A Randomized, Double-Blind Phase II Study of Adjuvant Pembrolizumab Versus Placebo in Head and Neck Cancers at High Risk for Recurrence- the PATHWay Study

Inclusion Criteria

• Patients must have histologically confirmed head and neck cancer (Squamous cell histology as well as HPV+ and/or EBV+ head and neck tumors), Stages IVA, IVB, and select cases of Stage III.
• HPV status required prior to randomization for oropharyngeal primary tumors
• EBV status is required prior to randomization for nasopharyngeal primary tumors
• Completed curative intent therapy, without additional standard of care curative intent therapy feasible within 20 weeks prior to study enrollment
• After prior curative intent treatment for HNC have estimated risk of recurrence ≥ 40-50% and fall into one of the below categories (A, OR B, OR C, OR D, OR E). While exact estimation of the risk of recurrence can be difficult the following categories will be included reflecting patients at substantial risk for tumor recurrence or already with early evidence of recurrence:
• A: Any of the below HNC patients are eligible for adjuvant treatment on this protocol AFTER completion of curative intent therapy:
• HPV(-) HNC: N2C, N3, bulky N2B disease (≥ 5cm LN/tumor conglomerate).
• HPV(+) HNC: N2C, N3, AND ≥ 10 pack years of tobacco use
• HPV(+) HNC with multilevel nodal involvement, AND bulky N2B disease (≥ 5cm LN/tumor conglomerate), AND ≥ 10 pack years of tobacco use
• EBV(+) NPC may be eligible if other criteria under A, or alternative criteria B, or C, or D, or E are met.
• HNC with supraclavicular or mediastinal nodal involvement (any HPV or EPV status ) at time of curative intent treatment and were treated as part of curative intent therapy
• Residual mass in area of prior tumor that on biopsy does not show residual tumor, is equivocal/not highly-suspicious on imaging but remains of concern, requires close follow-up AND is not resected/amenable to resection OR immediate palliative treatment.
• Non-responders to induction chemotherapy (PD on induction, or lack of tumor shrinkage ( 1 year.
• Male subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study therapy.

Exclusion Criteria

• Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 2 weeks of the first dose of treatment.
• Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of trial treatment.
• Has a known history of active TB (Bacillus Tuberculosis)
• Has hypersensitivity to pembrolizumab or any of its excipients.
• Has had a prior anti-cancer monoclonal antibody (mAb) within 4 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier.
• Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent.
• Note: Subjects with ≤ Grade 2 neuropathy or typical side effects from radiotherapy are an exception to this criterion and may qualify for the study.
• Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.
• Has a known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer or any tumors that are not likely to influence live expectancy in the subsequent 3 years without active treatment (e.g. low grade prostate cancer in absence of therapy).
• Has known active (=growing) central nervous system (CNS) metastases and/or carcinomatous meningitis. Radiation or resecte