bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4709: Cell-specific gene program-based small-molecule immunomodulators targeting solid-tumor microenvironments
Authors: Kischuk Erin , Majumder Joydeb , Fine Jonathan A. , Lantz Travis C. , Dhawan Deepika , Knapp Deborah W. , Ratliff Timothy L. , Chopra Gaurav
Published: August 2018

Cancer immunotherapy includes promising strategies based on immune checkpoint blockade (e.g., anti-PD-1/PD-L1, anti-CTLA-4). A limitation of such therapies for solid tumors stems from other immune-suppressive mechanisms mediated by myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages. We hypothesize that molecules that target specific suppressive immune cells in the tumor microenvironment can reprogram the pro-tumor microenvironment towards antitumor immunity. Using our proteome-scale target/antitarget network-based lead optimization method (CANDESIGN), we designed and synthesized cell-specific nontoxic chemical libraries with modular functions for anticancer potency and immunomodulation. We used machine learning iteratively on experimental data to identify cell-specific target/anti-target networks (gene programs) as well as designed and synthesized compound libraries targeting cell-specific programs for desired cancer and immune cell function ex vivo. Specifically, we altered suppressive function of MDSCs by targeting upregulated genes in activated monocytic MDSCs in the tumor microenvironment compared to cells in spleen. We synthesized a potent nontoxic compound that specifically modulates activated MDSC function and corresponding changes in CD4+ and CD8+ T-cell activity in a mouse bladder cancer model. We observed a significant reduction in tumor mass following treatment by oral gavage. Interestingly, the bladder cancer cells used in our mouse model (as well as human and dog bladder cancer cells) are insensitive to our lead compound in vitro, suggesting in vivo antitumor activity via immunomodulation. Our lead decreased frequency of monocytic and granulocytic MDSCs in the ascites and the tumor. Moreover, a decreased frequency of MDSC expressing suppressive functional markers (e.g., Arg1, iNOS, PD-L1) and increased IFNγ+CD8+ T cells were observed in the tumor microenvironment after compound treatment. Finally, we performed a small clinical trial on pet dogs with bladder tumors treated with our compound tablets for 4-5 weeks that resulted in ~50% reduction in tumor volume. We conclude that designing cell-specific compounds perturbing the tumor microenvironment to combat immune suppression gives a selective advantage to the immune system to combat solid tumors via single and combination drug/cell therapies.

Citation Format: Erin Kischuk, Joydeb Majumder, Jonathan A. Fine, Travis C. Lantz, Deepika Dhawan, Deborah W. Knapp, Timothy L. Ratliff, Gaurav Chopra. Cell-specific gene program-based small-molecule immunomodulators targeting solid-tumor microenvironments [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 4709.
Abstract 4725: Blockade of cyclin D-CDK4/6 sensitizes immune-refractory tumor cells to tumor antigen-specific T cell-mediated cytotoxicity by repressing SCP3-NANOG axis
Authors: Oh Se Jin , Kim Tae Woo
Published: August 2018

Antitumor immune drives tumor cell to acquire immune-refractory phenotypes. Previously, we demonstrated tumor antigen-specific T cells edited them resistant to CTL killing and enriched NANOGhigh cancer stem cell-like (CSC-like) cells. In this study, in an effort to elucidate targetable pathways of immune-edited tumor cells with the multiaggressiveness, we show synaptonemal complex protein 3 (SCP3), a member of Cor1 family, which is overexpressed in the immune-edited cells, upregulates NANOG by hyperactivating cyclin D1-CDK4/6 axis. The SCP3-cyclin D1-CDK4/6 axis was preserved across various types of human cancer and, notably, negatively correlated with the progression-free survival of cervical cancer patients. Moreover, targeting CDK4/6 with its inhibitor, palbociclib, succeeded in reversing the multiaggressive phenotypes of immune-edited tumor cells, and led to long-term control of the disease. Collectively, our findings establish a firm molecular link of multiaggressiveness among SCP3, NANOG, cyclin D1, and CDK4/6, and identify CDK4/6 inhibitors as an actionable drug for controlling SCP3high immune-refractory cancer.

Citation Format: Se Jin Oh, Tae Woo Kim. Blockade of cyclin D-CDK4/6 sensitizes immune-refractory tumor cells to tumor antigen-specific T cell-mediated cytotoxicity by repressing SCP3-NANOG axis [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 4725.
Abstract 477: Targeting of ErbB3 with functional cooperative miRNAs enhances efficacy of trastuzumab in ErbB2-overexpressing breast cancer cells
Authors: Lyu Hui , Huang Jingcao , Wang Bolun , Han Amy , Liu Bolin
Published: August 2018

Introduction: ErbB3 serves as a critical co-receptor of erbB2 and plays a vital role in the development of erbB2-overexpressing (erbB2+) breast cancer. It is thought to be an important compensatory target for combinatorial strategy to improve the treatments for erbB2+ breast cancer patients. MiRNAs regulate gene expression by the sequence-specific targeting of mRNAs, leading to translational repression or mRNA degradation. ErbB3 is a direct target of both miR-125a and miR-205. Here, we study the potential activity of miRNA based erbB3-targeted therapy in erbB2+ breast cancer cells.

