Project 1: Over the past years, considerable excitement has accompanied the clinical testing of new drugs in melanoma. In particular, the RAF-inhibitor, PLX4032, has showed remarkable efficacy when administered to melanoma patients harboring the BRAFV600E mutation. Unfortunately, the overall clinical benefit of targeted agents in melanoma remains limited, mainly due to the appearance of resistance after a few months of treatment. Work in our lab has discovered different resistance mechanisms involving the appearance of MEK mutant alleles upon treatment of BRAFV600E cells with the MEK inhibitor CI-1040, and the overexpression of CRAF or of MAPK38/COT kinase upon treatment of BRAFV600E cells with the BRAF inhibitor PLX-4720. How general, however, these recently-discovered resistance mechanisms are, remains poorly defined, and, undoubtedly, additional mechanisms of resistance to RAF inhibition remain to be discovered. The purpose of our proposal is to perform a systematic search for novel resistance mechanisms present in, and vulnerabilities of, tumor-derived MAPK-inhibition resistant tumors. This will be addressed by 1) interrogating genetic, as well as non-genetic alterations present in patient-derived MAPK-inhibition resistant tumors, by whole-exome and transcriptome sequencing, and 2) identifying novel dependencies unique to MAPK-inhibition resistant tumors, by pooled RNAi screening, and synthetic lethal RNAi screening in the presence of MAPK-inhibitors. In addition, we will establish pre-clinical in vivo mouse models to characterize the recently discovered resistance mechanisms. Upon completion of this research, we will have gained understanding of the resistance mechanisms operant in melanoma, and identified possible new drug targets for combinatorial treatments that could overpower the resistance.

Public Health Relevance

Our study addresses directly this need by performing a comprehensive genomic characterization of patient derived tumors following relapse after RAF/MEK-inhibition-based treatment to identify existing resistant mechanisms, and by performing a molecular characterization of known resistance mechanisms to RAF/MEK inhibition to be able to design of therapeutic regimens to intercept them.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Program Projects (P01)
Project #
5P01CA163222-05
Application #
9257300
Study Section
Special Emphasis Panel (ZCA1-RPRB-O)
Project Start
Project End
2019-02-28
Budget Start
2017-03-01
Budget End
2018-02-28
Support Year
5
Fiscal Year
2017
Total Cost
$365,192
Indirect Cost
$43,064
Name
Massachusetts General Hospital
Department
Type
Independent Hospitals
DUNS #
073130411
City
Boston
State
MA
Country
United States
Zip Code
02114
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Nguyen, Nhu T; Fisher, David E (2018) MITF and UV responses in skin: From pigmentation to addiction. Pigment Cell Melanoma Res :
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Kawakami, Akinori; Fisher, David E (2017) The master role of microphthalmia-associated transcription factor in melanocyte and melanoma biology. Lab Invest 97:649-656
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