Tofacitinib pharmacokinetics in children and adolescents with juvenile idiopathic arthritis.

These analyses characterized tofacitinib pharmacokinetics (PKs) in children and adolescents with juvenile idiopathic arthritis (JIA). Data were pooled from phase I (NCT01513902), phase III (NCT02592434), and open-label, long-term extension (NCT01500551) studies of tofacitinib tablet/solution (weight-based doses administered twice daily [b.i.d.]) in patients with JIA aged 2 to less than 18 years. Population PK modeling used a nonlinear mixed-effects approach, with covariates identified using stepwise forward-inclusion backward-deletion procedures. Simulations were performed to derive dosing recommendations for children and adolescents with JIA. Two hundred forty-six pediatric patients were included in the population PK model. A one-compartment model with first-order elimination and absorption with body weight as a covariate for oral clearance and apparent volume of distribution sufficiently described the data. Oral solution was associated with comparable average concentration (Cavg) and slightly higher (113.9%) maximum concentration (Cmax) versus tablet, which was confirmed by a subsequent randomized, open-label, bioavailability study conducted in healthy adult participants (n = 12) by demonstrating adjusted geometric mean ratios (90% confidence interval) between oral solution and tablet of 1.04 (1.00-1.09) and 1.10 (1.00-1.21) for area under the curve extrapolated to infinity and Cmax, respectively (NCT04111614). A dosing regimen of 3.2 mg b.i.d. solution in patients 10 to less than 20 kg, 4 mg b.i.d. solution in patients 20 to less than 40 kg, and 5 mg b.i.d. tablet/solution in patients greater than or equal to 40 kg, irrespective of age, was proposed to achieve constant Cavg across weight groups. In summary, population PK characterization informed a simplified tofacitinib dosing regimen that has been implemented in pediatric patients with JIA.

Influenza Adverse Events in Patients with Rheumatoid Arthritis, Ulcerative Colitis, or Psoriatic Arthritis in the Tofacitinib Clinical Development Programs.

INTRODUCTION: This post hoc analysis evaluated influenza adverse events (AEs) across rheumatoid arthritis (RA), ulcerative colitis (UC), and psoriatic arthritis (PsA) tofacitinib clinical programs. METHODS: Available data from phase 1, randomized phase 2/3/3b/4 clinical trials (completed by 2018), and long-term extension (LTE) studies (up to May 2019) in patients with RA, UC, and PsA were included [randomized or Overall (phase 1-3b/4 and LTE studies) tofacitinib cohorts]. Incidence rates (IRs; events per 100 patient-years) of combined influenza AEs (seasons 2004/2005 to 2018/2019) were analyzed, including by tofacitinib dose [5 or 10 mg twice daily (BID)] and age (< 65 versus ≥ 65 years). Logistic regression models evaluated risk factors for influenza AEs in the RA Overall tofacitinib cohort. RESULTS: In randomized cohorts, combined influenza AE IRs were generally similar across tofacitinib, adalimumab, methotrexate, and placebo groups, across indications. Among Overall tofacitinib cohorts, combined influenza AE IRs with tofacitinib 5/10 mg BID, respectively, were higher in the UC (3.66/5.09) versus RA (2.38/2.19) and PsA (1.74/1.29) cohorts. IRs were generally similar across tofacitinib dose and age groups. Most influenza AEs were nonserious and did not require changes to tofacitinib treatment. Significant risk factors for influenza AEs in patients with RA were geographic region, baseline oral corticosteroid and methotrexate use, and tofacitinib dose. CONCLUSIONS: In the RA, UC, and PsA clinical programs, combined influenza AE IRs were highest in UC, while in each indication they were generally similar across tofacitinib, placebo, and comparator groups. Influenza AEs were predominantly nonserious and not associated with changes to tofacitinib treatment. TRIAL REGISTRATION NUMBERS: NCT01262118, NCT01484561, NCT00147498, NCT00413660, NCT00550446, NCT00603512, NCT00687193, NCT01164579, NCT00976599, NCT01059864, NCT01359150, NCT02147587, NCT00960440, NCT00847613, NCT00814307, NCT00856544, NCT00853385, NCT01039688, NCT02281552, NCT02187055, NCT02831855, NCT00413699, NCT00661661, NCT00787202, NCT01465763, NCT01458951, NCT01458574, NCT01470612, NCT01877668, NCT01882439, NCT01976364.

