Lenalidomide is an immunomodulatory drug and is very effective in the management of a number of malignancies, including multiple myeloma. Like thalidomide, lenalidomide interacts with the cereblon E3 ligase complex, which results in targeted destruction of proteins. This study was conducted to study the teratogenic potential of lenalidomide when administered to pregnant cynomolgus monkeys. Lenalidomide was administered orally on gestation days 20-50 at dosages of 0 (vehicle control), 0.5, 1, 2 and 4 mg/kg/day. Thalidomide was used as a positive control and was administered orally at 15 mg/kg/day on gestation days 26-28. Each group consisted of 5 pregnant monkeys. Pregnancy was terminated on gestation day 100 +/- 1 by cesarean section and fetuses examined for external, internal and skeletal changes. Intrauterine loss was 40% in the thalidomide group and 20 % in each of the lenalidomide 2 and 4 mg/kg/day groups. Treatment with lenalidomide and thalidomide resulted in no effects on placental weights, fetal body weights and body measurements. External fetal examination revealed malformations in fetuses of all lenalidomide-treated groups, including malformations of upper and lower extremities. These external malformations had correlated skeletal findings and were similar to those seen in the thalidomide-treated group, where two of three fetuses showed the classic thalidomide syndrome of malformed upper and lower extremities. A no-observed-adverse-effect level was not identified in this study, and the mean maternal exposures at the lowest dosage, where fetal malformations were observed, were 5-folder lower than the exposures observed in the MM patients treated with 25 mg of lenalidomide.

Ozanimod is approved for the treatment of relapsing forms of multiple sclerosis. Absorption, metabolism, and excretion of ozanimod were investigated after a single oral dose of 1.0 mg [14C]ozanimod hydrochloride to six healthy subjects. In vitro experiments were conducted to understand the metabolic pathways and enzymes involved in the metabolism of ozanimod and its active metabolites. The total mean recovery of the administered radioactivity was ∼63%, with ∼26% and ∼37% recovered from urine and feces, respectively. Based on exposure, the major circulating components were active metabolite CC112273 and inactive metabolite RP101124, which together accounted for 50% of the circulating total radioactivity exposure, whereas ozanimod accounted for 6.7% of the total radioactive exposure. Ozanimod was extensively metabolized, with 14 metabolites identified, including two major active metabolites (CC112273 and CC1084037) and one major inactive metabolite (RP101124) in circulation. Ozanimod is metabolized by three primary pathways, including aldehyde dehydrogenase and alcohol dehydrogenase, cytochrome P450 isoforms 3A4 and 1A1, and reductive metabolism by gut microflora. The primary metabolite RP101075 is further metabolized to form major active metabolite CC112273 by monoamine oxidase B, which further undergoes reduction by carbonyl reductases to form CC1084037 or CYP2C8-mediated oxidation to form RP101509. CC1084037 is oxidized rapidly to form CC112273 by aldo-keto reductase 1C1/1C2 and/or 3β- and 11β-hydroxysteroid dehydrogenase, and this reversible oxidoreduction between two active metabolites favors CC112273. The ozanimod example illustrates the need for conducting timely radiolabeled human absorption, distribution, metabolism, and excretion studies for characterization of disproportionate metabolites and assessment of exposure coverage during drug development. SIGNIFICANCE STATEMENT: Absorption, metabolism, and excretion of ozanimod were characterized in humans, and the enzymes involved in complex metabolism were elucidated. Disproportionate metabolites were identified, and the activity of these metabolites was determined.

Targeted protein degradation via small-molecule modulation of cereblon offers vast potential for the development of new therapeutics. Cereblon-binding therapeutics carry the safety risks of thalidomide, which caused an epidemic of severe birth defects characterized by forelimb shortening or phocomelia. Here we show that thalidomide is not teratogenic in transgenic mice expressing human cereblon, indicating that binding to cereblon is not sufficient to cause birth defects. Instead, we identify SALL4 as a thalidomide-dependent cereblon neosubstrate. Human mutations in SALL4 cause Duane-radial ray, IVIC, and acrorenal-ocular syndromes with overlapping clinical presentations to thalidomide embryopathy, including phocomelia. SALL4 is degraded in rabbits but not in resistant organisms such as mice because of SALL4 sequence variations. This work expands the scope of cereblon neosubstrate activity within the formerly 'undruggable' C2H2 zinc finger family and offers a path toward safer therapeutics through an improved understanding of the molecular basis of thalidomide-induced teratogenicity.

