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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.

Introduction The aims of this study were to characterize the multiple-dose pharmacokinetics (PK) of ozanimod’s major active metabolites (CC112273 and CC1084037) and to evaluate the pharmacodynamic and PK interactions with pseudoephedrine (PSE). Methods In this phase 1, single-center, randomized, double-blind, placebo-controlled study, 56 healthy adult subjects were randomized to receive either placebo or ozanimod once daily for 30 days (0.23 mg on days 1–4, 0.46 mg on days 5–7, 0.92 mg on days 8–10, and 1.84 mg on days 11–30). On day 30, a single oral dose of PSE 60 mg was co-administered with placebo or ozanimod. Maximum time-matched change in systolic blood pressure (SBP) from baseline (day 29) following PSE administration on day 30 was calculated. Plasma PK parameters for ozanimod, CC112273, CC1084037, and PSE were estimated using noncompartmental methods. Results Fifty-two subjects (92.9%) completed the study. Following multiple dosing, approximately 94% of circulating total active drug exposure was represented by ozanimod (6%), CC112273 (73%), and CC1084037 (15%). Exposures of CC112273 and CC1084037 were highly correlated. Mean maximum time-matched change from baseline for SBP was not significantly different between ozanimod + PSE and placebo + PSE. Ozanimod also had no effect on the PK of PSE. Co-administration of ozanimod with a single dose of PSE in healthy subjects was generally well tolerated. While CC112273 and CC1084037 selectively inhibited monoamine oxidase (MAO)-B in vitro, both active metabolites do not inhibit platelet MAO-B activity in vivo. Conclusion Concomitant administration of ozanimod with PSE, a sympathomimetic agent, did not potentiate the effects on blood pressure. Trial Registration NCT03644576.

ObjectiveTo better understand ozanimod's mechanism of action (MOA), we conducted exploratory analyses from a phase 1 study to characterize ozanimod's effect on circulating leukocyte subsets in patients with relapsing multiple sclerosis.MethodsAn open-label pharmacodynamic study randomized patients to oral ozanimod hydrochloride (HCl) 0.5 (n = 13) or 1 mg/d (n = 11) for ∼12 weeks (including 7-day dose escalation). Circulating leukocyte subsets were quantified using flow cytometry (days 28, 56, and 85) and epigenetic cell counting (days 2, 5, 28, 56, and 85) and compared with baseline (day 1) using descriptive statistics.ResultsOzanimod caused dose-dependent reductions in absolute lymphocyte counts. Observed by both methodologies, circulating CD19+ B- and CD3+ T-cell counts were reduced by >50% with ozanimod HCl 0.5 mg and >75% with 1 mg at day 85. Based on flow cytometry, ozanimod HCl 1 mg showed greater decreases in CD4+ than CD8+ T cells, greater decreases in both CD4+ and CD8+ central memory vs effector memory T cells, and reductions in mean CD4+ and CD8+ naive T cells by ≥90% at day 85. In the flow cytometry analysis, changes in monocytes, natural killer, and natural killer T cells were minimal. Using epigenetic cell counting, greater reductions for Th17 than T regulatory cells were determined.ConclusionOzanimod induced dose-dependent reductions in circulating B- and T-cell counts and differential effects on naive and memory CD4+ and CD8+ T cells and CD19+ B cells. Data characterized with both a novel epigenetic cell-counting method and flow cytometry support ozanimod's MOA.Clinical trial registration:clinicaltrials.govNCT02797015.

Ozanimod, approved by regulatory agencies in multiple countries for the treatment of adults with relapsing multiple sclerosis, is a sphingosine 1‐phosphate (S1P) receptor modulator, which binds with high affinity selectively to S1P receptor subtypes 1 and 5. The relationships between plasma concentrations of ozanimod and its major active metabolites, {"type":"entrez-nucleotide","attrs":{"text":"CC112273","term_id":"29981328","term_text":"CC112273"}}CC112273 and CC1084037, and the QTc interval (C‐QTc) from a phase I multiple‐dose study in healthy subjects were analyzed using nonlinear mixed effects modeling. QTc was modeled linearly as the sum of a sex‐related fixed effect, baseline, and concentration‐related random effects that incorporated interindividual and residual variability. Common linear, power, and maximum effect (Emax) functions were assessed for characterizing the relationship of QTc with concentrations. Model goodness‐of‐fit and performance were evaluated by standard diagnostic tools, including a visual predictive check. The placebo‐corrected change from baseline in QTc (ΔΔQTc) was estimated based on the developed C‐QTc model using a nonparametric bootstrapping approach. QTc was better derived using a study‐specific population formula (QTcP). Among the investigated functions, an Emax function most adequately described the relationship of QTcP with concentrations. Separate models for individual analytes characterized the C‐QTcP relationship better than combined analytes models. Attributing QT prolongation independently to CC1084037 or {"type":"entrez-nucleotide","attrs":{"text":"CC112273","term_id":"29981328","term_text":"CC112273"}}CC112273, the upper bound of the 95% confidence interval of the predicted ΔΔQTcP was ~ 4 msec at the plateau of the Emax curves. Therefore, ΔΔQTcP is predicted to remain below 10 msec at the supratherapeutic concentrations of the major active metabolites.

The aims of this study were to characterize the single-dose pharmacokinetics (PK) of the major active metabolites of ozanimod, CC112273 and CC1084037, and to evaluate the effect of gemfibrozil (a strong inhibitor of cytochrome P450 [CYP] 2C8), itraconazole (a strong inhibitor of CYP3A and P-glycoprotein [P-gp]), and rifampin (a strong inducer of CYP3A/P-gp and moderate inducer of CYP2C8) on the single-dose PK of ozanimod and its major active metabolites in healthy subjects. This was a phase 1, randomized, parallel-group, open-label study with two parts. In part 1, 40 subjects were randomized to receive a single oral dose of ozanimod 0.46 mg (group A, n = 20) or oral doses of gemfibrozil 600 mg twice daily for 17 days with a single oral dose of ozanimod 0.46 mg on day 4 (group B, n = 20). In part 2, 60 subjects were randomized to receive a single oral dose of ozanimod 0.92 mg (group C, n = 20), oral doses of itraconazole 200 mg once daily for 17 days with a single oral dose of ozanimod 0.92 mg on day 4 (group D, n = 20), or oral doses of rifampin 600 mg once daily for 21 days with a single oral dose of ozanimod 0.92 mg on day 8 (group E, n = 20). Plasma PK parameters for ozanimod, CC112273, and CC1084037 were estimated using noncompartmental methods. Dose-proportional increases in maximum observed concentration (Cmax) and area under the concentration–time curve (AUC) were observed for ozanimod, CC112273, and CC1084037. The mean terminal elimination half-life (t1/2) for ozanimod was approximately 20–22 h while the mean t1/2 for CC112273 and CC1084037 were approximately 10 days. CC112273 and CC1084037 exposures were highly correlated with or without interacting drugs. Itraconazole increased ozanimod AUC by approximately 13% while rifampin reduced ozanimod AUC by approximately 24%, suggesting a minor role of CYP3A and P-gp in the overall disposition of ozanimod. Gemfibrozil increased the AUC for CC112273 and CC1084037 by approximately 47% and 69%, respectively. Rifampin reduced the AUC for CC112273 and CC1084037, primarily via CYP2C8 induction, by approximately 60% and 55%, respectively. Ozanimod’s major active metabolites, CC112273 and CC1084037, exhibited similar single-dose PK properties and their exposures were highly correlated. CYP2C8 is one of the important enzymes in the overall disposition of CC112273 and subsequently its direct metabolite CC1084037. Clinical trial: NCT03624959

