Complete Inhibition Of Tumor Growth Research Articles

Metabolism-based structure optimization: Discovery of a potent and orally available tyrosine kinase ALK inhibitor bearing the tetracyclic benzo[b]carbazolone core

A metabolism-based fine-tuning structure-optimization was conducted to address the oxidative metabolism and hERG blockade of our early ALK inhibitor. Compound 8 was identified showing high potency against both ALK wild type and gatekeeper mutant. In addition to the optimal PK properties and significant cell antiproliferative effects, 8 showed complete tumor growth inhibition at doses of 50 or 10mg/kg once daily in the Karpas299 xenograft model. All these results encouraged the further development of 8 as a potent and orally bioavailable ALK inhibitor.

Long-Circulating Au-TiO2 Nanocomposite as a Sonosensitizer for ROS-Mediated Eradication of Cancer

Although sonodynamic therapy (SDT) has emerged as a potential alternative to conventional photodynamic therapy, the low quantum yield of the sonosensitizer such as TiO2 nanoparticles (NPs) is still a major concern. Here, we have developed hydrophilized Au-TiO2 nanocomposites (HAu-TiO2 NCs) as sonosensitizers for improved SDT. The physicochemical properties of HAu-TiO2 NCs were thoroughly studied and compared with their counterparts without gold deposition. Upon exposure of HAu-TiO2 NCs to ultrasound, a large quantity of reactive oxygen species (ROS) were generated, leading to complete suppression of tumor growth after their systemic administration in vivo. Overall, it was evident that the composites of gold with TiO2 NPs significantly augmented the levels of ROS generation, implying their potential as SDT agents for cancer therapy.

Abstract 2828: Preclinical activity of abemaciclib as a single agent or in combination with anti-mitotic or targeted therapies for breast cancer

Abstract The cyclin D:CDK-4/6:Rb axis is dysregulated in a number of different cancers and is implicated in resistance to hormonal therapy in breast cancer. Pharmacologically targeting cyclin dependent kinase 4 and 6 (CDK4 and 6) has proven to be a successful therapeutic approach in ER+ breast cancer (BC). This study aimed to identify the molecular subtypes of BC that are sensitive to the novel CDK4 and 6 inhibitor, abemaciclib, and identify the best combination strategies for the clinical development. Growth inhibition activity of abemaciclib was assessed in a panel of 46 BC cell lines molecularly characterized by genomic, transcriptomic and proteomic profiling. IC50 values were determined from direct cell counts using a Z1-particle counter. In vivo activity of abemaciclib was assessed in cell line xenograft models of ER+ and HER2+/ER+ BCs. For ER+ BC, mice were treated daily with clinically achievable doses of abemaciclib (50-75 mg/kg) as a single agent or in combination with tamoxifen or fulvestrant. Combinations with trastuzumab, docetaxel and tamoxifen were assessed in the HER2+/ER+ xenografts. Sensitivity to abemaciclib was observed predominately in multiple luminal BC cell lines and a small subset of triple negative cell lines that had intact Rb signaling. Activating mutations in PIK3CA also marked for abemaciclib sensitivity. Abemaciclib potentiated the anti-proliferative effects of cytotoxic/anti-mitotic agents when given simultaneously or 48 hours prior to treatment in vitro. Significant tumor growth inhibition (TGI) was observed with single agent abemaciclib in the ER+ BC cell line xenografts. In ZR751 xenografts, the addition of either tamoxifen or fulvestrant to abemaciclib induced complete inhibition of tumor growth for the 12 weeks of treatment. In the MCF7 model, treatment was withdrawn after five weeks, which triggered tumor regrowth in each of the single agent arms. However, complete responses were maintained in the combination arms for a further six weeks post drug withdrawal. In HER2 amplified xenografts, abemaciclib single agent treatment induced significant TGI in trastuzumab sensitive and resistant xenografts, and combination with trastuzumab further increased this anti-tumor effect. The addition of tamoxifen to this combination induced a further increment in TGI. Consistent with the in vitro findings, the combination of abemaciclib and the anti-mitotic agent docetaxel was not antagonistic in vivo, and the addition of docetaxel to the triple combination of abemaciclib, trastuzumab, and tamoxifen induced the most efficacy of any of the treatment arms tested. Combinations were well tolerated in animals. These data highlight the potential of abemaciclib to have single agent activity in addition to combined activity with anti-mitotic or targeted therapies for breast cancer. Citation Format: Neil A. O’Brien, Dylan Conklin, Tong Luo, Ondrej Kalous, Erika von Euw, Sara A. Hurvitz, Richard P. Beckmann, Colleen Mockbee, Dennis J. Slamon. Preclinical activity of abemaciclib as a single agent or in combination with anti-mitotic or targeted therapies for breast 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 2828.

