bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2593: Combination therapy with EGFR-TKI and cMET-TKIs in non-small cell lung cancer: the golden duo
Authors: Van Der Steen Nele , Deschoolmeester Vanessa , Wouters An , Lardon Filip , Rolfo Christian , Pauwels Patrick
Published: August 2015

Intro: The use of targeted therapies confers great responses in non-small cell lung cancer patients, but ultimately results in acquired resistance, e.g. against epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) due to cMET amplification. Therefore, combination therapy with EGFR-TKI and cMET TKIs in cell lines with a different EGFR and cMET background was investigated.

Materials & methods: All experiments were performed in 5 cell lines with a different EGFR and cMET background: the cMET amplified squamous lung cancer cell line EBC-1, the HGF-secreting myeloma cell line JJN3, the HCC827 and H1975 lung adenocarcinoma cell lines with an activating EGFR exon 19 deletion and an L858 as well as a T790M resistance mutation, respectively. Finally LUDLU-1 is a squamous lung cancer cell line, wild-type for both EGFR and cMET.

The cytotoxicity of combination therapy with erlotinib (EGFR-TKI) and crizotinib (cMET-ALK-ROS1-TKI) or PHA665752 (cMET-TKI) was determined by the sulforhodamine B assay after 72h of simultaneous/sequential treatment (Table 1).

Results: For all treatments, the JJN3, EBC-1 and HCC827 cell lines showed no synergistic effect. For the H1975, a decrease in resistance could be observed, albeit not significant. For LUDLU-1, a trend towards synergism was observed when erlotinib was administered simultaneously with crizotinib (p = 0.074) and PHA665752 (p = 0.055). Also a significantly synergistic effect was observed when treatment with erlotinib was followed by PHA665752 (p = 0.014).

Discussion: Synergism between erlotinib and crizotinib/PHA665752 depends on the genetic background of the cells and the treatment schedule. This was most pronounced in the EGFR and cMET wild-type cell line. These results open up the discussion to include EGFR and cMET wild-type patients into future clinical trials.

Cell lineErlotinib (μM)Crizotinib (μM)PHA665752 (μM)Erlo+CrizErlo = >CrizCriz = >ErloErlo+PHAErlo = >PHAPHA = >ErloEBC-10-100-0.025-0.050-0.1-0.150-0.025-0.050-0.1-0.20-0.3-0.40-0.1-0.2JJN30-100-2-30-2-30-2-30-5-70-5-70-5-6HCC8270-50-3-50-3-50-1-20-7-90-7-90-4-5H19750-100-2-30-2-30-1-20-6-70-6-70-2-3LUDLU-10-100-3-50-3-50-2-30-7-80-7-80-3.5-4

Table 1: Therapeutic concentrations per cell line & treatment schedule: control-IC20-IC40.

Citation Format: Nele Van Der Steen, Vanessa Deschoolmeester, An Wouters, Filip Lardon, Christian Rolfo, Patrick Pauwels. Combination therapy with EGFR-TKI and cMET-TKIs in non-small cell lung cancer: the golden duo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2593. doi:10.1158/1538-7445.AM2015-2593
Abstract 2595: Efficacy of cetuximab and mutant selective EGFR inhibitor WZ4002 in EGFR T790M and non-T790M models of erlotinib resistant non-small cell lung cancer
Authors: Tricker Erin M. , Xu Chunxiao , Wong Kwok-Kin , Janne Pasi A.
Published: August 2015

Background: EGFR kinase inhibitors, including erlotinib, are effective treatments for patients with EGFR mutant lung cancer. However, resistance inevitably develops, most commonly (60%) mediated by an EGFR secondary mutation EGFR T790M. Mutant selective EGFR inhibitors (WZ4002, AZD9291, CO-1686) are effective in preclinical models and clinically (AZD9291 & CO-1686) in EGFR T790M patients (response rates (RR) > 50%) but are less effective in patients with non-T790M mediated drug resistance (AZD9291 RR ∼10%). Combination of afatinib and cetuximab is effective in both T790M (32% RR) and non-T790M (25% RR) mediated resistance but is associated with significant toxicity. We evaluated whether cetuximab could add to the efficacy of a mutant selective EGFR inhibitor and whether the combination was also effective in a model of non-T790M mediated resistance.

Methods: Mice harboring xenografts from PC9GR (EGFR Del 19/T790M), H1975 (EGFR L858R/T790M), HCC827GR (EGFR Del 19/MET amplification) cells or genetically engineered mouse models (GEMMS) expressing EGFR L858R/T790M were treated with vehicle, WZ4002 alone, cetuximab alone or the combination. We compared the efficacy of the treatments and evaluated for tumor cures (defined as tumor disappearance and lack of regrowth following 6 weeks of drug withdrawal). In addition, we evaluated the impact of the treatments on EGFR signaling and apoptosis.

Results: In the EGFR T790M xenograft models (PC9GR and H1975), the combination of WZ4002 and cetuximab was more effective than either single agent. Only the combination led to tumor cures (5/15 in PC9GR and 3/18 in H1975) while none were observed with the single agents. In the HCC827GR xenografts, the combination of WZ4002/cetuximab was more effective than the single agents but did not lead to any cures. Evaluation of the tumors from treated mice revealed that the efficacy of the combination correlates with effective degradation of EGFR and MET (in HCC827GR). In the L858R/T790M GEMMs, the combination led to significantly greater tumor shrinkage compared to single agents. Evaluation of treated tumors revealed enhanced apoptosis in the combination treated mice.

