Potent Focal Adhesion Kinase Inhibitor Research Articles

Identification of potential FAK inhibitors using mol2vec molecular descriptor-based QSAR, molecular docking, ADMET study, and molecular dynamics simulation.

This study aims to identify potential focal adhesion kinase (FAK) inhibitors through an integrated computational approach, combining mol2vec descriptor-based QSAR, molecular docking, ADMET study, and molecular dynamics simulation. A dataset of 437 compounds with known FAK inhibitory activities was used to develop QSAR models using machine learning algorithms combined with mol2vec descriptors. Subsequently, the most promising compounds were subjected to molecular docking against FAK to evaluate their binding affinities and key interactions. ADMET study and molecular dynamics simulation were also employed to investigate the pharmacokinetic, drug-like properties, and the stability of the protein-ligand complexes. The results showed that the mol2vec descriptor-based QSAR model established by support vector regression demonstrated good predictive performance (R2 = 0.813, RMSE = 0.453, MAE = 0.263 in case of training set, and R2 = 0.729, RMSE = 0.635, MAE = 0.477 in case of test set), indicating their reliability in identifying potent FAK inhibitors. Using this QSAR model and molecular docking, compound 21 (ZINC000004523722) was identified as the most potential compound, with predicted logIC50 value and binding energy of 2.59 and - 9.3kcal/mol, respectively. The results of molecular dynamics simulation and ADMET study also further suggested its potential as a promising drug candidate. However, because our research was merely theoretical, additional in vitro and in vivo studies are required for the verification of these results.

Discovery of novel pyrrolo [2,3-d] pyrimidine derivatives as potent FAK inhibitors based on cyclization strategy

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays a pivotal role in tumor invasion and metastasis. Many FAK inhibitors had been reported, but the development of FAK inhibitors in clinical studies are still limited. To facilitate the discovery of FAK modulators and further elucidate the role of FAK in cancer metastasis, it is necessary to discover a novel, potent and selective FAK inhibitor. In this study, a series of FAK inhibitors with novel scaffold were designed and synthesized based on cyclization strategy. Here, we reported compound 10b (HMC-18NH) with excellent inhibition of FAK (IC50 = 9.9 nM) and anticancer activity against several cancer cell lines including BxPC-3, PANC-1, MCF-7, MDA-MB-231, U-87MG, HepG2, HCT-15 and A549. Extraordinary, compound 10b showed the best cytotoxic effects against A549 with the IC50 value of 0.8 μM. In addition, 10b exhibited effective invasion and migration suppression in A549 cells. Further investigations revealed that compound 10b potently induced and promoted apoptosis in a dose-dependent manner and arrested A549 cells in the G2/M phase. Collectively, these results suggest that 10b is a promising FAK inhibitor and serve as a lead compound which deserve for further optimization.

Design, synthesis and biological evaluation of 7-((7H-pyrrolo[2,3-d]pyrimidin-4-yl)oxy)-2,3-dihydro-1H-inden-1-one derivatives as potent FAK inhibitors for the treatment of ovarian cancer

Focal adhesion kinase (FAK) promotes tumor progression by intracellular signal transduction and regulation of gene expression and protein turnover, which is a compelling therapeutic target for various cancer types, including ovarian cancer. However, the clinical responses of FAK inhibitors remain unsatisfactory. Here, we describe the discovery of FAK inhibitors using a scaffold hopping strategy. Structure–activity relationship (SAR) exploration identified 36 as a potent FAK inhibitor, which exhibited inhibitory activities against FAK signaling in vitro. Treatment with 36 not only decreased migration and invasion of PA-1 cells, but also reduced expression of MMP-2 and MMP-9. Moreover, 36 inhibited tumor growth and metastasis, and no obvious adverse effects were observed during the in vivo study. These results revealed the potential of FAK inhibitor 36 for treatment of ovarian cancer.

Design, synthesis, and biological evaluation of 2,4-diamino pyrimidine derivatives as potent FAK inhibitors with anti-cancer and anti-angiogenesis activities.

