Proposing Advancement Criteria for Efficient Dmpk Triage of New Chemical Entities

Abstract

With the goal of refining our discovery DMPK workflow, we conducted a retrospective analysis on internal Celgene compounds by calculating the physicochemical properties and gathering data from several assays including solubility, rat and human liver S9 stability, Caco-2 permeability, and rat intravenous (iv.) and oral pharmacokinetics. Our analysis identified plasma clearance to be most statistically relevant for prediction of oral exposure. In rat, compounds with rat S9 stability of ≥70% at 60 min and a plasma clearance of ≤43 ml/min/kg had the greatest chance of achieving oral exposures above 3 µM.h. Compounds with the dual advantage of plasma clearance ≤43 ml/min/kg and Caco-2 permeability ≥8 × 10(-6) cm/s or efflux ratio ≤8 were highly likely to achieve those oral exposures. Implementation of these criteria leads to a significant increase in efficiency, good pharmacokinetic properties, cost savings and a reduction in the use of animals.

Efficiency in Drug Discovery: Liver S9 Fraction Assay As a Screen for Metabolic Stability

“…Poor permeability would potentially lead to higher apparent rates of stability in hepatocytes, owing to their inability to enter the hepatocytes to be exposed to the metabolic enzymes. Indeed, we found that 75% of compounds that fell into this category and had Caco-2 data, exhibited poor permeability according to the permeability criteria that we have published previously [8] (P app < 8 X 10 -6 cm/s). Excluding such compounds from the analysis, the discrepancy between S9 and hepatocyte acceptance rate dropped to 13% in the rat (from 20%) and 7% in the human S9 (from 11%).…”

“…In doing so, we used the “70% remaining at 60 minutes” criteria post-incubation as listed in our prior publication [8]. Compounds with ≥ 70% parent remaining at 60 minutes were labeled as “pass” and the remaining were labeled as “fail”.…”

“…We have previously reported on our in vivo cut-off criteria in the DMPK workflow [8]. This includes 43 mL/min/kg for in vivo rat plasma clearance.…”

“…For about a decade, we have utilized the liver S9 system as our primary in vitro screen to ‘weed out’ compounds with poor metabolic stability and poor probability of success [8]. In order to further solidify the selection of liver S9 fractions as our system of choice for metabolic stability evaluations, we conducted a retrospective analysis comparing the results from our liver S9 assay to our hepaotocyte assay (the gold standard in representing the in vivo conditions).…”

In Vitro Biotransformation in Drug Discovery

“…Human hepatocytes are considered to be golden standard and 7-ethoxy coumarin has been used as an appropriate substrate to understand the phase-I and phase-II metabolism [31] in different matrices. Recently liver S9 fractions were shown as a matrix comparable to that of hepatocytes to screen compounds for metabolic stability assays [32]. Researchers have used 7-ethoxy coumarin and performed a comparative study on three different matrices i.e.…”