Abstract 1407: FPA144, a therapeutic monoclonal antibody targeting the FGFR2b receptor, promotes antibody dependent cell-mediated cytotoxicity and stimulates sensitivity to PD-1 in the 4T1 syngeneic tumor model

Abstract Five Prime Therapeutics, Inc. has developed an FGFR2b-specific humanized monoclonal antibody, FPA144, to treat patients with cancer bearing overexpression of the FGFR2b receptor, and is currently in clinical trials as a single agent for gastric cancer (NCT02318329). FGFR2 gene amplification and FGFR2b overexpression occur in approximately 5% of gastric cancers and are associated with a poor prognosis in gastric cancer patients. In addition to blocking ligand binding and inducing FGFR2b internalization, FPA144 is glycoengineered for enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). We have shown previously that FPA144 can produce complete and durable tumor growth inhibition in FGFR2b-over-expressing and FGFR2-amplified gastric cancer xenografts in immune-compromised mice (Gemo et al., Poster 5446, AACR 2014). In order to understand the contribution of the immune system to the mechanisms of action of FPA144, we evaluated the anti-tumor effects and immune cell recruitment of FPA144 in the 4T1 model of cancer in immune-competent mice. Although this model expresses FGFR2b, it is not FGFR2 amplified. Therapeutic treatment with FPA144 in the orthotopic 4T1 model resulted in a reduction in tumor burden (33%, P<0.001) and concomitant recruitment of NK cells to the site of tumor implantation, while a modified antibody lacking Fc effector function neither inhibited tumor growth nor lead to the recruitment of NK cells. Together these data support a potential role for ADCC as a mechanism of FPA144 tumor growth inhibition. In addition, treatment with FPA144 increased PD-L1 expressing cells within the tumor microenvironment, providing a strong rationale that FPA144 may combine effectively with PD-1 blockade for additional tumor growth inhibition. PD-1 blockade by the RPM1-14 antibody did not inhibit tumor growth as a single agent in the 4T1 model. Treatment with RPM1-14 in combination with FPA144, however, inhibited tumor growth by 49% (P<0.001), demonstrating an additive benefit of combination therapy. Overall, these data suggest that the enhanced ADCC activity of FPA144 may be critical for anti-tumor efficacy in tumors that have modest expression of FGFR2b. In addition, FPA144 may reprogram the tumor micro-environment in a way that primes the tumor for additional anti-tumor activity when combined with PD-1 blockade. Citation Format: Janine Powers, Servando Palencia, Susan Foy, Barbara Sennino, Toni Rose Hidalgo, Abigael Gemo, Thomas Brennan, Kisten Pierce. FPA144, a therapeutic monoclonal antibody targeting the FGFR2b receptor, promotes antibody dependent cell-mediated cytotoxicity and stimulates sensitivity to PD-1 in the 4T1 syngeneic tumor model. [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 1407.

Discovery of 3-(5'-Substituted)-Benzimidazole-5-(1-(3,5-dichloropyridin-4-yl)ethoxy)-1H-indazoles as Potent Fibroblast Growth Factor Receptor Inhibitors: Design, Synthesis, and Biological Evaluation.

Fibroblast growth factor receptor (FGFR) represents an attractive oncology target for cancer therapy in view of its critical role in promoting cancer formation and progression, as well as causing resistance to approved therapies. In this article, we describe the identification of the potent pan-FGFR inhibitor (R)-21c (FGFR1-4 IC50 values of 0.9, 2.0, 2.0, and 6.1 nM, respectively). Compound (R)-21c exhibited excellent in vitro inhibitory activity against a panel of FGFR-amplified cell lines. Western blot analysis demonstrated that (R)-21c suppressed FGF/FGFR and downstream signaling pathways at nanomolar concentrations. Moreover, (R)-21c provided nearly complete inhibition of tumor growth (96.9% TGI) in NCI-H1581 (FGFR1-amplified) xenograft mice model at the dose of 10 mg/kg/qd via oral administration.

Chimeric HBcAg virus-like particles presenting a HPV 16 E7 epitope significantly suppressed tumor progression through preventive or therapeutic immunization in a TC-1-grafted mouse model.