Ozanimod (RPC1063) is an oral selective modulator of the sphingosine‐1‐phosphate 1 and 5 receptors under development for the treatment of relapsing multiple sclerosis and inflammatory bowel disease. The effects of high‐fat and low‐fat meals on the pharmacokinetics (PK) of a single oral dose of ozanimod were evaluated in 24 healthy volunteers in a randomized, open‐label crossover trial. Each subject received a 1‐mg dose of ozanimod hydrochloride under 3 meal conditions (fasted, high‐fat, and low‐fat), each separated by 7 days. Mean plasma concentration–time profiles for ozanimod and its active metabolites (RP101988 [major], RP101075 [minor]) were similar under all 3 conditions. Moreover, all PK parameters for ozanimod, RP101988, and RP101075 were similar under the 3 meal conditions. The 90% confidence intervals (CIs) for the ratios of geometric least‐squares mean (fed/fasted) were within the equivalence limits of 0.80 to 1.25 for area under the concentration–time curve from time 0 to infinity (AUC0–∞) and maximum plasma concentration (Cmax) for ozanimod, RP101988, and RP101075, except for the high‐fat effect on RP101075 Cmax (90%CI, 0.76–0.88). Given this lack of a food effect on the exposure of ozanimod and its active metabolites, ozanimod can be taken without regard to meals.

Ozanimod is a novel, selective, oral sphingosine‐1‐phosphate (1 and 5) receptor modulator in development for multiple sclerosis and inflammatory bowel disease. This randomized, double‐blind, placebo‐controlled, positive‐controlled, parallel‐group thorough QT study characterized the effects of ozanimod on cardiac repolarization in healthy subjects. Eligible subjects were randomized to 1 of 2 groups: ozanimod (escalated from 0.25 to 2 mg over 14 days) or placebo (for 14 days). A single dose of moxifloxacin 400 mg or placebo was administered on days 2 and 17. The primary end point was the time‐matched, placebo‐corrected, baseline‐adjusted mean QTcF (ΔΔQTcF). A total of 113/124 (91.1%) subjects completed the study. The upper limits of the 2‐sided 90% confidence intervals for ΔΔQTcF for both ozanimod 1 and 2 mg were below the 10‐millisecond regulatory threshold. No QTcF >480 milliseconds or postdose change in QTcF of >60 milliseconds was observed. There was no evidence of a positive relationship between concentrations of ozanimod and its active metabolites and ΔΔQTcF. Although ozanimod blunted the observed diurnal increase in heart rate, excursions below predose heart rates were no greater than with placebo. Results demonstrate that ozanimod does not prolong the QTc interval or cause clinically significant bradycardia, supporting ozanimod's evolving favorable cardiac safety profile.

The sphingosine‐1‐phosphate 1 receptor (S1P1R) is expressed by lymphocytes, dendritic cells, and vascular endothelial cells and plays a role in the regulation of chronic inflammation and lymphocyte egress from peripheral lymphoid organs. Ozanimod is an oral selective modulator of S1P1R and S1P5R receptors in clinical development for the treatment of chronic immune‐mediated, inflammatory diseases. This first‐in‐human study characterized the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of ozanimod in 88 healthy volunteers using a range of single and multiple doses (7 and 28 days) and a dose‐escalation regimen. Ozanimod was generally well tolerated up to a maximum single dose of 3 mg and multiple doses of 2 mg/d, with no severe adverse events (AEs) and no dose‐limiting toxicities. The most common ozanimod‐related AEs included headache, somnolence, dizziness, nausea, and fatigue. Ozanimod exhibited linear PK, high steady‐state volume of distribution (73–101 L/kg), moderate oral clearance (204–227 L/h), and an elimination half‐life of approximately 17 to 21 hours. Ozanimod produced a robust dose‐dependent reduction in total peripheral lymphocytes, with a median decrease of 65% to 68% observed after 28 days of dosing at 1 and 1.5 mg/d, respectively. Ozanimod selectivity affected lymphocyte subtypes, causing marked decreases in cells expressing CCR7 and variable decreases in subsets lacking CCR7. A dose‐dependent negative chronotropic effect was observed following the first dose, with the dose‐escalation regimen attenuating the first‐dose negative chronotropic effect. Ozanimod safety, PK, and PD properties support the once‐daily regimens under clinical investigation.

Introduction Ozanimod, modulateur des recepteurs de la sphingosine-1-phosphate de sous-types 1 et 5, entraine la sequestration des lymphocytes dans les tissus lymphoides, reduisant le nombre de lymphocytes dans le sang peripherique. Objectifs Caracteriser le phenotype des leucocytes circulants dans la SEP-R chez les patients traites par ozanimod dans un essai pharmacocinetique/pharmacodynamique de phase 1. Patients et methodes Vingt-quatre patients atteints de SEP ont ete randomises avec ozanimod 0,46 mg/j (n = 13) ou 0,92 mg/j (n = 11) pendant 12 semaines, avec une augmentation de la dose initiale sur 7 jours (0,23 mg/j × 4 jours puis 0,46 mg/j × 3 jours). Les analyses exploratoires ont utilise la cytometrie de flux pour examiner les changements proportionnels par rapport a la reference dans les sous-groupes de leucocytes dans les cellules mononucleees du sang peripherique totale (PBMC) et les cellules T totales a j28/j56/j85. Resultats Ozanimod a entraine des reductions dose-dependante des LT CD4+ et CD8+. Dans le PBMC, ozanimod 0,92 mg a entraine une faible augmentation des CD8 + TEMRA sans modification des CD8 + TEM. Une diminution des CD4+ et CD8+ naives, des cellules TCM et CD4 + TEM a ete constatee. Dans la population totale de LT, il a entraine une augmentation des: CD4 + TEM, CD8 + TEM et TEMRA. Une diminution des CD4 + naives et CD8 + naives a ete observee. Les CD4+ et CD8 + TCM ont ete peu affectees. Discussion Les proportions des differents types de cellules en circulation dans le PBMC et dans la population restante de LT ont ete modifiees lors du traitement par ozanimod. Les modifications etaient plus prononcees avec ozanimod 0,92 mg vs 0,46 mg. Conclusion Ces changements soutiennent l’hypothese, que bien qu’ozanimod inhibe la circulation de certaines sous-groupes de lymphocytes, les cellules circulantes restantes sont toujours pretes a assurer une immunosurveillance. TEMRA: LT effecteurs memoires avec differenciation terminale. TEM: lymphocytes T effecteurs a memoire, TCM: lymphocytes T memoire centrale. PBMC: cellules mononucleees du sang peripherique totale. Original abstract@ECTRIMS 2020.

