# Prism Repurposing Primary Screen

**URL:** <https://forum.depmap.org/t/prism-repurposing-primary-screen/951>\
**Category:** Q&A\
**Created:** [October 11, 2021, 2:11am UTC](https://forum.depmap.org/t/prism-repurposing-primary-screen/951 "2021-10-11T02:11:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Giuliana5](https://avatars.discourse-cdn.com/v4/letter/g/b77776/32.png) [@Giuliana5](https://forum.depmap.org/u/Giuliana5)\
**Post date:** [October 11, 2021, 2:11am UTC](https://forum.depmap.org/t/prism-repurposing-primary-screen/951/1 "2021-10-11T02:11:39Z")

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Are the values for the PRISM Repurposing Primary Screen IC50 values? Do we know how many data points were used and what formula was used to calculate this value?

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**Author:** ![Mustafa\_Kocak](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/mustafa_kocak/32/11_2.png) [@Mustafa\_Kocak](https://forum.depmap.org/u/Mustafa_Kocak)\
**Post date:** [October 12, 2021, 2:25pm UTC](https://forum.depmap.org/t/prism-repurposing-primary-screen/951/2 "2021-10-12T14:25:11Z")

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Hi Giuliana,

The primary screen consists of only a single dose (2.5 uM), compounds are screened at three replicates and the reported values are the log2-fold change viability values between the treatment and the negative control (DMSO).

For the details, you can check the methods part of [Discovering the anticancer potential of non-oncology drugs by systematic viability profiling | Nature Cancer](https://www.nature.com/articles/s43018-019-0018-6)

Warmly,  
Mustafa

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**Author:** ![Giuliana5](https://avatars.discourse-cdn.com/v4/letter/g/b77776/32.png) [@Giuliana5](https://forum.depmap.org/u/Giuliana5)\
**Post date:** [October 12, 2021, 2:53pm UTC](https://forum.depmap.org/t/prism-repurposing-primary-screen/951/3 "2021-10-12T14:53:19Z")

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Mustafa,

Many thanks.

Derek