BackgroundTherapeutic human papillomavirus (HPV) vaccines are currently being developed. However, no therapeutic efficacy has been achieved in clinical trials for the treatment of cervical intraepithelial neoplasia or cancer. One of the important issues in increasing vaccine efficacy is determining the best way to enhance tumor antigen-specific cellular immune responses. This study aimed to explore the virus-like particles (VLPs) of hepatitis B core antigen (HBcAg) as potential therapeutic vaccine carriers and to assess its immunological characteristics.MethodsChimeric VLPs presenting a HPV 16 cytotoxic T lymphocytes epitope E749–57 (amino acid 49–57 of the E7 protein) were prepared using recombinant genes. C57BL/6 mice were immunized with VLPs and grafted with tumor cells TC-1 which is an E7-expressing tumorigenic cell line. The dynamic tumor growth was monitored and anti-tumor immune responses were investigated.ResultsUsing a preventive strategy, immunization with VLPs resulted in nearly complete suppression of tumor growth. In treatment studies, VLP immunization significantly suppressed the tumor progression in mice carrying 2–3 mm tumors and in those bearing even larger tumors with diameters up to 8–9 mm. The VLP structure was shown to be important to induce vigorous antitumor immunity and effects. In immunized mice, enhanced E749–57-specific cellular immune responses were evidenced by increased interferon (IFN)-γ expression and decreased interleukin (IL)-4 expression in splenic lymphocytes, as well as an elevated number of effector cells expressing IFN-γ in response to the in vitro stimulation of the specific peptide E749–57. In addition, effective immune memory after VLP immunization was maintained for at least 16 weeks, preventing significant tumor growth after subsequent TC-1 challenge.ConclusionWhile VLPs were highly immunogenic in stimulating humoral immunity, our results strongly indicated that VLPs, such as HBcAg particles, might also be potent therapeutic vaccine carriers to elicit robust cellular immune responses, even in the immunosuppressive microenvironment of a tumor.

Hyaluronic acid-shelled acid-activatable paclitaxel prodrug micelles effectively target and treat CD44-overexpressing human breast tumor xenografts in vivo

The therapeutic efficacy of nanoscale anticancer drug delivery systems is severely truncated by their low tumor-targetability and inefficient drug release at the target site. Here, we report the design and development of novel endosomal pH-activatable paclitaxel prodrug micelles based on hyaluronic acid-b-dendritic oligoglycerol (HA-dOG-PTX-PM) for active targeting and effective treatment of CD44-overexpressing human breast cancer xenografts in nude mice. HA-dOG-PTX-PM had a high drug content of 20.6 wt.% and an average diameter of 155 nm. The release of PTX was slow at pH 7.4 but greatly accelerated at endosomal pH. MTT assays, flow cytometry and confocal experiments showed that HA-dOG-PTX-PM possessed a high targetability and antitumor activity toward CD44 receptor overexpressing MCF-7 human breast cancer cells. The in vivo pharmacokinetics and biodistribution studies showed that HA-dOG-PTX-PM had a prolonged circulation time in the nude mice and a remarkably high accumulation in the MCF-7 tumor (6.19%ID/g at 12 h post injection). Interestingly, HA-dOG-PTX-PM could effectively treat mice bearing MCF-7 human breast tumor xenografts with little side effects, resulting in complete inhibition of tumor growth and a 100% survival rate over an experimental period of 55 days. These results indicate that hyaluronic acid-shelled acid-activatable PTX prodrug micelles have a great potential for targeted chemotherapy of CD44-positive cancers.

Blu-285, a Potent and Selective Inhibitor for Hematologic Malignancies with KIT Exon 17 Mutations