Methods: Cell growth assays were used to determine cell viability. Western blot analyses were performed to assess the expression and activation of proteins. Flow cytometry analysis was carried out to examine cell cycle progression. Lentiviral vector containing one or two miRNAs was used to ectopically express miR-125a and/or miR-205.

Results: Co-expression of miR-125a and miR-205 showed a potent activity to downregulate erbB3 while single miRNA had no or little effect on erbB3 when miR-125a or miR-205 was only increased below 10-fold in BT474 cells. Combination of the two miRNAs not only resulted in a dramatic reduction of phosphorylated erbB3 (P-erbB3) and the downstream signaling kinases Akt (P-Akt) and Src (P-Scr), it also inhibited cell proliferation and increased the cells at G1 phase. More importantly, concomitant expression of the two miRNAs significantly enhanced trastuzumab-mediated growth inhibition and cell cycle G1 arrest in BT474 cells. Interestingly, the expression levels of miR-125a, but not miR-205 in the trastuzumab-resistant BT474-HR20 cells were much lower than that in the parental BT474 cells. Ectopic expression of miR-125a alone profoundly inhibited proliferation of BT474-HR20 cells. These data suggested that reduced miR-125a might be a novel mechanism leading to trastuzumab resistance; and upregulation of miR-125a could be a useful tool to abrogate the resistance.

Conclusions: Co-expression of miR-125a and miR-205 is a new approach to inhibit erbB3. Specific targeting of erbB3 via the functional cooperative miRNAs enhances efficacy of trastuzumab against erbB2+ breast cancer cells. Our data support further exploration of the possible role of miR-125a in the development of trastuzumab resistance.

Keywords: ErbB3, ErbB2, miRNA, Trastuzumab, Breast Cancer

Citation Format: Hui Lyu, Jingcao Huang, Bolun Wang, Amy Han, Bolin Liu. Targeting of ErbB3 with functional cooperative miRNAs enhances efficacy of trastuzumab in ErbB2-overexpressing breast cancer cells [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 477.
Abstract 4803: CXCR6-directed therapeutic approach potentiates efficacy of docetaxel in prostate cancer
Authors: Kapur Neeraj , Mir Hina , Sonpavde Guru , Lillard James W. , Singh Shailesh
Published: August 2018

Development of chemo-resistance negatively impacts therapeutic outcome of advanced prostate cancer (PCa). Molecular mechanism used by cancer cells to overcome therapeutic effect is still undefined. Here, we demonstrate the influence of CXCR6/CXCL16 mediated molecular signals on the efficacy of docetaxel (DTX). Out data showed poor DTX efficacy on PCa cells (LNCaP, PC3, and DU145) after stimulating CXCR6 with soluble CXCL16, while significant improvement in cytotoxic effect of DTX was observed after CXCR6 blockade using anti-CXCR6 monoclonal antibody. Interestingly, CXCR6, CXCL16, and ADAM-10, a metalloproteinase involved in CXCL16 cleavage from PCa cell membranes, were significantly elevated in response to DTX treatment. This was further confirmed on xenograft tumor by immunohistochemistry. Further, phospho-proteomic profiling and western blot analysis showed activation of pro-survival molecules: GSK-3β, NFκB, ERK/1/2, and survivin following soluble CXCL16 treatment. Activation of CXCR6-CXCL16 axis also inhibited expression of the epithelial marker (E-cadherin) while increased expression of mesenchymal markers (β-catenin, α-SMA, vimentin, snail), which highlights the role of CXCR6 in promoting mesenchymal phenotype that is known to have a significant impact on cancer progression and therapeutic outcome. Thus, our study shows that CXCR6-CXCL16 signaling instigates chemotherapeutic resistance by increasing pro-survival signaling and promoting mesenchymal phenotype. Hence, combining CXCR6 blockade with DTX would be a better treatment option for advanced, drug-resistant PCa.

Citation Format: Neeraj Kapur, Hina Mir, Guru Sonpavde, James W. Lillard, Shailesh Singh. CXCR6-directed therapeutic approach potentiates efficacy of docetaxel in prostate cancer [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 4803.
Abstract 4844: Evidence of PARP-1 dependent cytotoxic agents with low target affinity
Authors: Puentes Laura , Reilly Sean
Published: August 2018

Introduction: Inhibition of nuclear protein poly (ADP-ribose) polymerase-1 (PARP1) is synthetically lethal in BRCA mutated cancers. However, the mechanism by which PARPi exert cytotoxic effects is not fully understood. In this study, we compare 16 olaparib analogs and measured their potency in a radioligand binding assay to measure their affinity for PARP1, and in a cytotoxicity assay to measure their ability to serve as a chemotherapeutic.

Methods: Compounds were prepared by replacing the piperazine core on olaparib with a series of diazaspiro ring systems. PARP1 affinity was assessed using radioligand binding competition assays. In vitro cytotoxicity was performed on BRCA1 methylated and PARP1-/- ovarian cancer cell lines to evaluate the relative potency of the analog compounds.

Results: The 16 analogs displayed lower affinity to PARP1 but comparable or higher potency in cell kill assays when compared to olaparib. Of the 16 compounds, those that contained the diazaspiro core with an N-Boc-functional group displayed the highest degree of potency. Cytotoxicity assays were performed for each compound using PARP1 -/- and PARP2 -/- cells to assess off-target effects. Dose response curves for PARP1-/- cells resulted in a rightward shift; no changes in the dose-response curves were detected for PARP2 -/- cells.

