A longitudinal model for the Mayo Clinical Score and its sub-components in patients with ulcerative colitis.

Clinical trials in patients with ulcerative colitis (UC) face the challenge of high and variable placebo response rates. The Mayo Clinical Score (MCS) is used widely as the primary endpoint in clinical trials to describe the clinical status of patients with UC. The MCS is comprised of four subscores, each scored 0, 1, 2 and 3: rectal bleeding (RB), stool frequency (SF), physician's global assessment (PGA), and endoscopy (ENDO) subscore. Excluding the PGA subscore gives the modified MCS. Quantitative insight on the placebo response, and its impact on the components of the MCS over time, can better inform clinical trial design and interpretation. Longitudinal modeling of the MCS, and the modified MCS, can be challenging due to complex clinical trial design, population heterogeneity, and limited assessments for the ENDO subscore. The current study pooled patient-level placebo/standard of care (SoC) arm data from five clinical trials in the TransCelerate database to develop a longitudinal placebo response model that describes the MCS over time in patients with UC. MCS subscores were modeled using proportional odds models, and the removal of patients from the placebo/SoC arm, or "dropout", was modeled using logistic regression models. The subscore and dropout models were linked to allow for the prediction of the MCS and the modified MCS. Stepwise covariate modeling identified prior exposure to TNF-α antagonists as a statistically significant predictor on the RB + SF subscore. Patients with prior exposure to TNF-α antagonists had higher post-baseline RB + SF subscores than naive patients.

Etrolizumab as induction therapy for ulcerative colitis: a randomised, controlled, phase 2 trial.

BACKGROUND: Etrolizumab is a humanised monoclonal antibody that selectively binds the ß7 subunit of the heterodimeric integrins α4ß7 and αEß7. We aimed to assess etrolizumab in patients with moderately-to-severely active ulcerative colitis. METHODS: In this double-blind, placebo-controlled, randomised, phase 2 study, patients with moderately-to-severely active ulcerative colitis who had not responded to conventional therapy were recruited from 40 referral centres in 11 countries. Eligible patients (aged 18-75 years; Mayo Clinic Score [MCS] of 5 of higher [or ≥6 in USA]; and disease extending 25 cm or more from anal verge) were randomised (1:1:1) to one of two dose levels of subcutaneous etrolizumab (100 mg at weeks 0, 4, and 8, with placebo at week 2; or 420 mg loading dose [LD] at week 0 followed by 300 mg at weeks 2, 4, and 8), or matching placebo. The primary endpoint was clinical remission at week 10, defined as MCS of 2 or less (with no individual subscore of >1), analysed in the modified intention-to-treat population (mITT; all randomly assigned patients who had received at least one dose of study drug, had at least one post-baseline disease-activity assessment, and had a centrally read screening endoscopic subscore of ≥2). This study is registered with ClinicalTrials.gov, number NCT01336465. FINDINGS: Between Sept 2, 2011, and July 11, 2012, 124 patients were randomly assigned, of whom five had a endoscopic subscore of 0 or 1 and were excluded from the mITT population, leaving 39 patients in the etrolizumab 100 mg group, 39 in the etrolizumab 300 mg plus LD group, and 41 in the placebo group for the primary analyses. No patients in the placebo group had clinical remission at week 10, compared with eight (21% [95% CI 7-36]) patients in the etrolizumab 100 mg group (p=0·0040) and four (10% [0·2-24]) patients in the 300 mg plus LD group (p=0·048). Adverse events occurred in 25 (61%) of 41 patients in the etrolizumab 100 mg group (five [12%] of which were regarded as serious), 19 (48%) of 40 patients in the etrolizumab 300 mg plus LD group (two [5%] serious), and 31 (72%) of 43 patients in the placebo group (five [12%] serious). INTERPRETATION: Etrolizumab was more likely to lead to clinical remission at week 10 than was placebo. Therefore, blockade of both α4ß7 and αEß7 might provide a unique therapeutic approach for the treatment of ulcerative colitis, and phase 3 studies have been planned. FUNDING: Genentech.

