bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4768: Determination of Rab GTPase-mediated pathways critical for the antimyeloma activity of Rab GGTase inhibitors
Authors: Dykstra Kaitlyn M. , Allen Cheryl L. , Holstein Sarah A.
Published: July 2016

Multiple myeloma (MM) is a plasma cell malignancy characterized by the production of high levels of monoclonal protein (MP). This leads to an increased protein folding burden in the endoplasmic reticulum (ER) in MM cells, resulting in a constitutively upregulated unfolded protein response (UPR) and a lower threshold for ER stress-mediated apoptosis. We have previously shown that inhibitors of Rab GGTase, the enzyme responsible for Rab GTPase geranylgeranylation, disrupt MP trafficking in MM cells, leading to an accumulation of MP in the ER and induction of the UPR and apoptosis. There are over 60 different Rab GTPases in mammalian cells involved in regulating a wide range of membrane trafficking events including exocytic, endocytic, and lysosomal pathways. In this study, we aimed to further define how disruption of RabGTPase function in MM cells leads to apoptosis by knocking down individual Rab proteins. Given the accumulation of MP and induction of UPR, our initial focus was on secretory Rabs. Knockdown of Rab1A/B (>50%) using siRNA in RPMI 8226 cells lead to moderate increases in intracellular lambda light chain in Rab1A/B knockdowns after 72 hours (∼120-140% of control levels by ELISA). However, despite the increase in intracellular MP, no increases in UPR or apoptosis markers were seen by western blot analysis or annexin-V/propidium iodide flow cytometry. Extended time course experiments (up to 120 hours) also did not exhibit any increase in UPR or apoptosis. Knockdown of Rab6A (>60%), another RabGTPase associated with the secretory pathway, did not lead to increases in intracellular lambda light chain or induction of apoptosis. These results suggest that although individual knockdown of Rab1 is sufficient to partially disrupt MP trafficking, either more complete knockdown of the individual Rabs or knockdown of multiple Rabs is necessary for induction of the UPR and apoptosis. Additional optimization of the knockdowns will be performed in order to verify these results. These studies support the further development of Rab GGTase inhibitors that globally effect Rab GTPase geranylgeranylation as a novel anti-myeloma strategy.

Citation Format: Kaitlyn M. Dykstra, Cheryl L. Allen, Sarah A. Holstein. Determination of Rab GTPase-mediated pathways critical for the antimyeloma activity of Rab GGTase inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4768.
Abstract 477: Correlation of PD-L1 expression and HPV status among primary and metastasized HNSCC tumors
Authors: Quon Chenglu C. , Xia Xiaoling , Manriquez Lupe , Schemp Crystal , Sloane Dawn , Alabagi Shahad , Abdelwahab Mohammed G. , Gu Pengfei , Pang Lizhen , Hanif Khalid , Schechter Nicole
Published: July 2016

Dysregulation of the immune checkpoints has been identified as one of the mechanisms tumor cells employ for immune escape. Human papillomavirus (HPV) plays an important role in the etiology of one subset of Head and Neck Squamous Cell Carcinomas (HNSCC). Recent studies reported that PD-1/PD-L1 pathway may be correlated with HPV-associated HNSCC. The degree of PD-L1 expression has been reported to be increased in those patients with HPV-positive disease. Also, PD-L1 expression in HNSCC was observed in the primary, recurrent, and metastatic disease setting. However, the clinicopathological implications associated with PD-L1 in HNSCC, as well as in disease metastasis, remain largely unclear.

Using immunohistochemistry (IHC) and In situ hybridization (ISH) on VENTANA BenchMark ULTRA automated stainers, 40 cases of HNSCC, with matching primary and metastatic cancer stages, were evaluated for expression of PD-L1, p16, a surrogate marker of transforming HPV infections, and presence of HPV. Formalin-fixed paraffin-embedded tumor samples were subjected to PD-L1- and p16-IHC as well as HPV-ISH. A potential association between PD-L1 expression and HPV status among primary tumors and matched metastases was analyzed.

Our data show that expression of PD-L1 or p16 is concordant in the majority of HNSCC primary vs metastatic tumor cases tested. Agreement rate of p16 expression among 40 case pairs of primary vs metastatic tumor was 88.2% with a 95% Confidence Interval (CI) of (73.4-95.3). PD-L1 expression was 76.9% (61.7-87.4) concordant among the 40 case pairs. Agreement rate between PD-L1 and p16 was 77.1% (61.0-87.9) in primary cases and 51.3% (35.9-66.6) in metastatic cases. No obvious association between PD-L1 and p16 expression was observed.

Citation Format: Chenglu C. Quon, Xiaoling Xia, Lupe Manriquez, Crystal Schemp, Dawn Sloane, Shahad Alabagi, Mohammed G. Abdelwahab, Pengfei Gu, Lizhen Pang, Khalid Hanif, Nicole Schechter. Correlation of PD-L1 expression and HPV status among primary and metastasized HNSCC tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 477.
Abstract 4772: Addiction to chaperones: Investigating the role of HSP70 isoforms in cancer
Authors: Suckling Lorna AB , Powers Marissa , Sharp Swee , Workman Paul
Published: July 2016