A series of 2,4-diamino pyrimidine (DAPY) derivatives were designed, synthesized, and evaluated as inhibitors of focal adhesion kinase (FAK) with antitumor and anti-angiogenesis activities. Most compounds effectively suppressed the enzymatic activities of FAK, and the IC50s of 11b and 12f were 2.75 and 1.87nM, respectively. 11b and 12f exhibited strong antiproliferative effects against seven human cancer cells, with IC50 values against two FAK-overexpressing pancreatic cancer cells (PANC-1 and BxPC-3) of 0.98μM, 0.55μM, and 0.11μM, 0.15μM, respectively. Moreover, 11b and 12f obviously suppressed the colony formation, migration, and invasion of PANC-1cells in a dose-dependent manner. Meanwhile, these two compounds could induce the apoptosis of PANC-1cells and arrest the cell cycle in G2/M phase according to the flow cytometry assay. Western blot revealed that 11b and 12f effectively inhibited the FAK/PI3K/Akt signal pathway and significantly decreased the expression of cyclin D1 and Bcl-2. In addition, compounds 11b and 12f potently inhibited the antiproliferative of HUVECs and obviously altered the cell morphology. 11b and 12f also significantly inhibited the migration, tube formation of HUVECs and severely impaired the angiogenesis in the zebrafish model. Overall, these results revealed the potential of compounds 11b and 12f as promising candidates for further preclinical studies.

G9a Promotes Invasion and Metastasis of Non-Small Cell Lung Cancer through Enhancing Focal Adhesion Kinase Activation via NF-κB Signaling Pathway.

Potential roles of euchromatic histone methyltransferase 2 (EHMT2 or G9a) in invasion and metastasis are not well understood in non-small cell lung cancer (NSCLC). Here, we investigated the effect and underlying mechanisms of G9a and therapeutic implications of targeting G9a in the invasion and metastasis of NSCLC. Overexpression of G9a significantly enhanced in vitro proliferation and invasion, while knockdown of G9a drastically suppressed in vivo growth and metastasis of A549 and H1299 NSCLC cells. Knockdown or inhibition of G9a significantly decreased the expression of focal adhesion kinase (FAK) protein and activation of FAK pathway. In addition, defactinib, a potent FAK inhibitor, partially abolished the G9a-enhanced invasion in these NSCLC cells. Furthermore, targeting G9a was found to suppress NF-κB transcriptional activity in NSCLC cells through stabilizing NF-κB inhibitor alpha (IκBα), while an NF-κB inhibitor Parthenilide partially abolished the G9a-enhanced FAK activation, which suggests that G9a-enhanced invasion and activation of FAK is mediated by elevated NF-κB activity. Notably, a strong positive correlation between the IHC staining of G9a and phosphorylated FAK proteins was identified in H1299 xenografts and 159 cases of NSCLC tissues (R = 0.408). IMPLICATIONS: The findings of this study strongly demonstrate that G9a may promote invasion and metastasis of NSCLC cells by enhancing FAK signaling pathway via elevating NF-κB transcriptional activity, indicating potential significance and therapeutic implications of these pathways in the invasion and metastasis of NSCLCs that overexpress G9a protein.

Abstract CT118: Phase I study of defactinib combined with pembrolizumab and gemcitabine in patients with advanced cancer: Experiences of pancreatic ductal adenocarcinoma (PDAC) patients

