Clarification Regarding DepMap's IC50 Data and Sanger's IC50 Data

Q&A
1

Hi DepMap,

I am a little confused regarding the information you have on your website and Sanger’s information. I am refering to your Drug sensitivity IC50 (Sanger GDSC1 and GDSC2) data as well as what Sanger has on their website if you go to compounds and look for a specific drug. Usually, Sanger will present a table like the following:

|Number of cell lines screened|913|
|Maximum IC50 (uM)|2.18e+3|
|Geometric mean (uM)|34.8|
|Minimum IC50 (uM)|0.151|
|Min screening concentration (uM)|0.125|
|Max screening concentration (uM)|32.0|

Maybe this is due to the fact that I need to research more information on IC50 values, but how can an IC50 value be higher than the max screening concentration? Thanks for your help.

Thanks,
SD

2

Hi SD,

The IC50 values are typically computed as the dose that the fitted curve would reach to 50% viability value. For the cases this number falls out of the range of the measured doses it is given based on the extrapolated curve and I don’t think that is a good number to use in any analysis. I would recomment to replace it with either an NA or capping it with a multiple of the maximum measured dose (maybe 2x).

Warmly,
Mustafa