Population pharmacokinetic analysis of peficitinib in patients with rheumatoid arthritis

Comparison of the effects of peficitinib and tofacitinib in the adjuvant-induced arthritis rat model

We investigated and compared the pharmacologic properties of two Janus kinase (JAK) inhibitors, peficitinib and tofacitinib, in an adjuvant-induced arthritis rat model. Repeated administration of peficitinib (3 - 30 mg/kg) or tofacitinib (1 - 10 mg/kg) exhibited a dose-related and significant attenuation of arthritis score, paw swelling, pain threshold, grip strength and histopathologic injuries in the model; peficitinib 10 mg/kg and tofacitinib 3 mg/kg demonstrated comparable efficacy. Equivalent C_max and AUC_0-12h values were observed with peficitinib 10 mg/kg and tofacitinib 3 mg/kg, suggesting that the two drugs may demonstrate comparable efficacy on arthritis-associated symptoms at comparable plasma concentration levels. However, peficitinib 10 mg/kg had greater efficacy than tofacitinib 3 mg/kg on some inflammation- and bone destruction-associated parameters in the paw fluid, including the production of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), receptor activator of nuclear factor kappa-B ligand, and matrix metalloproteinase-3, which are associated with arthritis exacerbation. Peficitinib 10 mg/kg also showed significantly greater inhibitory effects than tofacitinib 3 mg/kg on loss of bone mineral density and synovial thickening score, which might be a result of the VEGF and PDGF receptor kinase inhibitory effects of peficitinib, in addition to JAK inhibition. In conclusion, both tofacitinib and peficitinib potently improved arthritis and associated symptoms in adjuvant-induced arthritis rats; moreover, owing to possible differences in the mechanism of action of the two drugs, peficitinib may have exerted its effects through JAK inhibition and additional unique off-target properties.

Evaluating and Improving Neonatal Gentamicin Pharmacokinetic Models Using Aggregated Routine Clinical Care Data

Model-informed precision dosing (MIPD) can aid dose decision-making for drugs such as gentamicin that have high inter-individual variability, a narrow therapeutic window, and a high risk of exposure-related adverse events. However, MIPD in neonates is challenging due to their dynamic development and maturation and by the need to minimize blood sampling due to low blood volume. Here, we investigate the ability of six published neonatal gentamicin population pharmacokinetic models to predict gentamicin concentrations in routine therapeutic drug monitoring from nine sites in the United State (n = 475 patients). We find that four out of six models predicted with acceptable levels of error and bias for clinical use. These models included known important covariates for gentamicin PK, showed little bias in prediction residuals over covariate ranges, and were developed on patient populations with similar covariate distributions as the one assessed here. These four models were refit using the published parameters as informative Bayesian priors or without priors in a continuous learning process. We find that refit models generally reduce error and bias on a held-out validation data set, but that informative prior use is not uniformly advantageous. Our work informs clinicians implementing MIPD of gentamicin in neonates, as well as pharmacometricians developing or improving PK models for use in MIPD.

Efficacy of peficitinib in two patients with rheumatoid arthritis on maintenance hemodialysis

Objective: Treatment options for patients with rheumatoid arthritis on maintenance hemodialysis with an inadequate response to biologic agents have not been reported. In this report, we describe two patients who achieved remission after treatment with peficitinib.

Methods: Two 69- and 85-year-old patients with rheumatoid arthritis on maintenance hemodialysis were previously treated with biologics and started on peficitinib 100 mg/day after the secondary failure of biologics.

Discussion: In the two cases presented here, rheumatoid arthritis was almost in remission and there were no adverse events, although the patients were switched to peficitinib after secondary failure of the biologic agents. Among Janus kinase inhibitors, peficitinib has the lowest renal excretion; therefore, its administration in patients on dialysis is not contraindicated according to the package insert in Japan. The use of biologic agents in patients on hemodialysis has been reported to be associated with a high incidence of infections; therefore, care should be taken to avoid infections when administering Janus kinase inhibitors.

Conclusion: Janus kinase inhibitors with low renal excretion, such as peficitinib, may be effective in patients with rheumatoid arthritis on maintenance hemodialysis who have an inadequate response to biologic agents.

Peficitinib improves bone fragility by recovering bone turnover imbalance in arthritic mice

Peficitinib, a pan-JAK inhibitor, is known to suppress the activation of fibroblast-like synoviocytes (FLSs) and thereby reduces joint inflammation associated with rheumatoid arthritis (RA). However, the effect on osteoporosis in RA remains to be elucidated. In this study, the effect of peficitinib or etanercept on joint inflammation, and consequently decreased bone mineral density (BMD) was evaluated in mice with collagen-induced arthritis (CIA). Additionally, the effect on RANKL production from osteoblasts differentiated from the mesenchymal stem cells of RA patients was evaluated. Administration of peficitinib for established CIA ameliorated arthritis and improved BMD in the femoral metaphysis, but not in the femoral diaphysis. Conversely, etanercept suppressed an increase in synovial inflammatory markers but did not improve arthritic conditions or the reduction of BMD in either region. All elevated bone formation and bone resorption markers were decreased with peficitinib but only partially decreased with etanercept. Furthermore, production of RANKL by human osteoblasts was suppressed by peficitinib but enhanced by etanercept. Unlike etanercept, peficitinib is thought to increase BMD by ameliorating the high bone turnover associated with RA states, resulting in improvement of bone fragility. Our data provide evidence that peficitinib would be expected to show efficacy for osteoporosis associated with RA.

