# Is there a threshold in Drug Sensitivity AUC? **URL:** \ **Category:** Q&A\ **Tags:** data\ **Created:** [January 23, 2024, 2:19pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038 "2024-01-23T14:19:16Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![cht](https://avatars.discourse-cdn.com/v4/letter/c/13edae/32.png) [@cht](https://forum.depmap.org/u/cht)\ **Post date:** [January 23, 2024, 2:19pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/1 "2024-01-23T14:19:16Z")
![捕获](https://canada1.discourse-cdn.com/flex035/uploads/depmap/original/2X/2/28e03bef36d809d4fd273e86d50cede112f5a929.png) Is there a threshold in Drug Sensitivity AUC, below which it is considered that the drug has an impact on cell line proliferation? which threshold? Similarly, does a threshold also exist in the PRISM Repurposing Primary Screen dataset? ---
**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:** [May 10, 2024, 12:52pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/2 "2024-05-10T12:52:21Z")
Hi, For the Primary screen, the values are log2(Viabilities) at 2.5uM, and historically, we considered 30% viability (corresponding to log2(0.3) =~ -1.74 as a “sensitivity threshold.” For AUC, it is trickier since it is also a function of the dose range screened for the drug. I don’t know the particular analysis you are following, but my recommendation would be scaling AUCs (maybe z-scores) and treating cell lines on the left tail (maybe z \< -2) as sensitive lines. ---
**Author:** ![Deptective](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@Deptective](https://forum.depmap.org/u/Deptective)\ **Post date:** [May 4, 2025, 6:52pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/3 "2025-05-04T18:52:21Z")
Are we certain this is correct? The DepMap paper states “We label cell lines as sensitive to a treatment if the median-collapsed fold-change is less than 0.3.” Thus, it appears that the binary cutoff is actually log2(0.3), which is 1.23. Meaning that a 23% increase in cell line proliferation relative to the control. I am unclear why an increase relative to the control would be considered sensitive to the treatment, although I think I read about noise being an issue. If the metric were indicating 30% viability, the wording should state this, and not specifically mention “median-collapsed fold-change is less than 0.3.” Can I get a clarification from the Depmap team on this important point? Thanks ---
**Author:** ![Deptective](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@Deptective](https://forum.depmap.org/u/Deptective)\ **Post date:** [May 6, 2025, 11:52pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/4 "2025-05-06T23:52:46Z")
Apologies, I of course meant that since a “median-collapsed log-fold change” of 0.3 is the value reported, which itself is log2(1.23). So according to the paper, the reported value of 0.3 used as a threshold would correspond to cell proliferation relative to DSMO of 1.23, ie. a 23% increase. Can someone from the DepMap team please clarify this? ---
**Author:** ![Yangqi\_Su](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/yangqi_su/32/1574_2.png) [@Yangqi\_Su](https://forum.depmap.org/u/Yangqi_Su)\ **Post date:** [July 26, 2025, 1:15am UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/5 "2025-07-26T01:15:25Z")
Actually log2(0.3) is around -1.74, the fold change is calculated as treatment\_MFI/negative\_ctrl\_MFI, so 0.3 means it is only 0.3 of negative, indicating decreased viability. ---
**Author:** ![Deptective](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@Deptective](https://forum.depmap.org/u/Deptective)\ **Post date:** [July 31, 2025, 8:29pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/6 "2025-07-31T20:29:44Z")
Thanks, but the paper clearly states that the threshold is a “median-collapsed log-fold change” of 0.3, ie. after log2 is applied. I get your point, that a fold-change (treatment\_MFI/negative\_ctrl\_MFI) of 0.3 gives a log2 value of -1.74. But that is not what the paper states. So, do we assume that the paper used inaccurate language, and that the threshold was actually a fold-change (treatment\_MFI/negative\_ctrl\_MFI) of 0.3 before log2 transformation, and hence a “median-collapsed log-fold change” of -1.74? ---
**Author:** ![Yangqi\_Su](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/yangqi_su/32/1574_2.png) [@Yangqi\_Su](https://forum.depmap.org/u/Yangqi_Su)\ **Post date:** [July 31, 2025, 8:46pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/7 "2025-07-31T20:46:42Z")
In their paper ([https://doi.org/10.1038/s43018-019-0018-61](https://doi.org/10.1038/s43018-019-0018-61)) or PMID: [32613204](https://pubmed.ncbi.nlm.nih.gov/32613204/), they explicitly state in the Method section, under Data processing, the last sentence: “We labeled cell lines as sensitive to a treatment if the median-collapsed fold change was \< 0.3”, so I believe it is not on the log scale ---
**Author:** ![Deptective](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@Deptective](https://forum.depmap.org/u/Deptective)\ **Post date:** [July 31, 2025, 9:05pm UTC](https://forum.depmap.org/t/is-there-a-threshold-in-drug-sensitivity-auc/3038/8 "2025-07-31T21:05:32Z")
Hi, my apologies. I had it quoted as “median-collapsed **log** -fold change”. Now I looked again and saw that I had taken that from elsewhere in the paper. I stand corrected!