Conclusion: Radioligand binding assays demonstrated that these compounds have low PARP1 affinity. Evaluation of the relative potency of these compounds revealed that compounds having a lower PARP1 affinity relative to olaparib still retained a high potency in cell kill assays. In vitro cytotoxicity assays on PARP1 -/- and PARP2 -/- cells confirmed that these compounds are PARP1 but not PARP2 dependent. Future studies will focus on assessing catalytic inhibition of PARP1 and PARP1 trapping in order to better elucidate the antiproliferative effects of these compounds.

Citation Format: Laura Puentes, Sean Reilly. Evidence of PARP-1 dependent cytotoxic agents with low target affinity [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 4844.
Abstract 485: Modulation of microRNA expression in EGFR-tyrosine kinase inhibitor-resistant non-small cell lung cancer cell lines
Authors: Haque Inamul , Motes Hannah , Sharma Mukut , Reyes Emma Borrego-Diaz , Godwin Andrew K. , Huang Chao H.
Published: August 2018

Objectives: Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are now standard of care in lung cancer patients with EGFR mutation. Invariably, these patients develop resistance and require treatment with another EGFR-TKI or chemotherapy. The gatekeeper mutation T790M is responsible for about 50% of resistance. Other mechanisms may also confer resistance in these patients. High expression of microRNA-10b (miRNA-10b) is associated with worse prognosis in resected lung cancer patients with EGFR mutation. Both miRNA-27a and -27b are associated with increased expression of c-met, which is a potential mechanism of resistance to EGFR-TKI. The goal of this study is to determine the optimal treatment and miRNA characteristic of EGFR mutation lung cancer cells resistant to EGFR-TKI. We hypothesized that miRNA-10b, -27a and -27b modulated Erlotinib (ERL) resistance by different EGFR-TKIs and chemotherapeutic agents in EGFR mutant NSCLC cell lines.

Materials and Methods: Lung cancer cell lines with EGFR mutation HCC827 and HCC4006 resistant to ERL were generated. ERL-resistant cells were then treated with 10 nM afatinib (Afa), 0.5 mg/mL pemetrexed (Pem), and combination of 10 nM Afa/0.5mg/mL Pem for 72h. The cells were harvested and microRNA assay was performed by real-time PCR. NCI-H460 cell line without EGFR mutation was used as control.

Results: We observed increased expression of miRNA-10b, miRNA-27a and miRNA-27b in ERL-resistant HCC4006 compared to control cells NCI-H460. There was an upregulation of miRNA-27a and -27b but not of miRNA-10b in ERL-resistant HCC827. Treatment of ERL-resistant cells with Afa, Pem, and combined treatment changed the expression of miRNA-10b, miRNA-27a and miRNA-27b. These miRNAs were downregulated by 2nd-generation EGFR-TKI therapy alone or in combination with Pem. Different treatments had different effects on these miRNAs. There might be differences in miRNA regulation in different cell lines when treated with EGFR-TKI or chemotherapy. Our results suggest that microRNA may be used as targets for developing novel approach to treating patients with EGFR-TKI resistance.

Conclusion: This study may have implications in the management of patients resistant to EGFR TKI. MicroRNA analysis showed upregulation of several microRNAs that should be confirmed in clinical setting.

Citation Format: Inamul Haque, Hannah Motes, Mukut Sharma, Emma Borrego-Diaz Reyes, Andrew K. Godwin, Chao H. Huang. Modulation of microRNA expression in EGFR-tyrosine kinase inhibitor-resistant non-small cell lung cancer cell lines [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 485.
Abstract 4862: Protein arginine methyltransferase 5 as a tumor promoter and therapeutic target in gastrointestinal cancers
Authors: Prabhu Lakshmi , Chen Lan , Safa Ahmad , Korc Murray , Zhang Zhong-Yin , Lu Tao
Published: August 2018

Colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) are among the most commonly diagnosed forms of cancer in the United States. Due to their widespread prevalence and high mortality rate, it is vital to develop effective therapeutic drugs to combat these deadly diseases. In both CRC and PDAC, the multifunctional factor nuclear factor kappa B (NF-kB), a central coordinator of immune responses, is activated abnormally, leading to tumorigenesis and cancer progression. Therefore, controlling NF-kB activity is critical in the treatment of these cancers. Previously, we discovered a novel mechanism by which NF-kB is activated through methylation by an epigenetic enzyme known as protein arginine methyltransferase 5 (PRMT5). We showed that overexpression of PRMT5 significantly promoted several characteristics associated with cancer, including increased cell proliferation, migration, and anchorage-independent growth in both CRC and PDAC cells, thus, putting forward PRMT5 as a novel therapeutic target in these cancers. In this study, we successfully adapted AlphaLISA technique into a high-throughput screen platform, and further employed this approach to successfully identify PR5-LL-FDA1 as a potent PRMT5 inhibitor from commercially-available screening libraries. Furthermore, we confirmed that treatment of PDAC and CRC cells with PR5-LL-FDA1 led to decreased NF-kB activation, and reduced cancer associated properties in PDAC and CRC cells. Importantly, we show that PR5-LL-FDA1 is more efficacious than the commercial PRMT5 inhibitor, EPZ015666 in both PDAC and CRC. Our work clearly highlights the significant potential of PRMT5 as a therapeutic target in PDAC and CRC and hold the promise to establish PR5-LL-FDA1 as a promising basis for new drug development in the future.