Impact of age on the efficacy and safety of peficitinib (ASP015K) for the treatment of rheumatoid arthritis

OBJECTIVES

To evaluate peficitinib efficacy and safety in Asian patients with rheumatoid arthritis (RA), stratified by age (≥20-<50, ≥50-<65, and ≥65 years).

METHODS

Efficacy data from two Phase 3 studies were analysed. Safety data from one Phase 2, two Phase 3, and one open-label extension study were pooled. Incidence rates per 100 patient-years of adverse events of special interest were calculated, and Cox proportional hazard analysis was conducted.

RESULTS

1052 patients received peficitinib for 2 years (median). Peficitinib demonstrated efficacy improvements versus placebo across all age categories. Incidence rates (95% confidence interval) per 100 patient-years for ≥20-<50, ≥50-<65, and ≥65 years were 0.8 (0.4, 1.9), 2.6 (1.8, 3.7), and 4.7 (3.1, 7.0) for serious infections and 3.7 (2.5, 5.4), 6.4 (5.0, 8.2), and 11.2 (8.5, 14.7) for herpes zoster-related disease, respectively. Twenty patients reported malignancies in pooled Phase 2/3 studies. Incidences of serious infections and herpes zoster-related disease increased significantly with age, but there was no association with baseline estimated glomerular filtration rate.

CONCLUSIONS

Peficitinib was efficacious in adult Asian RA patients of all ages. Age, but not estimated glomerular filtration rate, was associated with serious infections and herpes zoster-related disease, demonstrating the importance of an appropriate RA treatment strategy in older patients.

Exposure-response modeling of peficitinib efficacy in patients with rheumatoid arthritis

The aim was to analyze the relationship between peficitinib exposure and efficacy response according to American College of Rheumatology (ACR) 20 criteria and 28‐joint disease activity score based on C‐reactive protein (DAS28‐CRP) in rheumatoid arthritis (RA) patients, and to identify relevant covariates by developing exposure–response models. The analysis incorporated results from three multicenter, placebo‐controlled, double‐blind studies. As an exposure parameter, individual post hoc pharmacokinetic (PK) parameters were obtained from a previously constructed population PK model. Longitudinal ACR20 response rate and individual longitudinal DAS28‐CRP measurements were modeled by a non‐linear mixed effect model. Influential covariates were explored, and their effects on efficacy were quantitatively assessed and compared. The exposure–response models of effect of peficitinib on duration‐dependent increase in ACR20 response rate and decrease in DAS28‐CRP were adequately described by a continuous time Markov model and an indirect response model, respectively, with a sigmoidal E_max saturable of drug exposure in RA patients. The significant covariates were DAS28‐CRP and total bilirubin at baseline for the ACR20 response model, and CRP at baseline and concomitant methotrexate treatment for the DAS28–CRP model. The covariate effects were highly consistent between the two models. Our exposure–response models of peficitinib in RA patients satisfactorily described duration‐dependent improvements in ACR20 response rates and DAS28‐CRP measurements, and provided consistent covariate effects. Only the ACR20 model incorporated a patient's subjective high expectations just after the start of the treatment. Therefore, due to their similarities and differences, both models may have relevant applications in the development of RA treatment.

Clinical trial registration

NCT01649999 (RAJ1), NCT02308163 (RAJ3), NCT02305849 (RAJ4).

Population pharmacokinetic analysis of peficitinib in patients with rheumatoid arthritis

Aims

To analyse the population pharmacokinetics (PK) of peficitinib in patients with rheumatoid arthritis (RA) and assess the potential PK covariates to identify the requirement for dose adjustment in RA patients.

Methods

The analysis incorporated 2464 observations from 98 healthy volunteers and 4919 observations from 989 RA patients. A population PK model for peficitinib in RA patients was constructed by a nonlinear mixed effect model using NONMEM with prior information from a healthy volunteer model.

Results

A 2‐compartment model with sequential zero‐ and first‐order absorption and lag time was constructed for RA patients. Covariate exploration in the RA patient model revealed that estimated glomerular filtration rate (eGFR) and lymphocyte count had a significant effect on apparent total systemic clearance (CL), which was 91.7 L/h (2.3% relative standard error). Compared with the mean population CL, the model predicted mean changes in CL of 12.3 and −10.7% in patients with observed minimum and maximum lymphocyte count of 500 and 4600 10⁶/L, respectively, and mean changes in CL of −17.8 and 16.7% in patients with minimum and maximum eGFR of 36.4 and 188 mL/min/1.73m², respectively. The simulated population mean area under plasma concentration–time curve for 24 hours after dosing showed a 1.35‐fold increase in patients with severe renal impairment (eGFR 22.5 mL/min/1.73m²) compared with patients with reference eGFR (91.5 mL/min/1.73m²).

Conclusion

The population PK model identified eGFR and lymphocyte count as covariates for CL. The magnitude of changes was not considered clinically relevant, indicating no requirement for dose adjustment.