bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 1825: PIK3CA E542K mutation in bladder cancer confers resistance to PI3K targeted therapy but synergy with BET inhibition
Authors: Elbanna May Faek , Damayanti Nur , Chintala Sreenivasulu , Pili Roberto 
Published: August 2018

Abstract
Background: We have previously reported that two bladder cancer PDX models that carry distinct PIK3CA helical domain (HD) mutations respond differently to dual PI3K/mTOR inhibitor (LY3023414), where one model is sensitive (RP-B-02, PIK3CA E545K MUT) while the other is resistant (PIK3CA, E542K MUT) (Wei L et al Oncotarget 2016). Thus, we transduced these mutations in isogeneic cells to determine whether each mutation is indeed associated with a distinct oncogenic potential, as well as differential therapeutic response. Subsequently, we tested rational drug combinations capable of overriding resistance to PI3K targeted therapy (i.e. bromodomain inhibitor). Methods: Isogeneic HEK cells and urothelial cells (SV-HUC) were transduced with plasmids carrying either wild type (WT) or mutant PIK3CA (E545K and E542K mutants). Proliferation and growth were compared both in 2D and 3D culture respectively. We tested the therapeutic response to LY3023414 in 2D and 3D culture. Western blotting was used to test target modulation in the PI3K/mTOR pathway in response to treatment. JQ1 and LY3023414 combination studies were done in vitro. Calcusyn™ was used to determine whether synergy between the two agents exists in the context of either mutation. Results: PIK3CA E542K mutation has a growth advantage compared to the E545K mutation. This observation was more significant in 3D culture, which more faithfully represents the complexity of the tumor microenvironment. Isogeneic HEK cells expressing the E542K mutation were significantly more resistant to LY3023414 treatment both in 3D and 2D. This resonates with the resistance we initially reported in the bladder cancer PDX models carrying the E542K mutation. Interestingly, LY3023414+JQ1 combination was synergistic in the RP-B-01 (E542K MUT, but not in the RP-B-02 cell line (E545K MUT). Conclusion: PIK3CA mutation status is predictive of response to PI3K targeted therapy in bladder cancer, where PIK3CA E542K mutation confers resistance to PI3K targeted therapy. The synergistic combination of LY3023414 and the bromodomain inhibitor JQ1 can override resistance to PI3K targeted therapy. This drug combination may be of clinical significance in the context of PIK3CA E542K, but not E545K mutation.
Citation Format: May Faek Elbanna, Nur Damayanti, Sreenivasulu Chintala, Roberto Pili. PIK3CA E542K mutation in bladder cancer confers resistance to PI3K targeted therapy but synergy with BET inhibition [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 1825.
Abstract 1826: Oncogenic KRAS mediates resistance to MET targeted therapy in non-small cell lung cancer (NSCLC) with MET mutations that induce exon14 skipping
Authors: Suzawa Ken , Offin Michael D. , Kurzatkowski Christopher , Liu Daniel , Vojnic Morana , Smith Roger S. , Mattar Marissa , Khodos Inna , Stanchina Elisa de , Sabari Joshua K. , Lockwood William W. , Drilon Alexander E. , Ladanyi Marc , Somwar Romel 
Published: August 2018

Abstract
Mutations in MET that induce skipping of exon 14 and lead to reduced ubiquitin ligase-mediated turnover of this receptor tyrosine kinase (RTK) are detected in 3-4% of non-small cell lung cancer (NSCLC), approaching the prevalence of ALK-rearranged lung cancers. Preclinical and clinical studies have revealed that MET exon14 alterations are actionable oncogenic drivers that are amenable to therapy with MET kinase inhibitors such as crizotinib. However, similar to most kinase-driven cancers, despite initial benefit, acquired resistance to therapy is inevitable. Next-generation sequencing (MSK-IMPACT 468 gene panel) was performed on samples from 81 NSCLC patients with MET exon14 alterations, including 7 with paired pre- and post-treatment tumor samples. A concurrent KRAS G12 mutation was identified in 5 patients. In 4 of these patients, the KRAS mutation was present prior to receiving crizotinib. The KRAS mutation was acquired post-crizotinib in the remaining patient. These findings implicate KRAS activation as a potential mechanism of acquired resistance. Using isogenic and patient-derived in vitro and in vivo models harboring MET exon14 skipping alteration, we confirmed that the KRAS mutation results in constitutive activation of RAS/ERK signaling and cells expressing both MET exon14 skipping and KRAS mutations are refractory to MET inhibition. Dual inhibition of MET and MEK with crizotinib and trametinib, respectively, has an additive effect in cell line and xenograft models. Whereas concurrent KRAS mutation is an extremely rare event in EGFR- and ALK-driven NSCLC, our findings confirm KRAS mutation as a recurrent mechanism of primary or secondary resistance to MET-directed therapies in lung cancers harboring MET exon14 alterations. We provide a new potential therapeutic strategy for NSCLC patients with both MET exon14 alterations and KRAS mutations.