Exposure-response relationships of etrolizumab in patients with moderately-to-severely active ulcerative colitis.

Etrolizumab is an IgG1-humanized monoclonal anti-ß7 integrin antibody. Phase III trials with induction and/or maintenance phases were conducted in patients with moderately-to-severely active ulcerative colitis (UC) who were either previously treated with tumor necrosis factor (TNF) inhibitors (HICKORY) or were TNF inhibitor naïve (HIBISCUS I/II, LAUREL, and GARDENIA). A total of eight exposure-response analyses were conducted for two clinical outcomes (remission and endoscopic improvement) at the end of induction for studies HIBISCUS I/II (combined) and HICKORY and at the end of maintenance for studies HICKORY and LAUREL. Trough concentration at week 4 (Ctrough,wk4 ) of induction was selected as the exposure metric. Exposure-response (ER) modeling was conducted using logistic regression. A full covariate model was used to examine the impact of covariates on clinical outcomes. Linear models with a single intercept for placebo and active treatments adequately described the data for all eight analyses. The etrolizumab exposure-response slope was significant (p < 0.05) for seven of the eight analyses. Baseline Mayo Clinic Score (MCS) was the only statistically significant covariate that impacted induction remission and endoscopic improvement. No statistically significant covariate was identified to impact maintenance outcomes except for baseline fecal calprotectin on endoscopic improvement for LAUREL study. A statistically significant positive ER relationship was identified for most of the clinical outcomes tested, reflecting a better treatment effect in patients with UC with higher etrolizumab Ctrough,wk4 of induction. Baseline MCS was the only other significant covariate impacting induction efficacy. Besides Ctrough,wk4 of induction, no consistent covariate was identified to impact maintenance efficacy.

Intermediate-affinity interleukin-2 receptor expression predicts CD56(bright) natural killer cell expansion after daclizumab treatment in the CHOICE study of patients with multiple sclerosis.

OBJECTIVE: The objective of this study was to evaluate whether interleukin-2 (IL-2) receptor expression on CD56(bright) natural killer (NK) cells predicted CD56(bright) NK cell expansion and therapeutic response to daclizumab (DAC) in multiple sclerosis (MS). METHODS: DAC exposure, CD56(bright) NK cell counts, IL-2 receptor alpha (CD25) and beta (CD122) subunits, and new or enlarged lesions on brain MRI were measured in 64 subjects in a pharmacokinetic/pharmacodynamic substudy of the phase 2 CHOICE trial at multiple time points. Peripheral blood mononuclear cell (PBMC) samples were obtained from healthy subjects to assess the relationship among DAC treatment, intermediate affinity IL-2 signaling, and CD56(bright) NK cell expansion. RESULTS: Increased CD56(bright) NK cell counts in DAC/interferon beta (IFNß)-treated subjects were observed by day 14, the first post-dosing time point (mean [SD] ln{CD56(bright) NK cell count}: DAC high/IFNß, 2.01 [1.25]; DAC low/IFNß, 2.29 [1.06]; placebo/IFNß, 1.01 [1.03]; adjusted p = 0.003), and persisted throughout the treatment period. Higher DAC dose predicted a faster rate of CD56(bright) NK cell expansion (p < 0.001), but individual subjects' increases in CD56(bright) NK cells from baseline levels were only weakly correlated with DAC exposure (r(2) = 0.167). Higher expression of the intermediate-affinity IL-2 receptor subunit (CD122) on CD56(bright) NK cells at baseline predicted fewer new gadolinium-enhanced (Gd+) lesions during the treatment period (1.77 vs. 0.62 adjusted mean new Gd+ lesions during weeks 8-24, lowest vs. highest quartile of percentage CD122(+) CD56(bright) NK cells; p = 0.033) and a greater increase in CD56(bright) NK cell counts at the end of DAC dosing (p = 0.029). CONCLUSION: CD56(bright) NK cell expansion after DAC treatment appears to reflect individual differences in the capacity for intermediate-affinity IL-2 signaling and could provide a basis for predicting clinical response to DAC in MS.

