Prediction of Transporter-Mediated Rosuvastatin Hepatic Uptake Clearance and Drug Interaction in Humans Using Proteomics-Informed REF Approach.

Suspended, plated, or sandwich-cultured human hepatocytes are routinely used for in vitro to in vivo extrapolation (IVIVE) of transporter-mediated hepatic clearance (CL) of drugs. However, these hepatocyte models have been reported to underpredict transporter-mediated in vivo hepatic uptake CL (CL uptake,in vivo ) of some drugs. Therefore, we determined whether transporter-expressing cells (TECs) can accurately predict the CL uptake,in vivo of drugs. To do so, we determined the uptake CL (CL int,uptake,cells ) of rosuvastatin (RSV) by TECs (organic anion transporting polypeptides/Na+-taurocholate cotransporting polypeptide) and then scaled it to that in vivo by relative expression factor (REF) (the ratio of transporter abundance in human livers and TEC) determined by liquid chromatography tandem mass spectrometry-based quantitative proteomics. Both the TEC and hepatocyte models did not meet our predefined success criteria of predicting within 2-fold the RSV CL uptake,in vivo value obtained from our positron emission tomography (PET) imaging. However, the TEC performed better than the hepatocyte models. Interestingly, using REF, TECs successfully predicted RSV CL int,uptake,hep obtained by the hepatocyte models, suggesting that the underprediction of RSV CL uptake,in vivo by TECs and hepatocytes is due to endogenous factor(s) not present in these in vitro models. Therefore, we determined whether inclusion of plasma (or albumin) in TEC uptake studies improved IVIVE of RSV CL uptake,in vivo It did, and our predictions were close to or just fell above our lower 2-fold acceptance boundary. Despite this success, additional studies are needed to improve transporter-mediated IVIVE of hepatic uptake CL of drugs. However, using REF and TEC, we successfully predicted the magnitude of PET-imaged inhibition of RSV CL uptake,in vivo by cyclosporine A. SIGNIFICANCE STATEMENT: We showed that the in vivo transporter-mediated hepatic uptake CL of rosuvastatin, determined by PET imaging, can be predicted (within 2-fold) from in vitro studies in transporter-expressing cells (TECs) (scaled using REF), but only when plasma proteins were included in the in vitro studies. This conclusion did not hold when plasma proteins were absent in the TEC or human hepatocyte studies. Thus, additional studies are needed to improve in vitro to in vivo extrapolation of transporter-mediated drug CL.

Evaluation of absorption, distribution, metabolism, and excretion of [14C]-rucaparib, a poly(ADP-ribose) polymerase inhibitor, in patients with advanced solid tumors.

Rucaparib, a poly(ADP-ribose) polymerase inhibitor, is licensed for use in recurrent ovarian, fallopian tube, or primary peritoneal cancer. We characterized the absorption, distribution, metabolism, and elimination of rucaparib in 6 patients with advanced solid tumors following a single oral dose of [14C]-rucaparib 600 mg (≈140 µCi). Total radioactivity (TRA) in blood, plasma, urine, and feces was measured using liquid scintillation counting. Unchanged rucaparib concentrations in plasma were determined using validated liquid chromatography with tandem mass spectrometry. Maximum concentration (Cmax) of TRA and unchanged rucaparib in plasma was 880 ng Eq/mL and 428 ng/mL, respectively, at approximately 4 h post dose; terminal half-life was >25 h for both TRA and rucaparib. The plasma TRA-time profile was parallel to yet higher than that of rucaparib, suggesting the presence of metabolites in plasma. Mean blood:plasma ratio of radioactivity was 1.0 for Cmax and 0.8 for area under the concentration-time curve from time zero to infinity. Mean postdose recovery of TRA was 89.3% over 12 days (71.9% in feces; 17.4% in urine). Unchanged rucaparib and M324 (oxidative metabolite) were the major components in plasma, contributing to 64.0% and 18.6% of plasma radioactivity, respectively. Rucaparib and M324 were the major rucaparib-related components (each ≈7.6% of dose) in urine, whereas rucaparib was the predominant component (63.9% of dose) in feces. The high fecal recovery of unchanged rucaparib could be attributed to hepatic excretion and/or incomplete oral absorption. Overall, these data suggest that rucaparib is eliminated through multiple pathways, including metabolism and renal and biliary excretion.

Evaluation of in vitro absorption, distribution, metabolism, and excretion and assessment of drug-drug interaction of rucaparib, an orally potent poly(ADP-ribose) polymerase inhibitor.