The heat shock protein 70kDa (HSP70) family of molecular chaperones are critical for the survival of cancer cells due to their antiapoptotic activity and role in protein homeostasis. Our laboratory has previously shown that silencing two members of this family (HSP72 and HSC70) causes tumour cell specific apoptosis and also sensitises cancer cells to HSP90 inhibitors. HSP70 has therefore become an appealing therapeutic target. The human HSP70 family comprises 17 genes and the individual roles of the isoforms in cancer are poorly understood. Here we use a systematic approach to determine the importance of HSP70 isoforms, and a selection of HSP70 binding partners, for the growth of cancer cells under stress. It was hypothesised that cancer cells are more dependent on HSP70 proteins when under stressed conditions, as encountered in the tumour environment. We used RNA interference (RNAi) to determine the effect of silencing HSP70 isoforms and binding partners on cancer cell viability, as measured by CellTiter-Blue®. The siRNA screens were carried out in human colon (RKO) and breast (BT474) cancer cells under serum deprivation, oxidative stress and hypoxia. The silencing of several HSP70 genes, including the HSP70 isoform HSPA5 (also known as BiP/Grp78), were found to cause a reduction in cancer cell viability under stress. Detailed validation of hits has been carried out to confirm their importance for cancer cell survival and validated hits may provide potentially important therapeutic targets for cancer drug discovery.

Citation Format: Lorna AB Suckling, Marissa Powers, Swee Sharp, Paul Workman. Addiction to chaperones: Investigating the role of HSP70 isoforms in cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4772.
Abstract 4778: Covalent bonding of a C8-conjugated pyrrolobenzodiazepine (PBD) monomer and dimer to a terminal guanine residue of DNA duplex and hairpin fragments
Authors: Mantaj Julia , Jackson Paul J. M. , Jackson Khondaker Miraz , Thurston David E.
Published: July 2016

The pyrrolobenzodiazepines (PBDs) are a family of covalent-binding DNA-interactive minor-groove binding agents that are of growing interest due to their potential as stand-alone anticancer agents, and for their use as payloads in Antibody Drug Conjugates (ADCs). For example, one PBD Dimer, SJG-136 has reached Phase II evaluation in the clinic for ovarian and haematological cancers, and a number of PBD-based ADCs are now being evaluated in pre-clinical, Phase I and II clinical trials (e.g., SGN-CD19B, SGN-CD33A [vadastuximab talirine], SGN-CD70A, SGN-CD123A, SC16LD6.5 [Rova-T, rovalpituzumab tesirine] and ADCT-402).

Until now, PBDs, which bind in the minor groove of DNA and covalently bond to a guanine residue through its C2-NH2 functional group, were thought to require a three-base-pair recognition sequence prior to covalent bonding to the central guanine (with a thermodynamic preference for binding to 5’-Pu-G-Pu-3’ sequences but a kinetic preference for 5’-Py-G-Py-3’; Pu = Purine, Py = Pyrimidine). Using HPLC/MS methodology with designed hairpin and duplex oligonucleotides, we have now demonstrated that the PBD dimer SJG-136 and the C8-conjugated PBD Monomer GWL-78 can covalently bond to a terminal guanine of DNA, with the PBD skeleton spanning only two base pairs. Control experiments with the non-C8-conjugated anthramycin along with molecular dynamics simulations suggest that the C8-substituent of a PBD monomer, or one-half of a PBD Dimer, may provide stability for the adduct.

This observation highlights the importance of PBD C8-substituents, and also suggests that PBDs may bind to terminal guanines within stretches of DNA in cells, thus representing a potentially novel mechanism of action at the end of DNA strand breaks.

Citation Format: Julia Mantaj, Paul J. M. Jackson, Khondaker Miraz Jackson, David E. Thurston. Covalent bonding of a C8-conjugated pyrrolobenzodiazepine (PBD) monomer and dimer to a terminal guanine residue of DNA duplex and hairpin fragments. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4778.
Abstract 478: A mouse model for highly metastatic, nonfunctioning pancreatic neuroendocrine tumors
Authors: Contractor Tanupriya , Kobayashi Shinta , Clausen Richard , da Silva Edaise , Tang Laura , Chan Chang , Harris Chris R.
Published: July 2016

Pancreatic neuroendocrine tumors are generally classified as functioning or nonfunctioning. Patients with functioning tumors can have severe hypoglycemia because their tumors express high amounts of insulin as well as chromogranin A; fortunately, these tumors are seldom metastatic. Patients with nonfunctioning tumors express high amounts of chromogranin A but little insulin; unfortunately these tumors are highly metastatic to the liver. Nonfunctioning tumors are more common, and a more severe health issue. The highly studied RT2 B6 mouse, in which the SV40 T antigen is expressed from an insulin promoter in an inbred C57Bl/6 genetic background, is a model for functioning pancreatic neuroendocrine tumors: liver metastasis is uncommon in RT2 B6 mice, which are very hypoglycemic and often die when tumors are very small. We have changed the genetic background and are studying RT2 AB6F1 hybrid mice, which have a C57Bl/6 father and a mother from an A/J inbred background. RT2 AB6F1 mice are much less hypoglycemic, and these mice develop liver metastasis with high frequency. We have mated the hybrid AB6F1 mice to their littermates in order to map metastasis genes by F2 analysis, and have discovered that a locus at mouse chromosome 2qG1 links tightly to liver metastasis. One gene within this locus, InsM1, is less expressed in the primary tumors of mice with liver metastatic disease. InsM1 is also less expressed in primary tumors from humans with liver metastatic disease. Previous studies of InsM1 have shown that this protein maintains the differentiated status of pancreatic beta cells. We find that tumors from mice with low expression of InsM1 also express lower amounts of several distinctive markers of differentiated beta cells, but higher amounts of several markers of liver cells. These data suggest that dedifferentiation to stem cells, which can then redifferentiate to other cell types such as liver cells, promotes metastasis of pancreatic beta cell tumors. Intratumoral expression of liver markers may be a useful predictor of metastatic disease in these patients. Dedifferentiation of mature beta cells is also a mechanism by which type 2 diabetes occurs, so there may be similarities between these two diseases.

