LAG3 and head and neck squamous cell carcinoma: Combination Study With Soluble LAG-3 Fusion Protein Eftilagimod Alpha (IMP321) and Pembrolizumab in Patients With Previously Untreated Unresectable or Metastatic NSCLC, or Recurrent PD-X Refractory NSCLC or With Recurrent or Metastatic HNSCC (TACTI-002) - TACTI-002Keynote-PN798 (Other Identifier: Merck Sharp & Dohme Corp)