Abstract Background: Focal adhesion kinase (FAK) is consistently hyperactivated in multiple tumor types including PDAC. Our preclinical work showed that FAK and PD-1 inhibitors elicit significant tumor regression, and that combining FAK and PD-1 inhibitors with gemcitabine achieves a maximal response. This suggests the need for a cytotoxic agent to bolster antigen presentation. Defactinib is an orally available, well-tolerated, potent FAK inhibitor. Methods: This study included a dose escalation phase (all solid tumors) and dose expansion phase (metastatic PDAC). A 3+3 design with five dose levels was used in the dose escalation phase. For the expansion phase, 10 PDAC patients with stable disease on front-line gemcitabine/nab-paclitaxel were enrolled in the Maintenance cohort (A), while 10 patients who progressed on at least one line of therapy were enrolled in the Refractory cohort (B). Pre and on-treatment biopsied were collected from all PDAC patients. The primary endpoint was to determine the recommended phase 2 dose (RP2D). Secondary endpoints included safety, toxicity, objective response rate, progression-free survival (PFS) and overall survival (OS). The exploratory endpoints included developing a molecular and immune profile for treatment response. Results: In dose escalation, the common low grade (G1/2) treatment-emergent adverse events included fatigue, anorexia, nausea and vomiting. No DLTs were seen. The RP2D was defactinib 400mg twice daily, gemcitabine 1000 mg/m2 days 1, 8 and pembrolizumab 200mg day 1 of a 21-day cycle. Safety and toxicity results in the escalation cohort were reported at the 2018 ASCO Annual Meeting. Among 8 evaluable PDAC patients enrolled on the dose escalation phase, we observed 1 (13%) partial response (PR), 3 (38%) stable disease (SD), 4 (50%) progressive disease (PD). In the Maintenance cohort, 1 (10%) PR, 6 (60%) SD, and 3 (30%) PD were observed. Two patients in the Maintenance cohort remain on study, and the median time on treatment was 4.6 months. In the Refractory cohort, 5 (50%) had SD, 4 (40%) PD, 1 not evaluable; median PFS was 2.9 months and median OS was 7.6 months. Interestingly, two confirmed PR patients both have MSS disease. Paired biopsies in PDAC patients show increased proliferating CD8+ T cells, while Tregs, macrophages, and stromal density decrease with treatment. Conclusions: The combination regimen was well tolerated. Encouraging efficacy signals were observed in both Maintenance and Refractory cohorts. Updated outcomes and correlative analyses are forthcoming. Citation Format: Andrea Wang-Gillam, Robert McWilliams, A. Craig Lockhart, Benjamin R Tan, Rama Suresh, Kian-Huat Lim, Katrina S. Pedersen, Nikolaos Trikalinos, Olivia Aranha, Haeseong Park, Lee Ratner, Nicholas Boice, David G. Denardo. Phase I study of defactinib combined with pembrolizumab and gemcitabine in patients with advanced cancer: Experiences of pancreatic ductal adenocarcinoma (PDAC) patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT118.

Abstract 3842: Histone methyltransferase G9a promotes migration, invasion of non-small cell lung cancer through enhancing FAK and NF-kB signal pathways

Abstract Overexpression of euchromatic histone methyltransferase 2 (EHMT2 or G9a) is associated with carcinogenesis and poor prognosis in a number of cancer types. In this study, we investigated the effect of G9a on invasion of non-small cell lung cancer (NSCLC) cells and the mechanism underlying cancer cell invasion. Knockdown of G9a was shown to drastically suppress in vitro cellular proliferation, migration, and invasion of A549 and H1299 NSCLC cells, while overexpression of G9a significantly enhanced the proliferation and invasion of these NSCLC cells. Additionally, knockdown of G9a led to significant decrease in expression of focal adhesion kinase (FAK) gene and activation of FAK pathway. UNC0638, a selective inhibitor of G9a, significantly suppressed both the proliferation, migration and invasion of these NSCLC cells, and concurrently led to a dramatic drop of global demethylation of H3K9 (H3K9me2) and suppressed the activation of FAK pathway. In addition, Defactinib, a potent FAK inhibitor, partially abolished the enhanced invasion by overexpression of G9a in these NSCLC cells. Furthermore, G9a was proved to regulate nuclear NF-κB transcriptional activity in NSCLC cells, and NF-κB inhibitor partially abolished the activated FAK signaling pathway by overexpressed G9a, which indicates that G9a-enhanced invasion and activation of FAK pathway may be mediated by NF-κB transcriptional activity. Notably, immunohistochemistry analysis further revealed that activation of FAK pathway was associated with overexpressed G9a in about 150 cases of NSCLC tissues. Altogether, these data have strongly demonstrated that G9a may promote invasion of NSCLC cells by upregulating FAK protein and pathway via enhancing NF-κB transcriptional activity, indicating a therapeutic implication of targeting these two pathways in NSCLC with overexpressed G9a. Citation Format: Ting Sun, Keqiang Zhang, Rajendra P. Pangeni, Wendong Li, Dan J. Raz. Histone methyltransferase G9a promotes migration, invasion of non-small cell lung cancer through enhancing FAK and NF-kB signal pathways [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3842.

