Synthetic-Lethal-Based Targeted Therapy for Oncogenic KRAS-Driven Cancer

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DESCRIPTION (provided by applicant): Despite recent significant advances in molecular targeted cancer therapy, success has remained limited to a small subset of oncogene-addicted tumors. Cancers known to harbor some of the most prevalent oncogenes, such as KRAS, remain refractory to effective treatment. Novel systematic genetic approaches have the potential to identify alternative functional dependencies in cells carrying cancer-causing mutations, a concept known as "synthetic lethality." Indeed, through computational analysis of cancer cell-based RNA interference (RNAi) screening datasets, it has been possible to identify and validate both known and novel genetic co- dependencies with common oncogenes such as PIK3CA and KRAS (Vasudevan, Barbie et al., Cancer Cell 2009, PMID: 19573809; Barbie et al., Nature 2009, PMID: 19847166). The goal of this project is to translate these synthetic lethal targets into effective genotype-specific cancer therapy, with a focus on KRAS-driven lung cancer, since it remains an intractable clinical problem. Specifically, the non-canonical I:B kinase TBK1, which is required for survival downstream of KRAS, will be the focus of further mechanistic studies, small molecule screening efforts, and pre-clinical validation. Elucidation of the TBK1-mediated NF-:B survival-signaling pathway will facilitate effective biochemical and cell-based assays for drug development and highlight other potential targets for therapy. Compounds that specifically inhibit TBK1 or other NF-:B signaling components will be characterized for KRAS-selective effects on cell viability in vitro, and then tested for efficacy in mouse model systems. The overall goal of these experiments is to identify effective TBK1/NF-:B small molecule inhibitors that validate in pre-clinical model systems and that can ultimately be evaluated in genotype-directed clinical trials for KRAS-driven lung cancer. Moreover, systematic efforts are currently underway to characterize synthetic lethal targets for a wide array of cancer-related genetic alterations. Effective clinical translation of TBK1 could serve as a model for development of synthetic-lethal-based targeted therapy in cancer in general. This project aligns well with the immediate career goal of applying functional genetic and computational biological approaches to identify novel targets for cancer therapy, and the long-term career goal of translating these findings into effective targeted therapy for KRAS mutant lung cancer. The mentorship of Dr. William Hahn, the resources and collaborative nature of the Broad Institute, and the expert clinical training in the MGH Thoracic Oncology division collectively provide an ideal environment to support career development and the achievement of these goals. PUBLIC HEALTH RELEVANCE: Similar to a car with a jammed accelerator, cancer cells are caught in a precarious balance by the oncogenes that push them to divide. Rather than targeting the accelerator directly, it may be possible to tip cancer cells over the edge by instead going after the adaptations that keep them on the road. Targeting these alternative vulnerabilities with effective drugs may lead to new ways to kill cancer cells, while sparing normal cells.