Phase-1 Interim Analysis

Once a drug candidate progresses into the clinic, quantitative systems pharmacology (QSP) modeling can be applied to help with critical issues such as observed variability in clinical data or how the candidate is fairing against competitors. The following case study is an example where QSP modeling was introduced into a project for the first time after Phase 1 for the purpose of explaining observed variability and nonlinearity which in turn saved a molecule from being discarded and helped position it as best-in-class.


  • Empirical PK/PD modeling used to enable Phase 1 (not systems pharmacology)
  • Competitor molecule still ahead in the clinic
  • Dose administration and frequency still a major Go/No-Go criteria
  • Observed high non-linear PK (IV and SC dosing) and high PK variability with SC dosing

Customer's Questions:

  • Can the non-linear PK and SC PK variability be explained?
  • Will it be possible to achieve >90% target inhibition in patients?
  • Should program be discontinued? Refocused on another disease indication?


  • Model results used to amend Ph1 protocol, to prepare Medicine and Marketing for counterintuitive Ph1 results and to obtain regulatory approval to change Ph2 trial design?
  • Customer best-in-class molecule now positioned to be first-in-class as well (competitor postponed clinical trials) ?

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