Discovery of 7H-pyrrolo[2,3-d]pyridine derivatives as potent FAK inhibitors: Design, synthesis, biological evaluation and molecular docking study

Focal adhesion kinase (FAK) is an intracellular non-receptor tyrosine kinase responsible for development of various tumor types. Aiming to explore new potent inhibitors, two series of 2,4-disubstituted-7H-pyrrolo[2,3-d]pyrimidine derivatives were designed and synthesized on the base of structure-based design strategy. Biological evaluation indicated that most of these new compounds could potently inhibit FAK kinase, leading to the promising inhibitors against the proliferation of U-87MG, A-549, and MDA-MB-231 cancer cell lines. Among them, the optimized compound 18h potently inhibited the enzyme (IC50 = 19.1 nM) and displayed stronger potency than TAE-226 in U-87MG, A-549 and MDA-MB-231 cells, with IC50 values of 0.35, 0.24, and 0.34 μM, respectively. Compound 18h is a multi-target kinase inhibitor. Furthermore, compound 18h also exhibited relatively less cytotoxicity (IC50 = 3.72 μM) toward a normal human cell line, HK2. According to the flow cytometry and wound healing assay results, compound 18h effectively induced apoptosis and G0/G1 phase arrest of MDA-MB-231 cells and suppressed the migration of U-87MG, A-549 and MDA-MB-231 cells. The docking study of compound 18h was performed to elucidate its possible binding modes and to provide a structural basis for the further structural guidance design of FAK inhibitors. Collectively, these data support the further development of compound 18h as a lead compound for FAK-targeted anticancer drug discovery.

Design, synthesis, biological evaluation and molecular docking study of novel thieno[3,2-d]pyrimidine derivatives as potent FAK inhibitors

A series of 2,7-disubstituted-thieno[3,2-d]pyrimidine derivatives were designed, synthesized and evaluated as novel focal adhesion kinase (FAK) inhibitors. The novel 2,7-disubstituted-thieno[3,2-d]pyrimidine scaffold has been designed as a new kinase inhibitor platform that mimics the bioactive conformation of the well-known diaminopyrimidine motif. Most of the compounds potently suppressed the enzymatic activities of FAK and potently inhibited the proliferation of U-87MG, A-549 and MDA-MB-231 cancer cell lines. Among these derivatives, the optimized compound 26f potently inhibited the enzyme (IC50 = 28.2 nM) and displayed stronger potency than TAE-226 in U-87MG, A-549 and MDA-MB-231 cells, with IC50 values of 0.16, 0.27, and 0.19 μM, respectively. Compound 26f also exhibited relatively less cytotoxicity (IC50 = 3.32 μM) toward a normal human cell line, HK2. According to the flow cytometry results, compound 26f induced the apoptosis of MDA-MB-231 cells in a dose-dependent manner and effectively arrested MDA-MB-231 cells in G0/G1 phase. Further investigations revealed that compound 26f potently suppressed the migration of MDA-MB-231 cells. Collectively, these data support the further development of compound 26f as a lead compound for FAK-targeted anticancer drug discovery.

Discovery of 2,4-diarylaminopyrimidine derivatives bearing dithiocarbamate moiety as novel FAK inhibitors with antitumor and anti-angiogenesis activities

A series of 2,4-diarylaminopyrimidine derivatives containing dithiocarbamate moiety were designed by molecular hybridization strategy and synthesized for screening as inhibitors of focal adhesion kinase (FAK). Most of these compounds exhibit significant antiproliferative activities on human cancer cell lines expressing high levels of FAK at nanomolar concentrations. The compound 14z was identified as the most potent FAK inhibitor among these candidates. 14z has excellent anti-proliferative effect with IC50 values from 0.001 μM to 0.06 μM on HCT116, PC-3, U87-MG and MCF-7 cell lines and relatively less cytotoxicity to a nonmalignant cell line MCF-10A compared with MCF-7 cells (SI value > 10). 14z also exhibits significant FAK inhibitory activity (IC50 = 0.07 nM). In addition, compound 14z causes cell cycle arrest at G2/M and prompted apoptosis in both HCT116 and MCF-7 cells in a dose-dependent manner. Further studies show that compound 14z inhibits migration of MCF-7 and has anti-angiogenesis effect on HUVEC cells.

