In another phase I study, the CD40 agonist CDX-1140 is being evaluated as monotherapy or in combination with pembrolizumab, chemotherapy or the recombinant fms-like tyrosine kinase 3 (Flt-3) ligand CDX-301 in advanced solid tumors including HNSCC (NCT03329950). Here, FLT3 is linked to head and neck squamous cell carcinoma.