Analysis of Disease Activity Metrics in a Methotrexate Withdrawal Study among Patients with Rheumatoid Arthritis Treated with Tofacitinib plus Methotrexate.

INTRODUCTION: The objective of this analysis was to assess disease activity metrics using a variety of disease outcome measures following methotrexate (MTX) withdrawal in ORAL Shift, a phase 3b/4 study of tofacitinib with/without MTX, in patients with rheumatoid arthritis (RA) achieving Clinical Disease Activity Index (CDAI)-defined low disease activity (LDA). METHODS: Patients aged ≥ 18 years with active RA and an inadequate response to MTX received open-label tofacitinib modified-release 11 mg once daily plus MTX for 24 weeks. In the double-blind MTX withdrawal phase, those who had achieved CDAI LDA (≤ 10) at week 24 were randomised 1:1 to receive tofacitinib monotherapy or continued tofacitinib plus MTX. Efficacy analyses were performed in subgroups defined by whether remission and/or LDA had been achieved at week 24 with: Disease Activity Score in 28 joints, erythrocyte sedimentation rate [DAS28-4(ESR)], Routine Assessment of Patient Index Data 3 (RAPID3), CDAI and Simplified Disease Activity Index (SDAI); or DAS28-4[C-reactive protein(CRP)] < 2.4/ < 2.6/ < 2.9/ ≤ 3.2. RESULTS: Five hundred and thirty patients received treatment in the double-blind MTX withdrawal phase. Proportions of patients achieving each disease activity criterion at week 24 varied by metric. Across disease activity metrics [excluding DAS28-4(ESR) remission], 58-89% of patients per group, and numerically more patients receiving tofacitinib plus MTX, achieved the same criterion at week 48 as at week 24. Differences between groups in least squares mean change from baseline (Δ) DAS28-4(ESR) from week 24-48 favoured tofacitinib plus MTX (nominal p values < 0.05). RAPID3 and DAS28-4(CRP) estimated a higher proportion of patients with acceptable disease state versus DAS28-4(ESR), CDAI remission and SDAI remission. CONCLUSION: Response rates at the beginning of the double-blind phase varied across metrics. A consistent trend towards higher response rates with tofacitinib plus MTX was observed across metrics after randomisation, with nominal differences in DAS28-4(ESR) responses. Compared with continued combination therapy, MTX withdrawal did not lead to a clinically meaningful reduction in the response to tofacitinib. DAS28-4(CRP) and RAPID3 were the least stringent metrics. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02831855.

Evaluation of the Effect of Abrocitinib on Drug Transporters by Integrated Use of Probe Drugs and Endogenous Biomarkers.

Abrocitinib is an oral Janus kinase 1 (JAK1) inhibitor currently approved in the United Kingdom for the treatment of moderate-to-severe atopic dermatitis (AD). As patients with AD may use medications to manage comorbidities, abrocitinib could be used concomitantly with hepatic and/or renal transporter substrates. Therefore, we assessed the potential effect of abrocitinib on probe drugs and endogenous biomarker substrates for the drug transporters of interest. In vitro studies indicated that, among the transporters tested, abrocitinib has the potential to inhibit the activities of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporter 3 (OAT3), organic cation transporter 1 (OCT1), and multidrug and toxin extrusion protein 1 and 2K (MATE1/2K). Therefore, subsequent phase I, two-way crossover, open-label studies in healthy participants were performed to assess the impact of abrocitinib on the pharmacokinetics of the transporter probe substrates dabigatran etexilate (P-gp), rosuvastatin (BCRP and OAT3), and metformin (OCT2 and MATE1/2K), as well as endogenous biomarkers for MATE1/2K (N1 -methylnicotinamide (NMN)) and OCT1 (isobutyryl-L -carnitine (IBC)). Co-administration with abrocitinib was shown to increase the plasma exposure of dabigatran by ~ 50%. In comparison, the plasma exposure and renal clearance of rosuvastatin and metformin were not altered with abrocitinib co-administration. Similarly, abrocitinib did not affect the exposure of NMN or IBC. An increase in dabigatran exposure suggests that abrocitinib inhibits P-gp activity. By contrast, a lack of impact on plasma exposure and/or renal clearance of rosuvastatin, metformin, NMN, or IBC suggests that BCRP, OAT3, OCT1, and MATE1/2K activity are unaffected by abrocitinib.

