ENB003 Plus Pembrolizumab Phase 1b/2a in Solid Tumors

Part A: Dose Escalation (with Run-in) A 7-day run-in period of ENB-003 monotherapy, will be administered to all Part A subjects on Days -7, -5 and -3, prior to initiating combination therapy with pembrolizumab at Day 1. ENB-003 will also be administered on Days 1, 3 and 5 in Cycle 1. In subsequent cycles, ENB-003 will be administered on Days 1, 3, 5, 8, 10, and 12 of alternate 21-day treatment cycles, starting with Cycle 3. Dose escalation will follow a standard 3+3 design, with the following doses being administered during Part A: * 150 µg ENB-003 * 300 µg ENB-003 * 500 µg ENB-003 * 750 µg ENB-003 * 1000 µg ENB-003 and 2000 µg ENB-003. For 2000 µg doses and above, ENB003 will be administered every 21 day cycle. Pembrolizumab will be administered as 200 mg on Day 1 of each 21-day cycle in all Part A cohorts. Part B: Dose Expansion Twelve (12) subjects with malignant melanoma, ovarian cancer, or pancreatic cancer will receive 1 x 21-day treatment cycle of ENB-003 at the recommended phase 2 dose (RP2D) selected in Part A + pembrolizumab. If dose limiting toxicities (DLT) occur in no more than 3 subjects , Part B will be expanded with an additional 27 subjects, plus 6 additional subjects with sarcoma. A review of efficacy will be conducted by a Data Safety Monitoring Board (DSMB) in Part B once 39 RP2D subjects (including 9 malignant melanoma subjects, 16 ovarian cancer subjects and 14 pancreatic cancer subjects) have completed their scheduled 12 week CT/MRI scans. Upon approval by the DSMB, a maximum of 64 further subjects will be treated at the RP2D.