Pharmacokinetic and Pharmacodynamic Modeling of Serum Etrolizumab and Circulating ß7 Receptor Occupancy in Patients With Ulcerative Colitis.

Etrolizumab, a humanized monoclonal antibody, specifically binds to the ß7 subunit of the heterodimeric integrins α4ß7 and αEß7. Pharmacokinetic (PK) and pharmacodynamic (PD) data were collected from an etrolizumab phase 1 trial in patients with moderate to severe ulcerative colitis (UC). We developed a mechanism-based model to simultaneously describe the kinetics of serum etrolizumab concentration and free ß7 receptors on circulating intestinal-homing CD4+ T lymphocytes. Included in the analysis were 38 phase 1 UC patients who received single or 3 monthly doses of etrolizumab intravenously or subcutaneously across a dose range of 0.3 to 10 mg/kg. A quasi-steady-state target-mediated drug disposition model was developed to describe the dynamic interaction between serum etrolizumab concentration and free ß7 receptors on intestinal-homing CD4+ T lymphocytes in UC patients. The time profiles of serum etrolizumab and absolute counts of ß7+ lymphocytes (expressed as percentage of baseline level) were well described by the quasi-steady-state target-mediated drug disposition model. The model was able to characterize the maximum drug occupancy of ß7 receptors on intestinal-homing CD4+ T lymphocytes and the concentration-dependent duration of occupancy. The 90% effective concentration for etrolizumab to saturate the ß7 receptors on intestinal homing CD4+ T cells was 1.3 µg/mL. PK and PD profiles predicted by the model were consistent with observations from a subsequent phase 2 study. In conclusion, an integrated PK/PD model developed in this analysis reasonably described serum etrolizumab PK profiles and the relationship between PK and PD (free ß7 receptors on circulating intestinal-homing CD4+ T lymphocytes) in UC patients.

Assessment of Disease-Related Therapeutic Protein Drug-Drug Interaction for Etrolizumab in Patients With Moderately to Severely Active Ulcerative Colitis.

The efficacy and safety of etrolizumab, a humanized IgG1 mAb, were evaluated in patients with ulcerative colitis (UC) in a phase 2 study (EUCALYPTUS). The current study assessed the risk of therapeutic protein drug-drug interaction (TP-DDI) of etrolizumab on CYP3A activity in patients with UC. Literature review was performed to compare serum proinflammatory cytokine levels and pharmacokinetic (PK) parameters of CYP3A substrate drugs between patients with inflammatory bowel disease (IBD) and healthy subjects. Treatment effect of etrolizumab on CYP3A activity was evaluated by measuring colonic CYP3A4 mRNA expression and serum C-reactive protein (CRP) in EUCALYPTUS patients. Literature data suggested similar levels between IBD patients and healthy subjects for serum proinflammatory cytokines and PK parameters of CYP3A substrate drugs. Additionally, treatment with etrolizumab did not change colonic CYP3A4 mRNA expression or serum CRP levels in UC patients. In conclusion, our results indicate a low TP-DDI risk for etrolizumab in UC patients, particularly on medications metabolized by CYP3A.

Short-Term Efficacy Reliably Predicts Long-Term Clinical Benefit in Rheumatoid Arthritis Clinical Trials as Demonstrated by Model-Based Meta-Analysis.

