This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug to learn whether the drug combination works in treating a specific disease. Investigational means that the drug is being studied.~Because AMD3100 and Pembrolizumab have not been administered together to individuals before, there will be a Run-In phase prior to the beginning of Phase II. This Run-In Phase is designed to identify what dosing schedule is best for participants on this study. Participants will be participating in the Run-In Phase.~The U.S. Food and Drug Administration (FDA) has approved Pembrolizumab as a treatment option for this disease.~The FDA has not approved AMD3100 as a treatment option for this disease, however it has approved the drug for use in individuals who have recently had bone marrow transplants.~Pembrolizumab is thought to block a receptor called PD-1. This receptor usually acts as a brake to prevent the body's immune system from attacking cancer cells. The antibody removes the brake to allow parts of the body's immune system (usually T cells) to attack the tumor~AMD3100 is a drug that inhibits CXCR4, which is a biological mechanism called a chemokine. CXCR4 is over-expressed in cancer cells and promotes cancer cell growth, spread, and survival and controls immune cell trafficking. Researchers believe that inhibiting CXCR4 expels the immune-suppressive cells out of the tumor and attract the cancer-killing immune cells into the tumor environment so that the body's immune system may be able to better attack the cancer cells.~In this research study, the investigators are assessing the safety and effectiveness of AMD3100 and pembrolizumab in participants with aggressive head and neck squamous cell carcinoma.
This research is studying the safety and effectiveness of AMD3100 and pembrolizumab in participants with metastatic head and neck squamous cell carcinoma.