Conclusions: The addition of cetuximab enhances the efficacy of the mutant selective EGFR inhibitor WZ4002 in vivo by increasing the single agent efficacy in both EGFR T790M and non-T790M models. Clinical trials of mutant selective EGFR inhibitors and cetuximab are warranted.

Citation Format: Erin M. Tricker, Chunxiao Xu, Kwok-Kin Wong, Pasi A. Janne. Efficacy of cetuximab and mutant selective EGFR inhibitor WZ4002 in EGFR T790M and non-T790M models of erlotinib resistant non-small cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2595. doi:10.1158/1538-7445.AM2015-2595
Abstract 2603: Combination activity of the MEK inhibitor Pimasertib and the hypoxia-activated prodrug TH-302 in pancreatic and biliary tract tumor xenograft models
Authors: Ma Jianguo , Syed Sakeena , Crowley Lindsey , Shaw Jamie , Ogden Janet , Elenbaas Brian , Goodstal Samantha
Published: August 2015

The efficacy and tolerability of the MEK inhibitor Pimasertib and the hypoxia-activated prodrug TH-302 combination were explored in pancreatic and biliary tract preclinical tumor xenograft models. These studies were based on the hypotheses that combination efficacy may occur by several possible mechanisms including inhibition of DNA repair or increase of hypoxia by Pimasertib, or by differential targeting of the oxic and hypoxic tumor compartments by Pimasertib and TH-302 respectively. Since Pimasertib and TH-302 had each been tested in separate clinical trials in pancreatic cancer with gemcitabine (NCT01016483 and NCT01144455 respectively), these data could provide the rationale for clinical testing of this novel combination in pancreatic cancer. The combination was also tested in biliary tract cancer models (cholangiocarcinoma and gall bladder) based on the reported sensitivity of these tumor types to MEK inhibitors, their hypoxic nature, and the prevalence and high unmet need of these indications, particularly in Asia. The results showed that in the MIA PaCa-2 human pancreatic xenograft model, combination efficacy was observed and found to be schedule dependent. The greatest combination efficacy occurred when Pimasertib was administered first, 2 hours prior to TH-302, suggesting a unique combination mechanism in cells when the MAPK signaling pathway is suppressed first. The combination was subsequently explored in 2 additional pancreatic models and a panel of biliary tract patient-derived xenograft (PDX) models. In 10 cholangiocarcinoma PDX models tested, 3 models were responders to Pimasertib monotherapy and 4 models converted from being a non-responder with either monotherapy to a responder with the Pimasertib TH-302 combination using the%TV (tumor volume) criteria, which is related to a clinical PR RECIST response. Combination effects were not observed in 2 additional pancreatic or 6 gall bladder models tested. Some models were highly sensitive to Pimasertib or TH-302 monotherapy, making combination effects difficult to observe. Biomarker analyses are ongoing to identify markers that could predict which tumors are the most sensitive to this combination therapy.

Citation Format: Jianguo Ma, Sakeena Syed, Lindsey Crowley, Jamie Shaw, Janet Ogden, Brian Elenbaas, Samantha Goodstal. Combination activity of the MEK inhibitor Pimasertib and the hypoxia-activated prodrug TH-302 in pancreatic and biliary tract tumor xenograft models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2603. doi:10.1158/1538-7445.AM2015-2603
Abstract 2610: Identifying a lead compound for mitigation of drug-induced PQTS
Authors: Helson Lawrence , Shaw Walter A. , Burgess Stephen W. , Shopp George , Bouchard Annie , Savail Dany , Majeed Muhammed
Published: August 2015

In addition to 170 approved therapeutic drugs whose adverse effects include QT prolongation, a prevalence of 1:2500 subjects in the US are genetically susceptible, or have a diabetic syndrome with increased risk of QT prolongation, torsade de pointes, and sudden death. To address this risk we determined the mitigating effect of a liposome and its components administered intravenously and orally on clinically approved QT-prolonging anticancer drugs, crizotinib and nilotinib, and an antibiotic moxifloxacin (MF) in vitro and in vivo in rats and guinea pigs. Intravenous MF at 20 mg/kg caused a statistically significant QTc prolongation of 35ms in guinea pigs. This observation is in line with peer-reviewed literature in which an oral dose of 400 mg (or approximately 6.1 mg/kg) in humans caused the FDA to black-label MF for causing QT interval prolongation in patients.

The mitigating effect of a liposome consisting of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylglycerol (DMPG) on curcumin, a compound that inhibits the IKr (hERG) current, was initially discovered during preclinical testing with Lipocurc™. Additional patch-clamp studies with DMPC, DMPG, their metabolites myristoyl lysophosphatidylcholine (14:0 LPC) and myristoyl lysophosphatidylglycerol (14:0 LPG), and a synthetic compound, myristoyl ethyleneglycolphosphatidylglycerol (EGPG), revealed mitigation of crizotinib- and nilotinib-induced inhibition of the IKr current. Formulation of 14:0 LPG in a eutectic mixture with a monoglyceride and myristic acid (EU8120) given orally to both normal and diabetic rats prior to challenge with intravenous nilotinib resulted in significantly reduced QT prolongation.

We quantified and compared the conduction delays on QT intervals in guinea pigs induced by MF alone with those of MF preceded by oral administration of EU8120, 14:0 LPG, 16:0 LPG, EGPG and DMPG. Three ratios of phospholipids:MF were tested for mitigation of conduction delays: 3:1, 1:1 and 0.3:1. At the 3:1 ratio, all the compounds tested mitigated MF-induced prolongation of QT intervals. While EGPG induced the most protection it caused bradycardia which limited its beneficial effects at that dose level. DMPG was the least potent. At lower ratios of 1:1 and 0.3:1 the mitigating effects of EU8120, EGPG and DMPG were maintained with equal potency. Lipid:MF ratios of 0.1:1 and 0.03:1 are currently being tested and will identify a lead compound for drug development, and offer insight into its mechanism of action.

