Hugh M. Davis

Pharmacokinetics and Safety of Golimumab, a Fully Human Anti‐TNF‐α Monoclonal Antibody, in Subjects With Rheumatoid Arthritis

Golimumab is a fully human antitumor necrosis factor alpha (TNF‐α) monoclonal antibody that is being developed for intravenous and subcutaneous administration. To assess the pharmacokinetics and safety of the intravenous formulation of golimumab, 36 adult subjects with rheumatoid arthritis were randomly assigned to receive a single infusion of placebo or golimumab (0.1, 0.3, 1, 3, 6, or 10 mg/kg). Serum concentrations of golimumab were determined using a validated enzyme‐linked immunosorbent assay method. In addition to the noncompartmental analysis and compartmental modeling, a population pharmacokinetics analysis using NONMEM was also conducted. Both the maximum serum concentration and the area under the serum concentration‐time curve appeared to increase in a dose‐proportional manner. The median half‐life ranged from 7 to 20 days. A 2‐compartment population pharmacokinetic model adequately described the pharmacokinetics of golimumab. The following pharmacokinetic parameters (typical value [% coefficient of variation]) were estimated from the population pharmacokinetic model: clearance (CL: 0.40 [10.1%] L/d), volume of distribution in the central compartment (Vc: 3.07 [6.4%] L), intercompartmental clearance (Q: 0.42 [15.5%] L/d), and volume of distribution in the peripheral compartment (Vp: 3.68 [11.8%] L). Interindividual variability of the pharmacokinetic parameters was quantified for CL (44.3%), Vc (25.5%), Q (44.6%), and Vp (44.6%). Residual variability was estimated to be 15.0%. Body weight was found to be an important covariate on Vc. Golimumab was generally well tolerated. The pharmacokinetics of golimumab appeared to be linear over the dose range evaluated in this study.

Association Between Serum Concentration of Infliximab and Efficacy in Adult Patients With Ulcerative Colitis

BACKGROUND & AIMS We analyzed data collected during the Active Ulcerative Colitis Trials (ACT-1 and ACT-2) to assess relationships between serum concentrations of infliximab and outcomes of adults with moderate-to-severe ulcerative colitis. METHODS We compared serum concentrations of infliximab with outcomes of 728 patients with moderately-to-severely active ulcerative colitis who participated in ACT-1 or ACT-2; efficacy data were collected at weeks 8, 30, and 54 (for ACT-1 only). Relationships between serum concentration of infliximab and efficacy outcomes were assessed using trend, logistic regression, and receiver operating characteristic curve analyses. We also evaluated factors that affected the relationship between exposure and response. RESULTS Median serum concentrations of infliximab at weeks 8, 30, and/or 54 were significantly higher in patients with clinical response, mucosal healing, and/or clinical remission than in patients who did not meet these response criteria. There were statistically significant relationships between quartile of infliximab serum concentration and efficacy at these time points (P < .01). Infliximab therapy was effective for a smaller proportion of patients in the lowest quartile, and these patients had lower serum levels of albumin and a higher incidence of antibodies to infliximab than patients in other quartiles. Although the relationship between exposure to infliximab and response varied among patients, approximate serum concentrations of 41 μg/mL infliximab at week 8 of induction therapy and 3.7 μg/mL at steady-state during maintenance therapy produced optimal outcomes in patients. CONCLUSIONS Serum concentrations of infliximab are associated with efficacy in patients with moderate-to-severe ulcerative colitis; however, complex factors determine the relationship between exposure to this drug and response. A prospective evaluation of the value of measuring serum concentrations of infliximab should be performed before these data can be included in patient management strategies. Clinicaltrials.gov numbers: NCT00036439 and NCT00096655.

Pharmacokinetic Properties of Infliximab in Children and Adults with Crohn's Disease: A Retrospective Analysis of Data from 2 Phase III Clinical Trials