BACKGROUND:Oncology therapy typically involves drug combinations since monotherapy seldom provides the desired outcome. But combination therapy presents the potential for drug-drug interactions (DDIs). Due to the narrow window between therapeutic concentrations and onset of toxicity often observed with oncology therapeutics, managing DDIs with combination therapy in cancer is critical. Physiologically based pharmacokinetic (PBPK) modeling can be effectively used for predicting DDIs and guiding dose-selection, but requires development of PBPK models of cancer drugs. Among various types of cancer, metastatic prostate cancer is an area of high unmet medical need with minimal therapeutic options. Recently, enzalutamide was approved for treatment of metastatic prostate cancer and is often dosed as a combination in clinical practice. Enzalutamide is a potent CYP3A inducer and a model-based approach to guide dose-selection for enzalutamide combinations that are CYP3A substrates is needed.OBJECTIVE:A "fit for purpose" PBPK model of enzalutamide was developed to illustrate the CYP3A4 induction potential, understand the kinetics of de-induction of CYP3A4 following cessation of enzalutamide dosing and guide dose-selection of a co-administered CYP3A substrate.METHOD:The population-based simulator, Simcyp, was used for model building purposes. Model input parameters were obtained from public information, primarily from the FDA summaries.RESULTS:The simulated concentration time profiles of enzalutamide in healthy male subjects were comparable to observed profiles in male patients. Model predicted enzalutamide pharmacokinetic (PK) parameters, i.e. AUC, Cmax and half-life were within 1.5-fold of observed results obtained from two reported studies, supporting verification of the PBPK model. Model application was demonstrated by simulating a drug-drug interaction between enzalutamide and midazolam, a sensitive CYP3A4 substrate. Based on simulations, the midazolam AUC ratio ranged from 0.06 to 0.16 and was comparable to the observed ratio of 0.14. Based on modeling, upon cessation of enzalutamide dosing, it is predicted that at least 8 weeks are needed to re-attain baseline CYP3A4 activity. Based on PBPK modeling, dose adjustment of up to 3-fold for a co-administered CYP3A substrate was shown to re-attain baseline exposure.CONCLUSION:A "fit for purpose" PBPK model of enzalutamide was successfully developed using public information that recapitulated it's observed pharmacokinetics, CYP3A4 induction potential and the potential need for dose-adjustment of co-administered CYP3A substrates.

1. In vitro metabolism of Tanzisertib [(1S,4R)-4-(9-((S)tetrahydrofuran-3-yl)-8-(2,4,6-trifluorophenylamino)-9H-purin-2-ylamino) cyclohexanol], a potent, selective c-Jun amino-terminal kinase (JNK) inhibitor, was investigated in mouse, rat, rabbit, dog, monkey and human hepatocytes over 4 h. The extent of metabolism of [14C]tanzisertib was variable, with <10% metabolized in dog and human, <20% metabolized in rabbit and monkey and >75% metabolized in rat and mouse. Primary metabolic pathways in human and dog hepatocytes, were direct glucuronidation and oxidation of cyclohexanol to a keto metabolite, which was subsequently reduced to parent or cis-isomer, followed by glucuronidation. Rat and mouse produced oxidative metabolites and cis-isomer, including direct glucuronides and sulfates of tanzisertib and cis-isomer.2. Enzymology of oxido-reductive pathways revealed that human aldo-keto reductases AKR1C1, 1C2, 1C3 and 1C4 were responsible for oxido-reduction of tanzisertib, CC-418424 and keto tanzisertib. Characterizations of enzyme kinetics revealed that AKR1C4 had a high affinity for reduction of keto tanzisertib to tanzisertib compared to other isoforms. These results demonstrate unique stereoselectivity of the reductive properties documented by human AKR1C enzymes for the same substrate.3. Characterization of UGT isoenzymes in glucuronidation of tanzisertib and CC-418424 revealed that, tanzisertib glucuronide was catalyzed by: UGT1A1, 1A4, 1A10 and 2B4, while CC-418424 glucuronidation was catalyzed by UGT2B4 and 2B7.