1. The absorption, distribution, metabolism, elimination, and drug-drug interaction (DDI) potential of the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib was characterised in vitro.2. Rucaparib showed moderate cellular permeability, moderate human plasma protein binding (70.2%), and slow metabolism in human liver microsomes (HLMs). In HLMs, cytochrome P450 (CYP) 1A2 and CYP3A contributed to the metabolism of rucaparib to its major metabolite M324 with estimated fractions of metabolism catalysed by CYP (fm,CYP) of 0.27 and 0.64, respectively. Rucaparib reversibly inhibited CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3As (IC50, 3.55, 12.9, 5.42, 41.6, and 17.2-22.9 µM [2 substrates], respectively), but not CYP2B6 or CYP2C8 (>190 µM). No time-dependent inhibition of any CYP was observed. In cultured human hepatocytes, rucaparib showed concentration-dependent induction of CYP1A2 mRNA and downregulation of CYP3A4 and CYP2B6 mRNA. In transfected cells expressing drug transporters, rucaparib was a substrate for P-gp and BCRP, but not for OATP1B1, OATP1B3, OAT1, OAT3, or OCT2. Rucaparib inhibited P-gp and BCRP (IC50, 169 and 55 µM, respectively) and slightly inhibited OATP1B1, OATP1B3, OAT1, and OAT3 (66%, 58%, 58%, and 42% inhibition, respectively) at 300 µM. Rucaparib inhibited OCT1, OCT2, MATE1, and MATE2-K (IC50, 4.3, 31, 0.63, and 0.19 µM, respectively).3. DDI risk assessment using static models suggested potential CYP-related DDIs, with rucaparib as a perpetrator. Caution is advised when co-administering rucaparib with sensitive substrates of MATEs, OCT1, and OCT2.

A Comparison of Total and Plasma Membrane Abundance of Transporters in Suspended, Plated, Sandwich-Cultured Human Hepatocytes Versus Human Liver Tissue Using Quantitative Targeted Proteomics and Cell Surface Biotinylation.

Suspended (SH), plated (PH), and sandwich-cultured hepatocytes (SCH) are commonly used models to predict in vivo transporter-mediated hepatic uptake (SH or PH) or biliary (SCH) clearance of drugs. When doing so, the total and the plasma membrane abundance (PMA) of transporter are assumed not to differ between hepatocytes and liver tissue (LT). This assumption has never been tested. In this study, we tested this assumption by measuring the total and PMA of the transporters in human hepatocyte models versus LT (total only) from which they were isolated. Total abundance of OATP1B1/2B1/1B3, OCT1, and OAT2 was not significantly different between the hepatocytes and LT. The same was true for the PMA of these transporters across the hepatocyte models. In contrast, total abundance of the sinusoidal efflux transporter, MRP3, and the canalicular efflux transporters, MRP2 and P-gp, was significantly greater (P < 0.05) in SCH versus LT. Of the transporters tested, only the percentage of PMA of OATP1B1, P-gp, and MRP3, in SCH (82.8% ± 7.3%, 57.5% ± 10.9%, 69.3% ± 5.7%) was significantly greater (P < 0.05) than in SH (73.3% ± 6.4%, 27.4% ± 6.4%, 53.6% ± 4.1%). If the transporters measured in the plasma membrane are functional and the PMA in SH is representative of that in LT, these data suggest that SH, PH, and SCH will result in equal prediction of hepatic uptake clearance of drugs mediated by the transporters tested above. However, SCH will predict higher sinusoidal efflux and biliary clearance of drugs if the change in PMA of these transporters is not taken into consideration.

Comparison of uptake transporter functions in hepatocytes in different species to determine the optimal model for evaluating drug transporter activities in humans.

A thorough understanding of species-dependent differences in hepatic uptake transporters is critical for predicting human pharmacokinetics (PKs) from preclinical data. In this study, the activities of organic anion transporting polypeptide (OATP/Oatp), organic cation transporter 1 (OCT1/Oct1), and sodium-taurocholate cotransporting polypeptide (NTCP/Ntcp) in cultured rat, dog, monkey and human hepatocytes were compared. The activities of hepatic uptake transporters were evaluated with respect to culture duration, substrate and species-dependent differences in hepatocytes. Longer culture duration reduced hepatic uptake transporter activities across species except for Oatp and Ntcp in rats. Comparable apparent Michaelis-Menten constant (Km,app) values in hepatocytes were observed across species for atorvastatin, estradiol-17ß-glucuronide and metformin. The Km,app values for rosuvastatin and taurocholate were significantly different across species. Rat hepatocytes exhibited the highest Oatp percentage of uptake transporter-mediated permeation clearance (PSinf,act) while no difference in %PSinf,act of probe substrates were observed across species. The in vitro hepatocyte inhibition data in rats, monkeys and humans provided reasonable predictions of in vivo drug-drug interaction (DDIs) between atorvastatin/rosuvastatin and rifampin. These findings suggested that using human hepatocytes with a short culture time is the most robust preclinical model for predicting DDIs for compounds exhibiting active hepatic uptake in humans.