KIT exon 17 mutants conferring ligand-independent constitutive kinase activity are known drivers of disease in both solid tumors and hematologic malignancies. KIT Exon 17 mutations have been identified in several human diseases such as systemic mastocytosis (SM), as resistance mutations in second and third line gastrointestinal stromal tumor (GIST), and certain subsets of acute myeloid leukemia (AML). We have developed BLU-285, a potent and selective exon 17 mutant KIT kinase inhibitor. BLU-285 has demonstrated biochemical in vitro activity on the KIT exon 17 mutant enzyme, KIT D816V (half-maximal inhibitory concentration [IC50] = 0.27 nM). Cellular activity of BLU-285 on KIT D816 mutants was measured by autophosphorylation in the human mast cell leukemia cell line HMC1.2, and the P815 mouse mastocytoma cell line with IC50= 4 and 22 nM, respectively. In vivo BLU-285 was well tolerated and has demonstrated dose dependent antitumor efficacy. Complete tumor growth inhibition and ≥ 75% KIT kinase inhibition was observed with 10 mg/kg once daily, oral dosing of BLU-285 in the aggressive KIT exon 17 mutant driven P815 mastocytoma model grown as a solid tumor allograft as well as in a disseminated model of disease.In AML, KIT mutations represent an uncommon molecular alteration. Yet in a defined subset of AML with core binding factor genomic rearrangements characterized by either t(8;21) or inv(16)(CBF-AML), approximately 25% of patients have an additional KIT exon 17 mutation at positions such as D816 or N822. In the case of t(8;21) AMLs, the presence of a KIT exon 17 mutation places a patient in an intermediate risk category with higher recurrence rates and lower median overall survival than t(8;21) patients without a KIT exon 17 mutation. In Kasumi-1 cells, a t(8;21)-positive AML cell line with a KIT exon 17 N822K mutation, BLU-285 potently inhibits KIT N822K mutant autophosphorylation (IC50 = 40 nM), downstream signaling, as well as cellular proliferation (IC50 = 75 nM). A Kasumi-1 luc+ AML NOG SCID mouse femoral injection model was used to assess the efficacy of BLU-285 in KIT exon 17-mutated CBF-AML. Following a 21 day post injection latency period, mice were dosed with BLU-285 orally, once daily at 10 mg/kg or 30 mg/kg through day 45. Control groups were treated with vehicle or cytarabine administered 100 mg/kg i.p once weekly. Disease burden, measured by whole body luciferase imaging (photons/second/mm2), increased 86-fold in the vehicle control animals over the 24 day dosing period with widespread disease detectable in both femurs, the pelvis and circulating in peripheral blood. Disease in the cytarabine-treated animals advanced more slowly with a 15-fold increase in luciferase values over the course of the experiment. Strikingly, BLU-285 at both doses (10 or 30 mg/kg orally, once daily) resulted in a marked reduction of disease burden throughout the study as compared to both vehicle controls and animals receiving cytarabine. BLU-285 at either 10 or 30 mg/kg resulted in tumor regression in all animals with disease abrogation indistinguishable from background signal measurements in several animals by the end of study. BLU-285 was also well tolerated in this in vivo model and had no adverse effects on body weight at either dose. Recently, a phase 1 clinical trial for the treatment of relapsed or refractory GIST with BLU-285 has been initiated. In addition, a clinical trial in SM, where KIT exon 17 mutations are believed to be genetic drivers of disease, is scheduled to begin in 2015. These data suggest that KIT exon 17-mutated CBF-AMLs and t(8;21) AMLs in particular, may be an additional therapeutic indication for the clinical evaluation of BLU-285. DisclosuresEvans:Blueprint Medicines: Employment, Equity Ownership. Gardino:Blueprint Medicines: Employment, Equity Ownership. Hodous:Blueprint Medicines: Employment, Equity Ownership. Davis:Blueprint Medicines: Employment, Equity Ownership. Zhu:Blueprint Medicines: Employment, Equity Ownership. Kohl:Blueprint Medicines: Employment, Equity Ownership. Lengauer:Blueprint Medicines: Employment, Equity Ownership.

Targeting Syndecan-1, a molecule implicated in the process of vasculogenic mimicry, enhances the therapeutic efficacy of the L19-IL2 immunocytokine in human melanoma xenografts.

Anti-angiogenic therapy of solid tumors has until now failed to produce the long lasting clinical benefits desired, possibly due to the complexity of the neoangiogenic process. Indeed, a prominent role is played by "vasculogenic" or "vascular" mimicry (VM), a phenomenon in which aggressive cancer cells form an alternative microvascular circulation, independently of endothelial cell angiogenesis. In this study we observed, in melanoma patient cell lines having vasculogenic/stem-cell like phenotype and in melanoma tumors, the syndecan-1 co-expression with VM markers, such as CD144 and VEGFR-2. We show that melanoma cells lose their ability to form tubule-like structures in vitro after blocking syndecan-1 activity by the specific human recombinant antibody, OC-46F2. Moreover, in a human melanoma xenograft model, the combined therapy using OC-46F2 and L19-IL2, an immunocytokine specific for the tumor angiogenic-associated B-fibronectin isoform(B-FN), led to a complete inhibition of tumor growth until day 90 from tumor implantation in 71% of treated mice, with statistically significant differences compared to groups treated with OC-46F2 or L19-IL2 as monotherapy. Furthermore, in the tumors recovered from mice treated with OC-46F2 either as monotherapy or in combination with L19-IL2, we observed a dramatic decrease of vascular density and loss of VM structures. These findings indicate for the first time a role of syndecan-1 in melanoma VM and that targeting syndecan-1, together with B-FN, could be promising in improving the treatment of metastatic melanoma.

Discovery of 1-(4-(5-(5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)-1-ethyl-1,2,4-triazol-3-yl)piperidin-1-yl)-3-hydroxypropan-1-one (AZD8835): A potent and selective inhibitor of PI3Kα and PI3Kδ for the treatment of cancers.

Starting from potent inhibitors of PI3Kα having poor general kinase selectivity (e.g., 1 and 2), optimisation of this series led to the identification of 25, a potent inhibitor of PI3Kα (wild type, E545K and H1047R mutations) and PI3Kδ, selective versus PI3Kβ and PI3Kγ, with excellent general kinase selectivity. Compound 25 displayed low metabolic turnover and suitable physical properties for oral administration. In vivo, compound 25 showed pharmacodynamic modulation of AKT phosphorylation and near complete inhibition of tumour growth (93% tumour growth inhibition) in a murine H1047R PI3Kα mutated SKOV-3 xenograft tumour model after chronic oral administration at 25mg/kg b.i.d. Compound 25, also known as AZD8835, is currently in phase I clinical trials.

