Transcript Dr. Shuler: Evaluating Potential Drug Therapies

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
In vitro
In vivo
 Tissue engineered tumors
recreate conditions in vivo
Increase in cell death
(propidium iodide)
2.5
2
1.5
1
0.5
0
2-D
2-D,
drug
3-D
3-D,
drug
Tumor cells cultured in biomimetic tumor
microenvironments
are less responsive to cytotoxic therapy
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”
lung
fat
1”
1”
Other
Tissues
liver
CCA: a physical
replica of the PBPK
We can model our body
model
as combinations of
tissue culture reactors
(physiologically based pharmacokinetic model)
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
Organ
Rationale
Cell Lines
Characteristics
Liver
Marrow
(Hematopoietic)
p450 activity
sensitive to chemo
dose limiting toxicity
Hep-G2/C3A
MEG-01
Tumor
(Sensitive)
Tumor (MDR)
(Resistant)
initial tumor primary
type
resistant tumors can
MES-SA
hepatoma
megakaryoblast line
attachment/suspension
inducible attachment
uteran sarcoma
sensitive to doxorubicin
variant
selected for resistance
to doxorubicin
MES-SA/DX-5
Model Drugs Used
• Doxorubicin as chemotherapeutic agent
(naturally fluorescent)
• Cyclosporin, Nicardipine as MDR
suppressors
Micro Cell Culture Analog
Application to Study Multidrug Resistance Suppressors
Other Tissues/
Debubbler
Device on peristaltic
pump in incubator
Sensitive Tumor
Cells (MES-SA)
Resistant Tumor
Cells (MES-SA/DX-5)
Liver Cells
(Hep-G2/C3-A)
Bone Marrow Blood
Cells (MEG-01)
All cells labeled with celltracker green before experiment
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.
Relative Proliferation of Cells in CCA device during 3 Day
Experiment
7
Relative Growth
6
5
4
3
2
1
0
C3A
Flow Control
1 Dox/10 NCB
DX5
MESSA
0.5 Dox
1 Dox/10 CSP
MEG01
1 Dox
1 DOX/5 CSP/5 NCB
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?