BACKGROUND Infliximab is a chimeric monoclonal antibody against TNFα. The pharmacokinetic (PK) properties of infliximab have been studied in several adult patient populations, but a literature search identified no reported comparative population PK properties of this drug in pediatric patients. OBJECTIVES The current analysis applied population PK techniques to compare data on the PK properties of infliximab in pediatric and adult patients with moderately to severely active Crohns disease (CD) from 2 Phase III studies. METHODS This analysis used serum infliximab concentration data from 692 patients (112 children, 580 adults; age range, 6-76 years) from 2 Phase III clinical studies (REACH [A Randomized, Multicenter, Open-Label Study to Evaluate the Safety and Efficacy of Anti-TNF-α Chimeric Monoclonal Antibody in Pediatric Subjects with Moderate-to-Severe Crohns Disease] and ACCENT I [A Crohns Disease Clinical Trial Evaluating Infliximab in a New, Long-term Treatment Regimen]). PK models were developed separately for children, adults, and a combination of both. The combined population was used for establishing important covariates of infliximab PK properties in the combined CD population. Exploratory simulations using combined PK and covariate data were performed to expand the interpretation of the results in children. RESULTS Based on the findings, in a typical child (who, based on the median values in REACH, weighs 42 kg, has a baseline serum albumin concentration [SAC] 3.8 mg/dL, and has not developed antibodies to infliximab [ATIs]) who is receiving infliximab and an immunomodulator, PK estimates (typical value [SE]) were as follows: clearance (CL), 5.43 (0.15) mL/kg/d; V(d) in the central compartment (V(1)), 54.2 (1.15) mL/kg; V(d) in the peripheral compartment (V(2)), 29.2 (2.03) mL/kg; and intercompartmental clearance (Q), 3.52 (0.71) mL/kg/d. Corresponding properties in a typical adult (weight, 68 kg; SAC, 4.1 mg/dL) were CL, 5.39 (0.13) mL/kg/d; V(1), 52.7 (0.49) mL/kg; V(2), 19.0 (1.53) mL/kg; and Q, 2.15 (0.39) mL/kg/d. V(2) decreased as body weight increased, predicting a possible undercompensation for exposure with infliximab dosing per kg weight in lower-weight individuals. In pediatric and adult patients, CL was higher in those in whom ATIs developed or who had low baseline SAC. Concurrent immunomodulator use (purine antimetabolites or methotrexate) was associated with a 14% decrease in CL. In the pediatric and adult patients, observed trough serum infliximab concentrations, median infliximab t(1/2) (in children, 13.2 days; and in adults, 12.4 days), and exploratory PK simulations predicted infliximab PK properties to be comparable between children and adults. CONCLUSIONS Infliximab PK properties appeared to be comparable between pediatric and adult patients with CD. Specifically, in this select population using nonlinear mixed effects modeling, infliximab CL increased as SAC decreased. CL also increased with ATI formation but decreased with immunomodulator coadministration. Although weight affects infliximab PK properties (total CL and total Vd increased with total body weight while per kg CL and Vd decrease with total body weight), age was not found to influence infliximab PK in the age range tested (6-76 years).

Population Pharmacokinetic Modeling of Ustekinumab, a Human Monoclonal Antibody Targeting IL-12/23p40, in Patients With Moderate to Severe Plaque Psoriasis

The population pharmacokinetics of ustekinumab are characterized in patients with moderate to severe plaque psoriasis in 2 Phase 3 studies (PHOENIX 1 and PHOENIX 2). Serum concentration data from 1937 patients are analyzed to determine pharmacokinetic characteristics of ustekinumab and to assess factors that may contribute to their variability. The population typical mean (percentage relative standard error) values for apparent clearance, apparent volume of distribution, and absorption rate constant from the final covariate model are 0.465 L·day−1 (2.0%), 15.7 L (2.0%), and 0.354 day−1 (16.2%), respectively. The interindividual variabilities for apparent clearance and apparent volume of distribution are 41.0% and 33.2%, respectively. Of the factors evaluated in this analysis, body weight, diabetes, and positive immune response (antibodies to ustekinumab) are important covariates affecting the apparent clearance and/or apparent volume of distribution of ustekinumab. To fully understand the clinical relevance of these results, the covariate findings need to be evaluated concurrently with the efficacy and safety data.

Interspecies Scaling of Therapeutic Monoclonal Antibodies: Initial Look

The authors evaluated interspecies scaling for the prediction of human clearance of 18 therapeutic monoclonal antibodies (mAbs). Human and monkey/chimpanzee data of 14 mAbs were classified based on the targeted antigens (soluble or membrane bound). Simple allometry and/or a time‐invariant method (elementary Dedrick plot) were performed. Results indicate that human clearance might be accurately predicted from monkey data for mAbs targeting soluble receptors or membrane‐bound receptors with limited tissue distribution using simplified allometry. The optimal exponents were estimated to be 0.85 or 0.90. If nonlinearity is anticipated at the human efficacious dose, pharmacokinetic parameters obtained at high doses in animals might not be sufficient for full pharmacokinetic characterization and prediction. Using prespecified criteria, including predicted human clearance (≤ or > 10 mL/d/kg), simplified allometric scaling might be helpful in predicting the effect of receptor‐mediated clearance for mAbs targeting membrane‐bound antigens. Furthermore, simplified allometry and an elementary Dedrick plot provide similar results in predicted clearance. Given the significant advantages offered by simplified allometry, it should be used when data are available from only 1 species. When reasonable data from ≥3 species are available, traditional allometry should be explored. Overall, clearance prediction is useful for human dose prediction in drug discovery and development.