Purpose Lenalidomide is an immunomodulatory agent used for the treatment of myelodysplastic syndromes and multiple myeloma. Renal clearance of lenalidomide is the predominant elimination route and is approximately twofold greater than the glomerular filtration rate (GFR), suggesting the potential contribution of an active secretory mechanism. In vitro studies were conducted to examine whether lenalidomide is a substrate of drug transporters, namely P-glycoprotein (P-gp), human breast cancer resistance protein (BCRP), multidrug resistance proteins (MRP1, MRP2, MRP3), organic anion transporters (OAT 1, OAT 3), organic cation transporters (OCT1 and OCT2), human organic cation transporter novel 1 and 2 (OCTN1 and OCTN2), multidrug and toxin extrusion (MATE1) and organic anion transporting polypeptide (OATP1B1). Lenalidomide was also evaluated as an inhibitor of P-gp, BCRP, MRP2, OCT2, OAT 1, OAT 3, OATP1B1, OATP1B3 and bile salt export pump (BSEP). In addition, inhibition of UDP-glucuronosyltransferase 1A1 (UGT1A1) variants by lenalidomide was also assessed.Method Cells or vesicles expressing each of the human transporters were used for uptake and inhibition studies, with appropriate probe substrates and known inhibitors.Results Results of these studies indicate that the lenalidomide is not a substrate for the transporters examined, except that it is weak substrate of P-gp. None of the transporters studied were inhibited by lenalidomide. Lenalidomide is not an inhibitor of UGT1A1*1/*1 or its polymorphic variants UGT1A1*1/*28 and UGT1A1*28/*28.Conclusions Drug interactions are unlikely to occur when lenalidomide is co-administered with substrates or inhibitors of these transporters. In addition, lenalidomide is unlikely to cause interactions when co-administered with substrates of UGT1A1.

Abstract 1. The disposition of tanzisertib [(1S,4R)-4-(9-((S)tetrahydrofuran-3-yl)-8-(2,4,6-trifluorophenylamino)-9H-purin-2-ylamino) cyclohexanol], a potent, orally active c-Jun amino-terminal kinase inhibitor intended for treatment of fibrotic diseases was studied in rats, dogs and humans following a single oral dose of [14C]tanzisertib (Independent Investigational Review Board Inc., Plantation, FL). 2. Administered dose was quantitatively recovered in all species and feces/bile was the major route of elimination. Tanzisertib was rapidly absorbed (Tmax: 1–2 h) across all species with unchanged tanzisertib representing >83% of plasma radioactivity in dogs and humans, whereas <34% was observed in rats. Variable amounts of unchanged tanzisertib (1.5–32% of dose) was recovered in urine/feces across all species, the highest in human feces. 3. Metabolic profiling revealed that tanzisertib was primarily metabolized via oxidation and conjugation pathways, but extensively metabolized in rats relative to dogs/humans. CC-418424 (S-cis isomer of tanzisertib) was the major plasma metabolite in rats (38.4–46.4% of plasma radioactivity), while the predominant plasma metabolite in humans and dogs was M18 (tanzisertib-/CC-418424 glucuronide), representing 7.7 and 3.2% of plasma radioactivity, respectively. Prevalent biliary metabolite in rats and dogs, M18 represented 16.8 and 17.1% of dose, respectively. 4. In vitro studies using liver subcellular fractions and expressed enzymes characterized involvement of novel human aldo-keto reductases for oxido-reduction and UDP-glucuronosyltransferases for conjugation pathways.

Lenalidomide, a weak substrate of P-glycoprotein (P-gp) in vitro, is an oral anticancer drug eliminated predominantly via renal excretion as unchanged compound. The role of P-gp in lenalidomide disposition and the associated clinical relevance were evaluated.

