Population pharmacokinetics analysis of camidanlumab tesirine in patients with relapsed or refractory Hodgkin lymphoma and non-Hodgkin lymphoma

Time-dependent clearance can confound exposure-response analysis of therapeutic antibodies: A comprehensive review of the current literature

Exposure-response (ER) analysis is used to optimize dose and dose regimens during clinical development. Characterization of relationships between drug exposure and efficacy or safety outcomes can be utilized to make dose adjustments that improve patient response. Therapeutic antibodies typically show predictable pharmacokinetics (PK) but can exhibit clearance that decreases over time due to treatment. Moreover, time-dependent changes in clearance are frequently associated with drug response, with larger decreases in clearance and increased exposure seen in patients who respond to treatment. This often confounds traditional ER analysis, as drug response influences exposure rather than the reverse. In this review, we survey published population PK analyses for reported time-dependent drug clearance effects across 158 therapeutic antibodies approved or in regulatory review. We describe the mechanisms by which time-dependent clearance can arise, and evaluate trends in frequency, magnitude, and time scale of changes in clearance with respect to indication, mechanistic interpretation of time-dependence, and PK modeling techniques employed. We discuss the modeling and simulation strategies commonly used to characterize time-dependent clearance, and examples where time-dependent clearance has impeded ER analysis. A case study using population model simulation was explored to interrogate the impact of time-dependent clearance on ER analysis and how it can lead to spurious conclusions. Overall, time-dependent clearance arises frequently among therapeutic antibodies and has spurred erroneous conclusions in ER analysis. Appropriate PK modeling techniques aid in identifying and characterizing temporal shifts in exposure that may impede accurate ER assessment and successful dose optimization.

Exposure-response analysis of Camidanlumab tesirine in patients with relapsed or refractory classical Hodgkin lymphoma and non-Hodgkin lymphoma

PURPOSE

To investigate camidanlumab tesirine (Cami) exposure-response (E-R) relationships, using an integrated population pharmacokinetic model, for patients with classical Hodgkin lymphoma (cHL) and non-Hodgkin lymphoma enrolled in an open-label, phase 1 study (NCT02432235).

METHODS

Exploratory analyses investigated relationships between exposure measures (C_maxss, C_minss, and C_avgss) and the occurrence of binary variables (overall response rate [ORR] and selected adverse events [AEs]) and nonbinary variables (overall survival [OS]).

RESULTS

Exploratory analyses showed a significant, positive relationship between exposure and ORR/OS. The final model showed this effect was non-significant due to the covariate effects. Cami exposures were higher in patients with selected grade ≥ 2 AEs at cycle 6 (the anticipated steady-state exposure level), confirmed in the final E-R models.

CONCLUSIONS

Based on univariate results, C_maxss was used as the exposure measure in all models, except for the autoimmune AE full E-R model in which C_avgss was used. The positive relationship between exposure and ORR/OS (higher exposure significantly associated with higher probabilities of ORR/OS) was not statistically significant in the final models. The final safety E-R models demonstrated a significant positive association between Cami exposure and selected grade ≥ 2 AEs, with higher exposures associated with higher probabilities of experiencing the grade ≥ 2 AEs at cycle 6. The results identify preliminary predictors of efficacy and safety and provide a basis for a dosing rationale and benefit-risk profile of Cami in patients with relapsed/refractory cHL.