Abstract NG06: The Trojan Horse Strategy: Packaging chemotherapeutics can help alleviate toxicity

Abstract NG06: The Trojan Horse Strategy: Packaging chemotherapeutics can help alleviate toxicity

Abstract LB-005: Monepantel a new first in class potent inhibitor of P70S6K potentiates the anti-tumor effects of gemcitabine and doxorubicin: In vitro and in vivo studies

Abstract Aims: Monepantel (MPL) is a new nematode-specific anthelmintic agent. We have recently communicated the preliminary results showing the anti-tumor activity of this agent in ovarian cancer through attenuation of mTOR/P70S6K pathway. As emerging data indicate that mTOR inhibitors are most effective when combined with other target agents, we evaluated whether MPL could favorably be combined with the clinically approved chemotherapeutic agents to improve therapeutic efficacy. Methods: The effects of MPL and/or chemotherapeutic agents gemcitabine (Gem)/ doxorubicin (Dox) on the growth of a panel of cancer cell lines were determined using SRB assay. In vitro drug synergy was determined using combination index (CI) methods derived from Chou-Talalay equations using CalcuSyn software. For in vivo studies, we evaluated the effect of MPL, alone and in combination with Gem/ Dox on the growth of established human ovarian (OVCAR-3) tumors implanted subcutaneously in BALB/C nude mice. Toxicity was evaluated measuring animal weight. In vivo combination effects was determined using Fractional Tumor Volume (FTV) method. Results: In vitro, MPL in combination with Gem or Dox synergistically reduced survival rates of a panel of malignant cells from different origins while having no additive effect upon non-malignant cell (HOSE) survival rates. In vivo, antitumor activity was observed in all treatment groups compared to the mock-treated animals after 4 weeks of treatment. However combination therapy with MPL and chemotherapeutics significantly attenuated tumor growth, compared to monotherapy without showing any toxicity. Combining MPL (50 mg/kg) increased the tumor inhibitory effect of low dose Gem (2 mg/kg), high dose Gem (5 mg/kg), low dose Dox (2 mg/kg) and high dose Dox (5 mg/kg) by 32.29, 35.1, 15.2 and 24.38% respectively. Moreover, MPL (25 mg/kg) enhanced the tumor inhibitory rate of Gem (5 mg/kg) by 36.26%. These resulted in complete tumor growth inhibition in Gem 5 mg/kg + MPL 25 or 50 mg/kg and Dox 2 or 5 mg/kg+ MPL 50 mg/kg treatment groups. Assessment of therapeutic synergy with FTV method revealed strong synergy in Gem 5 mg/kg + MPL 25 or 50 mg/kg, Gem 2 mg/kg + MPL 50 mg/kg and Dox 2 or 5 mg/kg+ MPL 50 mg/kg treatment groups with odds ratio of 2.48, 2.59, 1.48, 1.63 and 2.97 (>1 indicates synergy) respectively. Conclusion: These findings provide a rational to further investigate MPL in combination with standard chemotherapeutics as novel combination regimens which could hopefully provide strong anticancer synergy. Citation Format: Parvin A. Ataie-Kachoie, Javed Akhter, David L. Morris. Monepantel a new first in class potent inhibitor of P70S6K potentiates the anti-tumor effects of gemcitabine and doxorubicin: In vitro and in vivo studies. [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 LB-005. doi:10.1158/1538-7445.AM2015-LB-005

Abstract 3650: Discovery of the clinical candidate AZD9496: a potent and orally bioavailable selective estrogen receptor downregulator and antagonist