Efficacy and safety of tofacitinib modified-release 11 mg once daily plus methotrexate in adult patients with rheumatoid arthritis: 24-week open-label phase results from a phase 3b/4 methotrexate withdrawal non-inferiority study (ORAL Shift).

OBJECTIVES: To report the efficacy, safety and patient-reported outcome measures (PROs) of tofacitinib modified-release 11 mg once daily plus methotrexate in patients with rheumatoid arthritis (RA) from the open-label phase of Oral Rheumatoid Arthritis Trial (ORAL) Shift. METHODS: ORAL Shift was a global, 48-week, phase 3b/4 withdrawal study in patients with moderate to severe RA and an inadequate response to methotrexate. Patients received open-label tofacitinib modified-release 11 mg once daily plus methotrexate; those who achieved low disease activity (LDA; Clinical Disease Activity Index (CDAI)≤10) at week 24 were randomised to receive blinded tofacitinib 11 mg once daily plus placebo (ie, blinded methotrexate withdrawal) or continue with blinded tofacitinib 11 mg once daily plus methotrexate for another 24 weeks. Efficacy, PROs and safety from the open-label phase are reported descriptively. RESULTS: Following screening, 694 patients were enrolled and received tofacitinib plus methotrexate in the open-label phase. At week 24, 527 (84.5%) patients achieved CDAI-defined LDA. Improvements from baseline to weeks 12 and 24 were generally observed for all efficacy outcomes (including measures of disease activity, and response, LDA and remission rates) and PROs. Adverse events (AEs), serious AEs and discontinuations due to AEs were reported by 362 (52.2%), 20 (2.9%) and 41 (5.9%) patients, respectively. No deaths were reported. CONCLUSIONS: Tofacitinib modified-release 11 mg once daily plus methotrexate conferred improvements in disease activity measures, functional outcomes and PROs, with most (84.5%) patients achieving CDAI-defined LDA after 24 weeks of open-label treatment; the safety profile was generally consistent with the historic safety profile of tofacitinib.Funded by Pfizer Inc; NCT02831855.

Associations between Patient Global Assessment scores and pain, physical function, and fatigue in rheumatoid arthritis: a post hoc analysis of data from phase 3 trials of tofacitinib.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). We examined the degree to which Patient Global Assessment of Disease Activity (PtGA) was driven by patient-reported assessments of pain (Pain), physical function, and fatigue in patients receiving tofacitinib 5 mg twice daily or placebo, each with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs). METHODS: This post hoc analysis used data pooled from three randomized controlled trials in csDMARD-inadequate responder (csDMARD-IR) patients (ORAL Scan: NCT00847613; ORAL Standard: NCT00853385; ORAL Sync: NCT00856544). Using subgroup analysis from 2 × 2 tables, associations between PtGA and Pain, Health Assessment Questionnaire-Disability Index (HAQ-DI), and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) at month 3 were evaluated using Pearson's Phi correlation coefficients. To support the main analysis, associations between select patient-reported outcomes (PROs) were also evaluated in csDMARD-naïve (ORAL Start; NCT01039688) and biologic (b)DMARD-IR (ORAL Step; NCT00960440) patients. RESULTS: Across csDMARD-IR treatment groups, low disease activity (defined as PtGA ≤ 20 mm), and moderate (≥ 30%) and substantial (≥ 50%) improvements from baseline in PtGA were associated with mild Pain (Visual Analog Scale score ≤ 20 mm), and moderate (≥ 30%) and substantial (≥ 50%) improvements from baseline in Pain; lack of Pain improvement was associated with little/no improvement in PtGA. In contrast, large proportions of csDMARD-IR patients who reported PtGA improvements did not report HAQ-DI or FACIT-F scores ≥ normative values (≤ 0.25 and ≥ 43.5, respectively) or changes in HAQ-DI or FACIT-F scores ≥ minimum clinically important difference (≥ 0.22 and ≥ 4.0, respectively). Generally, PtGA and Pain outcomes were moderately-to-strongly correlated at month 3 in csDMARD-IR patients, with weaker correlations evident between PtGA and HAQ-DI/FACIT-F outcomes. Similar findings were generally evident in csDMARD-naïve and bDMARD-IR patients. CONCLUSIONS: This analysis supports the role of Pain as a key driver of PtGA in RA; physical function and fatigue play lesser roles in patients' perceptions of disease activity. These findings corroborate the importance of improved PROs and attainment of low symptom states for optimizing patient care. TRIAL REGISTRATION: Clinicaltrials.gov: NCT00847613 (registered: February 19, 2009); NCT00853385 (registered: March 2, 2009); NCT00856544 (registered: March 5, 2009); NCT01039688 (registered: December 25, 2009); NCT00960440 (registered: August 17, 2009).

