Galunisertib (LY2157299), a promising small-molecule inhibitor of the transforming growth factor-beta (TGF-β) receptor, is currently in mono- and combination therapy trials for various cancers including glioblastoma, hepatocellular carcinoma and breast cancer. Using genetically modified mouse models, we investigated the roles of the multidrug efflux transporters ABCB1 and ABCG2, the OATP1A/1B uptake transporters and the drug-metabolizing CYP3A complex in galunisertib pharmacokinetics. In vitro, galunisertib was vigorously transported by human ABCB1, and moderately by mouse Abcg2. Orally administered galunisertib (20 mg/kg) was very rapidly absorbed. Galunisertib brain-to-plasma ratios were increased by ~24-fold in Abcb1a/1b-/- and Abcb1a/1b;Abcg2-/- mice compared to wild-type mice, but not in single Abcg2-/- mice, whereas galunisertib oral availability was not markedly affected. However, recovery of galunisertib in the small intestinal lumen was strongly reduced in Abcb1a/1b-/- and Abcb1a/1b;Abcg2-/- mice. Oral coadministration of the ABCB1/ABCG2 inhibitor elacridar boosted galunisertib brain accumulation in wild-type mice to equal the levels seen in Abcb1a/1b;Abcg2-/- mice. Oatp1a/1b deficiency did not alter oral galunisertib pharmacokinetics or liver distribution. Cyp3a-/- mice showed a 1.9-fold higher plasma AUC0-1 hr than wild-type mice, but this difference disappeared over 8 hr. Also, transgenic human CYP3A4 overexpression did not significantly alter oral galunisertib pharmacokinetics. Abcb1 thus markedly restricts galunisertib brain penetration and affects its intestinal disposition, possibly through biliary excretion. Elacridar coadministration could fully inhibit both processes, without causing acute toxicity. Moreover, mouse Cyp3a, but not human CYP3A4, may eliminate galunisertib at high plasma concentrations. These insights may help to guide the further clinical development and application of galunisertib.
Because ifosforamide mustard (IFM) is the active alkylating metabolite of ifosfamide (IFO) it is of particular interest in the pharmacokinetic analysis of patients undergoing IFO treatment. This paper presents an assay for the simultaneous determination of IFM and IFO after derivatization with diethyldithiocarbamate (DDTC), subsequent liquid-liquid extraction of the plasma with acetonitrile (AcN) and using reversed phase high performance liquid chromatography (RP-HPLC) with ultra-violet (UV) detection at 276 nm. Structural confirmation of the analytes was accomplished using mass spectrometry (MS). Reaction conditions such as incubation duration, temperature, and concentration of derivatization agent were investigated; 30 min at 70°C with 100 mg/mL DDTC was optimal. The presented analytical method proved to be accurate, precise, and linear for IFM and IFO concentrations, ranging from 0.100–50.0 and 0.100–100 μg/mL, respectively, and with lower limits of quantitation of 0.100 μg/mL for both analytes. A typical patient pharmacokinetic profile is presented to demonstrate the applicability of the assay in clinical samples. The analytical method could be employed in high-throughput clinical analysis of IFM and IFO patient samples.
Milciclib is a promising cyclin-dependent kinase inhibitor currently in phase II clinical trials to treat several types of cancer. The first bioanalytical method for the quantitative analysis of milciclib in several biomatrices using liquid chromatography-tandem mass spectrometry is described here. This method was fully validated in human plasma according to FDA and EMA guidelines, and partially validated in mouse plasma, homogenates of mouse brain, kidney, liver, small intestine, spleen, and tissue culture medium. Palbociclib, an analog compound, was used as internal standard. A simple and fast sample pre-treatment by protein precipitation with acetonitrile was used, leading to efficient extraction of the analyte with recoveries between 95–100%. Chromatographic separation was achieved with a C18 analytical column and a gradient elution using 10 mM ammonium bicarbonate in water and 10 mM ammonium bicarbonate in water-methanol (1:9, v/v). This assay was selective, accurate, precise and linear in the concentration range of 1−1000 ng/mL. Moreover, samples above the upper limit of quantification can be integrally diluted up to 10-fold prior to analysis. The use of human plasma as a surrogate matrix to quantify milciclib in tissue culture medium and mouse matrices resulted in acceptable accuracy and precision, however tissue culture medium samples required a dilution with human plasma prior the pre-treatment. All performance parameters of the method complied with the acceptance criteria recommended by the guidelines, except for the carry-over, which was slightly above (22.9% of the lower limit of quantification) the recommended percentage (20%). Therefore, additional measures were taken to assure data integrity. Stability of milciclib in all matrices was evaluated, and in some matrices the analyte was unstable under the tested conditions. It is therefore recommended to keep these samples as briefly as possible at room temperature during the pre-treatment, and to store them at –70 °C to avoid analyte degradation. This method was successfully applied to support preclinical pharmacokinetic studies of milciclib.