The objective of this study was to assess the relationship between short-term and long-term treatment effects measured by the American College of Rheumatology (ACR) 50 responses and to assess the feasibility of predicting 6-month efficacy from short-term data. A rheumatoid arthritis (RA) database was constructed from 68 reported trials. We focused on the relationship between 3- and 6-month ACR50 treatment effects and developed a generalized nonlinear model to quantify the relationship and test the impact of covariates. The ΔACR50 at 6 months strongly correlated with that at 3 months, moderately correlated with that at 2 months, and only weakly correlated with results obtained at <2 months. A scaling factor that reflected the ratio of 6- to 3-month treatment effects was estimated to be 0.997, suggesting that the treatment effects at 3 months are approaching a "plateau." Drug classes, baseline Disease Activity Score in 28 Joints, and the magnitude of control arm response did not show significant impacts on the scaling factor. This work quantitatively supports the empirical clinical development paradigm of using 3-month efficacy data to predict long-term efficacy and to inform the probability of clinical success based on early efficacy readout.

Population pharmacokinetics of daclizumab high-yield process in healthy volunteers: integrated analysis of intravenous and subcutaneous, single- and multiple-dose administration.

BACKGROUND AND OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Daclizumab HYP is characterized by slow clearance, linear pharmacokinetics (at doses ≥100 mg), high subcutaneous bioavailability, and a half-life suitable for monthly administration.

Efficacy and safety of pateclizumab (anti-lymphotoxin-α) compared to adalimumab in rheumatoid arthritis: a head-to-head phase 2 randomized controlled study (The ALTARA Study).

INTRODUCTION: Tumor necrosis factor (TNF) and, possibly, lymphotoxin alpha (LTα) signaling contribute to inflammation and rheumatoid arthritis (RA) pathogenesis. Pateclizumab (anti-lymphotoxin- alpha; MLTA3698A) is a humanized monoclonal antibody that blocks and depletes anti-LTα. This phase 2, randomized, head-to-head, active- and placebo-controlled trial examined the safety and efficacy of pateclizumab compared to adalimumab in RA patients with an inadequate response to disease-modifying antirheumatic drugs (DMARD-IR). METHODS: Patients (n = 214) with active RA (≥ 6 swollen and tender joints, C-reactive protein ≥ 10 mg/L) on oral DMARDs were randomized (2:2:1) to receive pateclizumab 360 mg, adalimumab 40 mg, or placebo subcutaneously every 2 weeks. The primary endpoint, 4-variable, 28-joint disease activity score erythrocyte sedimentation rate (DAS28(4)-ESR) response, was evaluated at 12 weeks using an analysis of covariance (ANCOVA) model with adjustments for concomitant DMARD use and geographic region. Secondary efficacy endpoints included American College of Rheumatology (ACR) 20, ACR50, and ACR70 responses at Day 85. Pharmacokinetics, pharmacodynamics, and immunogenicity of pateclizumab were assessed. RESULTS: Pateclizumab reduced the DAS28(4)-ESR response (-1.89) at 12 weeks, however, this did not reach statistical significance compared to placebo (-1.54), while adalimumab (-2.52) differed significantly from both placebo and pateclizumab. Pateclizumab 12-week ACR20, ACR50 and ACR70 response rates (64%, 33%, and 14%) suggested clinical activity but were not statistically significant compared to placebo rates (46%, 24%, and 8%, respectively). CXCL13 serum levels decreased significantly following pateclizumab and adalimumab administration, demonstrating pharmacological target engagement by both drugs. Overall, adverse events (AEs) were comparable among all cohorts. Infections were the most common AE, occurring with comparable frequency in all groups. Serious AEs occurred in 0% of pateclizumab, 5.9% of adalimumab, and 2.3% of placebo patients, with serious infection in 2.3% of adalimumab patients and none in pateclizumab and placebo patients. CONCLUSIONS: Pateclizumab had a good safety profile in patients inadequately responsive to DMARDs, but no statistically significant improvement in RA signs and symptoms after 12 weeks of treatment. Adalimumab demonstrated efficacy and safety comparable to published results in this head-to-head comparison in DMARD-IR RA patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT01225393, Registered 18 October 2010.