Pomalidomide, a potent novel immunomodulatory agent, has been developed as a racemic mixture of its R- and S-isomers. Pharmacokinetic (PK) analyses were conducted to determine the PK disposition of the isomers from their PK profiles in humans and monkeys. Modeling and simulation were performed to describe the observed PK profiles and explore potential differences in isomer disposition and exposure. PK profiles of S- and R-isomers were measured in a human absorption, distribution, metabolism, and excretion study after oral administration of racemate. PK profiles of S- and R-isomers were measured in monkeys after intravenous and oral administration of S- or R-isomers and pomalidomide racemate. Modeling and simulation were performed using NONMEM 7.2 (Globomax, Ellicott City, MD) to describe the observed PK profiles of S- and R-isomers in humans and monkeys. The results showed that in humans, the in vivo elimination rate of pomalidomide isomers was lower than the R-/S-interconversion rate, resulting in no clinically relevant difference in overall exposure to the two isomers. However, in monkeys, the in vivo elimination rate was higher than the R-/S-interconversion rate, resulting in 1.72- and 1.55-fold differences in R- versus S-isomer exposures. Monte Carlo simulation indicated that exposure to R- and S-enantiomers in humans should be comparable even if single isomers are administered. Thus, in humans, rapid isomeric interconversion of pomalidomide isomers results in comparable exposure to R- and S-enantiomers regardless of whether pomalidomide is administered as a single enantiomer or as a racemate, therefore justifying the clinical development of pomalidomide as a racemate.

Pomalidomide offers an alternative for patients with relapsed/refractory multiple myeloma who have exhausted treatment options with lenalidomide and bortezomib. Little is known about pomalidomide's potential for drug-drug interactions (DDIs); as pomalidomide clearance includes hydrolysis and cytochrome P450 (CYP450)-mediated hydroxylation, possible DDIs via CYP450 and drug-transporter proteins were investigated in vitro and in a clinical study. In vitro pomalidomide was neither an inducer nor inhibitor of CYP450, nor an inhibitor of transporter proteins P glycoprotein (P-gp), BCRP, OAT1, OAT3, OCT2, OATP1B1, and OATP1B3. Oxidative metabolism of pomalidomide was predominately mediated by CYP1A2 and CYP3A4, and pomalidomide was shown to be a P-gp substrate. In healthy males, co-administration of oral (4 mg) pomalidomide with ketoconazole (CYP3A/P-gp inhibitor) or carbamazepine (CYP3A/P-gp inducer) did not result in clinically relevant changes in pomalidomide exposure. Co-administration of pomalidomide with fluvoxamine (CYP1A2 inhibitor) in the presence of ketoconazole approximately doubled pomalidomide exposure. Pomalidomide appears to have low potential for clinically relevant DDI and is unlikely to affect the clinical exposure of other drugs. Avoid co-administration of strong CYP1A2 inhibitors unless medically necessary. Pomalidomide dose should be reduced by 50% if co-administered with strong CYP1A2 inhibitors and strong CYP3A/P-gp inhibitors.

Studies in pregnant rabbits were conducted to evaluate if there are any differences in the uptake of thalidomide into the intrauterine compartment and developmental toxicity risk following oral and intravaginal administration. Thalidomide concentrations in maternal plasma, yolk sac cavity (YSC) fluid and embryo following intravaginal administration were 2- to 7-fold lower than their respective levels after oral administration. Ratios of thalidomide concentration in YSC fluid to maternal plasma were similar between these two routes, indicating no difference in uptake into the intrauterine compartment. A rabbit embryo–fetal development study using oral and intravaginal thalidomide administration at 2 mg/kg/day (a dose >10,000-fold higher than the expected amount of thalidomide in human semen) did not result in any developmental abnormalities. These data demonstrated no preferential transfer mechanism of thalidomide from vagina to conceptus, and no additional embryo–fetal developmental toxicity risks with thalidomide exposure via the vaginal route.

Studies in pregnant rabbits were conducted to evaluate if there are any differences in the uptake of thalidomide into the intrauterine compartment and developmental toxicity risk following oral and intravaginal administration. Thalidomide concentrations in maternal plasma, yolk sac cavity (YSC) fluid and embryo following intravaginal administration were 2- to 7-fold lower than their respective levels after oral administration. Ratios of thalidomide concentration in YSC fluid to maternal plasma were similar between these two routes, indicating no difference in uptake into the intrauterine compartment. A rabbit embryo-fetal development study using oral and intravaginal thalidomide administration at 2 mg/kg/day (a dose >10,000-fold higher than the expected amount of thalidomide in human semen) did not result in any developmental abnormalities. These data demonstrated no preferential transfer mechanism of thalidomide from vagina to conceptus, and no additional embryo-fetal developmental toxicity risks with thalidomide exposure via the vaginal route. (C) 2014 Elsevier Inc. All rights reserved.

