The fibroblast growth factor receptor inhibitor, derazantinib, has strong efficacy in human gastric tumor models and synergizes with paclitaxel in vivo.

Derazantinib (DZB) is an inhibitor of fibroblast growth factor receptors 1-3 (FGFR1-3), with additional activity against colony-stimulating-factor-1 receptor (CSF1R). We have profiled the activity of DZB in gastric cancer (GC) as monotherapy and combined with paclitaxel, and explored means of stratifying patients for treatment. The antiproliferative potency of DZB in vitro was quantified in 90 tumor cell lines and shown to correlate significantly with FGFR expression (<0.01) but not with FGFR DNA copy-number (CN) or FGFR mutations. In four GC cell lines in vitro , little or no synergy was observed with paclitaxel. In athymic nude mice, bearing cell-line derived xenografts (CDX) or patient-derived xenograft (PDX) GC models, DZB efficacy correlated highly significantly with FGFR gene expression ( r2 = 0.58; P = 0.0003; n = 18), but not FGFR mutations or DNA-CN. In FGFR-driven GC models, DZB had comparable efficacy to three other FGFR inhibitors and was more efficacious than paclitaxel. DZB had dose-dependent plasma pharmacokinetics but showed low brain penetration at all doses. GC models (one CDX and six PDX) were tested for sensitivity to the combination of DZB and paclitaxel and characterized by immunohistochemistry. The combination showed synergy (5) or additivity (2), and no antagonism, with synergy significantly associated ( P < 0.05) with higher levels of M2-type macrophages. The association of strong efficacy of the combination in vivo with M2 macrophages, which are known to express CSF1R, and the absence of synergy in vitro is consistent with the tumor microenvironment also being a factor in DZB efficacy and suggests additional means by which DZB could be stratified for cancer treatment in the clinic.

Probing the Effects of the FGFR-Inhibitor Derazantinib on Vascular Development in Zebrafish Embryos.

Angiogenesis is a fundamental developmental process and a hallmark of cancer progression. Receptor tyrosine kinases (RTK) are targets for cancer therapy which may include their action as anti-angiogenic agents. Derazantinib (DZB) is an inhibitor of the fibroblast growth factor receptors (FGFRs) 1-3 as well as other kinase targets including vascular endothelial growth factor receptor 2 (VEGFR2), colony stimulating factor-1 receptor (CSF1R) and platelet-derived growth factor beta receptor (PDGFRbeta). This study aimed to investigate the effect of DZB on blood vessel morphogenesis and to compare its activity to known specific FGFR and VEGFR inhibitors. For this purpose, we used the developing vasculature in the zebrafish embryo as a model system for angiogenesis in vivo. We show that DZB interferes with multiple angiogenic processes that are linked to FGF and VEGF signalling, revealing a potential dual role for DZB as a potent anti-angiogenic treatment.

Interlaboratory Analysis of Isavuconazole Plasma Concentration Assays Among European Laboratories.