Variability in Antinuclear Antibody Testing to Assess Patient Eligibility for Clinical Trials of Novel Treatments for Systemic Lupus Erythematosus.

OBJECTIVE: In the development of novel therapies for systemic lupus erythematosus, antinuclear antibody (ANA) positivity represents a criterion for trial eligibility. Since as many as 30% of patients enrolled in trials have been ANA negative, we evaluated the performance characteristics of immunofluorescence assays (IFAs) for ANA determinations for screening. METHODS: This study used 5 commercially available IFAs to assess the ANA status of 181 patients enrolled in a phase II clinical trial for an anti-interleukin-6 antibody. Enrollment included a detailed review of medical records to verify a historical ANA value. IFA results were related to various clinical and serologic features at enrollment. RESULTS: While the frequency of ANA negativity assessed by the central laboratory was 23.8% in a cohort of 181 patients, the evaluated IFA kits demonstrated frequencies of negativity from 0.6 to 27.6%. With 2 IFA kits showing a significant frequency of ANA negativity, positive and negative samples differed in levels of anti-double-stranded DNA, C3, and presence of other ANAs as well as the frequency of high interferon (IFN) expression. CONCLUSION: These findings indicate that, when used for screening, IFAs can vary because of performance characteristics of kits and thus can affect determination of trial eligibility. With kits producing a significant frequency of ANA negativity, ANA status can be associated with other serologic measures as well as the presence of the IFN signature, potentially affecting responsiveness to a trial agent.

Methotrexate withdrawal in patients with rheumatoid arthritis who achieve low disease activity with tofacitinib modified-release 11 mg once daily plus methotrexate (ORAL Shift): a randomised, phase 3b/4, non-inferiority trial.

BACKGROUND: Tofacitinib is an oral Janus kinase (JAK) inhibitor used for the treatment of rheumatoid arthritis. We assessed the efficacy and safety of tofacitinib after methotrexate withdrawal in patients who achieved low disease activity (LDA) with tofacitinib in combination with methotrexate. METHODS: ORAL Shift was a phase 3b/4 non-inferiority trial in patients aged at least 18 years with moderate-to-severe rheumatoid arthritis and an inadequate response to methotrexate done in 109 centres across 16 countries. After 24 weeks of open-label tofacitinib modified-release 11 mg once daily plus methotrexate, patients who achieved LDA (clinical disease activity index [CDAI] ≤10) were randomly assigned 1:1 via an automated web-based response system to receive tofacitinib plus placebo (tofacitinib monotherapy; ie, masked methotrexate withdrawal) or continue tofacitinib plus methotrexate for 24 weeks in a double-blind manner. The primary endpoint was the least squares mean change from week 24 to week 48 in disease activity score in 28 joints with four variables, including erythrocyte sedimentation rate (DAS28-4[ESR]). The primary analysis was done in all patients who received at least one dose of study treatment in both phases, and safety was assessed in all patients who received at least one dose of study treatment since enrolment. Non-inferiority of tofacitinib monotherapy versus tofacitinib plus methotrexate was declared if the upper bound of the 95% CI for the difference in change in DAS28-4(ESR) between treatment groups was less than 0·6. Safety was assessed in both phases. The trial is registered with ClinicalTrials.gov, NCT02831855, and is complete. FINDINGS: Between Sept 1, 2016, and Nov 1, 2017, 694 patients were enrolled in the open-label phase and 623 received study treatment for 24 weeks. 533 achieved CDAI-defined LDA and were randomly assigned into the double-blind phase (267 in the tofacitinib monotherapy group and 266 in the tofacitinib plus methotrexate group). Three participants in the monotherapy group did not start treatment so were not included in the primary analysis. Non-inferiority was demonstrated (difference 0·30 [95% CI 0·12-0·48]). 107 (41%) of 264 patients in the tofacitinib monotherapy group and 109 (41%) of 266 in the tofacitinib plus methotrexate group had adverse events; five patients from each group discontinued because of adverse events; two patients died in the tofacitinib plus methotrexate group. No new safety findings were reported up to 48 weeks. INTERPRETATION: Patients with rheumatoid arthritis who achieve LDA with a combination of tofacitinib plus methotrexate may consider withdrawing methotrexate without significant worsening of disease activity or unexpected safety issues. FUNDING: Pfizer.