Abundance of Phase 1 and 2 Drug-Metabolizing Enzymes in Alcoholic and Hepatitis C Cirrhotic Livers: A Quantitative Targeted Proteomics Study.

To predict the impact of liver cirrhosis on hepatic drug clearance using physiologically based pharmacokinetic (PBPK) modeling, we compared the protein abundance of various phase 1 and phase 2 drug-metabolizing enzymes (DMEs) in S9 fractions of alcoholic (n = 27) or hepatitis C (HCV, n = 30) cirrhotic versus noncirrhotic (control) livers (n = 25). The S9 total protein content was significantly lower in alcoholic or HCV cirrhotic versus control livers (i.e., 38.3 ± 8.3, 32.3 ± 12.8, vs. 51.1 ± 20.7 mg/g liver, respectively). In general, alcoholic cirrhosis was associated with a larger decrease in the DME abundance than HCV cirrhosis; however, only the abundance of UGT1A4, alcohol dehydrogenase (ADH)1A, and ADH1B was significantly lower in alcoholic versus HCV cirrhotic livers. When normalized to per gram of tissue, the abundance of nine DMEs (UGT1A6, UGT1A4, CYP3A4, UGT2B7, CYP1A2, ADH1A, ADH1B, aldehyde oxidase (AOX)1, and carboxylesterase (CES)1) in alcoholic cirrhosis and five DMEs (UGT1A6, UGT1A4, CYP3A4, UGT2B7, and CYP1A2) in HCV cirrhosis was <25% of that in control livers. The abundance of most DMEs in cirrhotic livers was 25% to 50% of control livers. CES2 abundance was not affected by cirrhosis. Integration of UGT2B7 abundance in cirrhotic livers into the liver cirrhosis (Child Pugh C) model of Simcyp improved the prediction of zidovudine and morphine PK in subjects with Child Pugh C liver cirrhosis. These data demonstrate that protein abundance data, combined with PBPK modeling and simulation, can be a powerful tool to predict drug disposition in special populations.

Transporter Expression in Noncancerous and Cancerous Liver Tissue from Donors with Hepatocellular Carcinoma and Chronic Hepatitis C Infection Quantified by LC-MS/MS Proteomics.

Protein expression of major hepatobiliary drug transporters (NTCP, OATPs, OCT1, BSEP, BCRP, MATE1, MRPs, and P-gp) in cancerous (C, n = 8) and adjacent noncancerous (NC, n = 33) liver tissues obtained from patients with chronic hepatitis C with hepatocellular carcinoma (HCV-HCC) were quantified by LC-MS/MS proteomics. Herein, we compare our results with our previous data from noninfected, noncirrhotic (control, n = 36) and HCV-cirrhotic (n = 30) livers. The amount of membrane protein yielded from NC and C HCV-HCC tissues decreased (31%, 67%) relative to control livers. In comparison with control livers, with the exception of NTCP, MRP2, and MATE1, transporter expression decreased in NC (38%-76%) and C (56%-96%) HCV-HCC tissues. In NC HCV-HCC tissues, NTCP expression increased (113%), MATE1 expression decreased (58%), and MRP2 expression was unchanged relative to control livers. In C HCV-HCC tissues, NTCP and MRP2 expression decreased (63%, 56%) and MATE1 expression was unchanged relative to control livers. Compared with HCV-cirrhotic livers, aside from NTCP, OCT1, BSEP, and MRP2, transporter expression decreased in NC (41%-71%) and C (54%-89%) HCV-HCC tissues. In NC HCV-HCC tissues, NTCP and MRP2 expression increased (362%, 142%), whereas OCT1 and BSEP expression was unchanged. In C HCV-HCC tissues, OCT1 and BSEP expression decreased (90%, 80%) relative to HCV-cirrhotic livers, whereas NTCP and MRP2 expression was unchanged. Expression of OATP2B1, BSEP, MRP2, and MRP3 decreased (56%-72%) in C HCV-HCC tissues in comparison with matched NC tissues (n = 8), but the expression of other transporters was unchanged. These data will be helpful in the future to predict transporter-mediated hepatocellular drug concentrations in patients with HCV-HCC.