Citation Format: Lawrence Helson, Walter A. Shaw, Stephen W. Burgess, George Shopp, Annie Bouchard, Dany Savail, Muhammed Majeed. Identifying a lead compound for mitigation of drug-induced PQTS. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2610. doi:10.1158/1538-7445.AM2015-2610
Abstract 2613: STAT3 mediates C6-ceramide-induced cell death in chronic lymphocytic leukemia via the MEK/ERK and PKC pathway
Authors: Doshi Ushma Atul , Loughran Thomas P. , Kester Mark
Published: August 2015

Chronic lymphocytic leukemia (CLL) constitutes 70% of adult leukemic cases in the Western world. Despite high incidence, its pathogenesis is still poorly understood and it remains incurable with current therapies. We have previously shown that nanoliposomal C6-ceramide, a liposomal formulation of a ‘tumor suppressor’ lipid, is an effective therapy in several solid and non-solid tumor models. Specifically in CLL, nanoliposomal C6-ceramide selectively induces cell death in leukemic cells by targeting the Warburg effect with no detrimental effects on normal peripheral blood mononuclear cells. Additionally, treatment with nanoliposomal C6-ceramide results in tumor regression in an in vivo murine model of CLL. However, the mechanism and key molecular players mediating C6-ceramide-induced cell death in CLL remains unknown. We hypothesize that STAT3 is a target of C6-ceramide in CLL cells. After validating STAT3 as a as a therapeutic target in CLL, we show that C6-ceramide treatment suppresses the levels of p-STAT3-Y705 and p-STAT3-S727 in both cell lines and patient cells, while having no effect on total STAT3 levels. C6-ceramide treatment also reduces STAT3-dependent expression of survival factors like Mcl-1, XIAP and survivin. Our results suggest that suppression in STAT3 phosphorylation might be critical for cell death induction since it precedes induction of C6-ceramide-mediated cell death in CLL cells. Analysis of the upstream kinases revealed that C6-ceramide-induced suppression of p-STAT3 might be, in part, a consequence of suppression of MEK1/2 kinase and protein kinase C (PKC). Preliminary results also demonstrate that C6-ceramide treatment reduces p-STAT3-S727 in the mitochondrial fraction, which might be critical to the cell death induction since overactivation of mitochondrial p-STAT3-S727 confers viability and stress protection to CLL cells. Ongoing studies will focus on identifying the specific phosphorylation site(s) that mediates cell death in an effort to delineate the molecular mechanism of C6-ceramide-induced cell death in CLL. We would also like to define the molecular link between CNL-induced dephosphorylation of mitochondrial STAT3 and suppression of the Warburg effect in CLL. In conclusion, our data suggests that targeting STAT3 with nanoliposomal C6-ceramide is a potential therapy for CLL. This work is the first body of evidence demonstrating an effect of C6-ceramide on STAT3 phosphorylation.

Citation Format: Ushma Atul Doshi, Thomas P. Loughran, Mark Kester. STAT3 mediates C6-ceramide-induced cell death in chronic lymphocytic leukemia via the MEK/ERK and PKC pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2613. doi:10.1158/1538-7445.AM2015-2613
Abstract 2615: Dual ErbB blockade with KTN3379 and cetuximab yields enhanced antitumor activity by inhibiting parallel signaling pathways in SCCHN
Authors: Alvarado Diego , Seibel Scott B. , Ligon Gwenda F. , Lillquist Jay S. , Pierce Andrew , Gedrich Richard , LaVallee Theresa M.
Published: August 2015

The receptor tyrosine kinase ErbB3/HER3 has been implicated as an oncogenic driver in pre-clinical models of solid tumors, and is the target of several monoclonal antibodies currently in clinical development. In squamous cell carcinoma of the head and neck (SCCHN), ErbB3 activation is regulated by its ligand neuregulin (NRG). Studies, including our own, have reported high NRG expression in a significant subset of SCCHN, providing a scientific rationale for the use of ErbB3 targeted therapies in this disease setting. Here we show that KTN3379, a potent human ErbB3 monoclonal antibody with a dual mechanism of action, demonstrates significant monotherapy activity in NRG expressing xenograft models of SCCHN and enhances cetuximab anti-tumor activity. Using a panel of SCCHN cell lines, we demonstrate that KTN3379 inhibits PI3K/AKT signaling whereas cetuximab chiefly suppresses the ERK pathway, providing an explanation for the increased anti-tumor activity of combining both drugs. Our data also suggest that ErbB3 and EGFR act independently of one another at the receptor level. Interestingly, mRNA analysis of 303 SCCHN human tumor samples shows a strong correlation between NRG expression and the EGFR ligands Amphiregulin (AREG) and TGFα. Moreover, KTN3379 activity correlates with expression of ErbB3, its ligand NRG, and both of these EGFR ligands. Overall, our data support evaluation of the combination of KTN3379 and cetuximab in SCCHN.

