Number of Patients, Male	15
Number of Patients, Female	6
Stage	IV
Age	Median (range): 64 years (42–85 years)
Number of Prior Systemic Therapies	Median (range): 2 (1–6)
Performance Status: ECOG	0 — 9 1 — 12 2 — 3 — Unknown —
Other
Eligible patients were aged least 18 years with previously treated locally advanced or metastatic esophageal, gastric, or gastroesophageal junction cancer. All patients had measurable disease per RECIST criteria and an Eastern Cooperative Oncology Group performance status of 0 or 1. Standard laboratory eligibility parameters were used. Tumors must have retained RB nuclear expression by immunohistochemistry. Patients could not have received cytotoxic chemotherapy within 3 weeks or investigational therapy within 4 weeks of the first dose of palbociclib, and prior toxicities of treatment must have returned to baseline or grade 1. Patients with uncontrolled intercurrent illness, human immunodeficiency virus, and untreated brain metastases were not permitted.
Cancer Types or Histologic Subtypes	Gastric adenocarcinoma, 5; gastroesophageal junction adenocarcinoma, 3; squamous cell carcinoma of the esophagus, 8; adenocarcinoma of the esophagus, 5.