Population Pharmacokinetics of Infliximab in Patients With Ankylosing Spondylitis

The population pharmacokinetics of infliximab were characterized in patients with active ankylosing spondylitis (n =274). Serum infliximab concentration data, from a 2‐year period, were analyzed using NONMEM. A 2‐compartment linear pharmacokinetic model was chosen to describe the pharmacokinetic characteristics of infliximab in serum. Population estimates (typical value ± standard error) were obtained from the final covariate model: clearance (CL: 0.273 ± 0.007 L/day), volume of distribution in the central compartment (V1: 3.06 ± 0.057 L), intercompartment clearance (Q: 1.72 ± 0.48 L/day), and volume of distribution in the peripheral compartment (V2:2.94 ± 0.17 L). Interindividual variability for CL and V1 was 34.1% and 17.5%, respectively. White blood cell count at baseline and the antibody‐to‐infliximab status were significant covariates to CL; body surface area and sex were significant covariates to V1. The CL for patients with a positive antibody‐to‐infliximab status was estimated to be 41.9% to 76.7% higher than for the remaining patients. Other covariates (baseline disease activity and the concomitant medication use of prednisolone, omeprazole, nonsteroidal anti‐inflammatory drugs, or analgesics) did not affect infliximab pharmacokinetics. The development of antibodies to infliximab was associated with accelerated infliximab clearance and may represent a potential underlying mechanism for an inadequate response, or loss of response, to infliximab treatment.

Pharmacokinetic and Pharmacodynamic Modeling of an Anti–Interleukin-6 Chimeric Monoclonal Antibody (Siltuximab) in Patients with Metastatic Renal Cell Carcinoma

Purpose: Interleukin-6 (IL-6) induces tumor growth, invasion, metastasis, and angiogenesis. Siltuximab (CNTO 328) is a chimeric, murine-human monoclonal antibody that specifically binds human IL-6 with high affinity. C-reactive protein (CRP) can be a pharmacodynamic (PD) marker of IL-6 bioactivity. Reductions in CRP may correlate with clinical activity and IL-6 bioactivity. Experimental Design: Starting-dose selection for this study was based on a previous siltuximab study in multiple myeloma patients. Pharmacokinetic (PK)/PD modeling explored the relationship between siltuximab PK and CRP suppression following i.v. siltuximab infusion in a three-part phase I/II study in 68 metastatic renal cell carcinoma patients. Modeling results were then used to simulate and determine which siltuximab dosage regimens would maintain CRP suppression below the lower limit of quantification (4 mg/L). Siltuximab was given at 1, 3, 6, or 12 mg/kg at weeks 1 and 4 and then every 2 weeks for 2 cycles in part 1; at 3 or 6 mg/kg every 3 weeks for 4 cycles in part 2; and at 6 mg/kg every 2 weeks for 6 cycles in part 3. Results: A two-compartment PK model adequately described the serum siltuximab concentration-time data. An inhibitory indirect response PD model examined the relationship between siltuximab concentrations and CRP suppression. PD parameter estimates seemed reliable and physiologically relevant. Simulations showed that 6 mg/kg siltuximab every 2 weeks or 9 mg/kg every 3 weeks would reduce serum CRP to below 4 mg/L. Conclusions: Using a stepwise design, PK/PD modeling was used to select the dose levels in this study. Furthermore, PK/PD modeling results were used to help select doses to be used in future siltuximab clinical development. Clin Cancer Res; 16(5); 1652–61