Citation Format: Tanupriya Contractor, Shinta Kobayashi, Richard Clausen, Edaise da Silva, Laura Tang, Chang Chan, Chris R. Harris. A mouse model for highly metastatic, nonfunctioning pancreatic neuroendocrine tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 478.
Abstract 4788: Discovery of potent and selective inhibitors of ERK1/2 with a unique mechanism of action
Authors: Deng Yongqi , Samatar Ahmed , Shipps Gerald , Cooper Alan , Long Brian , Carr Donnar , Xiao Li , Hruza Alan , Wang Tong , Zhu Liang , Nan Yang , Patel Mehul , Muppalla Kiran , Zhu Hugh , Boga Babu Sobhana , Gao Xiaolei
Published: July 2016

Activation of the RAS/MAPK pathway occurs via a cascade of protein phosphorylation events which culminate in the phosphorylation & activation of ERK 1/2. Aberrant activation of this pathway has been demonstrated in several human tumor types. Inhibitors of this pathway in clinical development target upstream kinases, BRAF or MEK. Only a few ERK 1/2 has been reported. The goal of the ERK program was to develop a targeted therapy that is guided by a clear patient selection / responder identification plan based on BRAF and K/NRAS mutations.

Utilizing an affinity based high-throughput screening strategy (ALIS), we discover a novel class of small molecule ERK 1/2 inhibitors. Optimization of this chemical series led to the discovery of SCH 772984, which is highly selective ERK1/2 inhibitor, inhibiting cell proliferation selectively in tumor cell lines with an activated MAPK pathway and causes significant tumor regression in vivo in BRAF & RAS mutant xenograft models. Based on insights gained through crystallographic analysis, SCH 772984 and related compounds have a unique ERK binding mode which results in a novel dual mechanism of inhibition, blocking ERK phosphorylation by MEK as well as inhibiting ERK kinase activity. This novel mechanism enables the use of ERK phosphorylation as a target engagement biomarker. Biological differences between pathway inhibition at the level or ERK vs. inhibition of upstream kinases are being examined. The SAR and crystal structures of this series ERK inhibitors will be reported.

Citation Format: Yongqi Deng, Ahmed Samatar, Gerald Shipps, Alan Cooper, Brian Long, Donnar Carr, Li Xiao, Alan Hruza, Tong Wang, Liang Zhu, Yang Nan, Mehul Patel, Kiran Muppalla, Hugh Zhu, Babu Sobhana Boga, Xiaolei Gao. Discovery of potent and selective inhibitors of ERK1/2 with a unique mechanism of action. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4788.
Abstract 4805: In vitro characterization of novel inhibitors of ROCK and MRCK kinases as anticancer agents
Authors: Desai Dhimant H. , Kale Vijay P. , Hengst Jeremy A. , Dick Taryn E. , Colledge Ashley L. , Amin Shantu G. , Yun Jong K.
Published: July 2016

Metastatic cancers are the second leading cause of deaths in the USA. RhoA and Cdc42 play critical roles in the regulation of plasticity of cancer cell migration/invasion and cell proliferation. ROCK1/2 and MRCKá/â are downstream kinases in the signaling pathways associated with cancer cell migration and invasion. Hence, we hypothesized that simultaneous targeting of these two kinase families would be an effective therapeutic strategy to block migration, invasion, and growth of metastatic cancers. We have identified DJ4 as a novel inhibitor of ROCK and MRCK kinases. In the cellular functional assays, DJ4 treatment significantly blocked stress fiber formation, and inhibited migration and invasion of multiple cancer cell lines in a concentration dependent manner. To study the critical functional groups required for its activity, we have modified the chemical structure of DJ4 at various functional groups and synthesized several analogs of DJ4 to perform the structural activity relationship (SAR) study for their ROCK1 inhibition. The effectiveness of these compounds were further investigated using National Cancer Institute's drug screening program in 60 human cancer cell lines representing nine different cancer types. These compounds effectively inhibit migration and invasion of multiple cancer cell types. Selected analogs were tested for their anti migration, pro-apoptotic, and anti-proliferative effects in breast cancer cells. Our studies strongly indicate that DJ4 and its analog, DJ110, are potent inhibitors of ROCK1, ROCK2, MERKá and MRCKâ. The results of our finding will be discussed.

