERK inhibition in vitro. Prospectively determining mechanisms of resistance to MAPK pathway inhibitors, such as an ERK inhibitor, before clinical trials begin may inform which patients will respond to therapy, potential markers of resistance, or best therapy combinations. Previous studies have shown that in vitro random mutagenesis screens can select specific alleles seen in resistant patient populations. Since ERK inhibitors are entering clinical trials, we wanted to determine mutations in ERK1 and ERK2 that could confer resistance to ERK or RAF/MEK inhibition. Therefore, we expressed dox-inducible ERK1 or ERK2 mutant libraries in A375 cells, which were then treated with MAPK inhibitor(s) and doxycycline until resistant cells emerged. Exogenous ERK1 or ERK2 was analyzed in resistant cells by massively parallel DNA sequencing. We validated 15 alleles that conferred resistance to the ERK inhibitor, VX-11e, and 11 alleles that conferred resistance to RAF, MEK, or RAF+MEK inhibition (dabrafenib and trametinib). Some resistance alleles were analogous between ERK1 and ERK2, while others were specific to ERK1 or ERK2. ERK inhibitor resistant alleles were localized to areas surrounding the ATP/drug binding site, including the glycine-rich loop, c-helix, and activation loop. These alleles were also cross-resistant to another ERK inhibitor, SCH-772984, albeit some only at lower concentrations. The RAF/MEK inhibitor resistant residues were located in the c-helix, activation loop, and common docking domain. Only a single ERK1 allele was found to confer resistance to RAF + MEK and ERK inhibition, suggesting that resistance mutations in ERK might be suppressed if RAF, MEK, and ERK inhibitors are given in combination. In addition, an ERK mutation arising in a patient treated with an ERK inhibitor would still be sensitive to RAF/MEK inhibition and vice versa. Screening for these alleles before administering therapy or after relapse may help inform patient treatment.

Citation Format: Eva M. Goetz, Mahmoud Ghandi, Daniel Treacy, Nikhil Wagle, Levi A. Garraway. Identification of ERK1/2 mutations that confer resistance to MAPK pathway inhibitors. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr PR02.
Abstract PR03: Identifying biomarkers of drug response and resistance using personalized Drosophila models of colorectal cancer
Authors: Bangi Erdem , Murgia Claudio , Teague Alexander , Sansom Owen , Cagan Ross
Published: May 2015

A fundamental difficulty in cancer research is the complex, multigenic and genetically diverse nature of human tumors, recently emphasized by cancer genome sequencing efforts. To capture this genetic complexity and diversity, we identified the most frequently observed double, triple and quadruple combinations of mutations in human colon cancer genomes and generated the corresponding combinations in Drosophila. We then investigated the tumorigenic and metastatic potential of 30 multigenic combinations we established by targeting them specifically to the adult Drosophila colon. These models recapitulate key features of human cancer, many of which arise as emergent properties of multigenic combinations. Importantly, we show that multigenic models are more resistant to compound effects than single-hit models and that combinatorial therapy is more effective against multigenic combinations. Specifically, we tested 16 clinically relevant targeted agents against our models using dissemination into the abdominal cavity as a quantitative read-out to monitor drug response. We found that 12 of these 16 compounds were effective against rasG12V alone while the four-hit model rasG12V p53RNAi ptenRNAi apcRNAi was resistant to all. We then uncovered a potential mechanism for resistance to PI3K pathway inhibitors as well as biomarkers for single agent response and resistance. We also developed a combination therapy that overcomes resistance of our four-hit model to single agent PI3K pathway inhibitors. We have validated our findings in human colorectal cancer cell lines, xenograft models as well as 3D colospheres and allografts derived from genetically engineered mouse models of colorectal cancer. We are currently investigating mechanisms mediating resistance of our four-hit model to the remaining compounds. We hope to use this information to devise additional rational combination therapies effective against genetically complex tumors. Overall, these models provide an excellent opportunity to study tumorigenesis and metastasis in the context of the whole animal and explore compound effects on a genetically diverse set of models. The emergent properties we identified in our multigenic combinations and interesting correlations we observed between tumor genotype and drug response also represent important steps towards personalized medicine.

Citation Format: Erdem Bangi, Claudio Murgia, Alexander Teague, Owen Sansom, Ross Cagan. Identifying biomarkers of drug response and resistance using personalized Drosophila models of colorectal cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr PR03.
Tumor Twitter: Cellular Communication in the Breast Cancer Stem Cell Niche
Authors: Brooks Michael D. , Wicha Max S.
Published: May 2015

Summary: Communication between the diverse assortment of cells that constitute the tumor microenvironment plays an important role in tumor development. Using a p53-null mouse model, Zhang and colleagues describe a novel feedback loop involving breast cancer stem cells and their progeny mediated by WNT2, CXCL12, and IL6. Cancer Discov; 5(5); 469–71. ©2015 AACR.

