Palbociclib Combined With Afatinib for Advanced Squamous Carcinoma of Esophagus or Gastroesophageal Junction

This is a prospective, multicenter, exploratory study. Patients with advanced esophageal or gastro-esophageal junction squamous carcinoma who had progressed on first-line chemotherapy combined with immune checkpoint inhibitors were treated with CDK4/6 inhibitor Palbociclib combined with Afatinib. Dose titration was used to determine the final dose, and objective antitumor efficacy was evaluated every 2 cycles (8 weeks +/- 7 days) according to RECIST 1.1 criteria, until tumor progression, intolerable toxicity, death, or withdrawal of informed consent. The primary endpoint is the objective response rate (ORR).