Safety, pharmacokinetics, and biologic activity of pateclizumab, a novel monoclonal antibody targeting lymphotoxin α: results of a phase I randomized, placebo-controlled trial.

INTRODUCTION: Pateclizumab (MLTA3698A) is a humanized mAb against lymphotoxin α (LTα), a transiently expressed cytokine on activated B and T cells (Th1, Th17), which are implicated in rheumatoid arthritis (RA) pathogenesis. This study was conducted to assess the safety, tolerability, < NOTE: For clarity and per AMA/S-W Style, please restore the use of Oxford/serial commas (ie: David likes vanilla, strawberry, and chocolate ice cream) throughout. and biologic activity of single and multiple doses of intravenous (IV) or subcutaneous (SC) pateclizumab in RA patients. METHODS: The single ascending dose (SAD) phase in patients with stable RA consisted of six cohorts (4:1 active:placebo at 0.3 mg/kg IV, 1.0 mg/kg IV, 1.0 mg/kg SC, 3.0 mg/kg IV, 3.0 mg/kg SC, and 5.0 mg/kg IV; n = 5/cohort). In the multiple ascending dose (MAD) phase, patients with prespecified RA disease activity received three doses of pateclizumab or placebo (4:1) every 2 weeks (1.0 mg/kg SC, n = 10; 3.0 mg/kg SC, n = 20; or 5.0 mg/kg IV, n = 5). Safety and tolerability were assessed throughout, and clinical activity was determined after three doses (Week 6). RESULTS: We observed no serious adverse events (AEs) or dose-limiting toxicities, and the majority of AEs were mild to moderate. The pharmacokinetic profiles were linear, and clearance was independent of dose. Reductions in levels of serum CXCL13 were observed, supporting the biologic activity of pateclizumab on the LTα pathway. Patients receiving pateclizumab in the 3.0 mg/kg MAD group (3.0 mg/kg SC) demonstrated ACR20, ACR50, and ACR70 response rates at week 6 of 75%, 56% and 25%, respectively, compared with 57%, 29%, and 0% in the placebo group. The median Disease Activity Score in 28 joints, C-reactive protein, reduction was 28% for pateclizumab, versus 8.4% for placebo. CONCLUSIONS: Pateclizumabwas generally well-tolerated in RA patients. Preliminary evidence of clinical activity was observed in active RA patients at the dose level targeted for clinical effect.

Bioanalytical approaches to quantify "total" and "free" therapeutic antibodies and their targets: technical challenges and PK/PD applications over the course of drug development.

The predominant driver of bioanalysis in supporting drug development is the intended use of the data. Ligand-binding assays (LBA) are widely used for the analysis of protein biotherapeutics and target ligands (L) to support pharmacokinetics/pharmacodynamics (PK/PD) and safety assessments. For monoclonal antibody drugs (mAb), in particular, which non-covalently bind to L, multiple forms of mAb and L can exist in vivo, including free mAb, free L, and mono- and/or bivalent complexes of mAb and L. Given the complexity of the dynamic binding equilibrium occurring in the body after dosing and multiple sources of perturbation of the equilibrium during bioanalysis, it is clear that ex vivo quantification of the forms of interest (free, bound, or total mAb and L) may differ from the actual ones in vivo. LBA reagents and assay formats can be designed in principle to measure the total or free forms of mAb and L. However, confirmation of the forms being measured under the specified conditions can be technically challenging. The assay forms and issues must be clearly communicated and understood appropriately by all stakeholders as the program proceeds through the development process. This paper focuses on monoclonal antibody biotherapeutics and their circulatory L that are either secreted as soluble forms or shed from membrane receptors. It presents an investigation into the theoretical and practical considerations for total/free analyte assessment to increase awareness in the scientific community and offer bioanalytical approaches to provide appropriate PK/PD information required at specific phases of drug development.