See related article by Zhang et al., p. 520
The Interplay of Immunotherapy and Chemotherapy: Harnessing Potential Synergies
Authors: Emens Leisha A. , Middleton Gary
Published: May 2015

Although cancer chemotherapy has historically been considered immune suppressive, it is now accepted that certain chemotherapies can augment tumor immunity. The recent success of immune checkpoint inhibitors has renewed interest in immunotherapies, and in combining them with chemotherapy to achieve additive or synergistic clinical activity. Two major ways that chemotherapy promotes tumor immunity are by inducing immunogenic cell death as part of its intended therapeutic effect and by disrupting strategies that tumors use to evade immune recognition. This second strategy, in particular, is dependent on the drug, its dose, and the schedule of chemotherapy administration in relation to antigen exposure or release. In this Cancer Immunology at the Crossroads article, we focus on cancer vaccines and immune checkpoint blockade as a forum for reviewing preclinical and clinical data demonstrating the interplay between immunotherapy and chemotherapy. Cancer Immunol Res; 3(5); 436–43. ©2015 AACR.
240 human tumor cell line profiling to evaluate relationships between tumor genotypes and cancer cell sensitivity
Authors: O'Day Christine , Ovechkina Yulia , Marcoe Karen , Keyser Robert , Yoshino Karen , Nguyen Phuong , Bernards Karen , Chesnut-Speelman Jessica
Published: May 2015

Multiple targeted therapies have been shown to be effective for treating cancer such as imatinib for treating chronic myelogenous leukemia, erlotinib for non-small-cell lung cancers and trastuzumab for HER2 positive breast cancer. The sporadic sensitivity to these reagents has precipitated many inquiries into the relationship between phenotype and genotype. We have developed an in vitro cellular system to evaluate the relationship between tumor genotypes and cancer cell sensitivity over 240 human tumor cell lines. We used a panel of targeted therapeutics (such as erlotinib, CL-1040, and dasatinib) to demonstrate the prognostic value of this in vitro approach for developing anticancer drugs. This is a novel approach for a drug testing strategy for targeted anticancer therapeutics of interest to those in personalized medicine. This approach would help to match the drugs to a more efficacious patient population.
Early cancer therapy response assessment by quantitative F-18 FDG PET/CT
Authors: Mountz James M. , Laymon Charles , Deeb Erin , Chen Yin Jie
Published: May 2015

Purpose: Reliable noninvasive quantitative methods for assessing early response to chemotherapy are vital for development of more personalized cancer therapy management, by allowing earlier decisions regarding therapy changes. The CT RECIST method is widely used; however, CT does not provide information on the physiologic properties of the tumor. In this study, F-18 FDG (FDG) PET is compared to CT in predicting response to chemotherapy using changes in imaging biomarkers of tumor metabolism and size early after initiation of therapy compared to baseline (BL) and follow-up.

Materials and Methods: Nine patients with malignant cancer (lung, colorectal, or lymphoma) entered this early therapy response study. All patients received a BL scan before the initiation of chemotherapy, an early therapy assessment (ETA) scan between 2 to 7 weeks after initiation of therapy, and a study end point (FTA) scan between 3 to 9 months. The average length of time between ETA and FTA scans was 4 months. All PET/CT scans were performed on GE ST PET/CT scanner, approximately 60 min after patients received IV injection of approximately 15 mCi of F-18 FDG. All PET/CT images were registered and analyzed on MIMvista workstation to calculate FDG SUV values and CT RECIST measurements. By comparing BL and FTA scans, patients were classified as responders or non-responders based on RECIST. To compare FDG PET and CT data, the largest tumor was identified on CT at BL and its area and SUV were measured at ETA and FTA in each patient.

Results: At FTA, responders had an average (FTA CT area)/(BL CT area) of 0.40 and average (FTA SUV)/(BL SUV) of 0.25. For non-responders, these values were 1.55 and 1.27 respectively. At ETA, for responders, (ETA CT area)/(BL CT area) averaged 0.65 and (ETA SUV)/(BL SUV) averaged 0.26. For non-responders, these values were 1.19 and 1.15 respectively.

Conclusion: FDG uptake reduction at ETA compared to BL can be used to distinguish responders from non-responders, classified based upon RECIST at FTA. This early change in FDG uptake is more sensitive than early CT changes in predicting response to chemotherapy at FTA.

Research Support: This research was supported in part by grant U01 CA140230 from the National Cancer Institute to Dr. Mountz.
Imaging end-points to predict response to IGF1R/IR inhibition in CRC models
Authors: Serkova Natalie J. , Bradshaw-Pierce Erica L. , Hasebroock Kendra M. , Merz Andrea L. , Pitts Todd M. , Eckhardt Gail S.
Published: May 2015

This abstract is being presented as a short talk in Plenary Session 6. A full abstract is printed in the Proffered Abstracts section (PR9) of the Conference Proceedings.
The Imaging Probe Development Center at NIH: A central core facility for the production and dissemination of molecular imaging probes
Authors: Griffiths Gary L.
Published: May 2015

The Imaging Probe Development Center (IPDC, Rockville, MD), founded as part of the 2003 trans-NIH Roadmap for Medical Research initiative, provides synthetic chemistry support needed by interdisciplinary researchers for the supply of molecular imaging probes. Such research projects run from basic through translational to clinical in nature. The IPDC has state-of-the-art equipment and is staffed by scientists drawn from diverse backgrounds encompassing expertise in synthetic, inorganic, radiochemical, and conjugation chemistries. The IPDC has worked with principal investigators from over a dozen different NIH Institutes, along with some extramural collaborators, with a preponderance of projects related to cancer imaging, and has supplied literature-reported and novel agents used in all types of imaging modalities, including MRI, optical fluorescence and PET/SPECT. Examples of probes used for cancer imaging studies will be discussed including several radiolabeled low molecular weight drugs synthesized from first principles and radiolabeled monoclonal antibodies and other proteins. Several agents are undergoing further studies in clinical and process development. Recently made probes will be used to illustrate the scope and capabilities of the Center. The Center is able to work with other interested parties in order to develop useful imaging agents, particularly those that also have therapeutic implications. For more information, or to make enquiries about probe availability or potential collaborations you may visit our website at: http://www.ipdc.nih.gov.