The purpose of this study is to explore the efficacy and safety of chidamide combined with etoposide and cisplatin/carboplatin in the first-line treatment of advanced extrapulmonary neuroendocrine carcinoma.

This study is a single-arm, multi-center, two-stage, phase II clinical trial conducted in China. This study adopts Simon's two-stage design, and the inclusion criteria and exclusion criteria of the two stages were consistent. Twelve patients with extrapulmonary neuroendocrine carcinoma will be enrolled in the first stage. If more than four complete or partial responses were seen at planned interim analysis, the additional 16 patients will be recruited in the second stage and a total of 28 patients will be treated.

Inclusion Criteria:

1. Age ≥ 18 years;
2. Histologically confirmed locally advanced and metastatic extrapulmonary neuroendocrine carcinoma;
3. No systematic treatments for neuroendocrine carcinoma are received before enrollment;
4. ECOG ≤ 2;
5. Have at least one measurable lesion according to RECIST version 1.1, and the lesion has not received any local treatments;
6. Absolute neutrophil count ≥ 1.5×109 / L, platelet count ≥ 100×109 / L, hemoglobin ≥ 90 g/L;
7. Have ability to sign a written informed consent.

Exclusion Criteria:

1. Have surgery or trauma within 4 weeks before enrollment, or are expected to receive surgical treatment;
2. Previous use of HDAC inhibitors;
3. Allergy to related drug components;
4. Have a medical history of immune deficiency diseases, or organ transplantation;
5. Have uncontrolled or significant cardiovascular disease;
6. Abnormal liver function (total bilirubin > 1.5×upper limit of normal); Transaminases (ALT/AST) >2.5×upper limit of normal (>5x upper limit of normal for patients with liver metastases), abnormal renal function (serum creatinine > 1.5×upper limit of normal);
7. Pregnancy ;
8. Have serious diseases that may endanger the safety of patients, or affect patients to complete the research;
9. Any serious mental or cognitive disorder;
10. Patients are currently enrolled in another drug clinical trial within 4 weeks prior to enrollment;
11. Any other condition which is inappropriate for the study in the opinion of the investigators.

Individual participant data are not available to others.