Aim Daclizumab high yield process (HYP) is a humanized IgG1 monoclonal antibody that binds to the α-subunit of the interleukin-2 receptor and is being developed for treatment of multiple sclerosis (MS). This manuscript characterized the pharmacokinetic–pharmacodynamic (PK–PD) relationships of daclizumab HYP in subjects with MS. Methods Approximately 1400 subjects and 7000 PD measurements for each of three biomarkers [CD25 occupancy, CD56bright natural killer (NK) cell count, regulatory T cell (Treg) count] from four clinical trials were analyzed using non-linear mixed effects modelling. Evaluated regimens included 150 or 300 mg subcutaneous (s.c.) every 4 weeks. Results CD25 occupancy was characterized using a sigmoidal maximum response (Emax) model. Upon daclizumab HYP treatment, CD25 saturation was rapid with complete saturation occurring after approximately 7 h and maintained when daclizumab HYP serum concentration was ≥5 mg l-1. After the last 150 mg s.c. dose, unoccupied CD25 returned to baseline levels in approximately 24 weeks, with daclizumab HYP serum concentration approximately ≤1 mgl-11L. CD56bright NK cell expansion was characterized using an indirect response model. Following daclizumab HYP 150 mg s.c. every 4 weeks, expansion plateaus approximately at week 36, at which the average maximum expansion ratio is 5.2. After the last dose, CD56bright NK cells gradually declined to baseline levels within 24 weeks. Treg reduction was characterized by a sigmoidal Emax model. Average maximum reduction of 60% occurred approximately 4 days post 150 mg s.c. dose. After the last dose, Tregs were projected to return to baseline levels in approximately 20 weeks. Conclusions Robust PK–PD models of CD25 occupancy, CD56bright NK cell expansion and Treg reduction by daclizumab HYP were developed to characterize its key pharmacodynamic effects in the target patient population.

Aims To characterize the potential effect of daclizumab high-yield process (DAC HYP), a monoclonal antibody that blocks the high-affinity interleukin-2 receptors for treatment of multiple sclerosis, on activity of cytochrome P450 (CYP) enzymes. Methods Twenty patients with multiple sclerosis received an oral cocktail of probe substrates of CYP1A2 (caffeine 200 mg), CYP2C9 (warfarin 10 mg/vitamin K 10 mg), CYP2C19 (omeprazole 40 mg), CYP2D6 (dextromethorphan 30 mg) and CYP3A (midazolam 5 mg) on two sequential occasions: 7 days before and 7 days after subcutaneous administration of DAC HYP 150 mg every 4 weeks for three doses. Serial pharmacokinetic blood samples up to 96 h post dose and 12-h urine samples were collected on both occasions. Area under the curve (AUC) for caffeine, S-warfarin, omeprazole and midazolam, and urine dextromethorphan to dextrorphan ratio were calculated. Statistical analyses were conducted on log-transformed parameters using a linear mixed-effects model. Results The 90% confidence intervals (CIs) for the geometric mean ratio (probe substrate with DAC HYP/probe substrate alone) for caffeine AUC from 0–12 h (0.93–1.15), S-warfarin AUC from 0 to infinity (AUC[0–inf]) (0.95–1.06), omeprazole AUC(0–inf) (0.88–1.13) and midazolam AUC(0–inf) (0.89–1.15) were within the no-effect boundary of 0.80–1.25. The geometric mean ratio for urine dextromethorphan to dextrorphan ratio was 1.01, with the 90% CI (0.76–1.34) extending slightly outside the no-effect boundary, likely due to high variability with urine collections and CYP2D6 activity. Conclusions DAC HYP treatment in patients with multiple sclerosis had no effect on CYP 1A2, 2C9, 2C19, 2D6 and 3A activity.

Daclizumab high-yield process (HYP) is a humanized IgG1 monoclonal antibody that binds to the α-subunit (CD25) of the interleukin-2 receptor. The present work characterized the population pharmacokinetics of daclizumab HYP in healthy volunteers (HVs) and subjects with relapsing–remitting multiple sclerosis (RRMS) and evaluated the effects of covariates on daclizumab HYP exposure. Measurable serum concentrations (n = 17,139) from 1670 subjects in seven clinical studies (three phase I, one immunogenicity, one phase II with extension, and one phase III) were included in this pharmacokinetic analysis using non-linear mixed–effects modeling. The three phase I studies evaluated single or multiple doses that ranged from 50 to 400 mg with either intravenous or subcutaneous (SC) administration in HVs (n = 71). The phase II with extension studies evaluated doses of 150 or 300 mg SC every 4 weeks (n = 567), and the immunogenicity (n = 113) and the phase III (n = 919) studies evaluated 150 mg SC every 4 weeks, all in RRMS patients. A two-compartment model with first-order absorption and elimination adequately described daclizumab HYP pharmacokinetics. Clearance (CL) was 0.212 L/day and the central volume of distribution was 3.92 L, scaled by [body weight (kg)/68] with exponents of 0.87 and 1.12, respectively. The peripheral volume of distribution was 2.42 L. Absorption lag time, mean absorption time, and absolute bioavailability (100–300 mg SC) were 1.61 h, 7.2 days, and 88 %, respectively. The daclizumab HYP terminal half-life was 21 days. Baseline CD25, age, and sex did not influence daclizumab HYP pharmacokinetics. Body weight explained 37 and 27 % of the inter-individual variability for CL and central volume of distribution, respectively. Neutralizing antibody (NAb)-positive status (included as a time-varying covariate) increased daclizumab HYP CL by 19 %. Consistent with previous findings in HVs, this analysis including extensive data from RRMS patients demonstrates that daclizumab HYP is characterized by slow CL, linear pharmacokinetics at doses above 100 mg, and high SC bioavailability. The pharmacokinetics of daclizumab HYP were not influenced by age (range 18–66 years), the sex of adult subjects, or the baseline CD4+CD25+ T cells (target level). The impact of covariates (body weight, NAb) on daclizumab HYP pharmacokinetics is unlikely to be clinically relevant.

