Single center, non-randomized, Phase 0 study. Sacituzumab Govitecan given preoperatively, followed by craniotomy with surgery or biopsy of brain tumors (GBM and metastatic brain tumors from Breast) and intraoperative tissue collection will follow with contemporaneous CSF (depending on tumor location) and whole blood (serum) sampling.

The primary objective of the trial is to assess whether there is no difference in disease-free survival for patients treated with a 1cm excision margin when compared to a 2cm margin for stage II primary melanomas (AJCC 8th edition; pT2b-pT4b).