Citation Format: Diego Alvarado, Scott B. Seibel, Gwenda F. Ligon, Jay S. Lillquist, Andrew Pierce, Richard Gedrich, Theresa M. LaVallee. Dual ErbB blockade with KTN3379 and cetuximab yields enhanced antitumor activity by inhibiting parallel signaling pathways in SCCHN. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2615. doi:10.1158/1538-7445.AM2015-2615
Abstract 2618: Gemcitabine based peptide conjugates: Overcoming the pitfalls of conventional therapies by targeted approaches
Authors: Tamvakopoulos Constantin , Karampelas Theodoros , Argyros Orestis
Published: August 2015

Although gemcitabine has been proved to be a valuable ally against several types of cancer, it is characterized by some weaknesses that limit its anticancer potential. These limitations are mainly associated with gemcitabine rapid inactivation as well as the different types of resistance that are related with its use. We have previously shown that conjugation of gemcitabine to a ligand peptide (molecule GSG) enhanced its metabolic stability systemically and locally (within the cancer cell), and lead to improved efficacy in a castration resistant prostate cancer (CRPC) animal model.

In order to refine our previous findings, a bioanalytical methodology based on mass spectrometry that allows the simultaneous monitoring of gemcitabine as well as its active (dFdCDP, dFdCTP) and inactive (dFdU) metabolites was developed in the context of this study. The balance of gemcitabine and its active/inactive metabolites was evaluated in in vitro and in vivo systems after treatment with gemcitabine or selected gemcitabine based peptide conjugates (GSG). Furthermore, since GSG's structure contains a potent agonist peptide of the GnRH-R we investigated whether it could have a central effect through the pituitary by performing testosterone measurements in animals dosed with GSG.

Interestingly, GSG appears to offer metabolic advantages in comparison to gemcitabine, an important attribute if we had to overcome gemcitabine acquired resistance. In addition, GSG is a potent GnRH-R agonist based on our in vivo biomarker model, suggesting that testosterone ablation might also represent a key attribute of the mechanism of action for our conjugate of interest.

These findings along with the targeted delivery nature of this approach could ameliorate the therapeutic status of gemcitabine and expand the use of gemcitabine based conjugates in other types of cancers.

Citation Format: Constantin Tamvakopoulos, Theodoros Karampelas, Orestis Argyros. Gemcitabine based peptide conjugates: Overcoming the pitfalls of conventional therapies by targeted approaches. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2618. doi:10.1158/1538-7445.AM2015-2618
Abstract 262: Inhibition of the novel immune checkpoint CEACAM1 enhances antitumor immunological activity
Authors: Markel Gal , Mandel Ilana , Sapir Yair , Hakim Motti , Hashmueli Sharon , Ben-Moshe Tehila
Published: August 2015

Blockade of co-inhibitory immune receptors has become a promising approach for the activation of anti-tumor immunity. CEACAM1, a recently characterized immune checkpoint, is a member of the Ig superfamily expressed by activated effector lymphocytes and cancer cells. Expression of CEACAM1 on cancer cells induces a co-inhibitory signal to T and NK cells through homophilic CEACAM1 interactions. CEACAM1 is expressed across multiple tumor types and its presence is independent of PD-L1 expression.

CM-24 is a humanized anti-CEACAM1 IgG4 antibody with high affinity and selectivity for CEACAM1. We investigated the activity of CM-24 and its ability to reverse CEACAM1-induced immune evasion alone and in combination with other checkpoint inhibitors. CM-24 was demonstrated to be a potent blocker of intercellular CEACAM1-CEACAM1 interactions and reversed inhibition of activated lymphocytes by restoring the phosphorylation signal of ZAP70. CM-24 enhanced the cytotoxic activity of cytotoxic T cell and NK cells against various cancer types, which was accompanied by higher secretion of Granzyme B and IFNγ. In addition, a synergistic activity with various immune checkpoint blockers was observed, including ones that target the PD-1 pathway. Various in vivo tumor xenograft models demonstrated that CM-24 has clear anti-tumor activity accompanied by an increase in immunological activity of T cells within the tumor. Collectively, preclinical data show that CM-24 has effective anti-tumor activity in various in vitro and in vivo models and demonstrate that CM-24 has the potential to enhance the cytotoxic activity of lymphocytes against malignant cells. CM-24 is now moving towards phase 1 clinical study.

Citation Format: Gal Markel, Ilana Mandel, Yair Sapir, Motti Hakim, Sharon Hashmueli, Tehila Ben-Moshe. Inhibition of the novel immune checkpoint CEACAM1 enhances antitumor immunological activity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 262. doi:10.1158/1538-7445.AM2015-262
Abstract 2620: Plumbagin induces growth inhibition of human glioma cells by downregulating the expression and activity of FOXM1
Authors: Liu Xuejiao , Cai Wei , Niu Mingshan , Yu Rutong
Published: August 2015

Plumbagin, a natural quinonoid constituent isolated from the root of medicinal plant Plumbago zeylanica L, has exhibited anti-tumor and anti-proliferative activities in various tumor cell lines as well as in animal tumor models. However, its anticancer effects and the mechanisms underlying its suppression of glioma cell growth have not been elucidated. Oncogenic transcription factor Forkhead Box M1 (FOXM1) has garnered particular interest in recent years as a potential target for the prevention and/or therapeutic intervention in glioma, nevertheless, less information is currently available regarding FOXM1 inhibitor. Here, we reported that plumbagin could effectively inhibit cell proliferation, migration and invasion and induce apoptosis of glioma cells. Cell cycle assay showed that plumbagin induced G2/M arrest. Interestingly, we found that plumbagin decreased the expression of FOXM1 both at mRNA level and protein level. Plumbagin also inhibited the transactivation ability of FOXM1, resulting in down-regulating the expression of FOXM1 downstream target genes, such as cyclin D1, Cdc25B, survivin, and increasing the expression of p21CIP1 and p27KIP1. Most importantly, down-regulation of FOXM1 by siFOXM1 transfection enhanced plumbagin-induced change in viability. On the contrary, over-expression of FOXM1 by cDNA transfection reduced plumbagin-induced glioma cell growth inhibition. Further investigation revealed that plumbagin inhibition of glioma cell growth was also evident in a nude mouse model. Taken together, these results suggest that plumbagin exhibits its anticancer activity partially by inactivation of FOXM1 signaling pathway in glioma cells. Our findings indicate that plumbagin may be considered as a potential natural FOXM1 inhibitor, which could contribute to the development of new anticancer agent for therapy of gliomas.