Abstract With over 70% of breast cancers expressing the estrogen receptor alpha (ERα), treatment with either anti-hormonal therapies that directly block ER function or therapies that block the production of estrogen itself have proven to be effective treatments of the disease. Following the pioneering discovery of the ERα antagonist tamoxifen in the 1960s, identification of the selective estrogen receptor downregulator (SERD) fulvestrant represented a further step forward in the treatment of advanced ER+ breast cancer especially in the endocrine resistance setting. The pure estrogen downregulator-antagonist fulvestrant offers the advantage of not only antagonising ERα-driven tumor cell growth but also degrading ERα via ubiquitinylation and thus diminishing growth due to reduced ERα content. Given its low level of bioavailability and metabolic profile, fulvestrant has been formulated as an intramuscular monthly injection. We have sought to identify a novel, non-steroidal ERα antagonist and down-regulator that can be administered orally and could yield improved exposure and clinical benefit. This presentation will describe the discovery of AZD9496, a novel, orally bioavailable small molecule that can induce ERα degradation in breast cancer cell lines at picomolar concentrations. Data will be shared for the first time on the medicinal chemistry efforts that led to AZD9496, the good oral pharmacokinetic properties of the compound which led to significant tumor efficacy in both endocrine sensitive model (complete tumor growth inhibition (TGI) in a MCF-7 model at a dose of 10 mpk) and resistant models (tumor regressions in a HCC1428 long term estrogen deprived (LTED) model, with significant down-regulation of ER protein (81%) at 1 mpk QD and tumour growth inhibition in an ESR1 mutant PDX model). These findings strongly supported selection of AZD9496 as a clinical candidate for the treatment of ER+ breast cancer, and on October 2014 the first patient was dosed with AZD9496. ER alpha human binding IC50 (μM)ER downregulation cell IC50 (μM)MCF7 anti-proliferation EC50 (μM)Aqueous solubility, (pH = 7.4, μM)MCF7 tumor xenograft efficacy (% TGI at 10 mpk PO QD for 22 days)AZD94960.00070.000140.0000411084 Citation Format: Chris De Savi, Robert H. Bradbury, Alfred A. Rabow, Richard A. Norman, David Buttar, Gordon S. Currie, Hazel Weir, Craig Donald, David Andrews, Phil MacFaul, Peter Ballard, Jon Curwen, Zena Wilson, Graham Richmond, Celina D'Cruz, Steve Powell, Graeme Walker, Michael Hulse, Michael Tonge. Discovery of the clinical candidate AZD9496: a potent and orally bioavailable selective estrogen receptor downregulator and antagonist. [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 3650. doi:10.1158/1538-7445.AM2015-3650

Discovery of (R)-8-(1-(3,5-difluorophenylamino)ethyl)-N,N-dimethyl-2-morpholino-4-oxo-4H-chromene-6-carboxamide (AZD8186): a potent and selective inhibitor of PI3Kβ and PI3Kδ for the treatment of PTEN-deficient cancers.

Several studies have highlighted the dependency of PTEN deficient tumors to PI3Kβ activity and specific inhibition of PI3Kδ has been shown activity against human B-cell cancers. We describe the discovery and optimization of a series of 8-(1-anilino)ethyl)-2-morpholino-4-oxo-4H-chromene-6-carboxamides as PI3Kβ/δ inhibitors, which led to the discovery of the clinical candidate 13, also known as AZD8186. On the basis of the lower lipophilicity of the chromen-4-one core compared to the previously utilized pyrido[1,2-a]pyrimid-4-one core, this series of compounds displayed high metabolic stability and suitable physical properties for oral administration. Compound 13 showed profound pharmacodynamic modulation of p-Akt in PTEN-deficient PC3 prostate tumor bearing mice after oral administration and showed complete inhibition of tumor growth in the mouse PTEN-deficient PC3 prostate tumor xenograft model. 13 was selected as a clinical candidate for treatment of PTEN-deficient cancers and has recently entered phase I clinical trials.

274 Novel cysteine derivatives for the next generation anticancer agents acting on KSP

physical properties for oral administration. AZD8186 showed profound pharmacodynamic modulation of p-Akt in PTEN-null PC3 prostate tumour bearing mice after oral administration and showed complete inhibition of tumour growth in the mouse PTEN-deficient PC3 prostate tumour xenograft model. AZD8186 was selected as a clinical candidate for treatment of PTEN-dependent cancers and has recently entered phase I clinical trials.

273 Significance of serine-167 and cysteine-129 residues in the active site of the immune-suppressive enzyme indoleamine 2,3-dioxygenase 1 (IDO1) for the binding of novel inhibitors

physical properties for oral administration. AZD8186 showed profound pharmacodynamic modulation of p-Akt in PTEN-null PC3 prostate tumour bearing mice after oral administration and showed complete inhibition of tumour growth in the mouse PTEN-deficient PC3 prostate tumour xenograft model. AZD8186 was selected as a clinical candidate for treatment of PTEN-dependent cancers and has recently entered phase I clinical trials.

SAR405838: an optimized inhibitor of MDM2-p53 interaction that induces complete and durable tumor regression.

Blocking the oncoprotein murine double minute 2 (MDM2)-p53 protein-protein interaction has long been considered to offer a broad cancer therapeutic strategy, despite the potential risks of selecting tumors harboring p53 mutations that escape MDM2 control. In this study, we report a novel small-molecule inhibitor of the MDM2-p53 interaction, SAR405838 (MI-77301), that has been advanced into phase I clinical trials. SAR405838 binds to MDM2 with K(i) = 0.88 nmol/L and has high specificity over other proteins. A cocrystal structure of the SAR405838:MDM2 complex shows that, in addition to mimicking three key p53 amino acid residues, the inhibitor captures additional interactions not observed in the p53-MDM2 complex and induces refolding of the short, unstructured MDM2 N-terminal region to achieve its high affinity. SAR405838 effectively activates wild-type p53 in vitro and in xenograft tumor tissue of leukemia and solid tumors, leading to p53-dependent cell-cycle arrest and/or apoptosis. At well-tolerated dose schedules, SAR405838 achieves either durable tumor regression or complete tumor growth inhibition in mouse xenograft models of SJSA-1 osteosarcoma, RS4;11 acute leukemia, LNCaP prostate cancer, and HCT-116 colon cancer. Remarkably, a single oral dose of SAR405838 is sufficient to achieve complete tumor regression in the SJSA-1 model. Mechanistically, robust transcriptional upregulation of PUMA induced by SAR405838 results in strong apoptosis in tumor tissue, leading to complete tumor regression. Our findings provide a preclinical basis upon which to evaluate SAR405838 as a therapeutic agent in patients whose tumors retain wild-type p53.

