Modelling pharmacokinetics and pharmacodynamics of the selective S1P1 receptor modulator cenerimod in healthy subjects and systemic lupus erythematosus patients

Sphingosine 1-phosphate signaling during infection and immunity

Sphingolipids are essential components of all eukaryotic membranes. The bioactive sphingolipid molecule, Sphingosine 1-Phosphate (S1P), regulates various important biological functions. This review aims to provide a comprehensive overview of the role of S1P signaling pathway in various immune cell functions under different pathophysiological conditions including bacterial and viral infections, autoimmune disorders, inflammation, and cancer. We covered the aspects of S1P pathways in NOD/TLR pathways, bacterial and viral infections, autoimmune disorders, and tumor immunology. This implies that targeting S1P signaling can be used as a strategy to block these pathologies. Our current understanding of targeting various components of S1P signaling for therapeutic purposes and the present status of S1P pathway inhibitors or modulators in disease conditions where the host immune system plays a pivotal role is the primary focus of this review.

Pharmacokinetics and Pharmacodynamics of Cenerimod, A Selective S1P1 R Modulator, Are Not Affected by Ethnicity in Healthy Asian and White Subjects

Cenerimod is a sphingosine‐1‐phosphate 1 receptor (S1P₁R) modulator in phase II development for treatment of systemic lupus erythematosus. Its pharmacokinetics (PKs), pharmacodynamics (PDs), as well as safety and tolerability were investigated in white and Asian subjects to allow for recruitment of Asian patients in future studies. A randomized, double‐blind, placebo‐controlled parallel‐group study was performed in 20 healthy male subjects (n = 10 per ethnicity). A single, oral dose of 4 mg cenerimod or placebo (ratio 8:2) was administered under fasted conditions. The PKs of cenerimod were similar in white and Asian subjects indicated by geometric mean ratios (90% confidence interval) of 0.99 (0.80–1.21) for maximum plasma concentration, 0.96 (0.75–1.24) for area under the plasma concentration‐time curve from 0 to infinity, and 1.04 (0.86–1.25) for terminal half‐life. Accordingly, the extent and time course of reduction in lymphocyte count (as PD biomarker) were also similar in white and Asian subjects as compared with placebo. As observed for other S1PR modulators, a transient mean (SD) heart rate reduction in white (15.1 (14.8) bpm) and Asian (11.8 (6.16) bpm) subjects was observed following administration of cenerimod. The drug was safe and well‐tolerated indicated by occurrence of a single adverse event of chemical conjunctivitis in a white subject that was not suspected as study drug related. In conclusion, the determined absence of any relevant PK or PD differences supports using the same doses of cenerimod in white and Asian patients in upcoming late‐phase studies.

Estimation of Attainment of Steady-State Conditions for Compounds With a Long Half-Life

Half-life is a standard result reported with analysis of pharmacokinetic data. Different definitions such as noncompartmental half-life, terminal half-life, effective half-life, and context-sensitive half-life can yield substantially different estimates of the quantity "half-life." Time to attainment of steady-state conditions is generally derived from (terminal) half-life and therefore sensitive toward the definition of half-life. Thus, estimates of the time to attain steady state must be provided with a precise definition of steady state and the method used for estimation, particularly for drugs with long (terminal) half-life. For clinical purposes, terminal half-life can have limited relevance if drug concentrations in the terminal elimination phase are low. A general rule for which half-life to use is infeasible. While limited accumulation can be negligible if a plateau in pharmacokinetics/pharmacodynamics is reached or with a wide therapeutic window (ie, exposure range), small additional drug accumulation can be highly relevant for drugs with a narrow therapeutic window. Beyond the average, estimation of individual time to attainment of steady state can add highly relevant information about the variability between subjects. Simulations from population models and the use of different definitions of steady state provide an assessment of robustness of the results. The relevance of accurate estimation of time to attainment of steady state is illustrated with cenerimod, an sphingosine-1-phosphate 1 receptor modulator with long half-life currently in clinical development for which estimates of time to steady state ranged from 35 to 110 days with different calculations.

Modelling pharmacokinetics and pharmacodynamics of the selective S1P1 receptor modulator cenerimod in healthy subjects and systemic lupus erythematosus patients

AIMS

Assessment of time to attain steady state as well as drug accumulation following long-term treatment with the selective sphingosine-1-phosphate 1 receptor modulator cenerimod and prediction of the incidence of low total lymphocyte (LY) counts. Differences in pharmacokinetics and pharmacodynamics based on demographic characteristics and between healthy subjects and systemic lupus erythematosus (SLE) patients were to be identified.

METHODS

Data from 4 Phase I studies and 1 Phase II study were pooled to develop a population pharmacokinetic/pharmacodynamic model describing cenerimod concentration and its effect on LY count. Simulations addressed the objectives.

RESULTS

Simulations of 365 days of treatment indicated a time to steady state of 49 days and changes in exposure of 15% beyond 35 days. For a dose of 2 mg, the predicted incidences of LY counts below 0.5 and 0.2 × 10⁹ cells/L were 18.2 and 0.6% for healthy subjects and 25.9 and 1.0% for SLE patients, respectively. Incidence increased with higher dose and lower baseline LY counts. For body weights of 50 and 100 kg compared to 75 kg, exposure was predicted to change by +37% and -20%, respectively.

CONCLUSION

Long-term cenerimod administration is not expected to result in exposure and LY count reduction substantially different from results of completed studies. Low LY counts are predicted to occur more frequently in SLE patients compared to healthy subjects. Dose individualization based on the model is not considered necessary. Model-based simulations enable benefit-risk evaluations, supporting planning of late-phase clinical studies and scientific exchange with health authorities.