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-KDRrelated 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. Cancer Res; 72(8); 2045-56. Ó2012 AACR.
This demonstration of their ability to directly activate nuclear receptors, leading to nuclear receptor cross-talk, has important potential implications for their use within a polypharmacy paradigm.
ABSTRACT:Intestinal secretory movement of the fluoroquinolone antibiotic, ciprofloxacin, may limit its oral bioavailability. Active ATP-binding cassette ( , and verapamil as ABC-selective inhibitors. In addition, the regional variation in secretory capacity was investigated using male Han Wistar rat intestine mounted in Ussing chambers, and the first indicative measurements of ciprofloxacin transport by ex vivo human jejunum were made. Active, Ko143-sensitive ciprofloxacin secretion was observed in bcrp1-MDCKII cell layers, but in low-passage (BCRP-expressing) Caco-2 cell layers only a 54% fraction was Ko143-sensitive. Ciprofloxacin accumulation was lower in MRP4-HEK293 cells than in the parent line, indicating that ciprofloxacin is also a substrate for this transporter. Ciprofloxacin secretion by Caco-2 cell layers was not inhibited by MK571. Secretory flux showed marked regional variability in the rat intestine, increasing from the duodenum to peak in the ileum. Ciprofloxacin secretion was present in human jejunum and was reduced by Ko143 but showed marked interindividual variability. Ciprofloxacin is a substrate for human and rodent BCRP. An additional pathway for ciprofloxacin secretion exists in Caco-2 cells, which is unlikely to be MRP(4)-mediated. BCRP is likely to be the dominant transport mechanism for ciprofloxacin efflux in both rat and human jejunum.
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