Design, synthesis and biological evaluation of sulfonamide-substituted diphenylpyrimidine derivatives (Sul-DPPYs) as potent focal adhesion kinase (FAK) inhibitors with antitumor activity

A class of sulfonamide-substituted diphenylpyrimidines (Sul-DPPYs) were synthesized to improve activity against the focal adhesion kinase (FAK). Most of these new Sul-DPPYs displayed moderate activity against the FAK enzyme with IC50 values of less than 100nM; regardless, they could effectively inhibit several classes of refractory cancer cell lines with IC50 values of less than 10µM, including the pancreatic cancer cell lines (AsPC-1, Panc-1 and BxPC-3), the NSCLC-resistant H1975 cell line, and the B lymphocyte cell line (Ramos cells). Results of flow cytometry indicated that inhibitor 7e promoted apoptosis of pancreatic cancer cells in a dose-dependent manner. In addition, it almost completely induced the apoptosis at a concentration of 10µM. Compound 7e may be selected as a potent FAK inhibitor for the treatment of pancreatic cancer.

Abstract A31: Merlin loss as a biomarker for defactinib (VS-6063) sensitivity: High frequency in malignant mesothelioma tumors.

Abstract Malignant pleural mesothelioma (MPM) is an aggressive tumor in the lining of the lung often caused by asbestos exposure. With a median survival on standard of care chemotherapy of only 12 months from diagnosis, new therapeutic modalities and predictive biomarkers are urgently needed for MPM patients. The Neurofibromatosis 2 (NF2) tumor suppressor gene that encodes the protein merlin is disrupted in approximately 50% of MPMs. The role of merlin in cell adhesion, invasion and cell motility may be partially mediated through the focal adhesion kinase (FAK), an important signaling node downstream of integrin cell adhesion proteins. An examination of 15 mesothelioma cell lines grown in 3-dimensional Matrigel culture demonstrates that low merlin by immunoblotting correlated with increased sensitivity to the FAK inhibitor, defactinib (VS-6063). An immunohistochemistry (IHC) test for merlin may be an optimal clinical tumor specimen measurement for merlin loss, provided that merlin reduction or loss is correlated with other indicators of NF2 change. The presence or absence of merlin and NF2 was evaluated using MPM patient-derived xenograft (PDX) tumor models using merlin IHC and an NF2 Fluorescence In situ Hybridization (FISH), as well as Western blotting to determine merlin levels in the tumor lysates. The PDX MPM-0235 tumor had low merlin by Western blotting, merlin IHC, and NF2 FISH, whereas PDX MPM-0237 showed high merlin levels by Western blotting, merlin IHC, and diploid chromosome 22 by FISH. In addition to PDX analysis, Merlin IHC and NF2 FISH optimized by these conditions was evaluated with in patient MPM Tissue Microarrays (TMAs) of 64 primary tumors. Chromosome 22 monosomy was significantly more frequent than NF2 regional deletion of chromosome 22. We observed that 42% of the tumors had a low merlin IHC score (merlin-low) that correlated with loss of NF2 (unpaired t-test, p<0.029). In a second cohort of archived tumor specimens from 300 MPM patients treated at one clinical site, we observed a similar association between NF2 loss/deletion by FISH and merlin-low IHC (unpaired t-test, p=0.0001). While phosphoFAK Y397 IHC (an indicator of FAK activation) have high IHC values in some tumors that are merlin-low, these two marker trends were not statistically associated for all the tumors in the cohort. These data support the clinical development of a merlin IHC test for evaluation of NF2-mutated malignant mesothelioma. Merlin IHC will be used as a predictive biomarker for responsiveness to defactinib, a selective and potent FAK inhibitor under investigation in a Phase 2 registration-directed clinical trial for patients with MPM. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A31. Citation Format: David T. Weaver, Irina Shapiro, Christian Vidal, Qunli Xu, Mahesh Padval, Jonathan Pachter, Daniel Paterson, Jullianne Barlow, William Richards, Sabina Signoretti, Raphael Bueno. Merlin loss as a biomarker for defactinib (VS-6063) sensitivity: High frequency in malignant mesothelioma tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A31.

