Evaluating Potential Drug Therapies Mike Shuler Biomedical Engineering.

Evaluating PotentialDrug Therapies

Mike Shuler

Biomedical Engineering

Can we use tissue engineeringand related approaches

to evaluate potentialeffectiveness of drugs?

Can they be adapted forpersonalized medicine?

Claudia Fischbach-TeschlAbe StroockLarry BonassarJonathan Butcher

Drug responsiveness in 3-D tumor cell culture

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2-D 2-D,drug

3-D 3-D,drug

Increase in cell death(propidium iodide)

Tumor cells cultured in biomimetic tumor microenvironments

are less responsive to cytotoxic therapy

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In vitro In vivo

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In vitro In vivo

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In vitro In 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 bodyas combinations of

tissue culture reactors(physiologically based pharmacokinetic model)

CCA: a physical replica of the PBPK

model

1”

1”

fat

lung

Other

Tissues

liver

Combination Therapies forCancer 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

Organ Rationale Cell Lines Characteristics

Liver p450 activity Hep-G2/C3A hepatomaMarrow sensitive to chemo MEG-01 megakaryoblast line(Hematopoietic) dose limiting toxicity attachment/suspension

inducible attachmentTumor initial tumor primary MES-SA uteran sarcoma(Sensitive) type sensitive to doxorubicinTumor (MDR) resistant tumors can MES-SA/DX-5 variant(Resistant) selected for resistance

to doxorubicin

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 StudyWe 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.

Relative Proliferation of Cells in CCA device during 3 Day

Experiment

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C3A DX5 MESSA MEG01

Relative Growth

Flow Control 0.5 Dox 1 Dox

1 Dox/10 NCB 1 Dox/10 CSP 1 DOX/5 CSP/5 NCB

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?