Citation Format: Lakshmi Prabhu, Lan Chen, Ahmad Safa, Murray Korc, Zhong-Yin Zhang, Tao Lu. Protein arginine methyltransferase 5 as a tumor promoter and therapeutic target in gastrointestinal cancers [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 4862.
Abstract 4866: BI 907828: A novel, potent MDM2 inhibitor that induces antitumor immunologic memory and acts synergistically with an anti-PD-1 antibody in syngeneic mouse models of cancer
Authors: Rudolph Dorothea , Reschke Markus , Blake Sophia , Rinnenthal Jörg , Wernitznig Andreas , Weyer-Czernilofsky Ulrike , Gollner Andreas , Haslinger Christian , Garin-Chesa Pilar , Quant Jens , McConnell Darryl B. , Norbert Kraut , Moll Jürgen
Published: August 2018

MDM2 inhibitors block the interaction between the Tumor Protein p53 (TP53) and MDM2, its key negative regulator, and represent a new therapeutic concept in cancer therapy. MDM2 inhibitors are designed to restore p53 activity in TP53 wild-type tumors. Several MDM2 inhibitors are currently being evaluated in early clinical development. While the tumor targeting activity of MDM2 inhibitors has been well documented, recent preclinical data with the tool compound Nutlin-3 have shown that p53 activation by local, intra-tumoral injections induces anti-tumor immunity (Cancer Res 2017, 77(9) 2292-2305). Here we present data on BI 907828, a novel and potent MDM2 inhibitor with optimized drug-like properties that is suitable for intermittent dose schedules in syngeneic mouse models of cancer. Our data show that immune modulation contributes to efficacy of BI 907828 after oral administration in a Colon-26 syngeneic mouse model. Responding mice develop anti-tumor immunity that can control the tumor growth of a secondary tumor without any further treatment in a re-challenge study. A T cell depletion study shows a contribution of CD8+ T cells but not of CD4+ T cells to single-agent efficacy with BI 907828. Moreover, preclinical data in a Colon-26 syngeneic mouse model of cancer show synergistic efficacy for the combination of a PD-1 checkpoint inhibitor with BI 907828. In summary, BI 907828 is a novel, potent, orally bioavailable MDM2 inhibitor that shows synergistic efficacy in combination with a PD-1 checkpoint inhibitor in syngeneic mouse models of cancer.

Citation Format: Dorothea Rudolph, Markus Reschke, Sophia Blake, Jörg Rinnenthal, Andreas Wernitznig, Ulrike Weyer-Czernilofsky, Andreas Gollner, Christian Haslinger, Pilar Garin-Chesa, Jens Quant, Darryl B. McConnell, Kraut Norbert, Jürgen Moll. BI 907828: A novel, potent MDM2 inhibitor that induces antitumor immunologic memory and acts synergistically with an anti-PD-1 antibody in syngeneic mouse models of cancer [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 4866.
Abstract 4882: Identification and optimization of chemical inhibitors that directly target KRAS G12D mutant
Authors: Tian Xiaohong , Geng Guoyan , Wu Jian Hui
Published: August 2018

KRAS mutations are enriched in three lethal cancers, such as pancreatic ductal adenocarcinoma (PDAC) (> 90% of cases), colorectal cancer (CRC) (~50%) and lung cancer (~25%). Within these cancers, specific KRAS mutations dominate. KRAS G12D is the most common mutation in pancreatic and colorectal cancer. To date, accumulating studies have firmly established that constitutive activation of KRAS mutants is a driver of PDAC and CRC. Inhibitors of the downstream components of KRAS signaling only have limited success. Due to the high affinity of KRAS with GTP and no other obvious binding pocket on the KRAS surface for the design of inhibitors, KRAS has been considered ‘undruggable' for a long period of time. As a breakthrough, a novel direct inhibitor of the KRASG12C mutant was discovered in 2013, which forms a covalent bond with the cysteine at residue 12. However, such KRASG12C inhibitor is inactive against the G12D mutant as there is no Cysteine at residue 12. In this project, we have learnt from the excellent work of the G12C inhibitors and identified a novel compound as a direct inhibitor of the KRASG12D mutant. Importantly, this compound is active against the G12D mutant, but inactive against the KRAR wild-type. We demonstrated that our compound at 10 uM significantly inhibits the KRAS signaling in PANC10.05 pancreatic cancer cells and SNU-C2B colorectal cancer cells, both of which express endogenous KRASG12D mutant.

Citation Format: Xiaohong Tian, Guoyan Geng, Jian Hui Wu. Identification and optimization of chemical inhibitors that directly target KRAS G12D mutant [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 4882.
Abstract 4897: An acquired vulnerability of drug resistant melanoma with therapeutic potential
Authors: Oliveira Rodrigo Leite de
Published: August 2018

BRAF(V600E) mutant melanomas treated with inhibitors of the BRAF and MEK kinases almost invariably develop resistance, which is frequently caused by reactivation of the Mitogen Activated Protein Kinase (MAPK) pathway. To identify novel treatment options for such patients, we searched for acquired vulnerabilities of MAPK inhibitor-resistant melanomas. We find that resistance to BRAF+MEK inhibitors is associated with increased levels of reactive oxygen species (ROS). Subsequent treatment with the histone deacetylase inhibitor (HDACi) vorinostat represses SLC7A11 that leads to a lethal increase in the already elevated levels of ROS in drug-resistant cells, thereby causing selective apoptotic death of only the drug resistant tumor cells. Consistently, treatment of BRAF inhibitor-resistant melanoma with HDACi in mice results in a dramatic tumor regression. In a study in patients with advanced BRAF+MEK inhibitor resistant melanoma, we find that HDACi can selectively ablate drug-resistant tumor cells, providing clinical proof of concept for the novel therapy identified here.

