Fit-For-Purpose Metabolite Bioanalysis—A IQ Metabolite Bioanalysis Working Group Perspective

This is the second presentation of the IQ metabolite bioanalysis symposia.

This presentation provides the IQ Working Group recommendations on metabolite bioanalysis. The recommendations capture the trigger and timing of metabolite bioanalysis in non-clinical and clinical studies and the level of quality rigor in the respective assays. Briefly, an in vitro potency (pharmacological activity) of metabolite(s) of interest might be primarily considered as the trigger of quantitative analysis of the metabolite(s) in early preclinical and/or clinical studies using fit-for-purpose bioanalytical method, which could be fully validated or scientifically qualified depending on the application. A total contribution (in vitro potency and exposure after correction with protein binding, if data available) of the metabolite(s) of interest to the effect of drug molecule should be evaluated in an integral decision making on whether such measurement should be continued. If a metabolite does not contribute significantly (e.g., ≥ 50%, taking into consideration of the in vitro potency and protein binding corrected exposure) to the effect of the drug molecule, such measurement is recommended to be stopped unless the metabolite is determined to be associated with MIST, DDI or off-target activity.
In practice, every effort should be made to identify human circulating metabolite(s) using First-in-Human (FIH) study samples. This is followed by timely assessment of metabolite exposure coverage between animals (typically at NOAEL or high dose) and human (ideally at therapeutic dose level at steady state) for the identification of potential human unique or disproportionate metabolite(s). The outcomes of metabolite exposure coverage assessment might trigger additional studies to confirm the identity and quantify (bioanalysis or radio studies) the metabolite(s) of interest to address the potential issues related to metabolite at levels posting the MIST and DDI concerns. The exercises might include but are not limited to (1) conduction of additional repeated dose preclinical study (including study with additional preclinical species), (2) absolute quantification of metabolite(s) of interest in the collected animal samples (from the repeated dose study) and/or human samples (collected at steady state) using fully validated or scientifically qualified bioanalytical method, (3) comparison of measured metabolite exposure in animals vs human (at steady state), and/or (4) nonclinical testing with the disproportionate human metabolite. These efforts in combination with modeling and simulation exercises are expected to support a smooth regulatory submission.