An Open-label, Dose Escalation, Phase 1 Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of TAK-676 as a Single Agent and in Combination With Pembrolizumab in Adult Patients With Advanced or Metastatic Solid Tumors

TAK-676 is a synthetic cyclic dinucleotide (CDN) exhibiting highly selective binding and activation of STING pathway.

In this study, the sponsor and investigators want to learn:

• How much of the study agent can be given with an acceptable level of side effects
• About the safety and tolerability of the study agent alone and in combination with Pembrolizumab
• How proteins that indicate the status of your immune system are affected with use of the study drug alone and in combination with Pembrolizumab
• If the study agent alone and in combination with Pembrolizumab prevents or delays tumor growth or shrinks existing tumors
• How quickly the study agent is removed from your blood stream

During the dose escalation part of this study, the amount of the study drug given is being increased in each group of research participants, to find the most appropriate dose for further study.  In the dose expansion part of the study, a larger number of people will receive the study drug dose determined to be appropriate in the dose escalation part of the study. The dose of the study drug you receive, and whether you will receive the study drug alone or in combination with pembrolizumab, will be determined based on when you enroll onto the study and experiences of any participants who may have enrolled before you.

All participants at each dose level will remain in the hospital for 24 hours following the first three infusions of the study drug (on Days 1, 8, and 15 of Cycle 1) so your study doctor can watch for any serious side effects. You will be admitted to Medical City Dallas. If you are assigned to receive Pembrolizumab in combination with the study drug, you will receive Pembrolizumab as an IV infusion on day 1 of each cycle.