Daclizumab is a humanized monoclonal antibody that blocks the α-subunit of the interleukin-2 receptor with demonstrated benefits in the treatment of multiple sclerosis. The present work aimed to characterize the pharmacokinetics of daclizumab high-yield process (HYP) in healthy volunteers. Three double-blind, randomized, placebo-controlled, phase I studies evaluated the pharmacokinetics of daclizumab HYP in healthy volunteers following single subcutaneous administration (50, 150, or 300 mg), multiple subcutaneous administrations (100 or 200 mg biweekly with a 200 mg loading dose), or single intravenous administration (200 or 400 mg). Measurable serum concentrations (n = 925) from 70 subjects treated with daclizumab HYP in the three studies were analyzed using non-linear mixed-effects modeling. A two-compartment model with a first-order absorption and elimination adequately described daclizumab HYP pharmacokinetics. Daclizumab HYP clearance, inter-compartmental clearance, and central and peripheral volumes of distribution were 10 mL/h, 44 mL/h, 3.89 L, and 2.52 L, respectively, scaled by [bodyweight (kg)/70] with 0.54 and 0.64 exponents for clearance and volume parameters, respectively. Lag-time, mean absorption time, and absolute bioavailability (100–300 mg) for subcutaneous administration were 2 h, 4.6 days, and 84 %, respectively. Bodyweight explained only ~20 % of daclizumab HYP pharmacokinetic variability. With this limited dataset, sex, age, race, or presence of antibodies did not correlate with daclizumab HYP clearance. The estimated effective half-life was 21–25 days. The developed model was robust in bootstrap evaluation and predicted the data adequately in stochastic simulations. Daclizumab HYP is characterized by slow clearance, linear pharmacokinetics (at doses ≥100 mg), high subcutaneous bioavailability, and a half-life suitable for monthly administration.

BACKGROUND: Danoprevir is a potent, highly selective, macrocyclic, orally bioavailable inhibitor of the hepatitis C virus protease, and a substrate of cytochrome P450 (CYP) 3A. It is co-administered with low-dose ritonavir, a potent CYP3A inhibitor, to enhance danoprevir pharmacokinetics. Ketoconazole is a substrate for and potent selective inhibitor of CYP3A. METHODS: In this open-label, 3-period study, the 2-way interaction potential between ritonavir-boosted danoprevir (danoprevir/r) and ketoconazole was investigated in 18 healthy subjects. Subjects initially received ketoconazole 200 mg q24h for 4 days (Period 1) followed by a 7-day washout period. Danoprevir/r 100/100 mg q12h was then given for 10 days (Period 2) followed by a further 4 days of danoprevir/r 100/100 mg q12h plus ketoconazole 200 mg q24h (Period 3). Serial blood samples were collected for the determination of danoprevir, ritonavir and/or ketoconazole plasma concentrations, and calculation of pharmacokinetic parameters. Safety and tolerability were monitored throughout the study. RESULTS: Co-administration of ketoconazole with danoprevir/r modestly increased the danoprevir AUCτ by 1.44-fold, with no effect on danoprevir Cmax. Co-administration of danoprevir/r with ketoconazole substantially increased ketoconazole AUCτ and Cmax by 3.71-fold and 1.73-fold, respectively. Danoprevir/r was well tolerated when administered alone or with ketoconazole. CONCLUSIONS: These results indicate that the effect of potent CYP3A inhibitors, such as ketoconazole, on danoprevir/r pharmacokinetics is not likely to be clinically relevant.

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a–ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a–ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (10 reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a–ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log 10 decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a–ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an IL28B non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a–ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. NCT01185860.)

Jonathan Q Tran,1 Ahmed A Othman,2,3 Alvydas Mikulskis,4 Paul Wolstencroft,5 Jacob Elkins6 1Clinical Pharmacology, Biogen, Cambridge, MA, USA; 2Clinical Pharmacology and Pharmacometrics, AbbVie Inc., North Chicago, IL, USA; 3Faculty of Pharmacy, Cairo University, Cairo, Egypt; 4Global Biomarker Discovery and Development, Cambridge, MA, USA; 5Global Clinical Operation, Biogen, Maidenhead, Berkshire, UK; 6Global Clinical Development, Biogen, Cambridge, MA, USA Background: Daclizumab high-yield process (DAC HYP), a humanized immunoglobulin G1 monoclonal antibody specific for the a subunit (CD25) of the high-affinity interleukin-2 receptor, has demonstrated efficacy for treatment of relapsing forms of multiple sclerosis in Phase II and III clinical trials. Objective: To characterize the pharmacokinetics (PK) of DAC HYP following repeated administration of the 150 mg subcutaneous (SC) dose every 4 weeks (q4wk), the proposed clinical regimen in patients with relapsing-remitting multiple sclerosis (RRMS). Methods: Twenty-six patients with RRMS received DAC HYP 150 mg SC q4wk for a total of six doses. Serial PK blood samples were collected over the first and last dosing intervals and trough PK samples were collected between these doses. Blood samples for immunogenicity assessment were collected throughout the study. Serum DAC HYP levels and anti-DAC HYP antibodies were characterized using validated immunoassays. PK parameters were estimated using noncompartmental analysis. Results: DAC HYP showed slow SC absorption with a median time to reach maximum observed concentration (Cmax) value of ~1 week. Steady state was reached by the fourth injection. At steady state, DAC HYP mean serum Cmax, minimum observed concentration (Cmin), and area under the concentration–time curve within a dosing interval (AUCtau) values were 29.1 µg/mL, 14.9 µg/mL, and 638 µg · day/mL, respectively, with intersubject variability of 35%–40%. The AUC accumulation ratio was ~2.5 at steady state. DAC HYP had a long elimination half-life of ~22 days and low apparent clearance (0.274 L/day). Nine patients tested positive for anti-DAC HYP antibodies, with no impact on DAC HYP clearance in this limited data set. Conclusion: The PK of DAC HYP in patients with RRMS are consistent with those previously reported in healthy volunteers. The half-life of ~3 weeks and the low fluctuations in peak and trough concentrations of serum DAC HYP support the once-monthly SC dosing regimen. Keywords: pharmacokinetics, daclizumab high-yield process, multiple sclerosis

Daclizumab high yield process (HYP) is a humanized IgG1 monoclonal antibody that binds to the α-subunit of the interleukin-2 receptor and is being developed for treatment of multiple sclerosis (MS). This manuscript characterized the pharmacokinetic-pharmacodynamic (PK-PD) relationships of daclizumab HYP in subjects with MS.Approximately 1400 subjects and 7000 PD measurements for each of three biomarkers [CD25 occupancy, CD56CD25 occupancy was characterized using a sigmoidal maximum response (ERobust PK-PD models of CD25 occupancy, CD56

