Abstract LB-044: In vitro assessment of combination dosing regimens with in vivo like pharmacokinetic concentration profiles enabled by a microfluidic addition and removal device
Authors: Golby Paul , Buffa Edoardo , Kostrzewski Tomasz , Hughes David 
Published: August 2018

Abstract
Combination dosing regimens offer the opportunity to improve the efficacy or better manage the toxicity profile of approved drugs and new therapies under development. Mouse xenograft models are currently used to select optimal combinations and administration schedules. Whilst well established these models, offer low throughput, limiting the number of combinations or schedules which might be explored. The pharmacokinetic (PK) profile of the drugs can also vary significantly between mice and humans, leading issues in translation of results from animal models to humans. As an alternative to xenograft models, we explored an in vitro methodology utilizing a device (Microformulator, Viibre, Vanderbilt University) capable of precision addition and removal of medium from the wells of a microtiter cell culture plates. Through stepwise addition and removal of medium the device was able to recapitulate PK-like concentration profiles of one, or more drugs in individual wells. This enabled the study of the combination dosing of Erlotinib with chemotherapy agents in non-small cell lung cancer (NSCLC) cell lines. The case study is of interest as the PK profiles of Erlotinib differ significantly between mice and humans, and clinical studies have shown combination dosing with pharmacodynamic separation can be clinically beneficial in NSCLC. The device was characterized for the accuracy of media addition and removal, using fluorescent probe molecules. Satisfactory accuracy was achieved over multiple wells with different PK profiles. Next, the effect of repeated addition and removal of medium on the growth rate of H1299 cell lines was explored. The growth rate was decreased but a viable and expanding population of cells was maintained. The IC50 of Erlotinib in H1299 cells under a 48 hr bolus dose was determined to be ~20µM, comparable to literature and confirming the cell line to be Erlotinib resistant. The half-life and Cmax for Erlotinib in mouse and human, are respectively 4.5 hr, 13 µM and 36 hr, 5 µM. The device was used to recapitulate the PK profiles for mouse and human. Dosing with either profile reduced inhibition as compared to a 5 µM bolus. The combination of Erlotinib and Pemetrexed was then explored, modelling the human PK profile, either with co-dosing or Pemetrexed dosing following by Erlotinib. In conclusion, the study demonstrates the use of the microfluidic addition and removal device as a tool for recapitulating PK-like profiles and for exploring combination dosing regimens in vitro.
Citation Format: Paul Golby, Edoardo Buffa, Tomasz Kostrzewski, David Hughes. In vitro assessment of combination dosing regimens with in vivo like pharmacokinetic concentration profiles enabled by a microfluidic addition and removal device [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-044.