Citation Format: Ken Suzawa, Michael D. Offin, Christopher Kurzatkowski, Daniel Liu, Morana Vojnic, Roger S. Smith, Marissa Mattar, Inna Khodos, Elisa de Stanchina, Joshua K. Sabari, William W. Lockwood, Alexander E. Drilon, Marc Ladanyi, Romel Somwar. Oncogenic KRAS mediates resistance to MET targeted therapy in non-small cell lung cancer (NSCLC) with MET mutations that induce exon14 skipping [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 1826.
Abstract 1835: PPARγ agonist in combination with bcr/abl tyrosine kinase inhibitors in patients of chronic myeloid leukemia in chronic phase with suboptimal molecular response
Authors: Malhotra Hemant , Yadav Ajay , Mathur Ashwin , Biswas Debashish , Malhotra Bharti 
Published: August 2018

Abstract
Introduction & background:
Ten to 20 % of patients of Chronic Myeloid Leukemia in chronic phase (CML CP) have suboptimal molecular response (MR) to first line Imatinib maleate (IM). Treatment options include IM dose increase or switch to a 2nd generation tyrosine kinase inhibitor (TKI), Nilotinib or Dasatinib. Recently, synergy has been demonstrated when PPAR γ agonists are added to TKIs. We describe our initial results on 15 patients of CML CP treated with the combination of IM and pioglitazone, a PPAR γ agonist.
Patients and methods:
Fifteen patients of CML CP with suboptimal MR (bcr/abl:abl RQ-PCR between 1 to 10) after more than two years of IM were recruited in this pilot study. Because of economic considerations, these patients were not candidates for 2nd gen. TKIs. Patients given IM 600 mg/day and pioglitazone 30 mg/day. Blood counts and biochemistry monitored monthly, bcr/abl tested every 3 months using a cartridge based IS assay using the Cepheid GenXpert.
Results & conclusions:
Twelve of the 15 patients achieved significant MR, with 6/16 achieving a major MR at 9 months. Only 3/15 did not show a response (Table). Treatment with pioglitazone was well tolerated. One patient was not analysed due to intolerance to pioglitazone are first dose. Two patients had grade 1 elevation of hepatic enzymes which returned to normal after one week treatment cessation.
We conclude that the combination of imatinib with pioglitazone is effective and well tolerated in patients with a sub-optimal MR to TKI in patients with CML-CP. The combination could be a cost-effective strategy in treating imatinib non/sub-optimal responders in the developing world. The combination needs further and larger studies for confirmation and evaluation of the mechanisms of the synergy.
S. No.Patient ID/SexDiagnosis dateBCR-ABL (Before Pio)BCR-ABL (After Pio)At 3 monthAt 6 monthAt 9 month1SCM/MOct 20125.352.741.830.0052MD/FAug 20061.130.880.480.13GPJ/MJan 20142.860.43ND0.54RRC/MOct 20082.861.070.25ND5RK/MMar20081.390.770.350.416RDS/FOct 200010.15.994.870.677RDR/FApril 20039.045.780.360.058MM/MMay 20114.48NDND0.149RD/FJuly 20108.331.290.440.7310RB/FJuly 20153.253.022.891.3911BRR/MJan 20107.135.613.821.7712BK/FNov 20042.060.040.030.0713DPS/MJan 20116.155.471.020.8414JKM/MApril 20074.2215.49.117.6215CS/MOct 20121.721.170.840.08
Citation Format: Hemant Malhotra, Ajay Yadav, Ashwin Mathur, Debashish Biswas, Bharti Malhotra. PPARγ agonist in combination with bcr/abl tyrosine kinase inhibitors in patients of chronic myeloid leukemia in chronic phase with suboptimal molecular response [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 1835.