Preclinical absorption, distribution, metabolism, excretion and pharmacokinetics of a novel selective inhibitor of breast cancer resistance protein (BCRP).

1. Breast cancer resistance protein (BCRP) plays an important role in drug absorption, distribution and excretion. It is challenging to evaluate BCRP functions in preclinical models because commonly used BCRP inhibitors are nonspecific or unstable in animal plasma. 2. In this work, in vitro absorption, distribution, metabolism and elimination (ADME) assays and pharmacokinetic (PK) experiments in Bcrp knockout (KO) (Abcg2-/-) and wild-type (WT) FVB mice and Wistar rats were conducted to characterize the preclinical properties of a novel selective BCRP inhibitor (ML753286, a Ko143 analog). 3. ML753286 is a potent inhibitor for BCRP, but not for P-glycoprotein (P-gp), organic anion-transporting polypeptide (OATP) or major cytochrome P450s (CYPs). It has high permeability, but is not an efflux transporter substrate. ML753286 has low to medium clearance in rodent and human liver S9 fractions, and is stable in plasma cross species. Bcrp inhibition affects oral absorption and clearance of sulfasalazine in rodents. A single dose of ML753286 at 50-300 mg/kg orally, and at 20 mg/kg intravenously or 25 mg/kg orally inhibits Bcrp functions in mice and rats, respectively. 4. These findings confirm that ML753286 is a useful selective inhibitor to evaluate BCRP/Bcrp activity in vitro and in rodent model systems.

Efflux transporter breast cancer resistance protein dominantly expresses on the membrane of red blood cells, hinders partitioning of its substrates into the cells, and alters drug-drug interaction profiles.

1. Red blood cell (RBC) partitioning is important in determining pharmacokinetic and pharmacodynamic properties of a compound; however, active transport across RBC membranes is not well understood, particularly without transporter-related cell membrane proteomics data. 2. In this study, we quantified breast cancer resistance protein (BCRP/Bcrp) and MDR1/P-glycoprotein (P-gp) protein expression in RBCs from humans, monkeys, dogs, rats and mice using nanoLC/MS/MS, and evaluated their effect on RBC partitioning and plasma exposure of their substrates. BCRP-specific substrate Cpd-1 and MDR1-specific substrate Cpd-2 were characterized using Caco-2 Transwell® system and then administered to Bcrp or P-gp knockout mice. 3. The quantification revealed BCRP/Bcrp but not MDR1/P-gp to be highly expressed on RBC membranes. The knockout mouse study indicated BCRP/Bcrp pumps the substrate out of RBCs, lowering its partitioning and thus preventing binding to intracellular targets. This result was supported by a Cpd-1 and Bcrp inhibitor ML753286 drug-drug interaction (DDI) study in mice. Because of enhanced partitioning of Cpd-1 into RBCs after BCRP/Bcrp inhibition, Cpd-1 plasma concentration changed much less extent with genetic or chemical knockout of Bcrp albeit marked blood concentration increase, suggesting less DDI effect. 4. This finding is fundamentally meaningful to RBC partitioning, pharmacokinetics and DDI studies of BCRP-specific substrates.

Transporter Expression in Liver Tissue from Subjects with Alcoholic or Hepatitis C Cirrhosis Quantified by Targeted Quantitative Proteomics.

Although data are available on the change of expression/activity of drug-metabolizing enzymes in liver cirrhosis patients, corresponding data on transporter protein expression are not available. Therefore, using quantitative targeted proteomics, we compared our previous data on noncirrhotic control livers (n = 36) with the protein expression of major hepatobiliary transporters, breast cancer resistance protein (BCRP), bile salt export pump (BSEP), multidrug and toxin extrusion protein 1 (MATE1), multidrug resistance-associated protein (MRP)2, MRP3, MRP4, sodium taurocholate-cotransporting polypeptide (NTCP), organic anion-transporting polypeptides (OATP)1B1, 1B3, 2B1, organic cation transporter 1 (OCT1), and P-glycoprotein (P-gp) in alcoholic (n = 27) and hepatitis C cirrhosis (n = 30) livers. Compared with control livers, the yield of membrane protein from alcoholic and hepatitis C cirrhosis livers was significantly reduced by 56 and 67%, respectively. The impact of liver cirrhosis on transporter protein expression was transporter-dependent. Generally, reduced protein expression (per gram of liver) was found in alcoholic cirrhosis livers versus control livers, with the exception that the expression of MRP3 was increased, whereas no change was observed for MATE1, MRP2, OATP2B1, and P-gp. In contrast, the impact of hepatitis C cirrhosis on protein expression of transporters (per gram of liver) was diverse, showing an increase (MATE1), decrease (BSEP, MRP2, NTCP, OATP1B3, OCT1, and P-gp), or no change (BCRP, MRP3, OATP1B1, and 2B1). The expression of hepatobiliary transporter protein differed in different diseases (alcoholic versus hepatitis C cirrhosis). Finally, incorporation of protein expression of OATP1B1 in alcoholic cirrhosis into the Simcyp physiologically based pharmacokinetics cirrhosis module improved prediction of the disposition of repaglinide in liver cirrhosis patients. These transporter expression data will be useful in the future to predict transporter-mediated drug disposition in liver cirrhosis patients.