Efficacy and safety of an interleukin 6 monoclonal antibody for the treatment of systemic lupus erythematosus: a phase II dose-ranging randomised controlled trial.

OBJECTIVES: This phase II trial evaluated the efficacy and safety of an interleukin (IL) 6 monoclonal antibody for systemic lupus erythematosus (SLE). METHODS: Patients with active disease were randomised to placebo or PF-04236921 10 mg, 50 mg or 200 mg, subcutaneously, every 8 weeks with stable background therapy. SLE Responder Index (SRI-4; primary end point) and British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA) were assessed at week 24. Post hoc analysis identified an enriched population based upon planned univariate analyses. RESULTS: 183 patients received treatment (placebo, n=45; 10 mg, n=45; 50 mg, n=47; 200 mg, n=46). The 200 mg dose was discontinued due to safety findings and not included in the primary efficacy analysis. The SRI-4 response rates were not significant for any dose compared with placebo; however, the BICLA response rate was significant for 10 mg (p=0.026). The incidence of severe flares was significantly reduced with 10 mg (n=0) and 50 mg (n=2) combined versus placebo (n=8; p<0.01). In patients with greater baseline disease activity (enriched population), the SRI-4 (p=0.004) and BICLA (p=0.012) response rates were significantly different with 10 mg versus placebo. Four deaths (200 mg, n=3; 10 mg, n=1) occurred. The most frequently reported adverse events included headache, nausea and diarrhoea. CONCLUSIONS: PF-04236921 was not significantly different from placebo for the primary efficacy end point in patients with SLE. Evidence of an effect with 10 mg was seen in a post hoc analysis. Safety was acceptable for doses up to 50 mg as the 200 mg dose was discontinued due to safety findings. TRIAL REGISTRATION NUMBER: NCT01405196; Pre-results.

Safety and Efficacy of SBI-087, a Subcutaneous Agent for B Cell Depletion, in Patients with Active Rheumatoid Arthritis: Results from a Phase II Randomized, Double-blind, Placebo-controlled Study.

OBJECTIVE: To evaluate subcutaneous SBI-087 to treat rheumatoid arthritis (RA). METHODS: A total of 210 adult patients with active RA were randomized to receive either 200 mg SBI-087 or placebo (Pbo), according to one of these patterns: SBI/Pbo/Pbo (SBI on Day 1), SBI/SBI/Pbo (SBI days 1 and 15), SBI/Pbo/SBI (SBI days 1 and 84), SBI/SBI/SBI (SBI days 1, 15, and 84), or Pbo/Pbo/Pbo (Pbo all 3 days). All patients were seropositive and taking background methotrexate. The primary endpoint was proportion of patients achieving 20% improvement from baseline at Week 16 by American College of Rheumatology criteria (ACR20). Other outcomes included 28-joint Disease Activity Score (DAS28)-C-reactive protein (CRP), physician's and patient's global assessments of disease activity (PGA and PtGA, respectively) and Health Assessment Questionnaire-Disability Index (HAQ-DI). Peripheral CD19+ B cells were measured by high-sensitivity flow cytometer. Statistical significance was set at 2-sided α 0.10 level. RESULTS: The SBI/SBI/SBI group demonstrated significant improvement in ACR20 and DAS28-CRP from Week 8 onward, sustained improvement in CRP levels from Week 12 onward, and significant improvements in PGA and PtGA in weeks 16 through 24, and in HAQ-DI at Week 24. The SBI/Pbo/Pbo and SBI/SBI/Pbo groups did not meet the primary endpoint but demonstrated improvements in several secondary endpoints. All treatment groups exhibited depletion of peripheral CD19+ B cells throughout the study. Overall, 61.5% of patients receiving SBI-087 and 55.0% of patients receiving Pbo reported adverse events. CONCLUSION: SBI-087 effectively depleted peripheral CD20 B cells and was well tolerated. Improvements were consistently observed in the SBI/SBI/SBI group for the majority of efficacy and quality-of-life outcomes.