Danoprevir, a potent, selective inhibitor of HCV NS3/4A protease, has a short half-life in humans. Therefore, the feasibility of a controlled release (CR) formulation to allow less frequent dosing was investigated using experimental approaches and physiological modeling to examine whether danoprevir is absorbed in the colon. Danoprevir absorption was studied in portal-vein-cannulated monkeys and in monkeys surgically modified to make intraduodenal, intrajejunal, intracolonic and oral administration possible. In portal-vein-cannulated monkeys, absorption was apparent up to 24 h after administration. The observed relative bioavailability from intracolonic delivery in the monkey was approximately 30% relative to oral administration, consistent with the model prediction of 40%. Human relative bioavailability for a tablet delivered to the colon compared with an immediate release (IR) formulation was predicted to be 4–28%. Preclinical data and modeling suggested that CR development would be challenging for this Biopharmaceutics Classification System Class IV compound. Therefore, a confirmative study in healthy volunteers was conducted to investigate the relative bioavailability of danoprevir in various regions of the gastrointestinal tract. In a randomized, open-label, crossover study, subjects received 100 mg danoprevir IR soft gel capsule, 100 mg danoprevir solution delivered to the distal small bowel and colon via an Enterion™ capsule (a remotely activated capsule for regional drug delivery) and 100 mg danoprevir powder to the colon via an Enterion™ capsule. The relative bioavailability of danoprevir (compared with IR) delivered to the colon was 6.5% for a solution and 0.6% for a powder formulation, indicating that a CR formulation is not feasible. Copyright © 2011 John Wiley & Sons, Ltd.

To characterize the potential effect of daclizumab high-yield process (DAC HYP), a monoclonal antibody that blocks the high-affinity interleukin-2 receptors for treatment of multiple sclerosis, on activity of cytochrome P450 (CYP) enzymes.Twenty patients with multiple sclerosis received an oral cocktail of probe substrates of CYP1A2 (caffeine 200 mg), CYP2C9 (warfarin 10 mg/vitamin K 10 mg), CYP2C19 (omeprazole 40 mg), CYP2D6 (dextromethorphan 30 mg) and CYP3A (midazolam 5 mg) on two sequential occasions: 7 days before and 7 days after subcutaneous administration of DAC HYP 150 mg every 4 weeks for three doses. Serial pharmacokinetic blood samples up to 96 h post dose and 12-h urine samples were collected on both occasions. Area under the curve (AUC) for caffeine, S-warfarin, omeprazole and midazolam, and urine dextromethorphan to dextrorphan ratio were calculated. Statistical analyses were conducted on log-transformed parameters using a linear mixed-effects model.The 90% confidence intervals (CIs) for the geometric mean ratio (probe substrate with DAC HYP/probe substrate alone) for caffeine AUC from 0-12 h (0.93-1.15), S-warfarin AUC from 0 to infinity (AUC[0-inf]) (0.95-1.06), omeprazole AUC(0-inf) (0.88-1.13) and midazolam AUC(0-inf) (0.89-1.15) were within the no-effect boundary of 0.80-1.25. The geometric mean ratio for urine dextromethorphan to dextrorphan ratio was 1.01, with the 90% CI (0.76-1.34) extending slightly outside the no-effect boundary, likely due to high variability with urine collections and CYP2D6 activity.DAC HYP treatment in patients with multiple sclerosis had no effect on CYP 1A2, 2C9, 2C19, 2D6 and 3A activity.

Daclizumab high-yield process (DAC HYP) is a humanized monoclonal antibody that selectively blocks the α-subunit (CD25) of the high-affinity interleukin-2 receptors, and has shown robust efficacy as a treatment for multiple sclerosis (MS). This work quantitatively characterized the relationship between DAC HYP serum concentrations and saturation of CD25 expressed on antigen-rich target T cells in blood. Serial pharmacokinetic and 968 CD25 measurements from three double-blind, randomized, placebo-controlled, phase I studies of DAC HYP (50–300 mg subcutaneous and 200–400 mg intravenous doses or placebo) in healthy volunteers (n = 95) were analyzed using nonlinear mixed-effects modeling. CD25 occupancy was determined using flow cytometry and a fluorescently-labeled DAC HYP-competing antibody. CD25 occupancy was described using a direct inhibitory sigmoidal maximum effect (E max) model (where DAC HYP fully inhibited CD25 labeling with competing antibody). Two IC50 (serum concentration corresponding to 50 % of maximal inhibition) parameters were used to describe rapid CD25 saturation at initiation of dosing and apparently slower desaturation during DAC HYP washout. Parameter estimates (95 % bootstrap confidence intervals) were: baseline CD25 labeling, 47 % (45–48); DAC HYP IC50(saturation), 0.023 µg/mL (0.005–0.073); IC50(desaturation) 0.86 µg/mL (0.74–0.98); Hill coefficient 5.6 (4.3–6.8). Based on the developed model, the 150 mg monthly subcutaneous regimen of DAC HYP in subjects with MS is predicted to saturate CD25 on target effector T cells within a few hours of dosing and maintain CD25 saturation during the entire dosing interval. Free CD25 levels return to baseline within 4–6 months of the last DAC HYP dose.

Objective: To evaluate the safety, tolerability, and pharmacokinetics (PK) of BIIB033 (anti-LINGO-1 monoclonal antibody) in healthy volunteers and participants with multiple sclerosis (MS). Methods: In 2 separate randomized, placebo-controlled studies, single ascending doses (SAD; 0.1–100 mg/kg) of BIIB033 or placebo were administered via IV infusion or subcutaneous injection to 72 healthy volunteers, and multiple ascending doses (MAD; 0.3–100 mg/kg; 2 doses separated by 14 days) of BIIB033 or placebo were administered via IV infusion to 47 participants with relapsing-remitting or secondary progressive MS. Safety assessments included adverse event (AE) monitoring, neurologic examinations, conventional and nonconventional MRI, EEG, optical coherence tomography, retinal examinations, and evoked potentials. Serum and CSF PK as well as the immunogenicity of BIIB033 were also evaluated. Results: All 72 healthy volunteers and 47 participants with MS were included in the safety analyses. BIIB033 infusions were well tolerated. The frequency of AEs was similar between BIIB033 and placebo. There were no serious AEs or deaths. No clinically significant changes in any of the safety measures were observed. BIIB033 PK was similar between healthy volunteers and participants with MS. Doses of ≥10 mg/kg resulted in BIIB033 concentrations similar to or higher than the concentration associated with 90% of the maximum remyelination effect in rat remyelination studies. The incidence of anti-drug antibody production was low. Conclusions: The emerging safety, tolerability, and PK of BIIB033 support advancing BIIB033 into phase II clinical development as a potential treatment for CNS demyelination disorders. Classification of evidence: This study provides Class I evidence that BIIB033 is well tolerated and safe (serious adverse event rate 0%, 95% confidence interval 0–7.6%).