Citation Format: Xuejiao Liu, Wei Cai, Mingshan Niu, Rutong Yu. Plumbagin induces growth inhibition of human glioma cells by downregulating the expression and activity of FOXM1. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2620. doi:10.1158/1538-7445.AM2015-2620
Abstract 2630: Inhibition of angiogenesis contributes to enhanced radiation response in tumors following MDM2 inhibition by AMG 232
Authors: Werner Lauryn R. , Huang Shyhmin , Armstrong Eric A. , Ma Fang , Canon Jude , Harari Paul M.
Published: August 2015

MDM2-p53 interaction and downstream signaling impacts cellular response to DNA damage. AMG 232 is a potent small molecule inhibitor that blocks the interaction of MDM2 and p53. We previously elucidated the capacity of AMG 232 to augment radiation response across a spectrum of human tumor cell lines and xenografts. In the current study, we examine the capacity of AMG 232 to inhibit angiogenesis and assess the resultant impact on AMG 232-induced radiosensitivity.

We first examined the impact of AMG 232 on the growth and radiosensitivity of human umbilical vein endothelial (HUVEC) and dermal lymphatic endothelial cells (HDLEC). We found that AMG 232 inhibited the proliferation of both endothelial cell types in a dose dependent manner. Importantly, treatment with AMG 232 significantly reduced angiogenesis-related tube formation in both endothelial cell types. Using clonogenic survival analysis, we identified that treatment with AMG 232 significantly enhanced radiosensitivity. Immunoblot analysis showed that combined treatment with AMG 232 and radiation resulted in a profound impact on molecules involved in cell cycle progression, DNA damage repair, and apoptosis signaling, including FoxM1, ATM/ATR, CHK2, Rad51, and Bax. Flow cytometric analysis also showed a significant cell cycle arrest in G2/M phase with an increase of DNA damage related γH2AX level at 48 hrs following radiation and AMG 232 treatment. In H460 and SJSA-1 tumor xenografts, we found a markedly increased antitumor capacity of AMG 232 when combined with radiation. Immunohistochemical analysis revealed a significant reduction of cellular proliferation and vascular density in both tumor types following combined treatment of AMG 232 and radiation. Taken together, these findings reveal the potential anti-angiogenic capacity of AMG 232 that may contribute to augmentation of radiation response previously observed in tumor xenograft studies. A detailed investigation is in progress to examine changes in the tumor microenvironment following AMG 232 and radiation treatment, including hypoxia and vascular normalization, to assess their respective impact on tumor response to radiation.

Citation Format: Lauryn R. Werner, Shyhmin Huang, Eric A. Armstrong, Fang Ma, Jude Canon, Paul M. Harari. Inhibition of angiogenesis contributes to enhanced radiation response in tumors following MDM2 inhibition by AMG 232. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2630. doi:10.1158/1538-7445.AM2015-2630
Abstract 2632: The COX inhibitor, diclofenac induces mantle cell lymphoma apoptosis independent of p53 status
Authors: Hassan Hesham M. , Varney Michelle L. , Aly Aalia M. , Joshi Shantaram S. , Singh Rakesh K. , Dave Bhavana J.
Published: August 2015

Mantle cell lymphoma (MCL) is characterized by a clinically aggressive course with frequent relapses and poor survival. The p53 pathway is frequently dysregulated and p53 status predicts clinical outcome in MCL. Diclofenac has been reported to increase p53 pathway activity, upregulates p73 expression and inhibit cell growth; hence we investigated the ability of diclofenac to induce apoptosis and/or cell cycle arrest in MCL, and its dependence on p53 status. To investigate the response of MCL to diclofenac, wild-type p53 [Granta-519 and JVM-2] and mutant p53 [Jeko-1 and Mino-1] expressing cells, therapy resistant cell lines and primary human cells isolated from MCL patients were used. Cell proliferation, apopotosis, and expression of down-stream signaling p53 targets were analyzed. Nontoxic concentrations of diclofenac induced concentration- and duration-dependent inhibition of MCL cell growth independent of p53 status. Diclofenac treatment also resulted in cell cycle arrest and cell death. Molecularly, diclofenac treatment was associated with increased activity of caspases 3, 7, and 8. Increased p53 pathway activity was demonstrated by duration-dependent induction of p53 transcriptional target genes, including the cell cycle regulatory molecule p21 and pro-apoptotic molecules including, PUMA, NOXA, BIM, and CD95. Most importantly, diclofenac treatment was associated with enhanced expression of the pro-apoptotic isoforms of the p53 homologue TAp73. Our data demonstrates that diclofenac treatment results in decreased cell cycle progression, and increased apoptosis that is associated with increased p53 pathway activity, independent of p53 status, and increased activity of its family member p73.