Citation Format: Rodrigo Leite de Oliveira. An acquired vulnerability of drug resistant melanoma with therapeutic potential [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 4897.
Abstract 4899: Establishment and characterization of SN-38 resistant metastatic colorectal cancer cells (SW620/SN100) reveals an ABCG2 (BCRP) transport mediated resistance
Authors: Barbuti Anna Maria , Chen Zhe-Sheng
Published: August 2018

Despite advances in anticancer drug research, chemotherapy options and response rates for metastatic colorectal cancer (mCRC) are poor. Irinotecan, a topoisomerase I inhibitor, is a commonly used chemotherapy against mCRC as a single agent, or in combination with other anti-cancer drugs such as fluorouracil and leucovorin. However, acquired resistance to chemotherapy, especially in metastatic patients, is a critical cause of treatment failure.

Multi-drug resistance (MDR) in cancer is a major challenge to chemotherapy success. Mechanisms of MDR involve deliberate alteration in cellular expression, function, and/or responses of the cancer. One of the most notable mechanism of MDR is an increased cellular drug efflux through up-regulation of membrane ATP-binding cassette (ABC) transporters.

To investigate a new and clinically relevant mechanism of MDR in mCRC cells, SN-38 (the potent and active metabolite of irinotecan) was regularly administered to SW620 cells with drug-free intervals to reflect a drug induced resistance to treatment. Through cytotoxicity and western blotting assays on the newly formed SW620/SN100 cells, we discovered ABCG2 (BCRP) to be the main mechanism of SN-38 resistance, with no alterations in the topoisomerase I, ABCB1 (P-gp) or ABCC1 (MRP1). These results confirmed our initial hypothesis, given SN-38 is a known substrate of ABCG2. This discovery of SN-38 induced efflux in mCRC is of a larger importance because this mechanism not only limits the efficacy of the chemotherapy, but also poses a threat to the efficacy of a variety of pharmacologically dissimilar drugs which are substrates of ABCG2.

As treatments for mCRC continue to be investigated it is important to also continue investigating resistant mechanisms of these drugs. More discoveries of MDR mechanisms which are specific to cancer patient populations will offer superior diagnosis, proper treatment regimens and greater prognosis for patient success.

Citation Format: Anna Maria Barbuti, Zhe-Sheng Chen. Establishment and characterization of SN-38 resistant metastatic colorectal cancer cells (SW620/SN100) reveals an ABCG2 (BCRP) transport mediated resistance [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 4899.
Abstract 4903: AXL inhibition overcomes erlotinib resistance in AXL-activated non-small cell lung cancer cells
Authors: Wang Feng
Published: August 2018

Mutations in the tyrosine kinase domain of epidermal growth factor receptor (EGFR) are present in 10-35% patients with NSCLC. In patients with EGFR-mutated NSCLC, EGFR tyrosine kinase inhibitors, including erlotinib, have demonstrated excellent initial responses. However, despite improved outcomes observed in patients treated with EGFR TKIs, most patients eventually develop drug resistance. We and others recently demonstrated that the activation of oncogene AXL is necessary to confers erlotinib resistance in both cell and mouse models as well as in human tumor tissues. While genetic aberrations affecting AXL appear rare, we recently identified two patients with EGFR-mutated lung cancer who simultaneously harbor AXL A273V or AXL V289M mutation. Both patients were resistant to erlotinib treatment (one case of primary and one case of acquired resistance). In this study, we first evaluated whether these AXL mutations conferred resistance to erlotinib treatment. Using HCC827 and PC-9 NSCLC cell lines stably expressing the AXL A273V or V289M mutation, we confirmed that AXL A273V significantly increased resistance to erlotinib treatment. Subsequently we also conducted a preclinical study to test if a new AXL inhibitor MGCD265 could overcome such erlotinib resistance in NSCLC cells. Using an in vitro MTS assay, we first validated that administration of MGCD265 in combination with erlotinib significantly inhibited the viability of erlotinib-resistant HCC827-ER cells, compared to erlotinib- or MGCD265-alone treatment. Through conducting an array of cell functional studies, we found that combination of MGCD265 and erlotinib significantly decreased cell cycle progression in S phase, enhanced apoptosis, and repressed cell migration relative to single-agent erlotinib or MGCD265 treatment in HCC827-ER cells. We further performed RNA-sequencing to evaluate the gene expression profile and the cellular pathways altered in cells treated with erlotinib alone, MGCD265 alone or a combination of erlotinib and MGCD265. RNA-sequencing analysis identified that several groups of genes involved in cell survival inhibition or apoptosis promotion were upregulated, whereas genes involved in cell cycle process, DNA replication or cancer metabolism were downregulated in cells treated with the combination of erlotinib and MGCD265. Taken together, our results indicated that AXL mutations may confer resistance to EGFR TKI treatment, and effective blockade of the AXL pathway may represent a novel strategy to overcome erlotinib resistance for the treatment of NSCLC patients.