Abstract Introduction Lenalidomide (LEN) is a weak substrate of P-glycoprotein (P-gp) in vitro and renal excretion of LEN is the primary elimination route following oral administration. A P-gp inhibitor may have the potential to increase systemic exposure to LEN by reducing renal elimination at the tubular level and enhancing oral absorption at the gut level. Recently, a single uncontrolled phase 1 study (Hofmeister, 2011) and a case report (Takahashi, 2012) described that plasma exposure to LEN and temsirolimus was increased in multiple myeloma patients when lenalidomide was co-administered with a P-gp inhibitor (temsirolimus and intraconazole, respectively). This clinical study assessed LEN-drug interactions via P-gp using two probe drugs under controlled conditions. Quinidine, a P-gp inhibitor with high in vivo inhibition potential and proven effect on plasma exposure of the prototype P-gp substrate digoxin in humans, was used to maximize the likelihood of detecting drug-drug interactions via P-gp. Temsirolimus, a P-gp inhibitor/substrate, was used to evaluate P-gp mediated interactions on either drug in comparison with the results reported in literature. Methods This was a phase 1, single-center, open-label, 2-part, fixed-sequence crossover study conducted in healthy men. Part 1 comprised of 2 treatment periods with LEN alone (25 mg single dose on Day 1) in period 1, followed by LEN (on Day 4) plus quinidine (300 mg twice daily [BID] on Day 1 and 600 mg BID on Days 2–5) in period 2. Part 2 consisted of three treatment periods with LEN (25 mg single dose on Day 1) alone in period 1, temsirolimus (25 mg single dose intravenously [IV] on Day 1) alone in period 2, and LEN plus temsirolimus in period 3 (Day 1). Treatment periods were separated by a washout of 7–10 days. Serial samples were collected to determine the plasma, whole blood or urine concentrations of LEN, quinidine, and temsirolimus (and its active metabolite, sirolimus [also a P-gp inhibitor/substrate]). Safety was monitored throughout the study. Results A total of 31 healthy men, aged 22 to 62 years; were enrolled (14 in Part 1 and 17 in Part 2). Renal excretion of LEN was almost complete at 12 h post dose for all treatments (Figure 1). In the absence or presence of a P-gp inhibitor, the mean percentage LEN dose excreted in the urine (74% vs 70% in Part 1, respectively; 81% vs 80% in Part 2) and renal clearance (227 vs 245 mL/min in Part 1; 251 vs 229 mL/min in Part 2) were similar, demonstrating that the rate and capacity of LEN renal excretion were not reduced by P-gp inhibition. Both the median time (1 h) to reach the maximum concentration (Cmax) and the oral bioavailability (70–80% of the administrated dose, as indicated by the renal excretion of unchanged drug) of LEN, were comparable in the absence or presence of a P-gp inhibitor (0.5–1 h and 74–81% of the dose, respectively); therefore, the rate and extent of LEN oral absorption were also not altered by P-gp inhibition. Consequently, there was no significant change in the plasma exposure to LEN in the presence of a P-gp inhibitor (Figure 1). The 90% confidence intervals (CIs) for the ratio of geometric means between LEN alone and LEN plus a P-gp inhibitor were completely contained within the equivalence limits of 80–125% for Cmaxand area under the concentration-time curve (AUC) of LEN. In addition, LEN had no effect on blood exposure to temsirolimus and sirolimus, with the 90% CIs for the ratio of their geometric mean Cmax and AUC between temsirolimus alone and temsirolimus plus LEN between 80–125%. No significant safety findings were reported when LEN was given with quinidine or temsirolimus compared to LEN alone. Conclusions Co-administration of either the P-gp inhibitor quinidine or temsirolimus had no clinically relevant effect on the systemic exposure of LEN. Similarly, co-administration of LEN had no clinically relevant effect on the systemic exposure of the P-gp substrates temsirolimus and sirolimus. A single dose of LEN was well tolerated when co-administered with quinidine or temsirolimus in healthy men. Disclosures: Chen: Celgene Corporation: Employment, Equity Ownership. Weiss:Celegene Corporation: Employment, Equity Ownership. Reyes:Celgene Corporation: Employment, Equity Ownership. Liu:Celgene Corporation: Employment, Equity Ownership. Kasserra:Celgene: Employment, Equity Ownership. Wang:Celgene Corporation: Employment, Equity Ownership. Zhou:Celgene Corporation: Employment, Equity Ownership. Kumar:Celgene Corporation: Employment, Equity Ownership. Weiss:Celgene Corporation: Employment, Equity Ownership. Palmisano:Celgene Corporation: Employment, Equity Ownership.

