The discovery and optimization of a series of 4-aminocinnoline-3-carboxamide inhibitors of Bruton's tyrosine kinase are reported. A fragment-based screening approach incorporating X-ray co-crystallography was used to identify a cinnoline fragment and characterize its binding mode in the ATP binding site of Btk. Optimization of the fragment hit resulted in the identification of a lead compound which reduced paw swelling in a dose- and exposure-dependent fashion in a rat model of collagen-induced arthritis.

PurposeThis study compared the pharmacokinetics of PF-06439535, a potential bevacizumab biosimilar, to bevacizumab sourced from the European Union (bevacizumab-EU) and USA (bevacizumab-US), and of bevacizumab-EU to bevacizumab-US.MethodsIn this double-blind study, 102 healthy males, aged 21–55 years, were randomized 1:1:1 to receive a single 5 mg/kg intravenous dose of PF-06439535, bevacizumab-EU, or bevacizumab-US. Pharmacokinetic assessments were conducted for 71 days, with additional safety and immunogenicity assessments until day 100. Pharmacokinetic similarity was achieved if 90 % confidence intervals (CIs) for the test-to-reference ratios of the maximum serum concentration (Cmax), area under the serum concentration–time curve from zero to infinity (AUC0–∞), and from zero to time of last quantifiable concentration (AUC0–t) were within the 80.00–125.00 % bioequivalence acceptance window.ResultsThe three study drugs exhibited similar pharmacokinetic properties. For the comparisons of PF-06439535 to bevacizumab-EU or bevacizumab-US, and of bevacizumab-EU to bevacizumab-US, the 90 % CIs for the ratios of Cmax, AUC0–t, and AUC0–∞ were all within 80.00–125.00 %. Two, one, and two subjects treated with PF-06439535, bevacizumab-EU, and bevacizumab-US, respectively, tested positive for antidrug antibodies, none of whom tested positive for neutralizing antibodies. Treatment-related adverse events were reported in 15.2, 25.7, and 18.2 % of subjects in the PF-06439535, bevacizumab-EU, and bevacizumab-US treatment arms, respectively.ConclusionsThis study demonstrated the pharmacokinetic similarity of PF-06439535 to both bevacizumab-EU and bevacizumab-US, and of bevacizumab-EU to bevacizumab-US. The safety profile (including immunogenicity) was similar in the three treatment groups, with no significant safety findings reported.Electronic supplementary materialThe online version of this article (doi:10.1007/s00280-016-3001-2) contains supplementary material, which is available to authorized users.

Fexofenadine is a nonsedative antihistamine that exhibits good oral bioavailability despite its zwitterionic chemical structure and efflux by P-gp. Evidence exists that multiple uptake and efflux transporters play a role in hepatic disposition of fexofenadine. However, the roles of specific transporters and their interrelationship in intestinal absorption of this drug are unclear. This study was designed to elucidate vectorial absorptive transport of fexofenadine across Caco-2 cells involving specific apical uptake and efflux transporters as well as basolateral efflux transporters. Studies with cellular models expressing single transporters showed that OATP2B1 expression stimulated uptake of fexofenadine at pH 6.0. Apical uptake of fexofenadine into Caco-2 cells was decreased by 45% by pretreatment with estrone 3-sulfate, an OATP inhibitor, at pH 6.0 but not at pH 7.4, indicating that OATP2B1 mediates apical uptake of fexofenadine into these cells. Examination of fexofenadine efflux from preloaded Caco-2 cells in the presence or absence of (i) the MRP inhibitor MK-571 and (ii) the P-gp inhibitor GW918 showed that apical efflux is predominantly mediated by P-gp, with a small contribution by MRP2, whereas basolateral efflux is predominantly mediated by MRP3. These results also showed that while OSTαβ is functionally active in the basolateral membrane of Caco-2 cells, it does not play a role in the export of fexofenadine. MK-571 decreased the absorptive transport of fexofenadine by 17%. However, the decrease in absorptive transport by MK-571 was 42% when P-gp was inhibited by GW918. The results provide a novel insight into a vectorial transport system mainly consisting of apical OATP2B1 and basolateral MRP3 that may play an important role in delivering hydrophilic anionic and zwitterionic drugs such as pravastatin and fexofenadine into systemic circulation upon oral administration.

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P-glycoprotein (P-gp) and CYP3A (cytochrome P450 3A, generally; Cyp3a, rodent enzyme) in the intestine can attenuate absorption of orally administered drugs. While some suggest that P-gp enhances intestinal metabolism by CYP3A/Cyp3a during absorption of a dual substrate, others suggest that P-gp reduces the metabolism in the intestine when substrates are at subsaturating concentrations. Hence, to elucidate the cellular mechanisms that can address these divergent reports, we studied intestinal absorption of the dual substrate loperamide in portal vein-cannulated P-gp-competent and P-gp-deficient mice. These studies showed that at low doses of loperamide, which produced intestinal concentrations near the apparent K m for oxidative metabolism, the bioavailability across the intestine (F G ) was 6-fold greater in the P-gp-competent mice than in P-gp-deficient mice. The higher F G of loperamide in the presence of P-gp was attributed to lower loperamide intestinal metabolism. However, at high doses of loperamide, the sparing of first-pass metabolism by P-gp was balanced against the attenuation of absorption by apical efflux, resulting in no net effect on F G . In vitro studies with intestinal tissue from P-gp-competent and -deficient mice confirmed that P-gp reduced the metabolic rate of loperamide during absorptive flux at concentrations near K m but had little effect on metabolism at higher (saturating) concentrations. Further, studies in which Cyp3a was chemically inactivated by aminobenzotriazole in P-gp-competent and -deficient mice, showed that P-gp and Cyp3a individually attenuated F G by 8-fold and 70-fold, respectively. These results confirmed that P-gp effectively protects loperamide at low doses from intestinal first-pass metabolism during intestinal absorption.