Citation Format: Feng Wang. AXL inhibition overcomes erlotinib resistance in AXL-activated non-small cell lung cancer cells [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 4903.
Abstract 4917: Tipifarnib is highly active in HRAS mutant lung squamous carcinoma tumor models
Authors: Kessler Linda , Scholz Catherine , Gualberto Antonio , Liu Yi , Burrows Francis
Published: August 2018

Genomic profiling of squamous tumors has revealed important similarities between lung squamous cell carcinoma (LSCC) and head and neck squamous cell carcinoma (HNSCC). For instance, HRAS is the most commonly mutated RAS species in both LSCC and HNSCC, observed in approximately 2% and 5% of cases, respectively (TCGA, Nature 2013). Tipifarnib is a potent and selective inhibitor of farnesyltransferase (FT) that catalyzes the post-translational attachment of farnesyl groups to proteins that require localization to the inner cell membrane. Although all RAS isoforms (KRAS/NRAS/HRAS) are FT substrates, HRAS is exclusively dependent upon farnesylation for membrane localization and signaling activation, making HRAS mutant tumors uniquely susceptible to tipifarnib mediated inhibition of FT. With limited treatment options, LSCC and HNSCC remain a significant unmet medical need. Recent evidence supports the clinical utility of tipifarnib for treatment of patients with HRAS-mutant HNSCC, and we present herein data supporting a potential utility of tipifarnib in the treatment of HRAS-mutant LSCC. We have characterized the antitumor activity of tipifarnib in CDX and PDX models of squamous cell carcinoma with activating HRAS mutations. Tipifarnib displayed robust antitumor activity in the majority of these models, including lung and head and neck tumors. Six of seven HRAS-mutant lung SCC PDX models responded to tipifarnib treatment with the majority either fully growth-inhibited or undergoing partial or complete regression. Importantly, even LSCC PDX tumors resistant to chemotherapy responded to tipifarnib, suggesting tipifarnib has the potential to offer clinical benefit in patients relapsed or refractory to standard therapies. The activity of tipifarnib in LSCC models is quite similar to that seen in HNSCC PDX models, where tipifarnib also induced regressions consistent with those observed in patients enrolled in the ongoing Phase 2 study in HRAS-mutant SCCHN patients (NCT02383927), including patients refractory to chemotherapy, cetuximab and/or immunotherapy. These data demonstrate that HRAS is a targetable mutation in lung SCC as well as in HNSCC and illustrate the potential for tipifarnib in the treatment of additional HRAS-mutant squamous cell carcinomas.

Citation Format: Linda Kessler, Catherine Scholz, Antonio Gualberto, Yi Liu, Francis Burrows. Tipifarnib is highly active in HRAS mutant lung squamous carcinoma tumor models [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 4917.
Abstract 4918: Pharmacokinetics and toxicity studies of AT1965, a B-cell activating immunotherapy
Authors: Sengupta Aniruddha , Samarla Mallik , Pandey Manoj , Sarkar Arindam , Roy Monideepa , Sengupta Shiladitya
Published: August 2018

Introduction: Cancer immunotherapy is the emerging paradigm in the search for a cure for cancer. AT1965 is a novel therapeutic that demonstrates remarkable anti-tumor activity across different preclinical tumor models, mediated through the activation of B-cells. In this study, we have evaluated the metabolism, pharmacokinetics (PK) and toxicity of AT1965 in rodent and non-rodent species.

Methods: AT1965 metabolism was studied in rodent, canine and primate liver microsomes. The PK of AT1965 was determined in 4T1 tumor bearing female Balb/c mice; female Sprague Dawley rats and female Beagle dogs at a variety of doses and schedules following single intravenous (i.v) injections. The extent and duration of the exposure was monitored over 120 hours in mice and rats, and till 192 hours in dogs, post dosing. Concentrations of AT1965 in plasma samples were determined either by LC-MS/MS or Atomic Absorption Spectroscopy. The toxicity of AT1965 in male and female Sprague Dawley Rats following single dose i.v. administration of 43.7, 87.4 and 174.8 mg/kg dosage of AT1965 were examined. During toxicity studies, clinical health status was observed daily for 14 days after treatment, followed by necropsy.

Results: AT1965 metabolism evaluated in mouse, rat, dog, monkey and human liver microsomes indicated high stability across all species. PK studies reveal that AT1965 exhibited a high exposure, slow systemic clearance and a proportional increase in dose normalized exposure across species. The elimination half-life (T1/2) varied from 34-40 hours in tumor-bearing mice to 29-44 hours in rats and ~ 66 hours in dogs. The excretion of AT1965 was predominantly through hepatobiliary route, with minimal renal clearance. Single i.v. administered acute dose toxicity studies for AT1965 reveal 87.4 mg/kg and 174.8 mg/kg as MTD and toxic doses respectively in rats.

Conclusion: The excellent pharmacokinetic profile of AT1965 showing high exposure and enhanced elimination half-life tested across species, in addition to striking antitumor activity coupled with low toxicity in multiple rodent tumor models, provide a compelling rationale for the development of AT1965 as a novel immunotherapeutic agent in the clinic.

