A Phase II Study of Palbociclib for Recurrent or Refractory Advanced Thymic Epithelial Tumor

Inclusion Criteria:

1. Histologically proven thymic epithelial tumor (TET) patients
2. Be ≥18 years of age on day of signing informed consent.
3. Documented progressive disease according to RECIST v1.1 following receipt of at least one cytotoxic chemotherapy regimen administered for inoperable or metastatic disease.
4. Measurable disease as defined per RECIST v 1.1. Tumor lesions previously irradiated or subjected to other locoregional therapy will only be deemed measurable if disease progression at the treated sited after completion of therapy is clearly documented.
5. Availability of a tumor tissue specimen (ie, archived formalin fixed paraffin embedded tissue \[block preferred, or 10 unstained slides\]), which will be used for retrospective biomarker analysis. If archived tumor tissue is not available, then a de novo biopsy will be required for patient participation.
6. ECOG performance status of 0 to 2

Exclusion Criteria:

1. Known active uncontrolled or symptomatic central nervous system (CNS) metastases, carcinomatous meningitis, or leptomeningeal disease as indicated by clinical symptoms, cerebral edema, and/or progressive growth. Patients with a history of CNS metastases or cord compression are eligible if they have been definitively treated with local therapy (eg, radiotherapy, stereotactic surgery) and are clinically stable off anticonvulsants and steroids for at least 4 weeks before randomization.
2. Inability to swallow capsules.
3. Prior treatment with any CDK4/6 inhibitor.