Abstract 1836: Induction of secreted soluble decoy EGFR variants by splicing interference overcomes drug resistance in human non-small cell lung cancer
Authors: Park Jeong Eun , Spraggon Lee , Stanchina Elisa de , Cartegni Luca 
Published: August 2018

Abstract
Activation of the epidermal growth factor receptor (EGFR) is involved in the oncogenesis of multiple cancers, particularly lung cancer. Current treatments are limited by the appearance of TKI resistance from secondary somatic mutations in the EGFR gene, such as the T790M mutation (&gt;50% of biopsies) in the EGFR kinase domain following erlotinib or gefitinib treatment. As these tumors are still EGFR-dependent, EGFR remains a prime therapeutic target in NSCLC. We have recently described multiple natural soluble decoy isoforms for multiple RTKs, including EGFR, which depend on the differential inclusion of functional domains by alternative splicing. We employ antisense oligo nucleotide (ASO) to reprogram EGFR pre-mRNA processing in order to increase expression of mRNA variants that encode for dominant-negative, soluble decoys EGFR (sdEGFR), at the expense of the oncogenic full-length EGFR receptor. These alternative splicing isoforms are generated via intronic polyadenylation (IPA) of pre-mRNA in a U1-snRNP (U1)-dependent manner. More specifically, we are able to induce the sdEGFR variants by using specific ASOs, designed to block the upstream U1 binding site and thus activate the appropriate IPA sites. Here, we show that our novel strategy effectively induces the expression of potent natural inhibitors of EGFR signaling in treatment-refractory lung cancer models in vitro and in vivo, leading to suppression of downstream pathways and tumor growth inhibition. The ASO-induced natural sdEGFR compounds function in a dominant-negative manner and induce dramatic cell death in NSCLC cells harboring multiple activating and resistance EGFR mutations, and thus provides a novel alternative strategy for treatment of refractory NSCLC, to overcome resistance mediated by the EGFR secondary mutations (including T790M, C797S and others).
Citation Format: Jeong Eun Park, Lee Spraggon, Elisa de Stanchina, Luca Cartegni. Induction of secreted soluble decoy EGFR variants by splicing interference overcomes drug resistance in human non-small cell lung 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 1836.
Abstract 1842: Novel KIF5B-RET+ NSCLC cell lines demonstrate differential responses to RET inhibitors
Authors: Schubert Laura , Le Anh T. , Doak Andrea E. , Doebele Robert C. 
Published: August 2018

Abstract
Chromosomal rearrangements involving the rearranged during transfection (RET) tyrosine kinase occur in 1-2% of NSCLCs. This results in the expression of a constitutively active fusion kinase that promotes cancer cell growth, proliferation and survival. In lung cancer, RET is most commonly fused to KIF5B, but can have many other 5' partners such as CCDC6, NCOA, TRIM33 and TRIM24. Clinical trials with several multi-kinase inhibitors, which potently inhibit RET, have had low response rates between 18-53%. Novel, more highly specific RET inhibitors are now in clinical development. Collectively, the clinical trial data suggest that patients with KIF5B-RET rearrangements have exceptionally low responses to RET inhibitors in relation to non-KIF5B-RET fusions. In order to understand the role of RET 5' partners in regulating response to RET inhibitors we have generated two novel KIF5B-RET+ patient-derived cell lines, CUTO22 (K23;R12) and CUTO32 (K15;R12). We have confirmed that each of these cell lines contain the KIF5B-RET fusion and express the RET fusion protein. MTS proliferation assays have revealed that the CUTO22 cell line is very sensitive to the highly specific RET inhibitor, CEP-32496/RXDX-105, and the multi-kinase inhibitor ponatinib. Conversely, the CUTO32 cell line is dramatically resistant to both RXDX-105 and ponatinib. Phospho-RET (pRET) is inhibited by RXDX-105 and ponatinib in a dose-dependent manner in both the CUTO22 and CUTO32 cell line. Interestingly, despite successful RET inhibition, downstream signaling in pERK and pAKT remains active. In a time-course experiment, pRET is inhibited for up to 24 hours while pERK and pAKT is sustained. Additionally, knockdown of RET with siRNA did not reduce downstream signaling activation in CUTO22 or CUTO32 cells. Combined inhibition of possible bypass pathways, EGFR or mTOR, did not significantly enhance sensitivity to RET inhibitors in CUTO22 and CUTO32 cell lines. To isolate the role of the 5' partners in response to RET inhibitors we have utilized CRISPR/Cas9 technology to generate Kif5b-Ret and Trim24-Ret rearrangements in Ba/F3 cells. We have confirmed with PCR or RT-PCR that these cell lines harbor the intended Ret fusions and express the RET protein. Both the Kif5b-Ret+ and Trim24-Ret+ Ba/F3 cell lines are highly sensitive to multiple RET inhibitors. In conclusion, these data suggest that RET inhibitors successfully inhibit the target protein, but not downstream signaling, suggesting that KIF5B-RET may have unique co-alterations or reliance on alternative pathways to promote growth and proliferation.