To investigate the pharmacokinetics and disposition of [14C]pomalidomide following a single oral dose to healthy male subjects.

Nab ® -paclitaxel is an albumin-bound nanoparticle formulation of paclitaxel (ptx) that does not contain Cremophor EL (CrEL), and results in higher drug levels in xenografts and increased clinical activity in breast and lung cancers compared to ptx formulated with CrEL (Taxol ® ). Above the critical micellar concentration of 0.009%, CrEL forms long-lived micelles in circulation that can sequester ptx (peak plasma concentration in clinical use is 0.3%). Previous studies have shown CrEL reduces ptx binding to albumin, and Taxol ® has reduced association with, and transport across endothelial cells compared to nab ® -ptx (Desai, CCR 2006). Endothelial cells take up albumin, which is trafficked into recycling or transcytosis pathways or into lysosomes for degradation. Here, we explore mechanisms of uptake and trafficking of albumin and ptx in endothelial cells and the effect of CrEL on these events. Using fluorescence microscopy, we visualized the uptake of rhodamine-albumin and fluorescent ptx (Flutax). Albumin was present in EEA1-positive early endosomes and LAMP1-positive lysosomes. Notably, ptx was also present in vesicular structures and was often co-localized with albumin. The uptake of albumin was blocked by increasing concentrations (0.003%-0.3%) of CrEL, and also by inhibitors of caveolin-mediated endocytosis including indomethacin (blocks internalization of caveolae) and methyl-β-cyclodextrin (prevents formation of lipid rafts). The effect of CrEL on paclitaxel and albumin cellular uptake was confirmed by flow cytometry studies. 0.3% CrEL reduced the uptake of Flutax in DMSO, Flutax-modified nab ® -ptx, and FITC-labeled albumin to close to background levels in both HUVEC and PC3 cells. Thus, in addition to its drug sequestration activity, CrEL directly affects endocytosis. We further evaluated CrEL effects on Flutax and ptx transport across endothelial monolayers in transwell chambers using a fluorescence detection assay. Two-fold more ptx crossed monolayers exposed to Flutax-containing nab ® -ptx as compared to Taxol ® . The effects of 0.001% to 0.3% CrEL on ptx transport at varying timepoints were investigated by mass spectrometry. Dose-dependent inhibition was observed, with a 3-fold reduction in transported ptx at 24 hrs. In summary, we have demonstrated that ptx co-localizes with albumin in endothelial cells, suggesting that the nab-ptx complex can remain intact within cells. Furthermore, CrEL interferes with albumin uptake at clinically relevant concentrations, thereby affecting paclitaxel cellular uptake and transport. These mechanistic studies further elucidate the basis of increased delivery of drug into the target cells by the nab ® -ptx formulation as compared to Taxol ® . Citation Format: Xiping Liu, Carrie Brachmann, Sean Hong, Shijuan Wu, Zeen Tong, Tapas De, Willard Foss, Gondi Kumar, Sekhar Surapaneni, Rajesh Chopra, Daniel Pierce, Carla Heise. Albumin and paclitaxel co-localize in endocytic vesicles in HUVEC cells, and uptake is blocked by Cremophor EL. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5666. doi:10.1158/1538-7445.AM2013-5666