There is currently great interest in developing oral taxanes due to their lower costs and greater patient friendliness. We here wanted to test whether oral ritonavir, a cytochrome P450 3A (CYP3A) inhibitor, could boost the pharmacokinetics and tissue distribution of orally administered cabazitaxel (10 mg/kg) in male wild-type, Cyp3a–/–, and Cyp3aXAV (transgenic overexpression of human CYP3A4 in liver and intestine) mice. Ritonavir was initially administered at a dose of 25 mg/kg, but lower dosages of 10 and 1 mg/kg were also studied to assess the remaining amount of boosting, aiming to minimize possible side effects. Compared to the respective vehicle groups, plasma exposure of cabazitaxel (AUC0–24h) was enhanced 2.9-, 10.9-, and 13.9-fold in wild-type mice and 1.4-, 10.1-, and 34.3-fold in Cyp3aXAV mice by treatment with 1, 10, and 25 mg/kg ritonavir, respectively. Upon treatment with 1, 10, and 25 mg/kg of ritonavir, the peak plasma concentration (Cmax) was increased by 1.4-, 2.3-, and 2.8-fold in wild-type mice, while it increased by 1.7-, 4.2-, and 8.0-fold in Cyp3aXAV mice, respectively. AUC0–24h and Cmax remained unchanged in Cyp3a–/–. Biotransformation of cabazitaxel to its active metabolites still took place when coadministered with ritonavir, but this process was delayed due to the Cyp3a/CYP3A4 inhibition. These data indicate that CYP3A is the primary limiting factor in the plasma exposure to cabazitaxel and that cabazitaxel oral bioavailability could be dramatically enhanced by coadministration of an effective CYP3A inhibitor such as ritonavir. These findings could be a starting point for the setup of a clinical study, which would be needed to verify the boosting of cabazitaxel by ritonavir in humans.
Azide is a highly toxic chemical agent to human being. Accidental, but also intentional exposure to azide occurs. To be able to confirm azide ingestion, we developed a method to identify and quantify azide in biological matrices. Cyanide was included in the method to evaluate suggested in vivo production of cyanide after azide ingestion. Azide in biological matrices was first derivatized by propionic anhydride to form propionyl azide. Simultaneously, cyanide was converted into hydrogen cyanide. After thermal rearrangement of propionyl azide, ethyl isocyanate was formed, separated together with hydrogen cyanide by gas chromatography (GC) and detected using a nitrogen phosphorous detector (NPD). The method was linear from 1.0-100 µg/mL for both analytes, and azide was stable in human plasma at -20°C for at least 49 days. Azide was measured in the gastric content of two cases of suspected azide ingestion (case 1:1.2 mg/mL, case 2:1.5 mg/mL). Cyanide was only identified in the gastric content of case 1 (approximately 1.4 µg/mL). Furthermore, azide was quantified in plasma (19 µg/mL), serum (24 µg/mL), cell pellet (21 µg/mL) and urine (3.0 µg/mL) of case 2. This method can be used to confirm azide and cyanide exposure, and azide concentrations can be quantified in several biological matrices.
