Alpelisib Terminated Phase 1 / 2 Trials for Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma / Recurrent Head and Neck Squamous Cell Carcinoma / Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma (RM HNSCC) Patients Who Are Resistant or Ineligible/Intolerant to Platinum-based Chemotherapy / Metastatic Head and Neck Squamous Cell Carcinoma Treatment