Query the Cancer Dependency Map (DepMap) for cancer cell line gene dependency scores (CRISPR Chronos), RNAi DEMETER2 scores, PRISM compound sensitivity, and gene effect profiles across the cell-line panel. Use for identifying cancer-selective vulnerabilities, separating pan-essential genes from selective ones, finding synthetic lethal interactions, correlating dependency with mutation, expression and copy number, and validating oncology drug targets. Also trigger on DepMap, Chronos gene effect, CRISPRGeneEffect.csv, DEMETER2, PRISM repurposing, co-essentiality, pan-essential, or ACH- cell line identifiers.
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
A direct command skips the review prompt. Inspect the source before running it.
Query the Cancer Dependency Map (DepMap) for cancer cell line gene dependency scores (CRISPR Chronos), RNAi DEMETER2 scores, PRISM compound sensitivity, and gene effect profiles across the cell-line panel. Use for identifying cancer-selective vulnerabilities, separating pan-essential genes from selective ones, finding synthetic lethal interactions, correlating dependency with mutation, expression and copy number, and validating oncology drug targets. Also trigger on DepMap, Chronos gene effect, CRISPRGeneEffect.csv, DEMETER2, PRISM repurposing, co-essentiality, pan-essential, or ACH- cell line identifiers.
license
MIT
compatibility
Requires Python 3.10+ with pandas, numpy, scipy and requests. Analysis is download-based — the DepMap release files (CRISPRGeneEffect.csv is roughly 500 MB) are fetched from the portal by hand and read locally. The portal gates programmatic access behind a browser verification page, so there is no usable REST API. Data is CC-BY-4.0 and requires registration to download.
allowed-tools
Read Write Edit Bash
metadata
{"version":"1.1","skill-author":"Kuan-lin Huang"}
DepMap — Cancer Dependency Map
Overview
The Cancer Dependency Map (DepMap) project, run by the Broad Institute, systematically characterizes genetic dependencies across hundreds of cancer cell lines using genome-wide CRISPR knockout screens (DepMap CRISPR), RNA interference (RNAi), and compound sensitivity assays (PRISM). DepMap data is essential for:
Identifying which genes are essential for specific cancer types
Data downloads are the supported route; see the warning below about the portal API.
There is no DepMap Python package. The PyPI project named depmap is "Dependency Mapper CLI",
an unrelated software-dependency tool — installing it will not get you cell-line data. Read the
release CSVs with pandas.
When to Use This Skill
Use DepMap when:
Target validation: Is a gene essential for survival in cancer cell lines with a specific mutation (e.g., KRAS-mutant)?
Biomarker discovery: What genomic features predict sensitivity to knockout of a gene?
Synthetic lethality: Find genes that are selectively essential when another gene is mutated/deleted
Drug sensitivity: What cell line features predict response to a compound?
Pan-cancer essentiality: Is a gene broadly essential across all cancer types (bad target) or selectively essential?
Correlation analysis: Which pairs of genes have correlated dependency profiles (co-essentiality)?
Core Concepts
Dependency Scores
Score
Range
Meaning
Chronos (CRISPR)
~ -3 to 0+
More negative = more essential. Common essential threshold: −1. Pan-essential genes ~−1 to −2
RNAi DEMETER2
~ -3 to 0+
Similar scale to Chronos
Gene Effect
normalized
Normalized Chronos; −1 = median effect of common essential genes
Checked live, August 2026: every path under https://depmap.org/portal/api/ answers a
programmatic request with HTTP 200 and an HTML browser-verification page, not JSON. That
combination is the trap — response.raise_for_status() sees the 200 and passes, so the failure
surfaces later as a JSONDecodeError, or worse as an HTML string quietly carried forward as data.
DepMap publishes no documented, stable, public REST API. Download the release files and work
locally; that is the supported route and the one the rest of this skill uses.
2. Download-Based Analysis (the supported route)
For large-scale analysis, download DepMap data files and analyze locally:
import pandas as pd
import requests, os
defdownload_depmap_data(url, output_path):
"""Download a DepMap data file."""
response = requests.get(url, stream=True)
withopen(output_path, 'wb') as f:
for chunk in response.iter_content(chunk_size=8192):
f.write(chunk)
# DepMap 24Q4 data files (update version as needed)
FILES = {
"crispr_gene_effect": "https://figshare.com/ndownloader/files/...",
# OR download from: https://depmap.org/portal/download/all/# Files available:# CRISPRGeneEffect.csv - Chronos gene effect scores# OmicsExpressionProteinCodingGenesTPMLogp1.csv - mRNA expression# OmicsSomaticMutationsMatrixDamaging.csv - mutation binary matrix# OmicsCNGene.csv - copy number# Model.csv - cell line metadata (was sample_info.csv before 23Q2)
}
defload_depmap_gene_effect(filepath="CRISPRGeneEffect.csv"):
"""
Load DepMap CRISPR gene effect matrix.
Rows = cell lines (DepMap_ID), Columns = genes (Symbol (EntrezID))
"""
df = pd.read_csv(filepath, index_col=0)
# Rename columns to gene symbols only
df.columns = [col.split(" ")[0] for col in df.columns]
return df
defload_cell_line_info(filepath="Model.csv"):
"""Load cell line metadata.
