A. Nigel Brooks

AZD4547: An Orally Bioavailable, Potent, and Selective Inhibitor of the Fibroblast Growth Factor Receptor Tyrosine Kinase Family

The fibroblast growth factor (FGF) signaling axis is increasingly implicated in tumorigenesis and chemoresistance. Several small-molecule FGF receptor (FGFR) kinase inhibitors are currently in clinical development; however, the predominant activity of the most advanced of these agents is against the kinase insert domain receptor (KDR), which compromises the FGFR selectivity. Here, we report the pharmacologic profile of AZD4547, a novel and selective inhibitor of the FGFR1, 2, and 3 tyrosine kinases. AZD4547 inhibited recombinant FGFR kinase activity in vitro and suppressed FGFR signaling and growth in tumor cell lines with deregulated FGFR expression. In a representative FGFR-driven human tumor xenograft model, oral administration of AZD4547 was well tolerated and resulted in potent dose-dependent antitumor activity, consistent with plasma exposure and pharmacodynamic modulation of tumor FGFR. Importantly, at efficacious doses, no evidence of anti-KDR-related effects were observed, confirming the in vivo FGFR selectivity of AZD4547. Taken together, our findings show that AZD4547 is a novel selective small-molecule inhibitor of FGFR with potent antitumor activity against FGFR-deregulated tumors in preclinical models. AZD4547 is under clinical investigation for the treatment of FGFR-dependent tumors.

Molecular Pathways: Fibroblast Growth Factor Signaling: A New Therapeutic Opportunity in Cancer

The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) signaling axis plays an important role in normal organ, vascular, and skeletal development. Deregulation of FGFR signaling through genetic modification or overexpression of the receptors (or their ligands) has been observed in numerous tumor settings, whereas the FGF/FGFR axis also plays a key role in driving tumor angiogenesis. A growing body of preclinical data shows that inhibition of FGFR signaling can result in antiproliferative and/or proapoptotic effects, both in vitro and in vivo, thus confirming the validity of the FGF/FGFR axis as a potential therapeutic target. In the past, development of therapeutic approaches to target this axis has been hampered by our inability to develop FGFR-selective agents. With the advent of a number of new modalities for selectively inhibiting FGF/FGFR signaling, we are now in a unique position to test and validate clinically the many hypotheses that have been generated preclinically. Clin Cancer Res; 18(7); 1855–62. ©2012 AACR.

Translating the Therapeutic Potential of AZD4547 in FGFR1-Amplified Non–Small Cell Lung Cancer through the Use of Patient-Derived Tumor Xenograft Models

Purpose: To investigate the incidence of FGFR1 amplification in Chinese non–small cell lung cancer (NSCLC) and to preclinically test the hypothesis that the novel, potent, and selective fibroblast growth factor receptor (FGFR) small-molecule inhibitor AZD4547 will deliver potent antitumor activity in NSCLC FGFR1–amplified patient-derived tumor xenograft (PDTX) models. Experimental Design: A range of assays was used to assess the translational relevance of FGFR1 amplification and AZD4547 treatment including in vitro lung cell line panel screening and pharmacodynamic (PD) analysis, FGFR1 FISH tissue microarray (TMA) analysis of Chinese NSCLC (n = 127), and, importantly, antitumor efficacy testing and PD analysis of lung PDTX models using AZD4547. Results: The incidence of FGFR1 amplification within Chinese patient NSCLC tumors was 12.5% of squamous origin (6 of 48) and 7% of adenocarcinoma (5 of 76). AZD4547 displayed a highly selective profile across a lung cell line panel, potently inhibiting cell growth only in those lines harboring amplified FGFR1 (GI50 = 0.003–0.111 μmol/L). AZD4547 induced potent tumor stasis or regressive effects in four of five FGFR1-amplified squamous NSCLC PDTX models. Pharmacodynamic modulation was observed in vivo, and antitumor efficacy correlated well with FGFR1 FISH score and protein expression level. Conclusions: This study provides novel epidemiologic data through identification of FGFR1 gene amplification in Chinese NSCLC specimens (particularly squamous) and, importantly, extends the clinical significance of this finding by using multiple FGFR1-amplified squamous lung cancer PDTX models to show tumor stasis or regression effects using a specific FGFR inhibitor (AZD4547). Thus, the translational science presented here provides a strong rationale for investigation of AZD4547 as a therapeutic option for patients with squamous NSCLC tumors harboring amplification of FGFR1. Clin Cancer Res; 18(24); 6658–67. ©2012 AACR.