BACKGROUND: Under certain circumstances, clinicians treating patients with isavuconazole for invasive aspergillosis or mucormycosis may use therapeutic drug monitoring. However, the accuracy and reproducibility of the various assays used by different laboratories for the quantification of isavuconazole plasma concentrations have yet to be determined. METHODS: Human plasma samples spiked with known concentrations of isavuconazole were provided to 27 European laboratories that took part in a "round-robin" test (an interlaboratory test performed independently at least 2 times; 2 rounds performed in the current study). Assay methods included liquid chromatography-tandem mass spectrometry (LC-MS/MS), LC with ultraviolet detection (LC-UV), LC with fluorescence detection (LC-FL), and bioassay. The accuracy and reproducibility compared with the known concentrations for each sample in each round were compared overall, between assays, and between laboratories. RESULTS: Twenty-seven laboratories participated in the study (LC-MS/MS, n = 15; LC-UV; n = 9; LC-FL, n = 1; bioassay, n = 2). In round 1, for nominal concentrations of 1000, 1700, 2500, and 4000 ng/mL, the mean (SD) determined concentrations were 1007 (183), 1710 (323), 2528 (540), and 3898 (842) ng/mL, respectively. In round 2, for nominal concentrations of 1200, 1800, 2400, and 4000 ng/mL, the mean (SD) determined concentrations were 1411 (303), 2111 (409), 2789 (511), and 4723 (798) ng/mL, respectively. Over both rounds, determined concentrations were consistently within 15% of the nominal concentrations for 10 laboratories (LC-MS/MS, n = 4; LC-UV, n = 5; bioassay, n = 1) and consistently exceeded the upper 15% margin for 7 laboratories (LC-MS/MS and LC-UV, n = 3 each; LC-FL, n = 1). CONCLUSIONS: Alignment of methodologies among laboratories may be warranted to improve the accuracy and reproducibility of therapeutic drug measurements.

Prediction of Safety Margin and Optimization of Dosing Protocol for a Novel Antibiotic using Quantitative Systems Pharmacology Modeling.

Elevations of liver enzymes have been observed in clinical trials with BAL30072, a novel antibiotic. In vitro assays have identified potential mechanisms for the observed hepatotoxicity, including electron transport chain (ETC) inhibition and reactive oxygen species (ROS) generation. DILIsym, a quantitative systems pharmacology (QSP) model of drug-induced liver injury, has been used to predict the likelihood that each mechanism explains the observed toxicity. DILIsym was also used to predict the safety margin for a novel BAL30072 dosing scheme; it was predicted to be low. DILIsym was then used to recommend potential modifications to this dosing scheme; weight-adjusted dosing and a requirement to assay plasma alanine aminotransferase (ALT) daily and stop dosing as soon as ALT increases were observed improved the predicted safety margin of BAL30072 and decreased the predicted likelihood of severe injury. This research demonstrates a potential application for QSP modeling in improving the safety profile of candidate drugs.

Tissue Distribution and Elimination of Isavuconazole following Single and Repeat Oral-Dose Administration of Isavuconazonium Sulfate to Rats.

Quantitative whole-body autoradiography was used to assess the distribution and tissue penetration of isavuconazole in rats following single and repeated oral-dose administration of radiolabeled isavuconazonium sulfate, the prodrug of isavuconazole. Following a single-dose administration of radiolabeled isavuconazonium sulfate (labeled on the active moiety), radioactivity was detectable within 1 h postdose in 56 of 65 tissue/fluid specimens. The highest maximum concentrations (Cmax) were observed in bile and liver (66.6 and 24.7 µg eq/g, respectively). The lowest Cmax values were in bone and eye lens (0.070 and 0.077 µg eq/g, respectively). By 144 h postdose, radioactivity was undetectable in all tissues/fluids except liver (undetectable at 336 h) and adrenal gland tissues (undetectable at 672 h). Following daily administration for up to 21 days, 1-h-postdose Cmax values were the highest on or before day 14 in all except seven tissues/fluids, of which only rectum mucosa and small intestine mucosa had Cmax values >25% higher than all other 1-h-postdose values. For 24-h-postdose Cmax values, only large intestine, large intestine mucosa, and urine had the highest Cmax values at day 21. The penetration of single oral doses of unlabeled isavuconazole (25 mg/kg of body weight isavuconazonium sulfate) and voriconazole (50 mg/kg) into rat brain (assessed using liquid chromatography-tandem mass spectrometry) was also compared. Brain concentration/plasma concentration ratios reached approximately 1.8:1 and 2:1, respectively. These data suggest that isavuconazole penetrates most tissues rapidly, reaches a steady state in most or all tissues/fluids within 14 days, does not accumulate in tissues/fluids over time, and achieves potentially efficacious concentrations in the brain.