Citation Format: Aniruddha Sengupta, Mallik Samarla, Manoj Pandey, Arindam Sarkar, Monideepa Roy, Shiladitya Sengupta. Pharmacokinetics and toxicity studies of AT1965, a B-cell activating immunotherapy [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 4918.
Abstract 4930: Epicatechin alleviates DOX-induced cardiovascular toxicity and improves its cytotoxic profile against breast cancer cells
Authors: Alshehri Ohoud Y. , Alabbasi Fahad A. , Mahmoud Islam F. , Abu-Sharib Alaa T. , El-Bassossy Hany M. , Abdallah Hossam A. , Al-Abd Ahmed M.
Published: August 2018

Epicatechin (EPI) has a well known and robust antioxidant properties which could alleviate drug-induced cardiovascular toxicities. On the other side, Doxorubicin (DOX) is a cornerstone anticancer drug used to treat breast cancer. However, DOX-induced cardiovascular complications might limit its treatment course continuation. Herein, we evaluated cardiovascular protective effects of EPI against DOX in-vivo and ex-vivo using isolated aortic ring preparation; meanwhile we assessed the potential ameliorating effects of EPI against DOX-induced cytotoxicity in breast cancer cells. Animals were given DOX (12 mg/kg, single IV injection) which induced cardiac ischemia appeared as increased QT and QTc intervals (1.8 folds for both). EPI (12 mg/kg, orally for 6 days) completely aborted DOX-induced cardiac ischemia and corrected all ECG abnormalities. Using isolated aortic ring preparation, DOX (10µM) impaired aortic ring vasodilatation and induced excessive vasoconstriction. Co-incubation of EPI (10µM) with DOX (10µM) entirely blocked DOX-induced impaired aortic ring vasodilatation, without affecting DOX-induced elevated vasoconstriction. EPI (10µM) combination with DOX in MDA-MB-231, MCF7 and T47D breast cancer cells significantly decreased the IC50‘s from 70.0±17.3 to 44.0±14.0 nM, from 554.0±30 to 240.0±10.0 nM and from 700.0±36.0 to 561.0±170 nM, respectively. Under hypoxic condition, EPI (10µM) significantly increased DOX cytotoxicity against MCF-7 cells and decreased its IC50 from 8.9±1.2 to 6.1±1.9 μM. This effect could be partially attributed to the inhibitory effect of EPI to P-glycoprotein (P-gp) and related efflux protein which would enhance DOX intracellular concentration. EPI increased the intracellular accumulation of rhodamine (P-gp probe) within MDA-MB-231 cells by 3-4 folds at concentration range from 3 to 100 μM. Moreover, EPI combination with DOX significantly increased cell apoptosis and necrosis assessed by annexin-V/FITC. However, EPI did not influence DOX effect on cell cycle distribution. In conclusion, EPI possesses potential cardiovascular protective effects against DOX. Meanwhile, EPI does not interfere with DOX-induced cytotoxic profile against breast cancer cells.

Citation Format: Ohoud Y. Alshehri, Fahad A. Alabbasi, Islam F. Mahmoud, Alaa T. Abu-Sharib, Hany M. El-Bassossy, Hossam A. Abdallah, Ahmed M. Al-Abd. Epicatechin alleviates DOX-induced cardiovascular toxicity and improves its cytotoxic profile against breast cancer cells [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 4930.
Abstract 4932: Neuro-endocrine negative SCLC is mostly RB1 WT and may be sensitive to CDK4/6 inhibition, especially if CCND1 is amplified
Authors: Sonkin Dmitriy , Thomas Anish , Teicher Beverly A.
Published: August 2018

Background: Small cell lung cancer (SCLC) is an aggressive form of lung cancer with limited therapeutic options, a very high mortality rate and is characterized, in most cases, by neuroendocrine features. A small but important subset of SCLC has intact RB1, however, other characteristics of this subset are not well-defined. Here we aim to characterize underlying genomics of SCLC cell lines with functional RB1.

Methods: To comprehensively assess the underlying genomics of SCLC cell lines with functional RB1, we examined 52 SCLC cell lines from the Cancer Cell Line Encyclopedia (CCLE) collection. We also integrated CCLE SCLC genomics data with drug sensitivity data from NCI SCLC screen of 420 approved and investigational oncology drugs.

Results: Out of 7 neuro-endocrine lineage marker-negative SCLC lines, 6 were RB1 WT. Out of 42 neuro-endocrine lineage marker-positive SCLC cell lines, 3 were RB1 WT. Two RB1 WT SCLC cell lines with CCND1 amplification were sensitive to CDK4/6 inhibitor. Oncogenic alterations in genes such as KRAS, NRAS, SMARCA4, and CDKN2A are rare in SCLC; however, these genes were altered in 7 of 9 RB1 WT SCLC cell lines.

Conclusions: Neuro-endocrine lineage marker-negative SCLC are enriched for RB1 WT and may be sensitive to CDK4/6 inhibition especially in context of CCND1 amplification. Neuro-endocrine lineage marker-negative SCLC cell lines are associated with low DLL3 expression. Therefore, RB1 WT SCLC are less likely to respond to DLL3 targeted drugs. However, this may present the opportunity to identify patients with WT RB1 among patients screened for DLL3 ADC clinical trials and having no or very low DLL3 expression.