Citation Format: Hesham M. Hassan, Michelle L. Varney, Aalia M. Aly, Shantaram S. Joshi, Rakesh K. Singh, Bhavana J. Dave. The COX inhibitor, diclofenac induces mantle cell lymphoma apoptosis independent of p53 status. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2632. doi:10.1158/1538-7445.AM2015-2632
Abstract 2636: Myc vs. Akt therapy in RapidCap, a GEM model for metastatic prostate cancer
Authors: Stahlhut Carlos E. , Watrud Kaitlin E. , Ambrico Alexandra J. , Cho Hyejin , Wang Lily , Qi Jun , Cantley Lewis C. , Bradner James , Trotman Lloyd C.
Published: August 2015

Metastasis is a major driver of mortality and morbidity in prostate cancer, the most common cancer type in men and the second leading cause of cancer-related deaths in the western world. To recapitulate the process in genetically engineered mice, we have developed the RapidCaP system, which uses prostate-directed viral infection to trigger focal loss of Pten and Trp53. The system provides a powerful platform for identification and validation of candidate driver genes and for efficient testing of novel therapeutics. Using this approach, we have recently identified Myc as a critical, spontaneously activated driver in Pten-negative metastatic prostate cancer. In agreement, our previous trials indicated that the Myc-suppressing Brd4 inhibitor JQ1 is ineffective towards primary disease, but causes metastatic regression. Mechanistically, this specificity correlates with the switch from Akt-driven primary to Myc-driven metastatic disease.

Intriguingly, however, advanced metastases in RapidCaP do not express the androgen receptor, in spite of being of epithelial origin as shown by the Nkx3.1 prostate marker. As a consequence, metastatic disease often shows little to no response to castration therapy and invariably results in lethal disease. Therefore, we will discuss how, when and why targeting of Myc using JQ1 and the PI 3-Kinase pathway using NVP-BKM120 are best used to treat naïve or castration-resistant metastatic disease.

Citation Format: Carlos E. Stahlhut, Kaitlin E. Watrud, Alexandra J. Ambrico, Hyejin Cho, Lily Wang, Jun Qi, Lewis C. Cantley, James Bradner, Lloyd C. Trotman. Myc vs. Akt therapy in RapidCap, a GEM model for metastatic prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2636. doi:10.1158/1538-7445.AM2015-2636
Abstract 2643: Small molecule identification for the restoration of p53 pathway through p73 and by degradation of mutant p53
Authors: Hernandez Borrero Liz J. , Zhao Shengliang , Dicker David T. , El-Deiry Wafik
Published: August 2015

One of the most explored cancer targets has been the tumor suppressor p53. p53 is mutated in more than half of all human tumors and therefore provides an attractive way to selectively target cancer cells that harbor the mutant protein. Mutant p53 protein can acquire a gain-of-function activity, losing its normal tumor suppressor properties and gaining oncogenic characteristics. Various approaches have been taken to restore the p53 pathway in mutant p53 expressing cells including the modulation of mutant p53 conformation to wild-type, and through the upregulation of p53 family members i.e. p73. Unlike p53, p73 is not commonly mutated in cancer cells and thus confers restoration of the p53 pathway through pharmacological stimulation. We characterized a small molecule that restores the p53 pathway through p73. A high-throughput cell-based screen identified small molecule CB002 as a potential candidate for the restoration of the p53 pathway in mutant p53 containing human colorectal cancer cells. Two colorectal cancer cell lines: SW480, DLD-1, and the RXF393 renal cancer cell line, were treated with different concentrations of CB002 for various time points. SW480 cells treated with CB002 for 8 hrs showed a decrease in p53 followed by an increase in DR5 expression at 16 hrs. DLD-1 cells treated with CB002 showed a decrease in p53 expression at 8 hrs. Although no change was observed in proteins involved in cell cycle arrest or cell death that were tested, colony formation was suppressed as compared to control. RXF393 cells treated with CB002 for 48 hrs showed decreased expression of p53 levels and increased levels of p21. These data suggest that CB002 is able to decrease mutant p53 protein expression, increase p53 target genes and promote expression of proteins involved in apoptosis, such as p21 and DR5, respectively. It appears that the CB002 mechanism is different depending on the cell line tested. We hypothesize that CB002 is capable of degrading mutant p53 and restoring the p53 pathway through p73 in colorectal cancer cells. Current undergoing experiments are focused on unraveling the p73 dependence through p73 knockdown and the mechanism of action involved in each cell line. The following project will aid in the understanding of the role of p73 in pharmacological restoration of the p53 pathway in cancer therapy.

Citation Format: Liz J. Hernandez Borrero, Shengliang Zhao, David T. Dicker, Wafik El-Deiry. Small molecule identification for the restoration of p53 pathway through p73 and by degradation of mutant p53. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2643. doi:10.1158/1538-7445.AM2015-2643
Abstract 2644: Inhibition of PAK4 attenuates renal cell carcinoma (RCC) growth
Authors: Abu Aboud Omran , Senapedis William , Landesman Yosef , Baloglu Erkan , Weiss Robert H.
Published: August 2015

