Patients receive cetuximab intravenously (IV) over 60-120 minutes on days -28, -21, -14, -7 of weeks -4 to -1. Patients then receive cetuximab IV on days 1, 8, 15, and 22 and TLR8 agonist VTX-2337 subcutaneously (SC) on days 1, 8, 15. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.