Hemopurifier Plus Pembrolizumab in Head and Neck Cancer

All 12 patients enrolled into this Early Feasibility Phase I clinical trial will receive the same treatment of Hemopurifier plus Pembrolizumab (i.e., 2 rounds of Hemopurifier plus Pembrolizumab followed by Pembrolizumab only up to 2 years). Prior to initiation of the Hemopurifier treatment on Day 1, each subject will undergo phlebotomy to provide a baseline EDTA anti-coagulated blood sample, 30ml (\< 3 tablespoons of blood) for the assessments of total exosome protein (TEP) levels and exosome profiles. The kinetics of exosome depletion will be evaluated in the study participants using serial blood samples (5ml) collected hourly during the 4h-depletion period by the Hemopurifier on Day 1. In addition, to evaluate kinetics of exosome recovery, 30ml of blood will be collected just prior to Pembrolizumab infusion (day 1) and on days 7 and 14 after Hemopurifier plus Pembrolizumab treatment during cycle 1 and 2. Exosome recovery after Hemopurifier + Pembrolizumab therapy will be evaluated and used to determine the rate of TEP recovery for each patient. Serial monitoring of TEP during Hemopurifier treatment (hourly during the 4h-depletion period), before Pembrolizumab infusion and after the second round of Pembrolizumab (days 7, and 14) will be done as for the first treatment. Only 2 Hemopurifier treatments will be given. For third and later rounds of Pembrolizumab, the investigators will continue to draw 30mL blood prior to Pembrolizumab infusion for the assessments of TEP levels and exosome profiles.