Synthesis of a new inhibitor of breast cancer resistance protein with significantly improved pharmacokinetic profiles.

The design, synthesis, in vitro inhibitory potency, and pharmacokinetic (PK) profiles of Ko143 analogs are described. Compared to commonly used Ko143, the new breast cancer resistance protein (BCRP) inhibitor (compound A) showed the same potency and a significantly improved PK profile in rats (lower clearance [1.54L/h/kg] and higher bioavailability [123%]). Ko143 on the other hand suffers from poor bioavailability. Compared to Ko143, compound A would be a useful probe for delineating the role of BCRP during in vivo studies in animals.

Liver cytochrome P450 3A endoplasmic reticulum-associated degradation: a major role for the p97 AAA ATPase in cytochrome P450 3A extraction into the cytosol.

The CYP3A subfamily of hepatic cytochromes P450, being engaged in the metabolism and clearance of >50% of clinically relevant drugs, can significantly influence therapeutics and drug-drug interactions. Our characterization of CYP3A degradation has indicated that CYPs 3A incur ubiquitin-dependent proteasomal degradation (UPD) in an endoplasmic reticulum (ER)-associated degradation (ERAD) process. Cytochromes P450 are monotopic hemoproteins N-terminally anchored to the ER membrane with their protein bulk readily accessible to the cytosolic proteasome. Given this topology, it was unclear whether they would require the AAA-ATPase p97 chaperone complex that retrotranslocates/dislocates ubiquitinated ER-integral and luminal proteins into the cytosol for proteasomal delivery. To assess the in vivo relevance of this p97-CYP3A association, we used lentiviral shRNAs to silence p97 (80% mRNA and 90% protein knockdown relative to controls) in sandwich-cultured rat hepatocytes. This extensive hepatic p97 knockdown remarkably had no effect on cellular morphology, ER stress, and/or apoptosis, despite the well recognized strategic p97 roles in multiple important cellular processes. However, such hepatic p97 knockdown almost completely abrogated CYP3A extraction into the cytosol, resulting in a significant accumulation of parent and ubiquitinated CYP3A species that were firmly ER-tethered. Little detectable CYP3A accumulated in the cytosol, even after concomitant inhibition of proteasomal degradation, thereby documenting a major role of p97 in CYP3A extraction and delivery to the 26 S proteasome during its UPD/ERAD. Intriguingly, the accumulated parent CYP3A was functionally active, indicating that p97 can regulate physiological CYP3A content and thus influence its clinically relevant function.

Ubiquitin-dependent proteasomal degradation of human liver cytochrome P450 2E1: identification of sites targeted for phosphorylation and ubiquitination.

Human liver CYP2E1 is a monotopic, endoplasmic reticulum-anchored cytochrome P450 responsible for the biotransformation of clinically relevant drugs, low molecular weight xenobiotics, carcinogens, and endogenous ketones. CYP2E1 substrate complexation converts it into a stable slow-turnover species degraded largely via autophagic lysosomal degradation. Substrate decomplexation/withdrawal results in a fast turnover CYP2E1 species, putatively generated through its futile oxidative cycling, that incurs endoplasmic reticulum-associated ubiquitin-dependent proteasomal degradation (UPD). CYP2E1 thus exhibits biphasic turnover in the mammalian liver. We now show upon heterologous expression of human CYP2E1 in Saccharomyces cerevisiae that its autophagic lysosomal degradation and UPD pathways are evolutionarily conserved, even though its potential for futile catalytic cycling is low due to its sluggish catalytic activity in yeast. This suggested that other factors (i.e. post-translational modifications or "degrons") contribute to its UPD. Indeed, in cultured human hepatocytes, CYP2E1 is detectably ubiquitinated, and this is enhanced on its mechanism-based inactivation. Studies in Ubc7p and Ubc5p genetically deficient yeast strains versus corresponding isogenic wild types identified these ubiquitin-conjugating E2 enzymes as relevant to CYP2E1 UPD. Consistent with this, in vitro functional reconstitution analyses revealed that mammalian UBC7/gp78 and UbcH5a/CHIP E2-E3 ubiquitin ligases were capable of ubiquitinating CYP2E1, a process enhanced by protein kinase (PK) A and/or PKC inclusion. Inhibition of PKA or PKC blocked intracellular CYP2E1 ubiquitination and turnover. Here, through mass spectrometric analyses, we identify some CYP2E1 phosphorylation/ubiquitination sites in spatially associated clusters. We propose that these CYP2E1 phosphorylation clusters may serve to engage each E2-E3 ubiquitination complex in vitro and intracellularly.