Mechanisms of hepatotoxicity associated with the monocyclic ß-lactam antibiotic BAL30072.

BAL30072 is a new monocyclic ß-lactam antibiotic under development which provides a therapeutic option for the treatment of severe infections caused by multi-drug-resistant Gram-negative bacteria. Despite the absence of liver toxicity in preclinical studies in rats and marmosets and in single dose clinical studies in humans, increased transaminase activities were observed in healthy subjects in multiple-dose clinical studies. We, therefore, initiated a comprehensive program to find out the mechanisms leading to hepatocellular injury using HepG2 cells (human hepatocellular carcinoma cell line), HepaRG cells (inducible hepatocytes derived from a human hepatic progenitor cell line), and human liver microtissue preparations. Our investigations demonstrated a concentration- and time-dependent reduction of the ATP content of BAL30072-treated HepG2 cells and liver microtissues. BAL30072 impaired oxygen consumption by HepG2 cells at clinically relevant concentrations, inhibited complexes II and III of the mitochondrial electron transport chain, increased the production of reactive oxygen species (ROS), and reduced the mitochondrial membrane potential. Furthermore, BAL 30072 impaired mitochondrial fatty acid metabolism, inhibited glycolysis, and was associated with hepatocyte apoptosis. Co-administration of N-acetyl-L-cysteine partially protected hepatocytes from BAL30072-mediated toxicity, underscoring the role of oxidative damage in the observed hepatocellular toxicity. In conclusion, BAL30072 is toxic for liver mitochondria and inhibits glycolysis at clinically relevant concentrations. Impaired hepatic mitochondrial function and inhibition of glycolysis can explain liver injury observed in human subjects receiving long-term treatment with this compound.

Investigation of the species-dependent in vitro metabolism of BAL30630 by stable isotope labeling and isotope exchange experiments analyzed by capillary liquid chromatography coupled to mass spectrometry.

The in vitro metabolic profile of BAL30630, an antifungal piperazine propanol derivative, which inhibits the 1,3-beta-D-glucansynthase, was investigated by incubation with microsomes of several species and with rat hepatocytes. For the spotting of the metabolites, mixtures of BAL30630 with a stable isotope (deuterium) labeled analogue were incubated. The metabolic pattern comprises several oxidized metabolites. Based on isotope exchange experiments, their structures could be assigned to epoxide- and hydroxylated metabolites. In hepatocyte incubations, several glucuronides formed from these oxidized metabolites could be observed. From the analysis of the metabolic pattern in microsomes, products of carbamate hydrolysis were characterized. This hydrolysis was highly species dependent. In activated incubations and in rat hepatocytes, those metabolites were further oxidized. In incubations without NADPH activation, the resulting hydrolytic metabolites could be enriched without the subsequent oxidation. Final structural elucidation of the metabolites was performed using accurate mass determination and isotope exchange experiments, in which incubations were analyzed by deuterium exchange and capillary HPLC-QTof-MS and MS/MS. The use of non-radioactive, stabile isotope labeled drug analogues in combination with isotope exchange studies was essential in particular for a defined assignment of the functional groups in the structures of the investigated metabolites.

Elucidation of the in vitro metabolic profile of stable isotope labeled BAL19403 by accurate mass capillary liquid chromatography/quadrupole time-of-flight mass spectrometry and isotope exchange.

The in vitro metabolic pattern of BAL19403, a novel macrolide antibiotic, was investigated by capillary liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS) in incubations with human microsomes. For the elucidation of the metabolic pathway, BAL19403 labeled with four deuterium atoms (D4) was used, and detection of metabolites performed using mixtures of the unlabeled (H4) BAL19403 and its D4 analogue (1:1) as substrate. All metabolites appeared with similar chromatographic behavior. MS/MS spectra of BAL19403 and its metabolites are dominated by non-informative fragment ions. Therefore, the structure of the metabolites was elucidated mainly by accurate mass measurements with subsequent proposals of elemental compositions. Main biotransformations were N-demethylation, lactone ring hydrolysis, and oxidation. Additionally, N-dealkylation of the aromatic moiety was identified. This dealkylation results not only in formation of an aldehyde, according to the classical pathway, but also in formation of the corresponding alcohol and carboxylic acid. Final elucidation of their structures was possible, since this dealkylation takes place vicinal to the deuterium-labeled part of BAL19403 and interferes with D/H exchange. The degree of D/H exchange, determined by analysis of the metabolite isotopic pattern, was used to elucidate the adjacent functional group.

