The biomarker component of this study will compare pre-treatment (PRE) with day 4-7, 'early during treatment' biopsies (EDT) and 12 week lymphadenectomy samples (POST). The tissue will be interrogated for immunologic, proteomic and genetic (RNA and DNA) features and changes in tissue and blood. The baseline PRE specimen will consist of at least two core, excisional or incisional biopsies taken prior to commencing combined dabrafenib and trametinib. The EDT specimen will consist of at least two core, excisional or incisional biopsies taken at days 4-7, very early after commencing combined dabrafenib and trametinib. The POST specimen will be the complete lymph node dissection specimen performed after 12 weeks of treatment with combined dabrafenib and trametinib.