Safety, Tolerability, Pharmacokinetic and Pharmacodynamic Properties of SBI-087, a CD20-Directed B-cell Depleting Agent: Phase 1 Dose Escalating Studies in Patients With Either Mild Rheumatoid Arthritis or Systemic Lupus.

PURPOSE: SBI-087 is a Small Modular Immunopharmaceutical Protein™(SMIP™) drug that binds to CD20 and has been reported to deplete B cells in murine/primate studies. The safety, tolerability and pharmacokinetic/pharmacodynamic properties of SBI-087 were evaluated in patients with rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE). METHODS: Single-dose SBI-087 was evaluated in 2 Phase I, open-label, escalating-dose studies in patients with RA or SLE. The studies included 6 IV/4 SC escalating doses (RA) and 1 IV/4 SC escalating doses (SLE). Escalation was determined by tolerability/rate of B-cell depletion. Serum was collected for analyses of pharmacokinetic and pharmacodynamic (CD19(+) B cells) properties and immunogenicity. Patients were followed until B-cell counts were normalized or stabilized. Safety, tolerability was evaluated from adverse events, physical examinations, vital sign measurements, ECG, and clinical laboratory results. FINDINGS: Sixty patients with RA (IV, 28; SC, 32) and 30 patients with SLE (6 per cohort) were enrolled. Mild to moderate infusion reactions occurred in several patients at the top doses in the RA study despite a pretreatment regimen of IV doses. Unanticipated reactions after SC administration of SBI-087 included fever, chills, and malaise, seen on the day of dosing in the lowest-dose cohorts in both studies. These events were abrogated in subsequent cohorts by a pre/postdose treatment regimen consisting of oral corticosteroids, acetaminophen, and an antihistamine. SBI-087 clearance (IV) ranged from 22 to 229 mL/h; volume of distribution at steady state ranged from 5 to 12 L. Apparent clearance (SC) ranged from 44.7 to 105 mL/h; volume of distribution ranged from 14.3 to 32.1 L. Overall, PK properties were similar at equivalent doses between IV/SC administrations in patients with RA/SLE. Mean t½ (IV) ranged from 2.1 to 10.7 days (less at lower doses). SBI-087 concentration and B-cell depletion were generally dose proportional across IV and SC cohorts. However, the extent of B-cell depletion was less, and rate of repletion was faster, in patients with SLE versus RA. In both studies, B-cell repletion to baseline did not occur in the majority of patients by the end of the observation period. Overall, the prevalence and type of adverse events were similar to those seen with other anti-CD20-depleting agents. IMPLICATIONS: In patients with mild RA/SLE, SBI-087 was well tolerated when administered intravenously or subcutaneously with pre- and posttreatment regimens. B-cell depletion is long lasting, and the duration and extent of depletion may be greater in RA compared with SLE. SBI-087 exhibited slow elimination and low distribution in both populations. Clinicaltrials.gov identifiers: NCT00641225 (RA) and NCT00714116 (SLE).

Reassessment of tigecycline bone concentrations in volunteers undergoing elective orthopedic procedures.

The goal of the this study was to re-evaluate tigecycline bone concentrations in subjects undergoing elective orthopedic surgery, using multiple doses and a more robust bone assay than was used in a previous study. Each subject received three intravenous doses of tigecycline (one 100-mg infusion followed by two 50-mg infusions, each administered over 30 minutes). A single bone sample was collected from each subject at one of the following times: 1, 2, 4, 6, 8, or 12 hours after the third dose. Four blood samples were collected from each subject: before the first dose, before and after the third dose, and within 15 minutes of the collection time of the bone sample. Noncompartmental pharmacokinetic analysis serum and bone area under the curve for the given dose interval (AUCτ ) values were 2,402 ng h/mL and 11,465 ng h/g, and maximum concentration (Cmax ) values were 974 ng/mL and 2,262 ng/g, respectively. The bone to serum ratio calculated using the AUCτ values was 4.77, confirming tigecycline penetration into bone.