Citation Format: Dhimant H. Desai, Vijay P. Kale, Jeremy A. Hengst, Taryn E. Dick, Ashley L. Colledge, Shantu G. Amin, Jong K. Yun. In vitro characterization of novel inhibitors of ROCK and MRCK kinases as anticancer agents. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4805.
Abstract 4809: Combination therapy targeting ribosome biogenesis and mRNA translation provides a novel and potent therapeutic approach to treat MYC-driven malignancy
Authors: Devlin Jennifer R. , Rebello Richard J. , Hannan Katherine M. , Cullinane Carleen , Drygin Denis , Risbridger Gail P. , Furic Luc , Hannan Ross D. , Pearson Richard B.
Published: July 2016

MYC-driven malignancies are associated with elevated rates of ribosome biogenesis and mTORC1/eIF4E-driven protein synthesis suggesting they may be vulnerable to therapeutic strategies that target the ribosome. We investigated the therapeutic efficacy of targeting multiple nodes of the network controlling the ribosome in mouse models of MYC-driven lymphoma (Eì-Myc) and prostate cancer (HI-MYC). Simultaneous inhibition of ribosomal RNA synthesis and repression of protein translation was achieved by utilizing the novel RNA polymerase I inhibitor CX-5461 and PI3K/AKT/mTORC1 and PIM 1 signaling inhibitors.

Combined inhibition of ribosome biogenesis and function significantly improved therapeutic outcomes in lymphoma and prostate cancer models. CX-5461 and Everolimus (mTORC1 inhibitor) co-treatment more than doubled the survival of Eì-Myc lymphoma-bearing mice. While both classes of inhibitor suppress rDNA transcription, they treat MYC-driven malignancy through distinct molecular mechanisms facilitating their combinatorial effects. In contrast to CX-5461, PI3K/AKT/mTOR pathway inhibitors did not activate a nucleolar stress response and p53-dependent apoptosis but instead induce B-lymphoma cell death via the upregulation of the BH3-only protein BMF (Devlin et al Cancer Discovery 2015 Oct 21. pii: CD-14-0673. [Epub ahead of print]). PIM kinase has been shown to regulate eIF4Edriven protein synthesis on prostate cancer cell lines. Co-treatment of HI-MYC mice with CX-5461 and the PIM kinase inhibitor CX-6258 reverted highly invasive disease to low-grade prostate intraepithelial neoplasia.

These findings demonstrate that MYC driven tumors are addicted to multiple regulatory steps associated with ribosome synthesis and function and coordinated targeting of these addictions provides an effective new therapeutic approach to treat MYC driven cancers.

Citation Format: Jennifer R. Devlin, Richard J. Rebello, Katherine M. Hannan, Carleen Cullinane, Denis Drygin, Gail P. Risbridger, Luc Furic, Ross D. Hannan, Richard B. Pearson. Combination therapy targeting ribosome biogenesis and mRNA translation provides a novel and potent therapeutic approach to treat MYC-driven malignancy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4809.
Abstract 4811: Global demethylation with decitabine increases DNA repair and sensitizes melanoma to carboplatin
Authors: Budden Timothy , Davey Ryan J. , Vilain Ricardo E. , Ashton Katie A. , Braye Stephen , van der Westhuizen Andre , Bowden Nikola A.
Published: July 2016

Global genome repair (GGR) is critical for recognizing DNA damage by the chemotherapy agent carboplatin, and triggering apoptotic signalling. XPC is a critical gene in the GGR pathway but in melanoma XPC is not induced in response to carboplatin resulting in extreme resistance. Despite low global methylation levels across the melanoma genome, there is evidence methylation plays a role in suppression of XPC. 5-aza-2’-deoxycytidine (decitabine), is a DNA methyltransferases inhibitor used as a chemotherapy agent that results in global loss of methylation and re-expression of silenced genes. We hypothesised that restoring expression of XPC in melanoma using decitabine could overcome resistance to carboplatin. To confirm low XPC in melanoma tumour tissue, transcript and protein expression from 196 advanced primary and metastatic melanomas was quantified and compared to normal tissue and other cancer types. Melanoma cell lines with low baseline XPC were treated with pharmacological doses of decitabine or carboplatin alone, or in sequential combination. XPC transcript, apoptosis, proliferation, senescence, global and CpG island shore demethylation was quantified. XPC transcript and protein was low in a proportion of melanoma tumours and expression correlated with overall survival. Treatment of melanoma cells with carboplatin alone did not significantly induce XPC expression or increase apoptosis in the majority of melanoma cell lines. Decitabine decreased global methylation (average 44.67% decrease) and increased XPC expression (0.9-3.0 fold increase). Hotspots of demethylation after decitabine treatment in the XPC CpG island shore were detected and could be responsible for the increase in XPC expression. When carboplatin was administered following decitabine, a greater XPC induction (1.5-7.6 fold increase) occurred with significantly increased levels of apoptosis (1.6-2.2 fold increase). This was coupled with a decreased proliferation and the presence of markers of senescence. Knocking down XPC expression with siRNA significantly reduced the effects of combination treatment. The outcomes of this study are evidence that silencing of XPC by methylation is a mechanism of carboplatin resistance in melanoma and sequential combination of decitabine followed by carboplatin may be used to restore GGR function and overcome resistance.

