A Study to Evaluate Safety and Efficacy of ACT001 and Anti-PD-1 in Patients With Surgically Accessible Recurrent Glioblastoma Multiforme

Phase 1b: The identified RP2D of combined ACT001 with Pembrolizumab will be determined by standard 3+3 dose escalation methodology among three ACT001 dosages (200mg, 400mg and 800mg, BID) with standard Pembrolizumab dosage. Patients will be dosed approximately 2 weeks prior to surgical resection with a single dose of Pembrolizumab and ACT001. Tumor resection will be performed and a biopsy will be obtained from the resected tumor tissue to evaluate the impact of the study drugs on the TME. After recovery from surgery, patients will resume ACT001 and Pembrolizumab until tumor progression (assessed by iRANO) or an AE requiring discontinuation of study drug. The Safety Monitoring Committee (SMC) will review the data available from all evaluable patients at each dose level prior to recommending escalation to the next dose level. Phase 2a: Using the same dosing schedule and ACT001 dosage as determined in Phase 1b. Patients will be randomized to receive either Pembrolizumab only treatment (Arm A, 10 patients) or ACT001 plus Pembrolizumab treatment (Arm B, 20 patients).