Comparative Sirolimus Pharmacokinetics After Single-Dose Administration of Two Prototype 0.5-mg Tablets in Healthy Volunteers.

Availability of a lower dose tablet would add to the dosing flexibility of currently available 1- and 2-mg sirolimus tablets for optimal concentrations and patient compliance. A randomized, 3-period crossover study was conducted in 30 fasting healthy volunteers (29 men, aged 31 ± 8 years, weight 79 ± 12 kg). Subjects were given 5 mg of sirolimus, either as doses of the 0.5-mg nonshellac-core prototype, 0.5-mg shellac-core prototype, or approved 1-mg tablet. Whole blood samples were collected at selected time points for 144 hours after dosing and analyzed using LC/MS/MS assay. Noncompartmental pharmacokinetic analysis was performed, followed by bioequivalence assessment. Twenty-four subjects completed all dosing periods, and no formulation-associated adverse events were reported. Ratios of maximum plasma concentration (Cmax ), area under the concentration-time curve to the last measured concentration (AUCT ), and area under the concentration-time curve from time 0 to infinity (AUC) for the nonshellac-core prototype compared with the 1-mg tablet were within the 80% to 125% range dictated by bioequivalence conventions. Similar results were observed when comparing the ratios of AUCT and AUC for the shellac-core prototype, while 90% confidence interval of the ratio of Cmax values was 105% to 129%. Within the context of clinical equivalence standards established by a phase 3 study comparing liquid to tablet formulations, it was concluded that both prototypes were clinically bioequivalent to the reference formulation.

The structure of MESD45-184 brings light into the mechanism of LDLR family folding.

Mesoderm development (MESD) is a 224 amino acid mouse protein that acts as a molecular chaperone for the low-density lipoprotein receptor (LDLR) family. Here, we provide evidence that the region 45-184 of MESD is essential and sufficient for this function and suggest a model for its mode of action. NMR studies reveal a ß-α-ß-ß-α-ß core domain with an α-helical N-terminal extension that interacts with the ß sheet in a dynamic manner. As a result, the structural ensemble contains open (active) and closed (inactive) forms, allowing for regulation of chaperone activity through substrate binding. The mutant W61R, which is lethal in Drosophila, adopts only the open state. The receptor motif recognized by MESD was identified by in vitro-binding studies. Furthermore, in vivo functional evidence for the relevance of the identified contact sites in MESD is provided.

Backbone and sidechain 1H, 13C and 15N resonance assignments of the RGS domain from human RGS14.

We have assigned 1H, 13C and 15N resonances of the RGS domain from the human RGS14 protein, a multi-domain member of the RGS (Regulators of G-protein signalling) family of proteins, important in the down-regulation of specific G-protein signalling pathways.

The solution structure of the core of mesoderm development (MESD), a chaperone for members of the LDLR-family.

Mesoderm development (MESD) is a 224 amino acid mouse protein that acts as a molecular chaperone for receptors of the low-density lipoprotein receptor (LDLR) family. By recording (15)N-HSQC-NMR spectra of six different MESD constructs, we could determine a highly structured core region corresponding to residues 104-177. Here we firstly present the solution structure of this highly conserved core of MESD. It shows a four-stranded anti-parallel beta-sheet and two alpha-helices situated on one side of the sheet. Although described in the literature as structurally homologues to ferredoxins, the connectivity of secondary structure elements is different in the MESD fold. A structural comparison to entries of the PDB reveals a frequent domain with low sequence homology annotated as HMA and P-II domains in Pfam.

The oxidized subunit B8 from human complex I adopts a thioredoxin fold.

Subunit B8 from ubiquinone oxidoreductase (complex I) (CI-B8) is one of several nuclear-encoded supernumerary subunits that are not present in bacterial complex I. Its solution structure shows a thioredoxin fold with highest similarities to the human thioredoxin mutant C73S and thioredoxin 2 from Anabeana sp. Interestingly, these proteins contain active sites in the same area, where the disulfide bond of oxidized CI-B8 is located. The redox potential of this disulfide bond is -251.6 mV, comparing well to that of disulfides in other thioredoxin-like proteins. Analysis of the structure reveals a surface area that is exclusively composed of highly conserved residues and thus most likely a subunit interaction site within complex I.