Argatroban, a direct thrombin inhibitor, is metabolized in vitro by CYP3A4/5 and therefore may be susceptible to clinically relevant CYP3A drug interactions. The effect of erythromycin, a potent CYP3A4/5 inhibitor, on the pharmacokinetics and pharmacodynamics of argatroban was evaluated in 14 healthy male volunteers in an open-label, crossover study with a 5-day washout between regimens. Argatroban 1 microgram/kg/min was infused alone for 5 hours (regimen A) and again on day 6 of a 7-day oral regimen of 500 mg erythromycin four times daily (regimen B). Serial blood samples for the determination of activated partial thromboplastin time (aPTT) and argatroban concentrations were collected for up to 48 hours following infusion. Mean values for argatroban area under the concentration-time curves (AUC0-inf), maximum concentration (Cmax), and half-life (t1/2) were similar between regimens. Mean aPTT values were not affected significantly by the concomitant administration of argatroban and erythromycin compared to argatroban alone. No serious adverse events or bleeding episodes occurred during the study. These results suggest that oxidative metabolism by CYP3A4/5 is unlikely to be an important in vivo elimination pathway for argatroban. Therefore, coadministration of CYP3A4/5 inhibitors should not require a modification in the dosage of argatroban.

A single spot urine collection to measure the ratio of 6 beta-hydroxycortisol (6 beta-OHC) to free cortisol (C) has been proposed as a research tool for the assessment of CYP3A4 induction. However, intraindividual variability in 6 beta-OHC/C under basal conditions and conditions of induction has not been prospectively evaluated, and findings on the correlation between morning spot and 24-hour urinary ratios have been conflicting. In this study, the variability in morning spot and 24-hour urinary 6 beta-OHC/C ratios was assessed in 15 healthy adult male volunteers before, during, and after oral administration of rifampin 600 mg once daily for 14 days. In addition, the correlation between morning spot and 24-hour urinary ratios measured under baseline, maximum induction, and postinduction was determined. Intraindividual coefficients of variation (CVs) at baseline for the morning spot and 24-hour ratios were 54.3% and 57.1%, respectively, and were not changed significantly during induction. No significant differences were detected in the variability between the morning spot and 24-hour ratios at baseline, maximum induction, or postinduction. A good correlation (r = 0.61, p < 0.0001) was detected between the mean morning spot and 24-hour urinary ratios. Mean (+/- SEM) percent increases in the morning spot and 24-hour ratios at maximum induction relative to baseline were 320% +/- 73% and 137% +/- 30%, respectively (p = 0.019). All 15 subjects had an increase in the mean morning spot ratio at maximum induction relative to baseline, whereas 12 subjects showed an increase in the mean 24-hour ratio. The time course of changes in the mean morning spot urinary ratio in response to a 14-day course of rifampin was also similar to that reported previously in a study using 24-hour urine collections. These findings suggest that measurement of the morning spot urinary 6 beta-OHC/C ratio is an effective and efficient method for evaluating the potential of investigational agents to induce CYP3A4.

The aim of this study was to evaluate the effects of danoprevir in combination with low-dose ritonavir (danoprevir/r) and placebo plus low-dose ritonavir on the pharmacokinetics of probe drugs for cytochrome P450 (CYP) 3A and CYP2C9, in patients with chronic hepatitis C.A total of 54 patients infected with hepatitis C virus genotype 1 received an oral drug cocktail (2 mg midazolam, 10 mg warfarin and 10 mg vitamin K) before and after 14 days of dosing with either danoprevir/r or placebo plus low-dose ritonavir (placebo/r). Serial pharmacokinetic samples were collected up to 24 (midazolam) and 72 (S-warfarin) h post-dose. Plasma concentrations of midazolam, α-hydroxymidazolam and S-warfarin were measured using validated assays. Pharmacokinetic parameters were estimated using non-compartmental analysis, and geometric mean ratios (GMRs) and 90 % confidence intervals (CIs) for the differences between baseline and post-dosing values were calculated.Danoprevir/r and placebo/r significantly increased midazolam area under the time-concentration curve (AUC0-∞) and reduced the midazolam metabolic ratio while S-warfarin AUC0-∞ was modestly decreased. When danoprevir data were pooled across doses, the midazolam GMR (90 % CI) AUC0-∞ was 9.41 (8.11, 10.9) and 11.14 (9.42, 13.2) following danoprevir/r and placebo/r dosing, respectively, and the S-warfarin GMR (90 % CI) AUC0-∞ was 0.72 (0.68, 0.76) and 0.76 (0.69, 0.85), respectively. The effects of danoprevir/r and placebo/r appeared to be qualitatively similar.Substantial inhibition of CYP3A- and modest induction of CYP2C9- activity were observed with danoprevir/r and low-dose ritonavir.

Danoprevir (RG7227; ITMN-191) is a potent inhibitor of the HCV NS3/4A serine protease. The aims of this double-blind, placebo-controlled, multiple-ascending dose phase Ib study were to evaluate safety, tolerability, antiviral activity, resistance, and pharmacokinetics of once- and twice-daily danoprevir in the presence of low-dose ritonavir (danoprevir/r) and in combination with peginterferon alfa-2a (40KD)/ribavirin in treatment-naive HCV genotype 1 patients.Thirty eligible patients were enrolled into three cohorts and treated with danoprevir/r or placebo/r all in combination with peginterferon alfa-2a (40KD)/ribavirin for 15 days. Cohort 1 received danoprevir/r at 100/100mg twice daily; Cohort 2 200/100mg once daily; and Cohort 3 200/100mg twice daily.The median reductions in HCV RNA from baseline after 14 days of treatment (day 15) were -5.1, -4.8, and -4.6 log(10)IU/ml in Cohorts 1, 2, and 3, respectively, and -2.7 log(10) in placebo/r and peginterferon alfa-2a (40KD)/ribavirin recipients. Viral breakthrough was not observed in any patient. On day 15, HCV RNA was undetectable (15IU/ml) in 6/9 (67%), 4/8 (50%), and 8/8 (100%) patients in Cohorts 1, 2, and 3, respectively. When co-administered with low dose ritonavir, danoprevir concentrations reached a steady state between 6 to 10 days of dosing. Danoprevir exposures increased more than dose proportionally between 100/100mg and 200/100mg. Danoprevir/r plus peginterferon alfa-2a (40KD)/ribavirin was well-tolerated with no safety-related discontinuations.Danoprevir/r plus peginterferon alfa-2a (40KD)/ribavirin provides profound and robust reductions in serum HCV RNA, at substantially lower systemic exposures compared to those observed with higher doses of danoprevir in the absence of ritonavir. These results support further studies of danoprevir/r.

