Molecular approaches to overcome intrinsic drug resistance in BRAF and NRAS-mutan

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DESCRIPTION (provided by applicant): The applicant is an assistant professor at Molecular and Cellular Oncogenesis Program at the Wistar Institute. Her overall goal is to develop effective and long-lasting treatment strategies for melanoma. This proposal serves the applicant's long-term objective of improving outcomes for melanoma patients by investigating the mechanisms of intrinsic resistance to targeted therapy in BRAF-V600E and NRAS mutant melanomas. The candidate will pursue training in research areas that are essential to foster a research niche and become an independent academic cancer researcher. A team of senior scientific advisors has been assembled to formally mentor the applicant by providing training and expertise in new research areas including proteomics, systems and computational biology, and autophagy. The mentoring team is committed to support the development of the applicant into a fully funded independent scientist. Melanoma is a highly aggressive disease with limited therapeutic options. Despite the success of BRAF inhibitors for the treatment of melanoma, responses are transient and most patients develop resistance. Therefore, a major challenge is to understand, overcome, and prevent drug resistance. This application proposes to investigate the mechanisms of intrinsic drug resistance, an important unmet medical need affecting a large subset of melanoma patients, for whom no effective therapies are available. The proposal focuses on NRAS mutant melanomas and BRAF-V6000E mutant melanomas that are intrinsically resistant to BRAF inhibitors. The overall hypothesis is that uncovering the mechanisms underlying intrinsic drug resistance in melanoma will allow designing more effective and longer lasting therapies. The applicant postulates that inhibition of BRAF induces rewiring of the system's signaling networks leading to receptor tyrosine kinase (RTK) activation and attenuated dependency on BRAF. To test this hypothesis, the expression and activation of RTKs will be evaluated in melanoma cell lines and patient-derived tumor samples grown in immunocompromised mice (patient-derived xenografts; PDX) following BRAF inhibition. Mechanistic studies will be performed to determine how inhibition of MAPK leads to RTK activation. Based on these studies rational drug combination strategies will be evaluated in melanoma cells grown as 3D tumor spheroids and in PDX models. The second working hypothesis is that by identifying critical downstream NRAS effectors, melanomas harboring mutations in NRAS can be targeted. The objective is to define the biochemical and biological consequences of silencing NRAS in melanoma cells that harbor mutations in this oncogene. To achieve this goal a candidate and an unbiased proteomic based approaches will be undertaken to identify NRAS effectors that are essential for survival of NRAS mutant melanomas. Collectively, this knowledge will be critical to develop new strategies that eliminate nearly all melanoma cells and inform the design of future clinical trials.