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Updated: Mar 6, 2026

A Data Integration Workflow to Identify Drug Combinations Targeting Synthetic Lethal Interactions
Published on: May 27, 2021
Synergistic drug combinations for cancer identified in a CRISPR screen for pairwise genetic interactions
Kyuho Han1, Edwin E Jeng1,2, Gaelen T Hess1
1Department of Genetics, Stanford University, Stanford, California, USA.
Abstract:
Identification of effective combination therapies is critical to address the emergence of drug-resistant cancers, but direct screening of all possible drug combinations is infeasible. Here we introduce a CRISPR-based double knockout (CDKO) system that improves the efficiency of combinatorial genetic screening using an effective strategy for cloning and sequencing paired single guide RNA (sgRNA) libraries and a robust statistical scoring method for calculating genetic interactions (GIs) from CRISPR-deleted gene pairs. We applied CDKO to generate a large-scale human GI map, comprising 490,000 double-sgRNAs directed against 21,321 pairs of drug targets in K562 leukemia cells and identified synthetic lethal drug target pairs for which corresponding drugs exhibit synergistic killing. These included the BCL2L1 and MCL1 combination, which was also effective in imatinib-resistant cells. We further validated this system by identifying known and previously unidentified GIs between modifiers of ricin toxicity. This work provides an effective strategy to screen synergistic drug combinations in high-throughput and a CRISPR-based tool to dissect functional GI networks.
Insights
A new CRISPR-based double knockout system efficiently screens cancer drug combinations. This approach identified synergistic drug pairs, including BCL2L1 and MCL1, effective against resistant leukemia cells.
Area of Science:
- Genomics
- Cancer Biology
- Drug Discovery
Background:
- Drug resistance in cancer necessitates novel combination therapies.
- Screening all potential drug combinations is computationally and experimentally challenging.
- CRISPR-based genetic screening offers a powerful approach to identify functional genetic interactions.
Purpose of the Study:
- To develop and validate a CRISPR-based double knockout (CDKO) system for efficient high-throughput screening of combinatorial genetic interactions.
- To construct a large-scale human genetic interaction (GI) map.
- To identify synthetic lethal drug target pairs and synergistic drug combinations for cancer therapy.
Main Methods:
- Development of a CRISPR-based double knockout (CDKO) system with efficient paired single guide RNA (sgRNA) library cloning and sequencing.
- Application of CDKO to generate a human GI map in K562 leukemia cells, targeting 21,321 gene pairs.
- Utilizing a robust statistical scoring method to calculate genetic interactions (GIs) from CRISPR-deleted gene pairs.
- Validation of the CDKO system using known modifiers of ricin toxicity.
Main Results:
- Generated a comprehensive human GI map of 490,000 double-sgRNAs.
- Identified synthetic lethal drug target pairs exhibiting synergistic killing upon drug treatment.
- Discovered the BCL2L1 and MCL1 drug combination, demonstrating efficacy in imatinib-resistant leukemia cells.
- Validated novel and known genetic interactions.
Conclusions:
- The CDKO system provides an effective high-throughput strategy for screening synergistic drug combinations.
- This CRISPR-based tool enables the dissection of functional genetic interaction networks.
- The identified synthetic lethal interactions offer potential therapeutic strategies for drug-resistant cancers.
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