Renal cell carcinoma (RCC) is an increasingly prevalent cancer type that is frequently asymptomatic on presentation and is associated with poor responses and resistance even to the current targeted therapies. Thus, novel therapeutic approaches to treat this disease are urgently needed. P21-activated kinase 4 (PAK4) is a mediator of filopodia formation and stabilizes β-catenin transcriptional activity. PAK4 lies in a pathway integral to both nephrogenesis and cancer. We hypothesized that inhibitors of the PAK4 signaling pathway would result in salutary effects on RCC. To test this, we evaluated the in vitro response of RCC cells to the specific PAK4 Allosteric Modulators (PAMs; KPT-8752 and KPT-9274). Similar to cells of other cancer types, 786-O (VHL-mutant RCC) showed decreases of both Phospho-PAK4 and Phospho-β-catenin after 24 h of incubation with 10 μM KPT-8752. In addition, both 786-O and ACHN (VHL-wildtype RCC cells) showed a marked time-dependent decrease in cell viability from 24 to 72 h of incubation from 2 to 10 μM of KPT-8752. KPT-9274 was orally administered at 25 and 100 mg/kg twice a day for 5 days/week to Caki-1 (VHL-wildtype RCC) and 786-O subcutaneous nude mouse xenograft models. In these studies the tumor growth rate was attenuated at both doses in the 786-O cells and at the higher dose for Caki-1 cells. There was no obvious change in the health of any of the animals suggesting manageable tolerability. We are currently evaluating combination therapy in our laboratory. In summary, PAK4 inhibitors show considerable promise as novel treatments of RCC as a single agent and warrant further investigation.

Citation Format: Omran Abu Aboud, William Senapedis, Yosef Landesman, Erkan Baloglu, Robert H. Weiss. Inhibition of PAK4 attenuates renal cell carcinoma (RCC) growth. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2644. doi:10.1158/1538-7445.AM2015-2644
Abstract 2645: Preclinical validation of Myc inhibition by a new generation of Omomyc-based inhibitors
Authors: Beaulieu Marie-Eve , Jauset Toni , Massó-Vallés Daniel , Whitfield Jonathan , Serrano Erika , Montagne Martin , Lavigne Pierre , Villaverde Antonio , Pesarrodona Mireia , Vazquez Esther , Soucek Laura
Published: August 2015

Deregulated Myc is associated with most human cancers suggesting that its inhibition would be a useful therapeutic strategy. Indeed, we have shown that Myc inhibition displays extraordinary therapeutic benefit in various transgenic mouse models of cancer (i.e. skin, lung, pancreatic cancer and glioma) and causes only mild, well-tolerated and reversible side effects in normal tissues. Furthermore, we demonstrated that Myc has a non-degenerate function in cancer that cannot be replaced by other pathways, even in the most aggressive p53-null tumors. Therefore, Myc could be targeted safely and successfully without eliciting resistance to therapy.

For these studies we employed a dominant negative inhibitor of Myc, called Omomyc, which is an effective inhibitor of Myc transactivation function both in vitro and in vivo. Omomyc has so far been utilized exclusively as a transgene and served as a successful proof of principle. Here we discuss our current research with Omomyc and our efforts to develop a clinically viable approach to Myc inhibition. One is based on the direct use of Omomyc itself as a peptide since we have discovered that it natively possesses cell-penetrating activity and it rapidly biodistributes to the lung and brain after intranasal administration. We are finding that the Omomyc peptide - like its transgenic counterpart before - has a therapeutic impact and we are continuing with the preclinical validation of this innovative therapeutic approach to pharmacological Myc inhibition. The second approach takes advantage of state-of-the-art nanocarrier technology to deliver Omomyc systemically, that can be combined with tumour-targeting ligands. These two novel Myc inhibition strategies have the potential to be translated rapidly to the clinic.

Citation Format: Marie-Eve Beaulieu, Toni Jauset, Daniel Massó-Vallés, Jonathan Whitfield, Erika Serrano, Martin Montagne, Pierre Lavigne, Antonio Villaverde, Mireia Pesarrodona, Esther Vazquez, Laura Soucek. Preclinical validation of Myc inhibition by a new generation of Omomyc-based inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2645. doi:10.1158/1538-7445.AM2015-2645
Abstract 2646: Targeting cancer stem cell pathways with cell-permeable peptide inhibitors
Authors: Arndt Verena , Friebe Annette , Meuser Elena , Ross Katharina , Agerer Franziska , Schulten-Schulz Carmen , Waak Jens , Friedrich Daniel , Hennemann Hanjo , Vollmer Jörg
Published: August 2015

Direct targeting of several important cancer pathways has so far proved challenging, owing to the lack of pathway-specific targets that can be accessed by conventional small molecule drugs or therapeutic antibodies. Nexigen develops and advances peptide-based cancer therapeutics, a new class of drugs that functionally modulate currently undruggable pathways by targeting intracellular protein-protein-interactions.

One of these undruggable pathways, the Wnt signaling cascade, has been identified as a key pathway in cancer stem cells maintenance. Targeting oncongenic Wnt signaling therefore holds great promise for tackling not only tumor growth but also disease relapse, metastasis and drug resistance. Using our proprietary next generation peptide screening system, we could identify cell-permeable peptides that efficiently inhibit the Wnt pathway through a specific interaction with a key component of intracellular signaling. Our most advanced preclinical candidate has nanomolar target affinity and significantly reduces the expression of Wnt target genes in triple-negative MDA-MB-231 breast cancer cells. The further functional analysis of the peptide in various cancer cell lines revealed a dose-dependent inhibition of cell migration, invasion, proliferation, and the cancer stem cell phenotype. The siRNA-mediated knock-down of the target protein or the inhibition of the Wnt pathway recapitulated the inhibitory peptide effect in these assays. Most importantly, we observed a significant suppression of primary tumor growth, tumor cell self-renewal and a reduction of metastatic potential after treatment in different xenograft models.

In summary, our data suggest that our Wnt pathway peptide inhibitor could be a promising new drug candidate for the treatment of cancer stem cells in a broad diversity of cancers.