Citation Format: Timothy Budden, Ryan J. Davey, Ricardo E. Vilain, Katie A. Ashton, Stephen Braye, Andre van der Westhuizen, Nikola A. Bowden. Global demethylation with decitabine increases DNA repair and sensitizes melanoma to carboplatin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4811.
Abstract 4826: ONC212 exhibits increased cytotoxicity relative to ONC201 in a subset of human pancreatic cancer cell lines
Authors: Lev Avital , Wagner Jessica , Dicker David T. , Stogniew Martin , Allen Joshua E. , Schalop Lee , Oster Wolfgang , Olson Gary L. , El-Deiry Wafik S.
Published: July 2016

Pancreatic cancer is one of the most deadly types of cancer with five-year survival rate of ∼6%. This poor prognosis is attributed to aggressive growth of the tumor cells, metastasis at an early stage and resistance to standard chemotherapy. Therefore, finding new treatments and improving outcomes of pancreatic cancer patients have been high priorities. ONC201 is a small molecule that selectively targets a broad range of tumor types tested. It is currently in phase I/II clinical trials for advanced solid, hematopoietic, and lymphoid tumors. The ONC201 analogue, ONC212, is in preclinical development for certain cancers that are not lead indications for the parent compound ONC201. We examined the efficacy of ONC201 and ONC212 in a panel of human pancreatic cancer cell lines. Among seven cell lines tested, three cell lines were relatively insensitive to ONC201, with IC50 values of 100 ìM or greater. However, these cell lines showed greater sensitivity to ONC212 with IC50 values of 31-56 ìM. We compared ONC201-resistant PANC-1 cells and ONC201-sensitive HPAF-II cells. Both ONC201 and ONC212 induced apoptosis in HPAF-II cells, as assessed by PARP cleavage, while PARP cleavage was detected only when PANC-1 cells were treated with ONC212 but not ONC201. We are currently evaluating the efficacy of ONC201 and ONC212 in a panel of patient-derived low passage pancreatic cancer cell lines. We found a correlation between high expression levels of RTKs (c-MET, ALK, EGFR, IGFR, HER2) and decreased sensitivity to ONC201 in pancreatic cancer cell lines. We investigated the effect of ONC201 on EGFR and IGFR, which are highly expressed in PANC-1 and found that ONC201 does not inhibit receptor activation by the specific growth factors. We are studying the effects of ONC201 and ONC212 on RTKs and their signal transduction pathways. Lastly, since aggressive drug-resistant pancreatic cancer cells express high levels of RTKs, we are developing a rationale combining ONC201/ONC212 with specific small molecule RTK inhibitors such as crizotinib or lapatinib. We are exploring these combination treatments using cell lines, organoids and PDX models to unravel specific therapy options for therapy-refractory pancreatic cancer cells. Our goal is to provide the preclinical rationale for clinical trials of ONC201 or ONC212 as mono-agents or in combination with other therapies for pancreatic cancer patients.

Citation Format: Avital Lev, Jessica Wagner, David T. Dicker, Martin Stogniew, Joshua E. Allen, Lee Schalop, Wolfgang Oster, Gary L. Olson, Wafik S. El-Deiry. ONC212 exhibits increased cytotoxicity relative to ONC201 in a subset of human pancreatic cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4826.
Abstract 4837: Design, synthesis, and biological evaluation of thieno[2,3-d] and thieno[3,2-d]pyrimidines as dual acting RTK inhibitors and microtubule targeting antitumor agents
Authors: Gangjee Aleem , Islam Farhana , Quadery Tasdique Mohammad , Mooberry Susan L. , Bastian Anja , Ihnat Michael A.
Published: July 2016

Microtubules, attractive targets for drug development as anticancer agents, play vital roles in multiple aspects of cellular metabolism. These agents have been successfully used in the clinic for the treatment of various cancers. However, the utility of such agents are often limited by the emergence of tumor resistance due to overexpression of P-glycoprotein and/or âIII-tubulin. Tumor angiogenic mechanisms are important for tumor growth and metastasis are inhibited by antiangiogenic agents (AAs). AAs are usually cytostatic, and their utility in cancer chemotherapy lies in their combination with cytotoxic chemotherapeutic agents. Clinical combinations of antiangiogenic agents with antitubulin agents have been particularly successful. Recently, we reported water-soluble tubulin targeting pyrrolo[2,3-d]- and pyrrolo[3,2-d]pyrimidine analogs as antitumor agents, that circumvent drug resistance. These analogs also possess RTK (EGFR, VEGFR2 and PDGFRâ) inhibitory activity. To further explore the activity of these dual RTK/tubulin inhibitors we designed isosteric thieno[2,3-d] pyrimidine and thieno[3,2-d]pyrimidine analogs which increased microtubule depolymerizing potency by 14 to 24-fold (AG95 IC50 = 7.0 ± 2.7 nM, AG370 IC50 = 7.6 ± 2.1 nM) compared with the lead compounds (AG85 IC50 = 96.6 ± 5.3 nM, AG20 IC50 = 183 ± 3.4 nM). Substitution at the 4-anilino position of both these scaffolds were also explored with various moieties to afford the 6-methoxy-tetrahydroquinoline moiety which possess the optimum balance of microtubule depolymerizing activity (AG372 IC50 = 4.3 ± 1.6 nM, AG337 IC50 = 3.4 ± 0.9 nM,) and RTK (EGFR, VEGFR2 and PDGFRâ) inhibitory activity. These two compounds demonstrated excellent inhibition for EGFR (IC50 = 12.6 ± 1.2 nM, 28.5 ± 3.9 nM), VEGFR-2 (25.2 ± 7.2 nM, 216.1 ± 18.6 nM) and PDGFRâ (IC50 = 25.6 ± 7.2 nM, 266.8 ± 35.4 nM) comparable to the standard clinically used agents. These attributes of the 4-N-substituted thieno pyrimidines provides the impetus for further development of these compounds as dual acting targeted antitumor agents.