Citation Format: Laura Schubert, Anh T. Le, Andrea E. Doak, Robert C. Doebele. Novel KIF5B-RET+ NSCLC cell lines demonstrate differential responses to RET inhibitors [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 1842.
Abstract 1863: Ursolic acid sensitizes rhTRAIL-resistant triple negative breast carcinoma to rhTRAIL-induced apoptosis
Authors: Manouchehri Jasmine , Kalafatis Michael 
Published: August 2018

Abstract
Recombinant human tumor necrosis factor-related apoptosis-inducing ligand (rhTRAIL) possesses the ability to induce apoptosis in cancer cells independent of their p53 status while exhibiting minimal toxicity to normal, non-transformed cells, and thus, it is a promising anti-cancer therapeutic. However, rhTRAIL-induced apoptosis is not as effective in a majority of breast cancers due to the up-regulation of anti-apoptotic proteins, down-regulation of pro-apoptotic proteins, and/or down-regulation of death receptors (DRs) 4 and 5. A combinatorial approach of rhTRAIL with the “mother nature”-derived compound ursolic acid (UA) has been applied to sensitize rhTRAIL-resistant triple negative breast carcinoma. UA is derived from the leaves and berries of various plants and found in the coatings of fruits and does not exhibit toxicity to normal, non-transformed cells. UA has been revealed to possess the ability to up-regulate DR5 and diminish the expression of anti-apoptotic proteins survivin and FLIP in cancer cells and thereby, making UA an encouraging choice to be utilized as a sensitizing agent. The aim of this study was to determine the capacity of UA to sensitize rhTRAIL-resistant triple negative breast cancer (TNBC) BT-20 and HCC1937 cells to rhTRAIL-induced apoptosis and elucidate the underlying mechanisms for UA's sensitization. The combinatorial treatment of UA and rhTRAIL augmented the induction of apoptosis when compared to single agent UA and rhTRAIL treatments as detected by Annexin V/PI assays and through by the execution of the extrinsic pathway as marked by the activation of caspase 8, activation of the executioner caspases 3 and 7, and eventual PARP cleavage (a hallmark of apoptosis). The underlying mechanisms for UA's sensitization of rhTRAIL-resistant TNBCs were established to be through the down-regulation of the anti-apoptotic protein FLIP and through the up-regulation of DR4 and DR5. Overall, these findings reveal that UA is an efficacious sensitizing agent for rhTRAIL-resistant TNBCs.
Citation Format: Jasmine Manouchehri, Michael Kalafatis. Ursolic acid sensitizes rhTRAIL-resistant triple negative breast carcinoma to rhTRAIL-induced apoptosis [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 1863.
Abstract 1891: Cross-resistance and synergy between idelalisib and bendamustine in chronic lymphocytic leukemia
Authors: Kost Sara E. F. , Saleh Ali , Mejia Edgard M. , Mostafizar Marina , Bouchard Eric D. J. , Banerji Versha , Marshall Aaron J. , Gibson Spencer B. , Katyal Sachin , Johnston James B. 
Published: August 2018

Abstract
Idelalisib (IDE) is an inhibitor of the δ isoform of PI3 kinase and has shown high activity in chronic lymphocytic leukemia (CLL) either when given alone or in combination with bendamustine (BEN) /rituximab (BR). In the present study, we have determined whether there is cross-resistance between BEN and IDE in primary CLL cells in vitro and whether synergy is observed upon combining these agents. In primary CLL cells in vitro, cross-resistance was not observed between BEN and IDE suggesting different modes of cytotoxicity. In contrast to BEN, sensitivity to IDE was not influenced by prior clinical treatment or the presence of a del 17p. Marked synergy in cytotoxicity was seen between BEN and IDE, which was paralleled by changes in γ-H2AX staining. These findings suggest that the synergistic antitumor effect was related to enhanced DNA damage by the drug combination. The degree of cytotoxic synergy varied and synergy was observed in some cases that were resistant to BEN or IDE, and those with del 17p. Synergy between BEN and IDE was also seen in the B cell lines, BJAB and I83, and in healthy donor peripheral blood mononuclear cells indicating that the phenomenon was not CLL-specific. To simulate the microenvironment, CLL cells were pre-stimulating with CD40L and IL4 prior to drug treatment. Interestingly this treatment caused the cells to become resistant to IDE, but BEN sensitivity was unaffected. However, combining BEN and IDE produced greater synergy than observed when cells were incubated without IL4/CD40. To examine the role of PI3Kδ for synergy, B cells from C57 BL/6 mice, both wild type and with non-functioning PI3Kδ protein, were exposed to BEN and/or IDE. Cells with the non-functioning PI3Kδ protein were more resistant to IDE than the wild-type cells and showed lesser synergy confirming the importance of this protein for the synergistic effect. In summary, these results confirm that IDE can be active against BEN-resistant CLL cells, while BEN may remain active against IDE-resistant samples, demonstrating different modes of anti-tumor activity. However, the unique yet inconsistent synergy seen between these two agents suggest an overlapping mechanism of action. Ongoing studies are evaluating the mechanism for this synergy.