Zotizalkib (TPX-0131), a fourth-generation macrocyclic anaplastic lymphoma kinase (ALK) inhibitor, is designed to overcome resistance due to secondary ALK mutations in non-small cell lung cancer (NSCLC). We here evaluated the pharmacokinetic roles of the ABCB1 (P-gp/MDR1) and ABCG2 (BCRP) efflux transporters, OATP1 influx transporters and the metabolizing enzymes CES1 and CYP3A in plasma and tissue disposition of zotizalkib after oral administration in relevant mouse models. Zotizalkib was efficiently transported by hABCB1 in vitro. In vivo, a significant ∼9-fold higher brain-to-plasma ratio was observed in
Transforming growth factor-beta (TGF-β) signaling plays a pivotal role in tumorigenesis and contributes to the hallmarks of cancer, including tumor proliferation, invasion and metastasis, inflammation, angiogenesis, and escape of immune surveillance. Galunisertib (LY2157299 monohydrate) is an oral small-molecule inhibitor of the TGF-β receptor I kinase that specifically down-regulates the phosphorylation of SMAD2, abrogating activation of this canonical pathway. Galunisertib showed promising antitumor activity in tumor-bearing animal models for breast, colon, and lung cancers, and for hepatocellular carcinoma.Potential drug transport mediated by ATP-binding cassette (ABC) transporters and metabolism by CYP3A are of clinical and regulatory concern, as these could modulate the systemic exposure and/or organ distribution of substrate drugs, and thus affect their therapeutic efficacy and toxicity. We here aimed to investigate the roles of two ABC transporters (P-glycoprotein/ABCB1 and Breast Cancer Resistance Protein/ABCG2) and CYP3A enzyme in the pharmacokinetics and tissue distribution of galunisertib.Transepithelial drug transport was tested using polarized monolayers of Madin-Darby Canine Kidney (MDCK-II) parental cells and its subclones overexpressing human (h) ABCB1, hABCG2, or mouse (m) Abcg2 cDNA. The results suggest that galunisertib is an excellent transport substrate of hABCB1 and endogenous canine ABCB1. mAbcg2 could modestly transport galunisertib, but hABCG2 could not. Based on the in vitro transport experiments, we performed an in vivo pharmacokinetic study in wild-type, ABC transporter knockout (Abcb1a/1b;Abcg2-/-), and Cyp3a knockout (Cyp3a-/-) mice. Following oral administration (20 mg/kg galunisertib), plasma exposure (AUC) in mice was similar to that achieved in humans dosed at 300 mg once daily. Interestingly, the brain-to-plasma ratio was 26-fold higher in Abcb1a/1b;Abcg2-/- mice compared to wild-type mice. However, no significant differences were observed in other tested tissue distributions or in oral availability of galunisertib among these three mouse strains.Our data suggest that ABC transporters play an important role in restricting the brain penetration of galunisertib, but have little impact on oral availability and other relative tissue distribution. Mouse Cyp3a appears to have little, if any, effect on the pharmacokinetics and metabolism of galunisertib. Our results suggest a potential way to boost brain penetration of galunisertib by pharmacological inhibition of transporters in the BBB with chemical inhibitors, especially for patients with brain metastases. These insights might be used to optimize the clinical application of galunisertib.Citation Format: Wenlong Li, Matthijs Tibben, Yaogeng Wang, Maria C. Lebre, Hilde Rosing, Jos H. Beijnen, Alfred H. Schinkel. The impact of P-glycoprotein, breast cancer resistance protein and CYP3A on pharmacokinetics and metabolism of galunisertib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1268.
A reversed-phase high performance liquid chromatographic (HPLC) method for the determination of the activated cyclophosphamide (CP) metabolite 4-hydroxycyclophosphamide (4-OHCP) in human plasma and red blood cells is described. 4-OHCP is very unstable in biological matrices. Therefore, it was treated, immediately after sampling, with semicarbazide to form a stable semicarbazone derivative, which was identified with electron spray mass spectrometry. The derivative was analysed with HPLC with ultraviolet (UV) detection at 230 nm. Sample pre-treatment consisted of a liquid-liquid extraction with ethyl acetate, the chromatography system was a 25 cm C8 column (particle size 5 μm) with a mobile phase of acetonitrile-0.025 M potassium phosphate buffer (15:85 v/v) pH 6.0. After assay optimisation, the method was validated and stability studies were carried out. The method proved linear in clinically relevant concentrations (50-5000 ng/mL). The lower limit of quantitation was 50 ng/mL. Accuracy and precision were below 7% over the full concentration range. A calibration curve in plasma can also be used for the quantification of 4-OHCP in red blood cells. The derivative was found to be stable for at least 11 months when stored at −70 °C. A pharmacokinetic pilot study in a patient treated with 1000 mg/m2 CP in combination with thioTEPA and carboplatin demonstrated the applicability of the assay for the determination of 4-OHCP in plasma and red blood cells.