Window Studies in Squamous Cell Carcinoma of the Head and Neck: Values and Limits.

OPINION STATEMENT: In head and neck cancer, we continue to work towards a more personalized approach to treatment of patients, where analysis of a patient's tumor guides targeting of molecular or immunologic pathways. Critically important to this pursuit is a better understanding of the direct biologic effect of a drug or combination on the tumor microenvironment in humans, as well as biomarker discovery. These goals are consistent with the primary purpose of a "window of opportunity" trial and while conduct of these trials requires a careful balance of benefits and potential risks, to date these trials have been both feasible and safe in HNSCC in the curative intent setting. In the era of immunotherapy, with countless possible combinations and ongoing clinical trials, window trials are even more important for informing clinical trial design and appropriate combination therapy, and ultimately a more personalized approach to our patients that leads to improvement in outcomes.