Release 23Q2 renamed this file from sample_info.csv AND renamed its columns:
DepMap_ID -> ModelID, cell_line_name -> CellLineName,
primary_disease -> OncotreePrimaryDisease, lineage -> OncotreeLineage.
Code written against the old names merges to an empty frame rather than
raising, so check the columns you actually got before trusting a join.
"""return pd.read_csv(filepath)
3. Identifying Selective Dependencies
import numpy as np
import pandas as pd
deffind_selective_dependencies(gene_effect_df, cell_line_info, target_gene,
cancer_type=None, threshold=-0.5):
"""Find cell lines selectively dependent on a gene."""# Get scores for target geneif target_gene notin gene_effect_df.columns:
returnNone
scores = gene_effect_df[target_gene].dropna()
dependent = scores[scores <= threshold]
# Add cell line info
result = pd.DataFrame({
"DepMap_ID": dependent.index,
"gene_effect": dependent.values
}).merge(cell_line_info[["DepMap_ID", "cell_line_name", "primary_disease", "lineage"]])
# On a 23Q2+ Model.csv these are ModelID / CellLineName /# OncotreePrimaryDisease / OncotreeLineage -- rename before merging.if cancer_type:
result = result[result["primary_disease"].str.contains(cancer_type, case=False, na=False)]
return result.sort_values("gene_effect")
# Example usage (after loading data)# df_effect = load_depmap_gene_effect("CRISPRGeneEffect.csv")# cell_info = load_cell_line_info("Model.csv") # see the column renames in the loader# deps = find_selective_dependencies(df_effect, cell_info, "KRAS", cancer_type="Lung")
import pandas as pd
defco_essentiality(gene_effect_df, target_gene, top_n=20):
"""Find genes with most correlated dependency profiles (co-essential partners)."""if target_gene notin gene_effect_df.columns:
returnNone
target_scores = gene_effect_df[target_gene].dropna()
correlations = {}
for gene in gene_effect_df.columns:
if gene == target_gene:
continue
other_scores = gene_effect_df[gene].dropna()
common = target_scores.index.intersection(other_scores.index)
iflen(common) < 50:
continue
r = target_scores[common].corr(other_scores[common])
ifnot pd.isna(r):
correlations[gene] = r
corr_series = pd.Series(correlations).sort_values(ascending=False)
return corr_series.head(top_n)
# Co-essential genes often share biological complexes or pathways
Query Workflows
Workflow 1: Target Validation for a Cancer Type
Download CRISPRGeneEffect.csv and Model.csv (cell-line metadata; this file was named
sample_info.csv before release 23Q2, and older code still asks for that name)
Filter cell lines by cancer type
Compute mean gene effect for target gene in cancer vs. all others
Calculate selectivity: how specific is the dependency to your cancer type?
Cross-reference with mutation, expression, or CNA data as biomarkers
Workflow 2: Synthetic Lethality Screen
Identify cell lines with mutation/deletion in gene of interest (e.g., BRCA1-mutant)
Compute gene effect scores for all genes in mutant vs. WT lines
Identify genes significantly more essential in mutant lines (synthetic lethal partners)
Filter by selectivity and effect size
Workflow 3: Compound Sensitivity Analysis
Download PRISM compound sensitivity data (primary-screen-replicate-treatment-info.csv)
Correlate compound AUC/log2(fold-change) with genomic features
Identify predictive biomarkers for compound sensitivity
Read references/dependency_analysis.md before acting on a
score — it covers what Chronos corrects for, the full score-band interpretation, selectivity
metrics, and the copy-number and expression confounders that produce false dependencies.
Best Practices
Use Chronos scores (not DEMETER2) for current CRISPR analyses — better controlled for cutting efficiency
Distinguish pan-essential from cancer-selective: Target genes with low variance (essential in all lines) are poor drug targets
Validate with expression data: A gene not expressed in a cell line will score as non-essential regardless of actual function
Use DepMap ID for cell line identification — cell_line_name can be ambiguous
Account for copy number: Amplified genes may appear essential due to copy number effect (junk DNA hypothesis)
open-targets → before: its depMapEssentiality roll-up is the summary of what is here. Come to
this skill when the roll-up says "essential" and you need to know in which lineages.
target-safety → alongside: cell-line essentiality is not human tolerance. A gene essential
across the panel may still have healthy human knockouts — gnomAD LOEUF answers that, DepMap
cannot.
chembl → after: once a dependency looks selective, what has already been made against it.
uniprot-rcsb → after: the structure, once the target survives triage.
clinicaltrials → after: whether anyone has taken this vulnerability into patients.
primekg / ncats-arax → alongside: mechanistic context for a co-essentiality pair that has no
obvious pathway explanation.
A pan-essential gene is a toxicity finding, not a target. The whole point of the panel is the
contrast between lineages; a gene at −1 everywhere kills normal cells too.
DepMap paper: Tsherniak A et al. (2017) Defining a Cancer Dependency Map. Cell. PMID: 28753430
Chronos paper: Dempster JM et al. (2021) Chronos: a cell population dynamics model of CRISPR
experiments that improves inference of gene fitness effects. Genome Biology. PMID: 34930405
Project Score (Sanger, complementary panel): Behan FM et al. (2019) Nature. PMID: 30971826