Pharmacokinetics, pharmacodynamics and safety of a human anti-IL-6 monoclonal antibody (sirukumab) in healthy subjects in a first-in-human study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Interleukin (IL)-6 is a cytokine known for pleiotropic and pro-inflammatory functions. IL-6 is involved in various disease processes including lupus erythematosus, rheumatoid arthritis, insulin resistance and malignancy. Anti-IL-6 receptor therapy has recently been demonstrated to be effective in the treatment of patients with rheumatoid arthritis. WHAT THIS STUDY ADDS Sirukumab, a human monoclonal antibody against soluble IL-6, has been found to bind to human IL-6 with high affinity and specificity and thus suppress the biological activity of IL-6. Preclinical studies have demonstrated the safety of sirukumab in cynomolgus monkeys, a toxicologically relevant animal species, following repeated intravenous and subcutaneous administrations. This study shows that sirukumab has desirable pharmacokinetic characteristics (linear pharmacokinetics with long half-life), a low incidence of immunogenicity and a well-tolerated safety profile in healthy subjects, supporting further development of sirukumab as a potentially valuable therapeutic agent. AIMS To assess the safety, tolerability, pharmacokinetics (PK) and immunogenicity of sirukumab (CNTO 136) following intravenous (i.v.) infusion in healthy subjects. METHODS Forty-five healthy adult subjects (38 men and seven women) were randomly assigned to receive a single i.v. dose of placebo or sirukumab (0.3, 1, 3, 6 or 10 mg kg(-1) in a dose-escalating manner). All treated subjects were observed for 96 h post infusion and underwent 20-week follow-up evaluations. Serum samples were collected to measure sirukumab concentrations, pharmacodynamic biomarkers and antibodies to sirukumab. Non-compartmental analysis and population PK modelling were conducted to characterize the PK of sirukumab. RESULTS Adverse events were generally brief in duration, mild or moderate in intensity and non-dose-dependent. No serious adverse events were observed in the sirukumab-treated subjects. Both C(max) and AUC(0,∞) increased in an approximately dose-proportional manner. Median terminal half-life ranged from 18.5 to 29.6 days. A two-compartment model adequately described the PK of sirukumab following i.v. administration. Population estimates for the clearance (CL), the central volume of distribution (V(1)), the inter-compartmental clearance (Q) and the peripheral volume of distribution (V(2)) were 0.364 l day(-1), 3.28 l, 0.588 l day(-1) and 4.97 l, respectively. Compared with placebo subjects, a sustained decrease from baseline in C-reactive protein was observed in all sirukumab-treated dose groups, although no clear dose-response relationship was observed. No subjects were positive for antibodies to sirukumab. CONCLUSIONS Sirukumab had a well-tolerated safety profile, desirable PK characteristics and a low incidence of immunogenicity following an i.v. infusion of 0.3 to 10 mg kg(-1) in healthy subjects.

Development of different analysis platforms with LC-MS for pharmacokinetic studies of protein drugs.

Three different analysis platforms using LC-MS were successfully developed for pharmacokinetic (PK) studies of an antibody drug in serum. These analysis platforms can be selectively used for different types of protein drugs, which ranged from a very specific for a particular drug (antibody enrichment) to a less specific for any antibody drugs with an Fc domain (protein A enrichment), and to a very generic method that can be used for any protein drugs (albumin depletion method). In this manner, the three platforms will be applicable to a wide range of antibody therapeutic studies for different species. The analysis using an albumin depletion method (with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)) achieved the detection of the drug (to 1 ng) in an aliquot of serum (30 microL) with a 5-order magnitude of linearity. The analysis using protein A enrichment (with SDS-PAGE) achieved the detection of the drug at a 50-fold lower level (to 0.02 ng). Without the use of SDS-PAGE for separation, the use of protein A enrichment achieved the detection to 10 ng and using the antidrug antibody enrichment achieved the detection to 0.1 ng, with a similar linear dynamic range. These three analysis platforms produced good agreement with a mimic PK study of the drug in monkey serum, as compared to the enzyme-linked immunosorbent assay (ELISA) approach. In addition, these analysis platforms can be selectively applied for PK studies of drugs with different requirements of development time and resources. Such as, the antibody enrichment method can be used in a high-throughput manner but limited to a specific protein drug only. On the other hand, the albumin depletion method can be applied to many types of protein drugs but with the laborious sample preparation steps (SDS-PAGE and the subsequent in-gel digestion). When antidrug antibodies are not available for antibody drugs or the sensitivity requirement is not stringent (e.g., >10 ng), using protein A enrichment (without using SDS-PAGE) seems to be a good choice for PK studies which require fast throughput.

Population Pharmacokinetics of Golimumab, an Anti-Tumor Necrosis Factor-α Human Monoclonal Antibody, in Patients With Psoriatic Arthritis

The population pharmacokinetics of subcutaneously administered golimumab (50 mg or 100 mg every 4 weeks) were characterized in patients with active psoriatic arthritis (PsA) in GO‐REVEAL, a randomized, double‐blind, placebo‐controlled, phase 3 study. A total of 2029 serum golimumab concentrations from 337 patients were analyzed using NONMEM. A 1‐compartment pharmacokinetic model with first‐order absorption and elimination was chosen to describe the observed concentration‐time data. For a patient of standard weight (70 kg), the population estimates (typical value ± standard error) for golimumab pharmacokinetic parameters were as follows: apparent clearance = 1.38 ± 0.04 L/d, apparent volume of distribution = 24.9 ± 1.04 L, and absorption rate constant = 0.908 ± 0.121 per day. The between‐subject variability was 37.6% in apparent clearance and 37.9% in apparent volume of distribution. Body weight, antibody‐to‐golimumab status, baseline C‐reactive protein level, and smoking status were identified as significant covariates on apparent clearance. Body weight was also a significant covariate on apparent volume of distribution. None of the concomitant medications examined (methotrexate, corticosteroids, and nonsteroidal anti‐inflammatory drugs) were significant covariates on apparent clearance, although the median trough golimumab concentration in patients receiving methotrexate was higher than for those not receiving methotrexate. These significant covariates account for part of the variability in systemic exposure to golimumab observed in patients with PsA.