Anti-PD-(L)1 Antibodies: Insights From QSP-Based Meta-Analysis

Area of Science:

• Immunology
• Pharmacology
• Computational Biology

Background:

• Monoclonal antibodies (mAbs) targeting PD-1 or PD-L1 have significantly impacted cancer treatment.
• Meta-analyses suggest superior survival outcomes with anti-PD-1 mAbs compared to anti-PD-L1 mAbs, though direct clinical comparisons are limited.
• The shared hypothesis posits that both drug classes inhibit the PD-1:PD-L1 signaling pathway.

Purpose of the Study:

• To investigate if differential inhibition of the PD-1:PD-L1 complex can explain the observed efficacy differences between anti-PD-1 and anti-PD-L1 mAbs.
• To utilize a Quantitative Systems Pharmacology (QSP) model to analyze the mechanism of action of these checkpoint inhibitors.

Main Methods:

• Development and application of a QSP model to simulate the inhibition of PD-1:PD-L1 complex formation.
• Analysis of model predictions under clinical dosing regimens for various anti-PD-1 and anti-PD-L1 mAbs.
• Incorporation of model parameter variability and bootstrap sampling to assess the robustness of the findings.

Main Results:

• The QSP model predicted high levels of PD-1:PD-L1 complex inhibition for all tested mAbs at clinical doses.
• The model did not support the hypothesis that anti-PD-1 mAbs achieve greater inhibition than anti-PD-L1 mAbs.
• Sensitivity analyses, including parameter variability and bootstrap sampling, did not alter the conclusion regarding comparable inhibition levels.

Conclusions:

• Anti-PD-1 and anti-PD-L1 mAbs do not appear to be mechanistically distinguishable based solely on PD-1:PD-L1 complex inhibition.
• The hypothesized shared mechanism of action for these two classes of checkpoint inhibitors may be incomplete.
• Further research is needed to elucidate the factors contributing to differential clinical efficacy between anti-PD-1 and anti-PD-L1 therapies.