The Multi-Kinase Inhibitor Lucitanib Enhances the Antitumor Activity of Coinhibitory and Costimulatory Immune Pathway Modulators in Syngeneic Models.

Lucitanib is a multi-tyrosine kinase inhibitor whose targets are associated with angiogenesis and other key cancer and immune pathways. Its antiangiogenic properties are understood, but lucitanib's immunomodulatory activity is heretofore unknown. Lucitanib exhibited such activity in vivo, increasing CD3 + , CD8 + , and CD4 + T cells and decreasing dendritic cells and monocyte-derived suppressor cells in mouse spleens. Depletion of CD8 + T cells from syngeneic MC38 colon tumor-bearing mice reduced the antitumor efficacy of lucitanib and revealed a CD8 + T-cell-dependent component of lucitanib's activity. The combination of lucitanib and costimulatory immune pathway agonists targeting 4-1BB, glucocorticoid-induced TNFR (GITR), inducible T-cell co-stimulator (ICOS), or OX40 exhibited enhanced antitumor activity compared with each single agent in immunocompetent tumor models. Lucitanib combined with blockade of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or programmed cell death protein-1 (PD-1) coinhibitory immune pathways also showed enhanced antitumor activity over the single agents in multiple models. In CT26 tumors, lucitanib, alone or combined with anti-PD-1, reduced CD31 + vessels and depleted F4/80 + macrophages. Combination treatment also increased the number of intratumoral T cells. Gene expression in pathways associated with immune activity was upregulated by lucitanib in MC38 tumors and further potentiated by combination with anti-PD-1. Accordingly, lucitanib, alone or combined with anti-PD-1, increased intratumoral CD8 + T-cell abundance. Lucitanib's antitumor and pharmacodynamic activity, alone or combined with anti-PD-1, was not recapitulated by specific vascular endothelial growth factor receptor-2 (VEGFR2) inhibition. These data indicate that lucitanib can modulate vascular and immune components of the tumor microenvironment and cooperate with immunotherapy to enhance antitumor efficacy. They support the clinical development of lucitanib combined with immune pathway modulators to treat cancer.

Population Pharmacokinetic Modeling of Lucitanib in Patients with Advanced Cancer.

BACKGROUND: Lucitanib is an oral, potent, selective inhibitor of the tyrosine kinase activity of vascular endothelial growth factor receptors 1‒3, fibroblast growth factor receptors 1‒3, and platelet-derived growth factor receptors alpha/beta. OBJECTIVE: We aimed to develop a population pharmacokinetics (PopPK) model for lucitanib in patients with advanced cancers. METHODS: PopPK analyses were based on intensive and sparse oral pharmacokinetic data from 5 phase 1/2 clinical studies of lucitanib in a total of 403 patients with advanced cancers. Lucitanib was administered at 5‒30 mg daily doses as 1 of 2 immediate-release oral formulations: a film-coated tablet or a hard gelatin capsule. RESULTS: Lucitanib pharmacokinetics were best described by a 2-compartment model with zero-order release into the dosing compartment, followed by first-order absorption and first-order elimination. Large between-subject pharmacokinetic variability was partially explained by body weight. No effects of demographics or tumor type on lucitanib pharmacokinetics were observed. The model suggested that the formulation impacted release duration (tablet, 0.243 h; capsule, 0.814 h), but the effect was not considered clinically meaningful. No statistically significant effects were detected for concomitant cytochrome P450 (CYP) 3A4 inhibitors or inducers, CYP2C8 or P-glycoprotein inhibitors, serum albumin, mild/moderate renal impairment, or mild hepatic impairment. Concomitant proton pump inhibitors had no clinically significant effect on lucitanib absorption. CONCLUSIONS: The PopPK model adequately described lucitanib pharmacokinetics. High between-subject pharmacokinetic variability supports a safety-based dose-titration strategy currently being used in an ongoing clinical study of lucitanib to optimize drug exposure and clinical benefit. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01283945, NCT02053636, ISRCTN23201971, NCT02202746, NCT02109016.