Citation Format: Aleem Gangjee, Farhana Islam, Tasdique Mohammad Quadery, Susan L. Mooberry, Anja Bastian, Michael A. Ihnat. Design, synthesis, and biological evaluation of thieno[2,3-d] and thieno[3,2-d]pyrimidines as dual acting RTK inhibitors and microtubule targeting antitumor agents. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4837.
Abstract 484: Pre-treatment platelet counts as a prognostic factor in stage II and III rectal adenocarcinoma
Authors: Voutsadakis Ioannis , Steele Morgan
Published: July 2016

Background. Thrombocytosis is often associated with malignancies and has been confirmed as an adverse prognostic factor in various cancers. We investigated if pre-treatment elevated platelet counts could provide prognostic information in patients with stage II and III rectal adenocarcinoma that received neo-adjuvant treatment before surgery.

Patients and Methods. Platelet number on diagnosis of stage II and III rectal cancer was evaluated in 51 patients receiving neo-adjuvant treatment and for whom there were complete follow-up data on progression and survival, as well as pathologic outcome at time of surgery. Pathologic response after neo-adjuvant treatment of patients with lower platelet counts (150-300× 109/L) was compared with that of patients with higher platelet counts (>300× 109/L) by the χ2 test. Overall and progression free survival Kaplan-Meier curves of the two groups were constructed and compared with the LogRank test.

Results. A significant difference was present between the two groups in regards to pathologic response with patients with lower platelet counts being more likely to exhibit a good or complete response to neo-adjuvant treatment than patients with higher platelet counts (P = 0.015). There was also a significant difference between the CEA at presentation of patients that exhibited a good or complete response and those that had no response or a minimal to moderate response. Patients with a good or complete response were more likely to present with a CEA of less than 5 (P = 0.00066). There was no significant difference in overall and progression free survival between the two groups (LogRank tests p = 0.42 and p = 0.35, respectively).

Conclusion. In this retrospective analysis of stage II and III rectal cancer patients, platelet counts at the time of diagnosis had prognostic value for neo-adjuvant treatment pathologic effect. Pre-treatment CEA also held prognostic value in regards to treatment effect.

Citation Format: Ioannis Voutsadakis, Morgan Steele. Pre-treatment platelet counts as a prognostic factor in stage II and III rectal adenocarcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 484.
Abstract 4840: The role of the metal scaffold in the development of cytotoxic metal complexes
Authors: Glazer Edith C.
Published: July 2016

Multiple cytotoxic metal compounds are known, but structure activity relationships can be difficult to determine in these complex molecules. It is tempting to generalize the activity or off-target effects of the compounds to being related to the identity of the metal, or alternatively, to some specific “active” ligand features, but this is a misleading oversimplification that can slow the development of new therapeutics. In this presentation a systematic study of the impact of the metal center, one specific “active” ligand, and the inactive “coligands” that create the metal scaffold will be presented. There is clear evidence that each component plays a role in both desired and potentially deleterious off-target activities, providing the opportunity to adjust each of these three components independently to generate optimized potential anti-cancer agents.

Citation Format: Edith C. Glazer. The role of the metal scaffold in the development of cytotoxic metal complexes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4840.
Abstract 4847: Discovery, semisynthesis, and structure-activity relationship studies of hirsutinolide derivatives as new STAT3 inhibitors and anti-glioma agents
Authors: Zhang Mingming , Youn Ui Joung , Miklossy Gabriella , Wongwiwatthananukit Supakit , Turkson James , Chang Leng Chee , Sun Dianqing
Published: July 2016

Clinically, natural product has played a pivotal role in anticancer drug discovery and development. Cancer chemotherapy and/or radiotherapy due to glioma treatment are not ideal, frequently cause unwanted adverse effects, and justify further research and development of alternative, novel, safe, and effective agents. In our continued efforts to identify new signal transducer and activator of transcription 3 (STAT3) and antiglioma agents with enhanced efficacy and specificity, we have initiated a collaborative and multidisciplinary natural product drug discovery project and the goal was to isolate, semisynthesize, and evaluate the potential of Vernonia cinerea-derived phytochemicals as STAT3 inhibitors with therapeutic remedy of human glioma and may be even more effective than the existing ones. To date, our preliminary studies have been conducted and resulted in the discovery of a class of sesquiterpene lactone hirsutinolide series with an á,â-unsaturated-ã-lactone ring as new STAT3 inhibitors. Specifically, on the basis of encouraging biological data and to expand the existing structure activity relationship (SAR) of isolated natural hirsutinolide analogues, chemical modifications were performed using conventional Steglich esterification protocol to produce a series of semisynthetic hirsutinolide derivatives in moderate to high yields. Thus far, biological evaluation revealed that several semisynthetic analogues showed low micromolar inhibitory activities against constitutively-active STAT3 and malignant glioma phenotype. SAR showed that a bulky and lipophilic ester functionality at position 13 is essential for STAT3 inhibition as well as whole cell based anticancer activity. A lipophilic side chain at position 8 also plays an important role in anticancer activity and may contribute a detrimental effect on specificity. In addition, the methoxy group at position 1 enhances the cell-type specificity and selectivity. Finally, selected promising lead candidates also demonstrated in vivo efficacy following oral gavage delivery, inhibiting human glioma tumor growth in subcutaneous mouse xenografts. Together, natural and chemically modified hirsutinolide-type sesquiterpene lactones represent a promising natural product class of new anticancer agents for the treatment of malignant human glioma.

