Identification of new molecular targets for drug therapy is an area of active investigation and continued need in oncology. The Mining Synthetic Lethals (MiSL) platform offered by SRI may accelerate the discovery of new targeted oncology drugs by integrating a computational approach that mines patterns from primary tumor data with pre-clinical validation of potential targets.
The MiSL platform works by "looking" for synthetic lethal (SL) partners among primary tumor data and then validating them in vivo. Synthetic lethality offers a new approach to finding targeted therapies for previously "undruggable" tumor mutations. In SL interactions, a diseased cell with a mutation is dependent on a second gene for cell survival. Inhibiting activity of the second gene in these cells leads to cell death.
"If you can inhibit the SL partner, you can very exquisitely kill cancer cells," said Dr. Sinha. "MiSL overcomes the limitations of cell line screening methods such as shRNA and CRISPR, and has previously demonstrated ability to identify valid SL partners in multiple tumor types, including acute myeloid leukemia and kidney cancer. Today we presented the first data demonstrating the platform's ability to identify new targets in triple-negative breast cancer."
BRCA1 is mutated in 15 to 20 percent of triple negative breast cancer (TNBC). SRI researchers used MiSL to identify and predict 22 SL partners of the BRCA1 mutation in TNBC, including XRCC6. To test the prediction that XRCC6 is an SL partner of BRCA1 in TNBC, SRI researchers examined the effect of inhibiting XRCC6 in a BRCA1-mutated TNBC cell line. The researchers found that this XRCC6 "knockdown" significantly increased cell death (37.3 percent) and reduced viability (50 percent reduction, p < 0.0001) as compared to controls. SRI researchers are testing the remaining SL partners identified by MiSL in an effort to expand the set of available molecular targets that may become the focus of new drug discovery projects.
"This platform opens the door for discovering new options to treat BRCA1-mutated breast cancers and could lead to new chemo-prevention strategies for individuals carrying germline BRCA1 mutations," added Dr. Sinha.
About the MiSL Platform
SRI's MiSL platform has numerous applications in precision cancer therapy, including identification of new drug targets for previously untreatable cancers, repurposing of existing drugs for cancer treatment and predicting patients who will best respond to targeted therapies. The platform offers several advantages over traditional screening-based approaches (e.g., shRNA, CRISPR) for targeted drug discovery:
- Identifies drug targets (i.e., mutation-specific synthetically lethal partners) by analyzing pan-cancer, primary human tumor data rather than artificial models. This captures in vivo interactions for more predictive power and means MiSL is not limited to cell lines that are often not representative of human tumors
- Enables discovery of novel drug targets for a diverse set of mutations in a variety of cancer types
- Improves identification of predictive biomarkers to targeted drugs using primary human tumor data instead of cell line screens
- Low cost and highly efficient compared to wet lab screening
SOURCE SRI International
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