Danoprevir, a potent, selective inhibitor of HCV NS3/4A protease, has a short half-life in humans. Therefore, the feasibility of a controlled release (CR) formulation to allow less frequent dosing was investigated using experimental approaches and physiological modeling to examine whether danoprevir is absorbed in the colon. Danoprevir absorption was studied in portal-vein-cannulated monkeys and in monkeys surgically modified to make intraduodenal, intrajejunal, intracolonic and oral administration possible. In portal-vein-cannulated monkeys, absorption was apparent up to 24 h after administration. The observed relative bioavailability from intracolonic delivery in the monkey was approximately 30% relative to oral administration, consistent with the model prediction of 40%. Human relative bioavailability for a tablet delivered to the colon compared with an immediate release (IR) formulation was predicted to be 4-28%. Preclinical data and modeling suggested that CR development would be challenging for this Biopharmaceutics Classification System Class IV compound. Therefore, a confirmative study in healthy volunteers was conducted to investigate the relative bioavailability of danoprevir in various regions of the gastrointestinal tract. In a randomized, open-label, crossover study, subjects received 100 mg danoprevir IR soft gel capsule, 100 mg danoprevir solution delivered to the distal small bowel and colon via an Enterion™ capsule (a remotely activated capsule for regional drug delivery) and 100 mg danoprevir powder to the colon via an Enterion™ capsule. The relative bioavailability of danoprevir (compared with IR) delivered to the colon was 6.5% for a solution and 0.6% for a powder formulation, indicating that a CR formulation is not feasible.

(E)-(S)-4-((S)-2-{3-[(5-methyl-isoxazole-3-carbonyl)-amino]-2-oxo-2H-pyridin-1-yl}-pent-4-ynoylamino)-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester (Compound 1) is a novel, irreversible inhibitor of human rhinovirus (HRV) 3C protease {inactivation rate constant (K obs /[I]) of 223,000 M −1 s −1 }. In cell-based assays, Compound 1 was active against all HRV serotypes (35 of 35), HRV clinical isolates (5 of 5), and related picornaviruses (8 of 8) tested with mean 50% effective concentration (EC 5 0 ) values of 50 nM (range, 14 to 122 nM), 77 nM (range, 72 to 89 nM), and 75 nM (range, 7 to 249 nM), respectively. Compound 1 inhibited HRV 3C-mediated polyprotein processing in infected cells in a concentration-dependent manner, providing direct confirmation that the cell-based antiviral activity is due to inhibition of 3C protease. In vitro and in vivo nonclinical safety studies showed Compound 1 to be without adverse effects at maximum achievable doses. Single oral doses of Compound 1 up to 2,000 mg in healthy volunteers were found to be safe and well tolerated in a phase I-ascending, single-dose study. Compound 1 estimated free observed maximum concentration in plasma ( C ma x ) for 500-, 1,000-, and 2,000-mg doses were higher than the protein binding-corrected EC 50 required to inhibit 80% of the HRV serotypes tested. Treatment of HRV 52-infected cells with one to five 2-h pulses of 150 nM Compound 1 (corresponding to the C max at the 500-mg dose) was sufficient to effect a significant reduction in viral replication. These experiments highlight Compound 1 as a potent, orally bioavailable, irreversible inhibitor of HRV 3C protease and provide data that suggest that C max rather than the C min might be the key variable predicting clinical efficacy.

Delavirdine, a non-nucleoside reverse transcriptase inhibitor (NNRTI), is a potent and specific inhibitor of HIV-1 reverse transcriptase. The approved therapeutic regimen for delavirdine is 400mg 3 times daily in combination with appropriate antiretroviral agents; however, a dose of 600mg twice daily appears to provide similar systemic exposure. The steady-state pharmacokinetics of delavirdine are not appreciably affected by food. Delavirdine undergoes extensive metabolism by cytochrome P450 (CYP) with little urinary excretion of unchanged drug. Metabolic drug interactions between delavirdine and nucleoside reverse transcriptase inhibitors are unlikely as their metabolic pathways differ; delavirdine has no effect on the pharmacokinetics of zidovudine. Concomitant use of CYP inducers, such as rifampicin (rifampin), rifabutin, phenytoin, phenobarbital or carbamazepine, should be avoided since delavirdine plasma concentrations are significantly lowered. Reduction in gastric acidity (pH > 3) decreases the extent of delavirdine absorption, so administration of antacids and the buffered formulations of didanosine should be separated from that of delavirdine by at least 1 hour. Delavirdine, unlike other currently available NNRTI agents, is an inhibitor rather than an inducer of CYP isozymes. Consequently, the drug interaction profile and rationale for combining delavirdine with other antiretroviral agents is unique among the current NNRTI agents. Delavirdine inhibits the CYP3A4-mediated metabolism of HIV protease inhibitors and thereby increases systemic exposure to protease inhibitors. The ability of delavirdine to enhance the pharmacokinetic profiles of protease inhibitors may permit the use of simplified administration regimens. Combining delavirdine and indinavir removes the food restrictions during indinavir administration. Furthermore, the superior virological response observed in antiretroviral regimens containing delavirdine and protease inhibitors has been attributed to the favourable pharmacokinetic interactions and the introduction of a new drug class in NNRTI-naive therapy-experienced patients. Pharmacokinetic drug interactions are an important consideration in selecting an HIV treatment regimen, due to the multiplicity of drugs that are coadministered and the varying direction and magnitude of interaction that can occur. Considerations for utilising delavirdine in a treatment regimen are different than for other NNRTI agents due to the unique drug interaction profile of delavirdine.

A randomized open-label study was conducted to compare the pharmacokinetics and pharmacodynamics of grepafloxacin with those of clarithromycin in patients with chronic bronchitis whose sputa were colonized with potential bacterial pathogens. Patients received oral grepafloxacin 400 mg od for 10 days (n = 15) or oral clarithromycin 500 mg bd for 10 days (n = 10). Sputum samples were collected before the first dose, 1, 4 and 8 h after a dose on day 1 and then before a dose on days 2, 3, 5, 7 and 10 to determine the time to eradication (T(erad)) of the potential bacterial pathogens. Blood samples for measurement of grepafloxacin or clarithromycin and 14-hydroxyclarithromycin concentrations were obtained before a dose and 1, 2, 4, 8 and 12 h after doses on days 1 and 5. The area under the inhibitory serum concentration-time curve over 24 h (AUIC(24)), peak serum concentration:MIC ratio (C(max):MIC) and the percentage of the dosing interval during which the serum concentration exceeded the MIC (%tauMIC) were calculated and serum inhibitory titres (SITs) were determined. Haemophilus spp. were the predominant potential bacterial pathogens and were recovered from the sputa of 24 patients. Strains of Streptococcus pneumoniae were isolated from two patients in the grepafloxacin group and a strain of Moraxella catarrhalis was isolated from one patient in the clarithromycin group. Haemophilus spp. isolates were eradicated from the sputa of 13 of 14 (93%) patients given grepafloxacin, but from only two of 10 (20%) patients given clarithromycin (P0.05). In the other eight (80%) patients who received clarithromycin, the sputum cultures remained positive throughout the 10 day course. Grepafloxacin eliminated potential bacterial pathogens more quickly than clarithromycin (median T(erad) 4 h versus 76 h). The S. pneumoniae strains were eradicated by grepafloxacin within 4 h and the single M. catarrhalis strain was eradicated by clarithromycin within 1 h. The greater efficacy of grepafloxacin, compared with that of clarithromycin, in terms of the incidence and speed of eradication of the Haemophilus spp. isolates, was associated with higher median values of AUIC(24) (169 SIT(-1)*h versus 8.1 SIT(-1)*h), C(max):MIC ratio (23.6 versus 0.7) and %tauMIC (100% versus 0%). A Hill-type model adequately described the relationship between the percentage probability of eradicating potential bacterial pathogens from sputa and the plasma grepafloxacin concentration.