Citation Format: Verena Arndt, Annette Friebe, Elena Meuser, Katharina Ross, Franziska Agerer, Carmen Schulten-Schulz, Jens Waak, Daniel Friedrich, Hanjo Hennemann, Jörg Vollmer. Targeting cancer stem cell pathways with cell-permeable peptide inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2646. doi:10.1158/1538-7445.AM2015-2646
Abstract 265: Robust anti-tumor effects of combined anti-CD4 depleting antibody and anti-PD-1/PD-L1 immune checkpoint antibody treatment in mice
Authors: Ito Satoru , Matsushima Kouji , Ueha Satoshi , Yokochi Shoji , Ishiwata Yoshiro , Hachiga Kosuke , Ogiwara Haru , Chand Krishant , Nakajima Takumi
Published: August 2015

Depletion of CD4+ cells in tumor-bearing mice has strong anti-tumor effects. However, the mechanisms underlying these effects and the therapeutic benefits of CD4+ cell depletion relative to other immunotherapies have not been fully evaluated. Here, we investigated the anti-tumor effects of an anti-CD4 depleting monoclonal antibody (mAb) as a monotherapy or in combination with immune checkpoint mAbs. In B16F10, Colon 26 or LLC subcutaneous tumor models, administration of the anti-CD4 mAb alone had strong anti-tumor effects that were superior to those elicited by CD25+ Treg depletion or other immune checkpoint mAbs, and which were completely reversed by CD8+ cell depletion. CD4+ cell depletion led to the proliferation of tumor-specific CD8+ T cells in the draining lymph node and increased infiltration of PD-1+CD8+ T cells into the tumor, with a shift towards type I immunity within the tumor. Combination treatment with the anti-CD4 mAb and immune checkpoint mAbs, particularly anti-PD-1 or anti-PD-L1 mAbs, synergistically suppressed tumor growth and greatly prolonged survival. To our knowledge, this work represents the first report of robust synergy between anti-CD4 and anti-PD-1 or anti-PD-L1 mAb therapies.

Citation Format: Satoru Ito, Kouji Matsushima, Satoshi Ueha, Shoji Yokochi, Yoshiro Ishiwata, Kosuke Hachiga, Haru Ogiwara, Krishant Chand, Takumi Nakajima. Robust anti-tumor effects of combined anti-CD4 depleting antibody and anti-PD-1/PD-L1 immune checkpoint antibody treatment in mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 265. doi:10.1158/1538-7445.AM2015-265
Abstract 2650: PI 3-Kinase inhibitors enhance the synthetic lethality of Parp inhibitors
Authors: Juvekar Ashish P. , Yadegarynia Sina , Hu Hai , Lyssiotis Costas A. , Liu Hui , Asara John M. , Scully Ralph , Cantley Lewis C. , Wulf Gerburg M.
Published: August 2015

Introduction: Clinical trials have shown promising responses of BRCA-linked breast and ovarian cancers to PARP inhibitor therapy, but remissions are often short-lived and incomplete. Frequent loss of INPP4B and PTEN leads to activation in the PI3K pathway in TNBC, making the PI3K pathway an attractive treatment target. Here we present mechanistic data that explain how PI3K- and PARP-inhibition enhance each other.

Methods: We examined the effects of PI3K-inhibitors BKM120 or BYL719 and PARP-inhibitor Olaparib on the metabolism of HCC1937 cells (BRCA1 5382C mutation and homozygous deletion of PTEN and p53) measuring lactic acid production, via seahorse analysis, carbon metabolism using targeted Mass Spectrometry (LC-MS/MS) and DNA synthesis. PI3K- but not Akt- or SGK-inhibition induced a DNA damage response in this BRCA1 mutant cell line as well as in a mouse model of BRCA1-related breast cancer (K14-Cre BRCA1f/f p53f/f) mouse model.

Summary: Metabolic profiling showed that PI3K-inhibition decreased flux through glycolysis and specifically through the non-oxidative pentose-phosphate pathway, the main source of ribose-5-phosphate required for the de novo synthesis of nucleotides in BRCA1-mutant breast cancer cells. Nucleotide shortage led to replication stress with the appearance of γH2AX, increased poly-ADP-ribosylation and an acute drop in DNA synthesis in cell cultures as well as in vivo. PI3K inhibition led to a reduced and error-prone S-phase due to a decrease in nucleotide biosynthesis which could be rescued upon exogenous supply of nucleosides. In a mouse model (K14-Cre BRCA1f/fp53f/f induced breast cancers) we could confirm that both BKM120 and BYL719 enhanced the efficacy of Parp-inhibitor Olaparib (median PFS for Olaparib 50 days, for BKM120 4 days, for BYL719 6 days and for both combinations, BKM120+Olaparib and BYL719+Olaparib > 120 days).

Conclusion: Preceding cell cycle arrest, PI3K-inhibition leads to a decrease in DNA synthesis due to decreased Ribose-5-phosphate production required for nucleotide synthesis. PI3K-inhibitors lower nucleotide pools, lead to impaired DNA damage repair and S-phase progression and further augment the synthetic lethality of Parp-inhibitors in BRCA1-related breast cancer.

Citation Format: Ashish P. Juvekar, Sina Yadegarynia, Hai Hu, Costas A. Lyssiotis, Hui Liu, John M. Asara, Ralph Scully, Lewis C. Cantley, Gerburg M. Wulf. PI 3-Kinase inhibitors enhance the synthetic lethality of Parp inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2650. doi:10.1158/1538-7445.AM2015-2650