Pharmacokinetics (PK) of PF-562271, a focal adhesion kinase (FAK) inhibitor, and its effect on CYP3A in patients with advanced nonhematologic malignancies.

2553 Background: FAK transduces signaling from integrins and growth factors to modulate tumor cell invasion, proliferation, and survival. PF-562271, a potent FAK inhibitor, is under development as an anticancer agent. Preclinical studies demonstrated that PF-562271 is an inhibitor of its primary metabolizing enzyme, CYP3A. PF-562271 PK and its effect on CYP3A were investigated in a dose-escalation trial in patients with nonhematologic malignancies. Methods: Escalating doses of PF-562271 were administered orally to a total of 67 patients twice a day (BID) or once a day (QD), with or without food. Serial serum samples were collected after the first dose and at steady state to determine PK of PF-562271. To evaluate the effect of PF-562271 on CYP3A activity, plasma PK of orally administered midazolam were determined prior to PF-562271 administration and after repeated PF-562271 dosing to steady state in 8 patients who received the recommended phase 2 dose of 125 mg BID. Serum PF-562271 and plasma midazolam concentrations were determined using validated HPLC-MS/MS methods. The concentration-time data for PF-562271 and midazolam were analyzed by noncompartmental methods. Results: After a single oral dose, PF-562271 was readily absorbed with the maximum serum concentration achieved in 0.5 to 6 hours. The increases in systemic exposure (AUCinf) were dose proportional over the 5 to 25 mg range, but greater than dose proportional from 35 to 225 mg. After multiple oral doses, PF-562271 demonstrated nonlinear accumulation in exposure; the mean ratio of steady state AUC during a dose interval to AUCinf after the first dose ranged from 1.3 to 5.3, indicating time-dependent PK. Similar PK parameters for PF-562271 were observed at comparable doses given with or without food. When co-administered, PF-562271 (125 mg BID) increased total midazolam plasma exposure approximately 5.9-fold. Conclusions: PF-562271 displayed time- and dose-dependent nonlinear PK, and is a potent CYP3A inhibitor. The nonlinear PK of PF-562271 likely resulted from auto-inhibition of CYP3A. In the limited number of subjects evaluated, food did not substantially alter the PK of PF-562271. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Pfizer Pfizer

Abstract A86: Design, synthesis, and SAR of focal adhesion kinase (FAK) inhibitors

Abstract Focal adhesion kinase (FAK) is a non-tyrosine kinase that localizes to focal adhesion plaques. It is activated in response to intergin binding to cellular ligands and when phosphorylated inhibits anoikis allowing for anchorage independent cell growth. Recent studies have shown increased FAK expression and phosphorylation status in many types of invasive and aggressive human tumors strongly suggesting FAK is a possible target for anticancer chemotherapy. Literature, in house HTS and de novo studies identified 2, 4-diaminopyrimidines as potent FAK inhibitors. Early SAR efforts quickly determined that smaller substituents, particularly CF3, were optimal in the C5 position. Parallel medicinal chemistry strategies were executed for the C2 and C4 positions. These studies suggested that substituted aryl and fused heteroaryl groups at the C2 position in conjunction with substituted phenyl and heterocycles at the C4 position imparted optimum activity and metabolic stability. Inhibitor-FAK co-crystal structures were utilized to guide in the SAR strategy around the 2, 4-diaminopyrimidine template which afforded several lead compounds. The team's effort culminated in the advancement of PF-562,271 as a potent and reversible inhibitor of FAK (kinase IC50 of 2 nM and cell IC50 of 5 nM) that is > 100x selective against a long list of non-target kinases. In summary, detailed SAR studies were executed on the 2, 4-diaminopyrimidine templates that produced potent inhibitors of FAK with improved ADME properties, and identified a novel and potent series of FAK inhibitors that are selective against most other kinases and have shown activity in clinical trials. This poster will present design, synthesis, challenging chemistry, optimization, and complete inhibitor chemical structures of lead analogs. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A86.