Objective: To evaluate the safety, tolerability, and pharmacokinetics (PK) of the anti-LINGO-1 monoclonal antibody BIIB033 in healthy volunteers and subjects with multiple sclerosis (MS). Background LINGO-1 antagonism enhances remyelination and functional recovery in diverse rodent models. Biogen Idec is developing the anti-LINGO-1 monoclonal antibody, BIIB033, as a potential therapy to promote remyelination and functional recovery in MS. Design/Methods: In two separate randomized, placebo-controlled Phase 1 studies, single ascending doses (0.1 to 100 mg/kg) and multiple ascending doses (0.3 to 100 mg/kg; 2 doses separated by 14 days) of BIIB033 or placebo were administered via intravenous infusion to 64 healthy adult volunteers and 42 subjects with RRMS or SPMS, respectively. Safety was assessed by adverse event (AE) monitoring, vital signs, ECGs, laboratory tests, physical and neurological examinations, brain MRIs, VEP, SSEP, OCT, and retinal examination. Serum and cerebrospinal fluid (CSF) samples were collected to measure BIIB033 concentrations. All subjects were followed for 12-16 weeks after the last dose. Results: BIIB033 infusions were well tolerated. The frequency of AEs was similar between BIIB033 and placebo, with headache being the most frequently reported AE. There were no serious AEs or deaths. No clinically significant changes in any of the safety parameters were observed. BIIB033 PK was similar between healthy adults and MS subjects. Both Cmax and AUC increased in an approximately dose-proportional manner. The mean terminal half-life (t1/2) was approximately 15-21 days. Doses at 10 mg/kg or higher resulted in BIIB033 concentrations similar to or higher than concentration associated with 90% of the maximum remyelination effect in rats (EC90). The mean CSF/serum ratio of BIIB033 was approximately 0.06-0.09% which is similar to that observed in rat models. Conclusions: BIIB033 exhibits favorable safety profile, desirable PK and predicted brain penetration as suggested from CSF levels. These findings support advancing its development into proof-of-concept studies in MS. Supported by: Biogen Idec. Disclosure: Dr. Tran has received personal compensation for activities with Biogen Idec as an employee. Dr. Tran holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Tran was involved as an investigator. Dr. Tran has received research support from Biogen Idec. Dr. Palaparthy has received personal compensation for activities with Biogen Idec as an employee.Dr. Palaparthy holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Palaparthy was involved as an investigator.Dr. Palaparthy has received research support from Biogen Idec. Dr. Zhao has received personal compensation for activities with Biogen Idec as an employee. Dr. Zhao holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Zhao was involved as an investigator. Dr. Zhao has received research support from Biogen Idec. Dr. Brosofsky has received personal compensation for activities with ALG Partners Inc. Dr. Brosofsky has received research support from ALG Partners Inc. Dr. Ray has received personal compensation for activities with Biogen Idec as an employee.Dr. Ray holds stock and/or stock options in Biogen Idec.Dr. Ray has received research support from Biogen Idec. Dr. Rana has received personal compensation for activities with Biogen Idec as an employee.Dr. Rana holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Rana was involved in as an investigator.Dr. Rana has received research support from Biogen Idec. Dr. Cadavid has received personal compensation for activities with Biogen Idec as an employee. Dr. Cadavid holds stock and/or stock options in Biogen Idec, which sponsored research in which Dr. Cadavid was involved as an investigator. Dr. Cadavid has received research support from Biogen Idec.

BACKGROUND Conventional parametric estimates to assess dose proportionality (DP) are sometimes unreliable due to outliers and/or variability from model assumptions. A confidence interval (CI)-based approach using FDA bioequivalence criteria (0.80–1.25) has been proposed to assess DP in contrast to the power-law method (Smith, et al, 2000). Evaluation of robust methods was performed to determine if they improved estimation reliability and statistical inference. METHODS Conventional methods of ordinary least squares regression (OLS) for independent data and mixed-effects procedure for longitudinal data, and robust methods including Huber's Estimation, Least Trimmed Regression (LTS) and Least Absolute Deviation Regression (L1) for independent data and the recently developed Robust Estimation Equations (REE) (Hu, et al, 2001) for longitudinal data were applied to area under the curve (AUC) data from a parallel-group study and a fixed-sequence study. Monte Carlo simulation was used to compare the power in detecting dose proportionality for different estimation approaches. RESULTS The results are shown in Table 1 and Table 2. Table 1. Parallel-group design evaluated by different estimation approaches Methods Slope 90% CI: Lower limit 90% CI: Upper limit Dose proportionality (DP) Note: Acceptance interval for slope is (0.8219, 1.1781). OLS 1.1910 1.0194 1.3680 DP is suggested Huber 1.1002 0.9974 1.2030 DP is suggested LTS 1.1054 0.9895 1.2214 DP is suggested L1 1.1499 1.0427 1.2573 DP is suggested Table 2. Fixed-sequence design evaluated by different estimation approaches Methods Slope 90% CI: Lower limit 90% CI: Upper limit Dose proportionality (DP) Note: Acceptance interval for slope is (0.8219, 1.1781). PROC MIXED 1.2487 1.1829 1.3145 non-DP is documented %REE Macro 1.1451 1.0714 1.2188 DP is suggested CONCLUSIONS Robust methods based on CI estimation tend to lessen the impact of outliers or other departures from normality and could improve dose proportionality assessment. Further research is ongoing to study the magnitude of the power reduction in detecting dose proportionality of conventional (power-law) estimation against robust methods. Clinical Pharmacology & Therapeutics (2005) 79, P4–P4; doi: 10.1016/j.clpt.2005.12.013