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.

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.

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 (GI(50) = 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.

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.

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.

Epigenetic silencing of the endothelin-B receptor gene in non-small cell lung cancer.

Endothelin-1 is overexpressed in several tumor types. Activation of the endothelin-A (ETA) receptor may promote cell growth, angiogenesis and invasion, and inhibits the apoptotic process, while activation of the endothelin-B (ETB) receptor may induce cell death by apoptosis and inhibit tumor progression. Hypermethylation and subsequent silencing of the ETB receptor gene promoter has been reported in some cancer types. As the endothelin pathway is subject to research for pharmacological cancer treatment, we investigated the extent of epigenetic deregulation of the ETB receptor gene in non-small cell lung cancer (NSCLC). We scanned 64 NSCLC paired tumor/normal surgical specimens for the ETB receptor promoter for methylation by developing four pyrosequencing assays that covered 24 CpGs. The ETB receptor promoter was significantly hypermethylated in 31 (48%) of tumor samples, presenting considerably higher methylation in 22/24 CpG sites compared with the normal counterpart tissues. ETB receptor mRNA levels were reduced in all lung tumors compared with normal adjacent lung tissue, indicating the potentially important involvement of this gene in lung cancer development. Furthermore, tumor samples with ETB receptor gene methylation tended to have lower receptor mRNA levels compared with unmethylated tumor specimens, suggesting a primary epigenetic role in ETB receptor silencing. Our results point to a significant involvement of ETB receptor epigenetic deregulation in the pathogenesis of lung cancer making the gene a promising candidate biomarker for response to regimens modulating the endothelin axis.

Neurotrophic effects of BDNF on embryonic gonadotropin-releasing hormone (GnRH) neurons.

Secretion of gonadotropin-releasing hormone (GnRH) at the median eminence is the essential activator of the reproductive axis. The mechanisms by which embryonic GnRH neurons migrate from the olfactory placode to the preoptic area and then elaborate neurites that course through the hypothalamus to terminate at the median eminence are largely unknown. We investigated the hypothesis that GnRH neurite outgrowth is promoted by brain-derived neurotrophic factor (BDNF) because GnRH neurites course through BDNF-rich areas of the forebrain during their development. Confocal microscopy revealed that most (86%) cultured embryonic GnRH cells tagged with a green fluorescent protein reporter were immunoreactive for TrkB. In primary cultures of E12.5 olfactory tissue, treatment with BDNF induced a dose-dependent increase in neurite outgrowth, but had no discernible effect on branching. BDNF induced phosphorylation of Ca(2+)/cAMP response element-binding protein (pCREB) in both GnRH and non-GnRH cells in these cultures. This was not associated with phosphorylation of ERK in GnRH-immunoreactive cells, though BDNF treatment did stimulate pERK in neighbouring non-GnRH cells. Promotion of neurite outgrowth is unlikely therefore to result from activation of the Ras-MAPK/ERK pathway. We conclude that the developing GnRH secretory system is directly sensitive to BDNF and that this polypeptide functions as a neurotrophic factor for GnRH neurons.