Citation Format: Sara E. F. Kost, Ali Saleh, Edgard M. Mejia, Marina Mostafizar, Eric D. J. Bouchard, Versha Banerji, Aaron J. Marshall, Spencer B. Gibson, Sachin Katyal, James B. Johnston. Cross-resistance and synergy between idelalisib and bendamustine in chronic lymphocytic leukemia [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 1891.
Abstract 1909: NR4A2 role in head and neck cancer: Mechanistic and functional analysis
Authors: Chaudhary Sanjib , Pothuraju Ramesh , Atri Pranita , Rachagani Satyanarayana , Batra Surinder K. , Macha Muzafar A. 
Published: August 2018

Abstract
Background: Nuclear receptor related 1 protein (NURR1/NR4A2) is a transcription factor that mediates numerous functions in differentiation/development, maintenance and metabolism. In cancer cells, NR4A2 promotes proliferation, migration, transformation and chemo-resistance in many cancers. Here, we explore the role of NR4A2 in head and neck squamous cell cancers (HNC) tumorigenesis and define its target genes. Methods: NR4A2 expression was determined by immunohistochemistry (IHC) and in publically available databases (Oncomine, TCGA). NR4A2 was knockedout/knockdown by CRISPR or shRNA. Coimmunoprepitation and reverse chromatin immunoprecipitation were done to study the interaction between EGFR/STAT3. ChIPSeq analysis was done by using Illumina NextSeq 500 Genome Analyzer and integrated with microarray (HPV+/- patients) to identify the true target genes of NR4A2 using BETA Software and validated by PCR/qPCR. Results: IHC and database analysis demonstrated overexpression of NR4A2 in HNC patients. NR4A2 was significantly overexpressed in HPV+ HNC patients, SCC47 and SCC104 cell lines. Functionally, CRISPR/shRNA knockout/knockdown of NR4A2 in cell lines significantly decreased colonogenicity, proliferation and migration. Expression of NR4A2 was positively correlated with EGFR expression (R2=0.92), and EGF treatment (100ng/ml; 24-48h) induced NR4A2 (~2 fold) expression coupled with epithelial to mesenchymal transition in SCC1 and SCC10B cells (HPV-). We also observed EGF mediated NR4A2 induction was abrogated by panEGFR inhibitor (afatinib) with concomitant decrease in STAT3 expression. Physical interaction between EGFR and STAT3 with EGF treatment regulated NR4A2 expression. Whole genome integration of ChIPseq and microarray demonstrates 9% (2015) and 23% (3002) of the enriched up and down-regulated target genes, respectively were canonically regulated in HPV+ HNC. ChIP PCR validation indicates enrichment of NR4A2 in some of the target genes, wnt10, p53, cxcl13, cln10 and hoxb8 in HPV+ cells. Conclusions: Our data indicate overexpression of NR4A2 in HNC, and its positive correlation with EGFR expression. We also noted the physical interaction between EGFR and STAT3 which functionally attribute the NR4A2 expression. Integration and validation data showed the differential enrichment of NR4A2 target genes in HPV+/- cell lines which suggest its possible discriminatory role in HNC pathogenesis which needs to be confirmed.
Citation Format: Sanjib Chaudhary, Ramesh Pothuraju, Pranita Atri, Satyanarayana Rachagani, Surinder K. Batra, Muzafar A. Macha. NR4A2 role in head and neck cancer: Mechanistic and functional analysis [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 1909.