Clinical Pharmacokinetics and Pharmacodynamics of Rucaparib.

Rucaparib is an oral small-molecule poly(ADP-ribose) polymerase inhibitor indicated for patients with recurrent ovarian cancer in the maintenance and treatment settings and for patients with metastatic castration-resistant prostate cancer associated with a deleterious BRCA1 or BRCA2 mutation. Rucaparib has a manageable safety profile; the most common adverse events reported were fatigue and nausea in both indications. Accumulation in plasma exposure occurred after repeated administration of the approved 600-mg twice-daily dosage. Steady state was achieved after continuous twice-daily dosing for a week. Rucaparib has moderate oral bioavailability and can be dosed with or without food. Although a high-fat meal weakly increased maximum concentration and area under the curve, the effect was not clinically significant. A mass balance analysis indicated almost a complete dose recovery of rucaparib over 12 days, with metabolism, renal, and hepatic excretion as the elimination routes. A population pharmacokinetic analysis of rucaparib revealed no effect of age, sex, race, or body weight. No starting dose adjustments were necessary for patients with mild-to-moderate hepatic or renal impairment; the effect of severe organ impairment on rucaparib exposure has not been evaluated. In patients, rucaparib moderately inhibited cytochrome P450 (CYP) 1A2 and weakly inhibited CYP3As, CYP2C9, and CYP2C19. Rucaparib weakly increased systemic exposures of oral contraceptives and oral rosuvastatin and marginally increased the exposure of oral digoxin (a P-glycoprotein substrate). In vitro studies suggested that rucaparib inhibits transporters MATE1, MATE2-K, OCT1, and OCT2. No clinically meaningful drug interactions with rucaparib as a perpetrator were observed. An exposure-response analysis revealed dose-dependent changes in selected clinical efficacy and safety endpoints. Overall, this article provides a comprehensive review of the clinical pharmacokinetics, pharmacodynamics, drug-drug interactions, effects of intrinsic and extrinsic factors, and exposure-response relationships of rucaparib.

A phase 1, open-label, drug-drug interaction study of rucaparib with rosuvastatin and oral contraceptives in patients with advanced solid tumors.

PURPOSE: This study aimed at evaluating the effect of rucaparib on the pharmacokinetics of rosuvastatin and oral contraceptives in patients with advanced solid tumors and the safety of rucaparib with and without coadministration of rosuvastatin or oral contraceptives. METHODS: Patients received single doses of oral rosuvastatin 20 mg (Arm A) or oral contraceptives ethinylestradiol 30 µg + levonorgestrel 150 µg (Arm B) on days 1 and 19 and continuous doses of rucaparib 600 mg BID from day 5 to 23. Serial blood samples were collected with and without rucaparib for pharmacokinetic analysis. RESULTS: Thirty-six patients (n = 18 each arm) were enrolled and received at least 1 dose of study drug. In the drug-drug interaction analysis (n = 15 each arm), the geometric mean ratio (GMR) of maximum concentration (Cmax) with and without rucaparib was 1.29 for rosuvastatin, 1.09 for ethinylestradiol, and 1.19 for levonorgestrel. GMR of area under the concentration-time curve from time zero to last quantifiable measurement (AUC0-last) was 1.34 for rosuvastatin, 1.43 for ethinylestradiol, and 1.56 for levonorgestrel. There was no increase in frequency of treatment-emergent adverse events (TEAEs) when rucaparib was given with either of the probe drugs. In both arms, most TEAEs were mild in severity and considered unrelated to study treatment. CONCLUSION: Rucaparib 600 mg BID weakly increased the plasma exposure to rosuvastatin or oral contraceptives. Rucaparib safety profile when coadministered with rosuvastatin or oral contraceptives was consistent with that of rucaparib monotherapy. Dose adjustments of rosuvastatin and oral contraceptives are not necessary when coadministered with rucaparib. ClinicalTrials.gov NCT03954366; Date of registration May 17, 2019.

Pharmacokinetics and safety of rucaparib in patients with advanced solid tumors and hepatic impairment.

