Plate-based proliferation assays are used in oncology drug discovery to evaluate the potency of compounds and sensitivity of cell lines. A dose-response curve describes the relationship between increasing drug concentration and the resulting change in response. To determine the IC50, which is the dose that inhibits 50% of the response, one should test at least three doses around the estimated proper dose, use a negative control, and blank wells. The assay is run and optical densities are determined using assays like MTS, MTT, or Orangu, with the data exported to Excel. The ODs are normalized to the mean control and inhibition curves are constructed to find the IC50.

1. IC50
BY: SAMIEH ASADIAN

2. Introduction
 Plate-based proliferation assays are a fundamental tool in oncology drug discovery for
evaluating potency of compounds and sensitivity of different cell lines to specific agents.
 In pharmacology experiments, a drug’s effect on a receptor is typically investigated by
constructing a dose-response curve. A dose-response curve describes the relationship
between increasing the dose (or concentration) of the drug and the change in response
that results from this increase in concentration. A typical dose-response curve will span a
large concentration range.

3. How to determine IC50?
You should know mechanism of action of your drug
You should estimate the proper dose
You need 3 doses at least: proper dose/2 , proper dose, proper dose +(proper dose/2)
Determine your time points and repetition of your tests in each experiments
You need negative control
You need Blank wells(without cells and drug)
Do MTS or MTT or Orangu and determine ODs

4. OD of blankTest groups
that treated
with different
doses of drug
MTS or MTT or
ORANGU in 96
well plate
Export data in
excel
Follow these
slides!
Negative
control
group
Every single ODs( control group and
test groups) – OD of blank Determine mean of ODs of
control group

5. Every single ODs/ mean of OD of control * 100
Then SD of these