Introduction Pomalidomide (POM) is an IMiD® immunomodulatory agent recently approved by the FDA for the treatment of patients with relapsed/refractory multiple myeloma. The prevalence of polypharmacy in disease treatment raises the possibilities of drug-drug interactions. Therapies that are CYP450 inhibitors, inducers, or transporter inhibitors, may alter the clinical exposure of substrates of these enzymes and transporters when they are administered concomitantly. POM is known to be predominantly metabolized via CYP450-mediated hydroxylation.1 The aim was to investigate the inhibition/induction potential of POM and its sensitivity as a CYP450 substrate in vitro , and to evaluate the impact of strong CYP450 inhibitors/inducers and a P-glycoprotein (P-gp) inhibitor on the pharmacokinetics (PK) of POM in healthy male subjects. Methods In vitro analyses were conducted using standard published methodologies.2-7 The in vitro data were followed up with a phase 1, open-label, non-randomized study in healthy men with single doses (SD) of POM. The study comprised a screening phase, 2 parallel treatment groups and a safety follow-up. Subjects in Part 1 received POM (4 mg SD) alone; ketoconazole (KETO 200 mg twice daily [BID] for 7 days) + POM (4 mg SD on day 5); and KETO (200 mg BID) + fluvoxamine (FLUV 50 mg BID) for 7 days + POM (4 mg SD on day 5) in three sequential periods to evaluate the effect of CYP3A4 and P-gp (KETO) and CYP1A2 (FLUV) inhibition on POM PK. Subjects in Part 2 received POM (4 mg SD) alone followed by carbamazepine (CARB 200 mg BID) for 11 days + POM (4 mg SD on day 10) in two sequential periods to evaluate the effect of CYP3A4 induction on POM PK. Serial blood samples were collected to determine the plasma concentrations of POM, FLUV, KETO, CARB and CARB-10, 11-epoxide by validated LC-MS/MS assay. PK and safety data were summarized using descriptive statistics. An analysis of variance model was performed on natural log transformed PK data, and used to estimate the ratio of geometric means between POM and the other drugs with treatments as fixed effects and subjects as random effect. Results In vitro, POM did not inhibit or induce CYP450 enzymes, nor the transporters P-gp, BCRP, OAT1, OAT2, OAT3, OATP1B1, or OATP1B3. The in vitro oxidative metabolism of POM was predominately mediated by CYP3A4 and CYP1A2. In the clinical trial, all 32 enrolled subjects (age 20–54 years; BMI 19.3–30.3 kg/m2) were included in the PK and safety analyses. Statistical comparison showed that the mean exposure of POM administered after multiple doses of KETO was increased by ∼19% (AUC0-inf) and 7% (Cmax) compared to exposure of POM alone (Table). Addition of FLUV to the POM + KETO regimen increased mean exposure of POM by ∼107% (AUC0-inf) and 13% (Cmax) compared to POM + KETO. Overall, co-administration of POM + KETO + FLUV increased mean exposure of POM by ∼146% (AUC0-inf) and 21% (Cmax) compared to POM alone. The mean exposure of POM when administered after multiple doses of CARB decreased by ∼20% (AUC0-inf) and 25% (Cmax) compared to exposure of POM alone. The mean estimated terminal half-life of POM was similar with or without KETO or CARB (range 5.85 to 6.77 h), but increased in the presence of KETO + FLUV (12.37 h), suggesting that the predominant interaction may be on the clearance (CL/F) rather than the absorption phase of POM. POM CL/F was decreased by ∼16% in the presence of KETO (6.96 L/h), and decreased by ∼56% in the presence of KETO + FLUV (3.64 L/h), compared to POM alone (8.27 L/h). In contrast, POM + CARB increased POM CL/F compared to POM alone (9.49 versus 7.56 L/h). POM 4 mg SD was generally well tolerated either alone or with the other drugs. The most common POM-related adverse event (AE) was nausea (6.3% of subjects). No deaths or serious AEs were reported. Conclusions POM appears to have a low potential for drug-drug interactions. POM is not a CYP450 inhibitor, inducer, or transporter inhibitor, in vitro and is therefore unlikely to affect the exposure of other drugs clinically. Co-administration of POM with the strong CYP3A4/5 and P-gp inhibitor KETO, or the strong CYP3A4/5 inducer CARB, had no clinically relevant effect on exposure to POM. Co-administration of POM with a strong CYP1A2 inhibitor (FLUV) will likely increase systemic exposure to POM and subjects receiving these concomitantly should be closely monitored for the occurrence of side-effects. POM 4 mg was generally well tolerated. View this table: ![Figure][1] Disclosures: Kasserra: Celgene: Employment, Equity Ownership. Assaf: Celgene Corporation: Employment, Equity Ownership. Hoffmann: Celgene Corporation: Employment, Equity Ownership. Li: Celgene Corporation: Employment, Equity Ownership. Liu: Celgene Corporation: Employment, Equity Ownership. Wang: Celgene Corporation: Employment, Equity Ownership. Kumar: Celgene Corporation: Employment, Equity Ownership. Palmisano: Celgene Corporation: Employment, Equity Ownership. [1]: pending:yes

Assessment of the absorption, metabolism and excretion of [14C]-lenalidomide in healthy male subjects following a single oral dose.