3D cell cultures of human head and neck squamous cell carcinoma cells are radiosensitized by the focal adhesion kinase inhibitor TAE226

Background and purpose Focal adhesion kinase (FAK), a main player in integrin signaling and survival, is frequently overexpressed in human cancers and therefore postulated as potential target in cancer therapy. The aim of this study was to evaluate the radiosensitizing potential of the FAK inhibitor TAE226 in three-dimensional (3D) tumor cell cultures. Materials and methods Head and neck squamous cell carcinoma (HNSCC) cells (FaDu, UT-SCC15, UT-SCC45), lung cancer cells (A549), colorectal carcinoma cells (DLD-1, HCT-116) and pancreatic tumor cells (MiaPaCa2, Panc1) were treated with different concentrations of TAE226 (0–1 μm; 1 or 24 h) without or in combination with irradiation (0–6 Gy, X-ray, single dose). Subsequently, 3D clonogenic survival assays (laminin-rich extracellular matrix) and Western blotting (expression/phosphorylation, e.g. FAK, Akt, ERK1/2) were performed. Results All investigated 3D cell cultures showed a dose-dependent reduction in clonogenic survival by TAE226. Intriguingly, TAE226 only significantly radiosensitized 3D HNSCC cell cultures accompanied by a pronounced dephosphorylation of FAK, Akt and ERK1/2. Conclusions Our data demonstrate TAE226 as potent FAK inhibitor that enhances the cellular radiosensitivity particularly of HNSCC cells grown in a 3D cell culture model. Future in vitro and in vivo investigations will clarify, to which extent this approach might be clinically relevant for radiotherapy of HNSCC.

3′,4′‐Dihydroxyflavonol down‐regulates monocyte chemoattractant protein‐1 in smooth muscle: role of focal adhesion kinase and PDGF receptor signalling

We investigated the effects of a synthetic flavonol, 3',4'-dihydroxyflavonol (DiOHF) on the expression of monocyte chemoattractant protein-1 (MCP-1) in rat vascular smooth muscle cells. MCP-1 expression was assessed by quantitative real-time PCR and protein phosphorylation by immunoprecipitation and Western blots. DiOHF (1-30 micromol x L(-1)) concentration-dependently reduced MCP-1 expression in both quiescent cells and cells stimulated with platelet-derived growth factor (PDGF) or interleukin 1-beta. The effect of DiOHF was associated with a suppression of focal adhesion kinase (FAK)-mediated signalling. In vitro kinase assays demonstrated that DiOHF is a potent inhibitor of FAK kinase activity (EC(50)= 2.4 micromol x L(-1)). Expression of FAK-related non-kinase reduced basal MCP-1 expression, but not that induced by PDGF or interleukin 1-beta. DiOHF also inhibited autophosphorylation of PDGF receptors. The PDGF receptor inhibitor AG-1296 potently suppressed basal and PDGF-induced MCP-1 expression. Inhibition of extracellular signal-regulated kinase activation by DiOHF, either directly or indirectly, may also be involved in its effects on MCP-1 expression. DiOHF had no inhibitory effect on either p38 or nuclear factor-kappaB activation. Moreover, DiOHF inhibited smooth muscle cell spreading (a FAK-mediated response) and proliferation. This is the first report on a flavonoid compound (DiOHF) that is a potent FAK inhibitor. DiOHF also inhibits PDGF receptor autophosphorylation. These effects underlie the inhibitory action of DiOHF on MCP-1 expression in smooth muscle cells. Our results suggest that DiOHF might be a useful tool for dissection of the (patho)physiological roles of FAK signalling.

Design and synthesis of 7H-pyrrolo[2,3-d]pyrimidines as focal adhesion kinase inhibitors. Part 2

A series of 2-amino-9-aryl-7H-pyrrolo[2,3-d]pyrimidines were designed and synthesized as focal adhesion kinase (FAK) inhibitors using molecular modeling in conjunction with a co-crystal structure. Chemistry was developed to introduce functionality onto the 9-aryl ring, which resulted in the identification of potent FAK inhibitors. In particular, compound 32 possessed single-digit nanomolar IC50 and represents one of the most potent FAK inhibitors discovered to date.