Phytoestrogens and gonadotropin-releasing hormone pulse generator activity and pituitary luteinizing hormone release in the rat

Phytoestrogens can produce inhibitory effects on gonadotropin secretion in both animals and humans. The aims of this study were 2-fold: 1) to determine in vivo whether genistein and coumestrol act on the GnRH pulse generator to suppress hypothalamic multiunit electrical activity volleys and associated LH pulses and/or on the pituitary to suppress the LH response to GnRH; and 2) to examine the effect of these phytoestrogens on GnRH-induced pituitary LH release in vitro and to determine whether estrogen receptors are involved. Wistar rats were ovariectomized and chronically implanted with recording electrodes and/or indwelling cardiac catheters, and blood samples were taken every 5 min for 7--11 h. Intravenous infusion of coumestrol (1.6-mg bolus followed by 2.4 mg/h for 8.5 h) resulted in a profound inhibition of pulsatile LH secretion, a 50% reduction in the frequency of hypothalamic multiunit electrical activity volleys, and a complete suppression of the LH response to exogenous GnRH. In contrast, both genistein (1.6-mg bolus followed by 2.4 mg/h for 8.5 h) and vehicle were without effect on pulsatile LH secretion. Coumestrol (10(-5) M; over 2 or 4 h) suppressed GnRH-induced pituitary LH release in vitro, an effect blocked by the antiestrogen ICI 182,780. It is concluded that coumestrol acts centrally to reduce the frequency of the hypothalamic GnRH pulse generator. In addition, the inhibitory effects of coumestrol on LH pulses occur at the level of the pituitary by reducing responsiveness to GnRH via an estrogen receptor-mediated process.

Obstacles to the prediction of estrogenicity from chemical structure: assay-mediated metabolic transformation and the apparent promiscuous nature of the estrogen receptor.

Information on structure-activity relationships (SAR) and pathways of metabolic activation would facilitate the preliminary screening of chemicals for estrogenic potential. Published crystallographic studies of the estrogen receptor (ER) imply an essential role of the two hydroxyl groups on estradiol (17beta-E(2)) for its binding to ER. The influence of these hydroxyl groups on ER binding and estrogenicity was evaluated by the study of 17beta-E(2) with one or both of these hydroxyl groups removed (17beta-desoxyestradiol and 3, 17beta-bisdesoxyestradiol, respectively). 6-Hydroxytetralin (17beta-E(2) with its C- and D-rings removed) and other synthetic estrogens were also studied. The estrogenicity assays comprised a yeast ER-mediated transcription assay, mammalian cell transcription assays incorporating either ER alpha or ER beta, and the immature rat uterotrophic assay. With the exception of 6-hydroxytetralin in the uterotrophic assay, all the chemicals were active in all the assays. Hydroxylation of the two desoxy compounds to estradiol was shown to occur in immature female rats, but metabolism was not implicated in the responses observed in the ER-binding and yeast systems. It is concluded that the 3-hydroxyl and 17beta-hydroxyl groups of 17beta-E(2) are not absolute requirements for estrogenicity. It would therefore be of value to the derivation of SAR for estrogenicity were the crystal structure of the bisdesoxy-E(2)/ER complex to be evaluated.

AZD3514: A Small Molecule That Modulates Androgen Receptor Signaling and Function In Vitro and In Vivo

Continued androgen receptor (AR) expression and signaling is a key driver in castration-resistant prostate cancer (CRPC) after classical androgen ablation therapies have failed, and therefore remains a target for the treatment of progressive disease. Here, we describe the biological characterization of AZD3514, an orally bioavailable drug that inhibits androgen-dependent and -independent AR signaling. AZD3514 modulates AR signaling through two distinct mechanisms, an inhibition of ligand-driven nuclear translocation of AR and a downregulation of receptor levels, both of which were observed in vitro and in vivo. AZD3514 inhibited testosterone-driven seminal vesicle development in juvenile male rats and the growth of androgen-dependent Dunning R3327H prostate tumors in adult rats. Furthermore, this class of compound showed antitumor activity in the HID28 mouse model of CRPC in vivo. AZD3514 is currently in phase I clinical evaluation. Mol Cancer Ther; 12(9); 1715–27. ©2013 AACR.

Identification of a possible association between carbon tetrachloride–induced hepatotoxicity and interleukin‐8 expression

Hepatotoxicants can elicit liver damage by various mechanisms that can result in cell necrosis and death. The changes induced by these compounds can vary from gross alterations in DNA repair mechanisms, protein synthesis, and apoptosis, to more discrete changes in oxidative damage and lipid peroxidation. However, little is known of the changes in gene expression that are fundamental to the mechanisms of hepatotoxicity. We have used DNA microarray technology to identify gene transcription associated with the toxicity caused by the hepatotoxicant carbon tetrachloride. Labeled poly A+ RNA from cultured human hepatoma cells (HepG2) exposed to carbon tetrachloride for 8 hours was hybridized to a human microarray filter. We found that 47 different genes were either upregulated or downregulated more than 2‐fold by the hepatotoxicant compared with dimethyl formamide, a chemical that does not cause liver cell damage. The proinflammatory cytokine interleukin‐8 (IL‐8) was upregulated over 7‐fold compared with control on the array, and this was subsequently confirmed at 1 hour and 8 hours by Northern blot analyses. We also found that carbon tetrachloride caused a time‐dependent increase in interleukin‐8 protein release in HepG2 cells, which was paralleled by a decrease in cell viability. These data demonstrate that carbon tetrachloride causes a rapid increase in IL‐8 mRNA expression in HepG2 cells and that this increase correlates with a later and significant increase in the levels of interleukin‐8 protein. These results illustrate the potential of microarray technology in the identification of novel gene changes associated with toxic processes.