Citation Format: Mingming Zhang, Ui Joung Youn, Gabriella Miklossy, Supakit Wongwiwatthananukit, James Turkson, Leng Chee Chang, Dianqing Sun. Discovery, semisynthesis, and structure-activity relationship studies of hirsutinolide derivatives as new STAT3 inhibitors and anti-glioma agents. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4847.
Abstract 4851: Second generation 2,3-dihydroimidazo[1,2-c]quinazoline PI3K inhibitors: development of BAY 1082439, a novel balanced PI3Ká / PI3Kâ inhibitor
Authors: Scott William J. , Liu Ningshu , Hägebarth Andreas , Möwes Manfred , Mönning Ursula , Bömer Ulf , Mumberg Dominik , von Nussbaum Franz , Brands Michael , Lafranc Julien
Published: July 2016

The phosphoinositide-3 kinase (PI3K) pathway plays critical roles in cancer cell growth and survival, as well as in intrinsic and acquired resistance to both chemotherapy and targeted agents. These essential roles of PI3K in human cancer have led to the clinical development of PI3K pathway inhibitors. Due to the complexity derived from the existence of various PI3K isoforms (á, ß, ã, ∂), and their differential roles in signal transduction as well as cancer pathology, investigation of PI3K inhibitors with differential isoform activity profiles would allow potential use in novel indications. Mutation or amplification of PIK3CA and/or activation of PI3Ká (e.g., through oncogenic RTKs) are found frequently in a variety of cancers, making this isoform a prime target for anti-cancer therapy. In addition, the role of PI3Kß in PTEN-deficient tumors, as well as in acquired resistance to PI3Ká, has been described. This led to the hypothesis that development of a dual PI3Ká / PI3Kß inhibitor might provide a unique efficacy profile.

The discovery of a novel class of 2,3-dihydroimidazo[1,2]quinazoline PI3K inhibitors, and its optimization to afford the i.v. PI3Ká/∂ inhibitor copanlisib (IC50 ratio of 1:7 in biochemical assays of PI3Ká vs. PI3Kß) has been reported recently. Herein is described the structure-activity relationship (SAR) leading to potent oral 2,3-dihydroimidazo[1,2]quinazoline PI3K inhibitors with balanced PI3Ká and PI3Kß activity, and to the selection of BAY 1082439, as a clinical candidate.

BAY 1082439 has an IC50 ratio of 1:3 in biochemical assays of PI3Ká (4.9 nM) vs. PI3Kâ (15.0 nM). In addition, BAY 1082439 has unique pharmacokinetic (PK) properties with very high plasma free fractions across all species tested (33-50%), large Vss, high clearance and intermediate T1/2. Thus, BAY 1082439 represents a PI3K inhibitor with a novel pharmacological profile, warranting exploration in clinical development. BAY 1082439 is currently being studied in a phase I trial for subjects with advanced malignancies (NCT01728311).

Citation Format: William J. Scott, Ningshu Liu, Andreas Hägebarth, Manfred Möwes, Ursula Mönning, Ulf Bömer, Dominik Mumberg, Franz von Nussbaum, Michael Brands, Julien Lafranc. Second generation 2,3-dihydroimidazo[1,2-c]quinazoline PI3K inhibitors: development of BAY 1082439, a novel balanced PI3Ká / PI3Kâ inhibitor. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4851.
Abstract 4858: LADR™: A novel linker activated drug release technology for drug delivery
Authors: Abu Ajaj Khalid , Koester Stephan David , Nollmann Friederike Inga , Waltzer Simon , Fuchs Olga , Warnecke André , Kratz Felix
Published: July 2016

Drug delivery systems in oncology for treating cancer are based on different drug release mechanisms at the tumor site including primarily hydrolytic, reductive, enzymatic and/or acid-sensitive cleavage. Drug carrier conjugates that incorporate an acid-sensitive breaking-point exploit the extra- and intracellular acidic environment of the tumor. Important requirements for acid-sensitive bonds are high stability of the carrier-bound drug in the blood circulation and an effective or sustained release of the active drug in the acidic tumor interstitium and acidic endosomes/lysosomes of tumor cells. In addition, sufficient stability of the acid-sensitive bond is a prerequisite for galenic formulation and reconstitution. As a continuation of our development of aldoxorubicin, an acid-sensitive albumin-binding drug of doxorubicin, which is being clinically assessed in advanced clinical trials (www.cytrx.com), we have set out to design a novel acid-sensitive drug release platform that is applicable to carriers such as serum proteins and antibodies.

The key components of this specific drug delivery system are linkers containing a thiol-binding maleimide group and a substituted aromatic hydrazine to form an acid-cleavable hydrazone bond with suitable carbonyl-containing drugs. For establishing and fine-tuning the pH-dependent release profiles, the aromatic moiety of the linker was substituted with a spectrum of electron-withdrawing groups, and reacted with the anthracyclines doxorubicin and nemorubicin. The resulting hydrazone derivatives were conjugated to the cysteine-34 position of albumin as a model protein. Subsequently, the drug release was determined at physiological and acidic conditions as well as in human plasma. It was discovered that by variation of the electron-withdrawing groups, the pH dependent release of the drug could be substantially varied between 1-50 h in the pH range of 4-5. The technology using these linkers was coined LADR™ (Linker Activated Drug Release) and has the additional advantage that the galenic formulation and reconstitution of LADR™-based drugs is facilitated. We have applied the LADR™ technology to several anticancer drugs such as vinblastine and gemcitabine. In summary, LADR™ is an innovative and versatile linker technology creating a platform for developing acid-sensitive drug carrier conjugates that allow the carrier-bound drug to be released in a controlled manner resulting in sustained exposure to cancer cells.