PURPOSE: The poly(ADP-ribose) polymerase inhibitor rucaparib is approved for the treatment of patients with recurrent ovarian and metastatic castration-resistant prostate cancer; however, limited data are available on its use in patients with hepatic dysfunction. This study investigated whether hepatic impairment affects the pharmacokinetics, safety, and tolerability of rucaparib in patients with advanced solid tumors. METHODS: Patients with normal hepatic function or moderate hepatic impairment according to the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria were enrolled and received a single oral dose of rucaparib 600 mg. Concentrations of rucaparib and its metabolite M324 in plasma and urine were measured. Pharmacokinetic parameters were compared between hepatic function groups, and safety and tolerability were assessed. RESULTS: Sixteen patients were enrolled (n = 8 per group). Rucaparib maximum concentration (Cmax) was similar, while the area under the concentration-time curve from time 0 to infinity (AUC0-inf) was mildly higher in the moderate hepatic impairment group than in the normal control group (geometric mean ratio, 1.446 [90% CI 0.668-3.131]); similar trends were observed for M324. Eight (50%) patients experienced ≥ 1 treatment-emergent adverse event (TEAE); 2 had normal hepatic function and 6 had moderate hepatic impairment. CONCLUSION: Patients with moderate hepatic impairment showed mildly increased AUC0-inf for rucaparib compared to patients with normal hepatic function. Although more patients with moderate hepatic impairment experienced TEAEs, only 2 TEAEs were considered treatment related. These results suggest no starting dose adjustment is necessary for patients with moderate hepatic impairment; however, close safety monitoring is warranted.

Inhibition of hepatic organic anion-transporting polypeptide by RNA interference in sandwich-cultured human hepatocytes: an in vitro model to assess transporter-mediated drug-drug interactions.

Organic anion-transporting polypeptides (OATPs), members of the SLCO/SLC21 family, mediate the transport of various endo- and xenobiotics. In human liver, OATP1B1, 1B3, and 2B1 are located at the basolateral membrane of hepatocytes and are involved in hepatic drug uptake and biliary elimination. Clinically significant drug-drug interactions (DDIs) mediated by hepatic OATPs have drawn great attention from clinical practitioners and researchers. However, there are considerable challenges to prospectively understanding the extent of OATP-mediated DDIs because of the lack of specific OATP inhibitors or substrates and the limitations of in vitro tools. In the present study, a novel RNA interference knockdown sandwich-cultured human hepatocyte model was developed and validated. Quantitative polymerase chain reaction, microarray and immunoblotting analyses, along with uptake assays, illustrated that the expression and transport activity of hepatic OATPs were reduced by small interfering (siRNA) efficiently and specifically in this model. Although OATP siRNA decreased only 20 to 30% of the total uptake of cerivastatin into human hepatocytes, it caused a 50% reduction in cerivastatin metabolism, which was observed by monitoring the formation of the two major metabolites of cerivastatin. The results suggest that coadministration of a drug that is a hepatic OATP inhibitor could significantly alter the pharmacokinetic profile of cerivastatin in clinical studies. Further studies with this novel model demonstrated that OATP and cytochrome P450 have a synergistic effect on cerivastatin-gemfibrozil interactions. The siRNA knockdown sandwich-cultured human hepatocytes may provide a new powerful model for evaluating DDIs.

Positron Emission Tomography Imaging of [11 C]Rosuvastatin Hepatic Concentrations and Hepatobiliary Transport in Humans in the Absence and Presence of Cyclosporin A.

Using positron emission tomography imaging, we determined the hepatic concentrations and hepatobiliary transport of [11 C]rosuvastatin (RSV; i.v. injection) in the absence (n = 6) and presence (n = 4 of 6) of cyclosporin A (CsA; i.v. infusion) following a therapeutic dose of unlabeled RSV (5 mg, p.o.) in healthy human volunteers. The sinusoidal uptake, sinusoidal efflux, and biliary efflux clearance (CL; mL/minute) of [11 C]RSV, estimated through compartment modeling were 1,205.6 ± 384.8, 16.2 ± 11.2, and 5.1 ± 1.8, respectively (n = 6). CsA (blood concentration: 2.77 ± 0.24 µM), an organic-anion-transporting polypeptide, Na+ -taurocholate cotransporting polypeptide, and breast cancer resistance protein inhibitor increased [11 C]RSV systemic blood exposure (45%; P < 0.05), reduced its biliary efflux CL (52%; P < 0.05) and hepatic uptake (25%; P > 0.05) but did not affect its distribution into the kidneys. CsA increased plasma concentrations of coproporphyrin I and III and total bilirubin by 297 ± 69%, 384 ± 102%, and 81 ± 39%, respectively (P < 0.05). These data can be used in the future to verify predictions of hepatic concentrations and hepatobiliary transport of RSV.