Abstract 183: Immune dysfunction cascades caused by ALCAM+ mesenchymal stem cells toward tumor progression

Abstract Purposes: We have been investigating the interplay between cancer cells and host immunity, and previously demonstrated that Snail expression in tumor cells accelerates metastasis not only by enhancing tumor motility but also by inducing immune dysfunction through increase of a variety of immunoregulatory cells using murine tumor models implanted with snail-transduced B16-F10 melanoma (F10-snail+). We additionally found that Snail+ tumor cells frequently metastasize into bone marrow (BM) of the mice, and pluripotent CD45-ALCAM+ mesenchymal stem cells (MSCs) consequently increased in the mice. In this study, we attempted to characterize the Snail+ tumor-induced CD45-ALCAM+ MSCs (sMSCs). Results: The sMSCs were prepared by stimulating BMCs with F10-snail+ tumor supernatant for 5-7 days, or by sorting CD45-ALCAM+ cells from BM or spleen of the F10-snail+ tumor cells 2-3 weeks after implantation. When the mixture of the sMSCs and F10-mock tumor cells was subcutaneously injected in C57BL/6 mice, tumor growth was aggressively promoted, and spontaneous tumor dissemination in BM indicating de novo bone metastasis was observed, accompanied by increase of sMSCs in BM. In the tumor milieu and spleen of these mice, functionally impaired CD8(low) T cells and immunosuppressive Treg-inducible CD11b+Gr1+ MDSCs predominantly increased. Indeed, CD8(low) T cells were generated in the culture with splenic T cells and sMSCs, and MDSCs were expanded in the culture with BM cells and sMSCs. We identified key molecules responsible for the sMSC-induced events: ALCAM, ANGPT2 and FSTL1, which significantly increased only in the sMSC but not F10-mock-derived MSCs and normal MSCs. FSTL1 inhibited bone metastasis and consequent increase of sMSCs, CD8(low) T cells and MDSCs. Blocking ALCAM with mAb inhibited both sMSC expansion and CD8(low) T-cell induction. Blocking ANGPT2 inhibited expansion of MDSCs and Tregs rather than angiogenesis. Blocking FSTL1, which is a key trigger to initiate these cascades, in combination with elimination of other sMSC-associated factors significantly induced anti-tumor immune responses, resulting in complete inhibition of tumor growth and metastasis. Conclusions: These results suggest that sMSCs play a central role in the cancer EMT-induced immune dysfunction leading to tumor progression. Snail is reported to regulate acquisition of stem-like properties in tumor cells. However, how cancer stem cells would modulate the BM microenvironment and alter anti-tumor immune responses also remains unclear. Targeting sMSCs and its associated molecules may be a promising strategy for abrogating even cancer stem cells through reprogramming and activating anti-tumor immune responses appropriately. Citation Format: Chie Kudo-Saito, Takafumi Fuwa, Kouichi Murakami. Immune dysfunction cascades caused by ALCAM+ mesenchymal stem cells toward tumor progression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 183. doi:10.1158/1538-7445.AM2014-183

Abstract 3808: Preclinical efficacy of the novel, oral Selective Inhibitor of Nuclear Export (SINE) Selinexor (KPT-330) on castration resistant prostate cancer