Citation Format: Dmitriy Sonkin, Anish Thomas, Beverly A. Teicher. Neuro-endocrine negative SCLC is mostly RB1 WT and may be sensitive to CDK4/6 inhibition, especially if CCND1 is amplified [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 4932.
Abstract 4964: Metabolically activated macrophages mediate obesity-driven TNBC progression
Authors: Tiwari Payal , Blank Ariane , Cui Chang , Schoenfelt Kelly , Khan Seema A. , Rosner Marsha R. , Becker Lev
Published: August 2018

Triple-negative breast cancer (TNBC) patients have the poor prognosis due to their high metastatic potential and lack of targeted therapies. Emerging epidemiological data suggest that obesity is associated with increased incidence of more aggressive triple-negative breast cancer; however, mechanisms are unclear. During obesity, adipocytes within breast tissues recruit macrophages. M2-like macrophages can exacerbate TNBC progression; however, obese breast tissue is reported to be enriched with M1-like adipose tissue macrophages (ATMs), which are anti-tumorigenic. These results raise a paradox: how does obesity promote tumor progression if it activates an anti-tumorigenic macrophage phenotype?

Here we show that obesity promotes a distinct pro-inflammatory phenotype (metabolically activated macrophages; MMe) in breast ATMs, which promotes TNBC progression. We showed that ATMs isolated from obese women express cell surface markers of MMe (CD36, ABCA1) but not M1 (CD38, CD319) macrophages. We further found that pretreating TNBC cells with MMe (but not M1) derived conditioned media increase tumorsphere growth, and frequency of tumor-incidence when injected into mice in limited dilutions. Remarkably, we saw the same effect with obesity on tumor-incidence in both spontaneous and syngeneic TNBC mouse models. Moreover, blocking cytokine expression specifically in MMe using myeloid specific genetic knockout mice diminishes the effect of obesity on tumor-incidence. Interestingly, a subset of these MMe-secreted cytokines shared a common signal transducer, gp130, which led us to investigate the role of gp130 in tumors. Knocking down gp130 in cancer cells inhibits the MMe-induced stat-3 phosphorylation and tumorsphere growth in vitro, and diminishes the MMe-mediated effect of obesity on tumor-incidence in mice. Together these findings suggest that obesity-induced metabolically activated macrophages (MMe) in breast adipose tissue secrete inflammatory cytokines that promotes the TNBC tumor-progression by activating gp130 in cancer cells.

A comprehensive understanding of the signaling mechanism(s) involved in metabolic activation of mammary ATMs would enable development of targeted therapies towards this specific pro-tumorigenic macrophage phenotype, thereby leaving the immune system of cancer patients intact.

Citation Format: Payal Tiwari, Ariane Blank, Chang Cui, Kelly Schoenfelt, Seema A. Khan, Marsha R. Rosner, Lev Becker. Metabolically activated macrophages mediate obesity-driven TNBC progression [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 4964.
Abstract 4968: Tumor innate immunity primed by specific interferon stimulated endogenous retroviruses
Authors: Barbie David A.
Published: August 2018

Introduction: Tumor cell heterogeneity is a key determinant of cancer progression and drug resistance, which is often mediated by mesenchymal cell subpopulations. While these subclones can secrete growth factors, chemokines and cytokines, the immune signaling networks that fuel this pro-tumorigenic state remain incompletely defined. Elucidating what underlies this state would provide insights into tumor biology and inform clinical strategies to improve anti-cancer therapies.

Methods: Because of their well-defined nature, we used the phenotypically distinct H69M and H69AR Small Cell Lung Cancer (SCLC) mesenchymal subclones to uncover a novel mechanism of dysregulated innate immune signaling as compared with parental neuroendocrine H69 cells. Analysis of gene signatures across TCGA and CCLE databases, functional studies in additional cell lines, and ex vivo testing of patient-derived organotypic tumor spheroids (PDOTS) were conducted to determine the broader relevance across human cancers.

Results: We discovered a novel epigenetically regulated subclass of endogenous retroviruses (ERVs) that engages innate immune signaling in mesenchymal cancer subpopulations. Stimulated 3 Prime Antisense Retroviral Coding Sequences (SPARCS) are oriented inversely in 3'UTRs of certain interferon-inducible genes and silenced by EZH2. De-repression of these loci resulted in dsRNA generation following IFNγ exposure due to bi-directional transcription from the STAT1-activated gene promoter and the 5' LTR of the antisense ERV. We found that dsRNA sensing preferentially by MAVS fuels activation of TBK1, IRF3, and STAT1 signaling, sustaining a positive feedback loop. SPARCS induction across specific human tumors and cell lines is tightly associated with downregulation of chromatin modifying enzymes, including EZH2, a mesenchymal AXL positive cell state, and B2M and MHC class 1 antigen expression. SPARCS high tumors were marked by immune infiltration, but also exhibited multiple features of tumor

immune suppression. IFNγ treatment of PDOTS with de-repressed SPARCS markedly enhanced CXCL10 production and sensitized them to PD-1 blockade.

Conclusions: Together, these data unveil a novel subclass of ERVs whose de-repression triggers pathologic innate immune signaling in cancer, with potentially important implications for cancer immunotherapy.

Citation Format: David A. Barbie. Tumor innate immunity primed by specific interferon stimulated endogenous retroviruses [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 4968.