Comparative in vivo activity of BAL4815, the active component of the prodrug BAL8557, in a neutropenic murine model of disseminated Aspergillus flavus.

BACKGROUND: BAL8557 (WSA) is the water-soluble prodrug of the triazole BAL4815 with in vitro anti-Aspergillus activity. We compared the activity of oral BAL8557 with oral itraconazole, oral voriconazole and intravenous caspofungin in a temporarily neutropenic murine model of disseminated Aspergillus flavus. METHODS: Mice were immunosuppressed using cyclophosphamide, then infected. Mice were treated either 2 h pre-infection (PRE), or 4 or 24 h post-infection (4POST and 24POST, respectively). Treatment was for 10 days followed by 4 days of observation. Surviving mice were killed and liver, kidneys, lungs and brain cultured. BAL8557 groups included doses corresponding to approximately 30, 15, 6 and 3 mg/kg of the active BAL4815; comparators included itraconazole 25 and 10 mg/kg/dose, voriconazole (plus oral grapefruit) 25 and 10 mg/kg/day or caspofungin 1 mg/kg/day. In a simultaneous tissue burden study mice were treated for 3 days, kidneys removed and homogenized and burden measured by quantitative culture and quantitative PCR using fluorescence resonance energy transfer (FRET). RESULTS: Control mice had 83-100% mortality. Over 66% of BAL8557-treated mice survived after >6 mg/kg PRE or >15 mg/kg POST. In the PRE models BAL8557 (6 mg/kg) and caspofungin were 100% protective and itraconazole 67% protective, but voriconazole 10 mg/kg had 100% mortality (P = 0.0016). In the 4POST and 24POST models survival was >66% with BAL8557 30 and 15 mg/kg/dose and similar to voriconazole or itraconazole. In the 24POST groups, sterilization of all organs was achieved in 11/16 survivors treated with BAL8557. The quantitative PCR correlated with kidney fungal burden (r2 = 0.59). Earlier treatment reduced burdens. CONCLUSIONS: BAL8557 demonstrated impressive antifungal activity against A. flavus in this model, in both survival and tissue burden.

Investigation of low-abundant in vitro metabolites of stable isotope-labelled BAL4815 by accurate mass capillary-LC-ESI-qTof-MS and MS/MS.

The metabolic profile of BAL4815, an antifungal azole drug, was determined using in vitro rat hepatocyte incubations and subsequent analysis by capillary LC-qTof-MS and MS/MS including accurate mass determination. For the detection of the metabolites, a mixture of the drug and its deuterium-labelled analogue was used for incubations. Metabolic stability of BAL4815 was high in cultured rat hepatocytes. However, several low-abundant metabolites were detected by the use of capillary LC-qTof-MS and manual investigation of the data. The peak intensity of the most abundant metabolite was close to the limit of detection. Except for an apparent oxidation product, the masses of the other detected metabolites could not be assigned to a single and frequently occurring biotransformation. Accurate mass determination and possible elemental compositions suggested that metabolism occurred through a combination of glutathionylation and defluorination. This was verified using accurate mass MS/MS. The use of accurate mass measurements and the derived suggestions for the elemental compositions were essential to elucidate this atypical metabolic pathway. A mass accuracy better than 8 ppm could be achieved for most assigned MS and MS/MS signals with intensities less than 6 cps in the spectra.