Abstract Exportin 1/ Chromosomal Maintenance Protein 1 (XPO1/CRM1) is a key nuclear export protein whose inhibition leads to the nuclear accumulation of tumor suppressor proteins such as p53, FOXO, PTEN, pRB and I-κB. Selinexor is an orally bioavailable XPO1 inhibitor that represents a novel class of small molecule compounds with potent activity against a wide variety of cancers. Here we report the activity of Selinexor against Castration resistant prostate cancer (CRPC). CRPC progression is mediated by activation of various adaptive Androgen Receptor (AR) signaling pathways. These pathways are currently being targeted by novel anti-androgen therapies such as abiraterone acetate and enzalutamide with favorable outcomes. However, resistance to anti-androgen therapy can be developed through deregulation of tumor suppressor pathways. XPO-1 is highly expressed in prostate cancer cells and therefore we tested the effects of Selinexor on CRPC cells and tumors models. Treatment of the C4-2B prostate cancer cell line with Selinexor in vitro significantly inhibited cell proliferation and resulted in nuclear accumulation of p53 and p21. In addition, Selinexor inhibited expression of the tumor-promoting gene Ubiquitin-Conjugating Enzyme E2C (UBE2C), which is activated by AR in these cells. Selinexor was also tested in tumor graft models of two patient tumors in castrated male mice. The MDA-PCa-133 tumor is an adenocarcinoma derived from a clinical CRPC bone metastasis. Subcutaneous MDA-PCa-133 tumors in castrated male mice express full-length AR and Prostate-Specific Antigen (PSA) but lack expression of p53. The MDA-PCa-144-13 tumor is a small cell carcinoma derived from a lethal variant of prostate cancer with anaplastic clinical phenotype and does not express AR or PSA but expresses a gain-of-function p53 mutant. Vehicle or Selinexor treatment (10 mg/kg p.o. QoDX3 M/W/F) of MDA-PCa-133 tumors for 34 days resulted in almost complete inhibition of tumor growth with a 30-fold reduction of PSA (p<0.001). Treatment of MDA-PCa-144-13 tumors for 22 days also resulted in significant reduction of tumor volume (>8 fold compared to vehicle only; p<0.0047). Immunohistochemical analysis of MDA-PCa-133 tumors showed that Selinexor induced nuclear accumulation of XPO1 cargos FOXO3a and p27 with concomitant reduction in the proliferation marker KI67. In conclusion, Selinexor demonstrated robust inhibition of CRPC tumor growth and activated multiple tumor suppressors in prostate cancer cells. Selinexor is now being evaluated in Phase 1 clinical studies in patients with advanced hematological and solid tumor cancers, and preliminary results show adequate tolerability with evidence of anti cancer activity. Future clinical studies in patients with CRPC are planned and will provide more information on the use of Selinexor as monotherapy and in combination with anti-androgen therapy of CRPC. Citation Format: Sankar Narayan Maity, Guanglin Wu, Jing-Fang Lu, Anh Hoang, Yosef Landesman, Dilara McCauley, Sharon Shacham, Michael G. Kauffman, Ana M. Aparicio, Eleni Efstathiou, John C. Araujo, Christopher J. Logothetis. Preclinical efficacy of the novel, oral Selective Inhibitor of Nuclear Export (SINE) Selinexor (KPT-330) on castration resistant prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3808. doi:10.1158/1538-7445.AM2014-3808

Translational Study for Mechanisms of Synergy and Toxicity of Tivozanib in Combination with Capecitabine in a Population-Based Murine Tumor Model

ABSTRACT Aim: Clinical trials combining vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI) and capecitabine have been promising but often met with increased toxicities requiring dose reductions. Tivozanib is a highly selective VEGFR TKI with demonstrated antitumor activity. Translational studies were conducted using a genetically diverse population of tumor models to understand tivozanib+capecitabine potential synergistic responses and possible toxicities. Methods: The antitumor activity of tivozanib+capecitabine at various dose levels was assessed in multiple tumors that exhibited partial or no response to either agent alone. Tumor growth, cell proliferation, angiogenesis, and the effect of tivozanib on capecitabine conversion to 5-fluorouracil (FU) were investigated. Results: The combination of tivozanib+capecitabine enhanced antitumor activity of capecitabine and blocked inflammatory and angiogenic reactions triggered by capecitabine monotherapy. A subset of tumors exhibited strong synergistic response to the combination treatment and complete tumor growth inhibition was achieved at capecitabine doses reduced to as low as 25% of maximum tolerated dose. RT-PCR analysis of the treated tumors revealed that tivo significantly induced the expression of thymidine phosphorylase (TP), an enzyme for cape conversion in the body. Increased TP expression in tumors was associated with elevated local 5-FU concentration, suggesting a pharmacokinetic mechanism of synergy. In addition, TP expression was induced by tivozanib treatment in both the epidermis of treated mice and in cultured human keratinocytes suggesting increased capecitabine conversion in the skin. Conclusions: These results indicate tivozanib TP induction may be a key mechanism of synergistic response to the combination treatment and suggests clinical antitumor activity may be achieved with a reduced capecitabine dose. The elevated epidermal TP expression may provide a mechanistic explanation for increased Hand-Foot Syndrome observed in phase 1 trial patients treated with tivozanib+capecitabine (NCT01306630). Further exploration is warranted. Disclosure: J. Lin: AVEO Oncology employee • Stock • Salary Other financial relationships • None; G. Li: AVEO Oncology employee • Stock • Salary Other financial relationships • None; F. Jiang: AVEO Oncology employee • Stock • Salary Other financial relationships • None; L. Shen: AVEO Oncology employee • Stock • Salary Other financial relationships • None; J. Gyuris: AVEO Oncology employee • Stock • Salary Other financial relationships • None.