Discovery of AZD3514, a small-molecule androgen receptor downregulator for treatment of advanced prostate cancer.

Removal of the basic piperazine nitrogen atom, introduction of a solubilising end group and partial reduction of the triazolopyridazine moiety in the previously-described lead androgen receptor downregulator 6-[4-(4-cyanobenzyl)piperazin-1-yl]-3-(trifluoromethyl)[1,2,4]triazolo[4,3-b]pyridazine (1) addressed hERG and physical property issues, and led to clinical candidate 6-(4-{4-[2-(4-acetylpiperazin-1-yl)ethoxy]phenyl}piperidin-1-yl)-3-(trifluoromethyl)-7,8-dihydro[1,2,4]triazolo[4,3-b]pyridazine (12), designated AZD3514, that is being evaluated in a Phase I clinical trial in patients with castrate-resistant prostate cancer.

A phase 1b open label multicentre study of AZD4547 in patients with advanced squamous cell lung cancers.

Purpose: Squamous cell lung cancers (SQCLC) account for 25% of all NSCLCs, yet the prognosis of these patients is poor and treatment options are limited. Amplified FGFR1 is one of the most common oncogenic events in SQCLCs, occurring in approximately 20% of cases. AZD4547 is a potent and selective FGFR1-3 inhibitor with antitumor activity in FGFR1-amplified SQCLC cell lines and patient-derived xenografts. Experimental Design: On the basis of these data, we performed a phase I study of AZD4547 in patients with previously treated stage IV FGFR1-amplified SQCLCs (NCT00979134). FGFR1 amplification (FGFR1:CEP8 ≥ 2) was determined by FISH. The primary endpoint was safety/tolerability. Secondary endpoints included antitumor activity, pharmacokinetics, pharmacodynamics, and molecular analyses. Results: Fifteen FGFR1-amplified patients were treated. The most common related adverse events (AE) were gastrointestinal and dermatologic. Grade ≥3–related AEs occurred in 3 patients (23%). Thirteen patients were evaluable for radiographic response assessment. The overall response rate was 8% (1 PR). Two of 15 patients (13.3%) were progression-free at 12 weeks, and the median overall survival was 4.9 months. Molecular tests, including next-generation sequencing, gene expression analysis, and FGFR1 immunohistochemistry, showed poor correlation between gene amplification and expression, potential genomic modifiers of efficacy, and heterogeneity in 8p11 amplicon. Conclusions: AZD4547 was tolerable at a dosage of 80 mg oral twice a day, with modest antitumor activity. Detailed molecular studies show that these tumors are heterogeneous, with a range of mutational covariates and stark differences in gene expression of the 8p11 amplicon that likely explain the modest efficacy of FGFR inhibition in this disease. Clin Cancer Res; 23(18); 5366–73. ©2017 AACR.

Abstract 1917: Translating the therapeutic potential of AZD4547 in FGFR1-amplified non-small cell lung cancer through the use of primary lung explant models

Lung cancer remains one of the most lethal and prevalent cancer types within developed nations. Despite recent advances in molecularly-targeted treatment options (epidermal growth factor and anaplastic lymphoma kinase inhibitors for EGFR mutations and EML4-ALK fusions respectively), there still remains significant therapeutic need, particularly for squamous cell lung cancer. Indeed, further molecular segmentation has been suggested recently through the discovery of frequent genetic amplification of the fibroblast growth factor receptor 1 gene (FGFR1) in squamous cell lung clinical samples. Preclinical validation of the tumour cells’ dependence on FGFR1 signaling in FGFR1-amplified lung cell lines has subsequently been confirmed, both in vitro and in vivo (1) . AZD4547 is an orally bioavailable, highly selective and potent small molecule inhibitor which competes with ATP for binding to FGF receptors 1, 2 and 3, thereby inhibiting autophosphorylation and downstream signalling (2) . This agent is currently in Phase I clinical studies. Cell line derived xenografts have proven utility as models for pharmacological studies (PK/PD) and as efficacy models in cases of oncogene addiction. However, the utility of cell line xenografts is limited by the lack of molecular and cellular heterogeneity. Primary explants offer the promise of better disease models through increased diversity of molecular lesions and the presence of significant stromal cell components. Characterisation of 127 Chinese NSCLC clinical samples using FGFR1 fluorescent in-situ hybridisation (FISH) analysis revealed an FGFR1 amplification rate of 13% (6/48) within squamous cell carcinoma. A bank of 26 primary lung explant tumour models were established and characterised - 4 of these harboured genetically amplified FGFR1 and corresponding high level protein expression. In vivo efficacy studies demonstrated rapid, potent and durable tumour regression in these models in response to oral daily dosing of AZD4547 (94-199% tumour growth inhibition after 2-3 weeks dosing of 12 or 25mg/kg AZD4547, all models p= Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1917. doi:1538-7445.AM2012-1917