Evaluating Potential Drug Therapies Mike Shuler Biomedical Engineering

Can we use tissue engineering and related approaches to evaluate potential effectiveness of drugs? Can they be adapted for personalized medicine? Claudia Fischbach-Teschl Abe Stroock Larry Bonassar Jonathan Butcher

Drug responsiveness in 3-D tumor cell culture Tumor cells cultured in biomimetic tumor microenvironments are less responsive to cytotoxic therapy In vitroIn vivo  Tissue engineered tumors recreate conditions in vivo

Observations Individual cancers vary/many possible combination of mechanisms Metabolizing tissue – significant variation throughout human population – metabolites can vary in amount and kind Dose-limiting normal tissues; tolerance varies

Premise Single drugs are unlikely to be broadly effective Combination therapy should be more effective How can we predict accurately the best therapy for an individual?

In vitro Replacements for Animals and Humans Animal studies are expensive, long, and not particularly predictive of human response Currently only 1 in 10 drugs entering human clinical trials emerge as FDA approved products

“Microscale Cell Culture Analog” We can model our body as combinations of tissue culture reactors (physiologically based pharmacokinetic model)  CCA: a physical replica of the PBPK model 1” fat lung Other Tissues liver

Combination Therapies for Cancer Treatment Could exposure to multiple agents more effectively treat cancer? With multiple agents the potential number of combinations and scenarios to be tested is impracticable for animal studies Could CCA with PBPK explore a broad experimental range to predict a testable subset for detailed study?

Multidrug Resistant (MDR) Cancer Tumor responds initially but reoccurs and in non-responsive or MDR Multiple causes of MDR; may need multiple agents to control Best studied case is P-glycoprotein (P-gp) overexpression: Pump protein intercepts chemotherapeutic agent before it enters cell

MDR Suppressing Agents Fail No MDR suppressing agent has passed clinical trials Toxicity to normal tissue/altered pharmacokinetics for chemotherapeutic Animal studies not good predictor -Rat has 3 P-gp isoforms; humans have 2

Human Cell Culture Analog

Model Drugs Used Doxorubicin as chemotherapeutic agent (naturally fluorescent) Cyclosporin, Nicardipine as MDR suppressors

Sensitive Tumor Cells (MES-SA) Resistant Tumor Cells (MES-SA/DX-5) Bone Marrow Blood Cells (MEG-01) Liver Cells (Hep-G2/C3-A) Micro Cell Culture Analog Device on peristaltic pump in incubator All cells labeled with celltracker green before experiment Other Tissues/ Debubbler Application to Study Multidrug Resistance Suppressors

Proliferative Toxicity Study We challenged the MDR CCA device to 3 day exposure to mixtures of Doxorubicin and 2 modulators: nicardipine and cyclosporine A in McCoys 5A medium with 10% FBS. The ratio of final cell density to initial cell density for each condition is displayed below. Result: Modulators have strong response on resistant cell line, moderate in others, and a synergistic effect is observed between the two modulators in the resistant cell type.

Can we use biopsy tissue from the cancer target, the liver, and other relevant tissue to test patient specific response using a microCCA?

Relevant Features Can be made disposable/polystyrene Requires few cells – multiple tests possible from modest tissue sample Screen large set of drug combinations Could also be used to study mechanisms?

Challenges Maintenance of tissue specific characteristics in vitro Automated processing and “simple” to use Validation?