- Candidate for MLA based on the size, location, and shape of the recurrent tumor as determined by the performing neurosurgeon. Surgical resection/debulking prior to MLA is allowed per standard of care but is not required; if the patient undergoes resection or debulking, it must have occurred at least 3 weeks prior to the first dose of MK-3475. For Phase II: if surgical resection/debulking prior to MLA is not indicated, a biopsy of the tumor will be done at the same time of MLA to obtain tumor tissue for both diagnostic purposes and immune monitoring.