Accounting for Pharmacokinetic Variability of Certolizumab Pegol in Patients with Crohn's Disease.

BACKGROUND: Certolizumab pegol is an effective biologic for patients with Crohn's disease (CD). Individual differences in certolizumab pegol apparent clearance (CL/F) affect exposure and possibly efficacy. A previously developed population pharmacokinetic (PK) model did not account for dynamic changes in clinical parameters during therapy. OBJECTIVE: The aim of this study was to refine the existing PK model to capture the time-varying influence of covariates. METHODS: Data collected from 2157 Crohn's disease patients in nine studies were analyzed using nonlinear mixed-effects modeling software (NONMEM). Certolizumab pegol concentration-time data were described by a one-compartment PK model with first-order absorption, and one-compartment disposition with linear, time-dependent elimination using antidrug antibody (ADAb) concentration as a continuous variable. RESULTS: The final dataset consisted of 12,926 analyzable records. Parameter estimates were absorption rate constant 1.83/day, CL/F 0.527 L/day, and apparent volume of distribution (V/F) 8.33 L. ADAb concentration (2.5-214 units/mL) increased the median CL/F by 142-174%. For a typical patient, body weight (46.8-100.5 kg) increased the median CL/F and V/F from 82 to 120%. Albumin (32-48 g/L) decreased and C-reactive protein (0.5-54.0 mg/L) increased the median CL/F from 123 to 85% and from 83 to 113%, respectively. Between-patient variability of CL/F was 19.6%. CONCLUSIONS: By incorporating time-varying covariates, this population PK model reduces between-patient variability on CL/F estimates, and the relative influence of ADAb can now be assessed. As Crohn's disease patient covariates are often time-dependent, this model is more reflective of patient drug exposure with sustained treatment.

Reinduction with Certolizumab Pegol in Patients with Crohn's Disease Experiencing Disease Exacerbation: 7-Year Data from the PRECiSE 4 Study.

BACKGROUND: Patients with Crohn's disease in whom tumor necrosis factor antagonist therapy fails have limited treatment options, and the benefit of reintroducing the same therapy remains unclear. Here, we report results from PRECiSE 4 (NCT00160706), an open-label extension study of certolizumab pegol in patients who withdrew from the placebo-controlled studies PRECiSE 1 or 2. METHODS: Patients eligible for PRECiSE 4 had Crohn's disease exacerbation on placebo or primary or secondary failure to certolizumab pegol in PRECiSE 1 or 2, and received 400 mg certolizumab pegol subcutaneously at weeks 0, 2, and 4 and every 4 weeks thereafter up to 360 weeks. We assessed safety (adverse events) and efficacy (clinical remission) of extended certolizumab pegol therapy. RESULTS: Patients enrolled in PRECiSE 4 (N = 310; mean age, 37 yr; 58% female; 95% white) had a mean Crohn's disease duration of 8.5 years before entering the qualifying studies. At weeks 52, 104, and 156, remission rates were 28.5%, 17.5%, and 12.6% by nonremitter imputation, and 63.8%, 60.0%, and 63.5% by observed cases, with 47.4%, 31.9%, and 23.2% of patients, respectively, remaining on therapy. By study end (7.5 yr), 92.3% of patients discontinued therapy, 49% on account of adverse events. No new safety signals emerged. Incidence rate (new cases)/100 patient-years was 6.11 for serious infections and 1.29 for malignancies. CONCLUSIONS: Certolizumab pegol was effective in many patients who previously discontinued certolizumab pegol for lack or loss of response. Thus, discontinuation of therapy may not always be necessary. Safety was consistent with previous findings.