Citation Format: Khalid Abu Ajaj, Stephan David Koester, Friederike Inga Nollmann, Simon Waltzer, Olga Fuchs, André Warnecke, Felix Kratz. LADR™: A novel linker activated drug release technology for drug delivery. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4858.
Abstract 4860: The BTK inhibitor ibrutinib modulates T cell immunity in mouse models and in differentiated human T cells
Authors: Huang Yujun , Hsu Jeff , Sirisawad Mint , Kuo Hsu-Ping , Chang Betty Y.
Published: July 2016

Ibrutinib inhibits Bruton's tyrosine kinase (BTK) and effectively treats B-cell malignancies. Ibrutinib also targets IL-2-inducible T-cell kinase (ITK) and modulates the T-cell receptor signaling pathway. Because ibrutinib enhanced antitumor immunity when combined with anti-PD-L1 in various syngeneic solid tumor and lymphoma models (Sajiv-Barfi, PNAS 2015), we sought to determine the effect of ibrutinib on T-cell function and activation. Using in vitro human primary T-cell activation assays, we found that ibrutinib did not suppress T-cell proliferation but slightly inhibited IFNã production in CD4 and CD8 effector T cells when human peripheral blood mononuclear cells (PBMCs) were stimulated with anti-CD3 and anti-CD28 antibodies. Ibrutinib also inhibited PD-1 expression on human CD8 effector T cells. More strikingly, ibrutinib significantly suppressed naïve murine CD4 T-cell differentiation in vitro into Foxp3+ regulatory T cells (Treg) in the presence of TGF-â. Further, we evaluated the immunomodulatory effect of ibrutinib in tumor-bearing mice. In pancreatic (Pan02) and renal cell carcinoma (Renca) models, we found that single-agent ibrutinib, as well as in combination with standard-of-care agents, effectively inhibited tumor growth. In the syngeneic Renca tumor model, combination ibrutinib treatment significantly reduced CD4+Foxp3+ Treg cells both in the spleen (P < 0.001) and tumor microenvironment (P < 0.05), compared with everolimus alone. Ibrutinib also significantly reduced the percentage of PD-1hi cells among CD8 tumor-infiltrating lymphocytes in A20 lymphoma-bearing mice (P < 0.05). These data demonstrate that ibrutinib, a BTK inhibitor, can suppress immune-inhibitory factors and enhance antitumor immunity in vivo. Ibrutinib may serve as a promising immunomodulatory agent in potentiating current cancer immunotherapy in solid tumors.

Citation Format: Yujun Huang, Jeff Hsu, Mint Sirisawad, Hsu-Ping Kuo, Betty Y. Chang. The BTK inhibitor ibrutinib modulates T cell immunity in mouse models and in differentiated human T cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4860.
Abstract 4866: Development and characterization of novel CD40 antibody agonists for cancer immunotherapy
Authors: Vitale Laura A. , O’Neill Thomas , Widger Jenifer , Crocker Andrea , He Li-Zhen , Weidlick Jeffrey , Sundarapandiyan Karuna , Storey James , Thomas Lawrence , Goldstein Joel , Marsh Henry C. , Keler Tibor
Published: July 2016

CD40 is a key molecule in the regulation of immune responses and its activity can be modulated using antibodies. In particular, agonist CD40 antibodies are highly effective in preclinical tumor models either through direct interaction with CD40-expressing lymphomas, or indirectly through the activation of an adaptive anti-tumor immune response. To date, limited clinical data have been reported with strong CD40 agonist antibodies; nonetheless it seems likely that targeting this pathway will require a balance between the benefits of immune stimulation to drive anti-tumor responses, and the damage that can result from non-specific immune cell activation. We set out to develop novel human anti-CD40 antibodies with different levels of agonist activity to identify a lead candidate for systemic application.

Anti-CD40 monoclonal antibodies (mAbs) were generated by immunization of human Ig transgenic mice with recombinant and cell surface expressed human CD40. Hybridomas developed from these mice were screened using CD40 binding assays and activity on a reporter cell line engineered to express CD40 and NFêB-responsive luciferase. The variable regions of lead antibodies that displayed differential activity were cloned into vectors containing human IgG1 or IgG2 constant domains and expressed in CHO cells.

These human CD40 mAbs were further characterized by analysis of binding affinity, CD40L blocking activity, B cell and dendritic cell activation, and anti-tumor activity in xenograft tumor models. We found a wide range of activities among the CD40 mAbs that is linked to epitope specificity as well as the isotype. In general, the IgG2 isotype mAbs had greater signaling activity than their IgG1 counterparts. The lead candidate mAbs are undergoing additional testing related to functional and toxicity parameters before a final candidate is nominated for clinical development.

Citation Format: Laura A. Vitale, Thomas O’Neill, Jenifer Widger, Andrea Crocker, Li-Zhen He, Jeffrey Weidlick, Karuna Sundarapandiyan, James Storey, Lawrence Thomas, Joel Goldstein, Henry C. Marsh, Tibor Keler. Development and characterization of novel CD40 antibody agonists for cancer immunotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4866.