Neuroblastoma is a malignant tumor that develops in infants and kids. Dysregulation of histone acetylation is associated with a series of malignant tumors. Neuroblastoma is caused by defective neural crest differentiation due to abnormal gene regulation.

Inclusion Criteria:

1. Age 3~18 years old;
2. Patients must have a life expectancy of at least 6 weeks and a Lansky (≤16 years) or Karnofsky (>16 years) score of at least 50;
3. Histologically confirmed neuroblastoma and/or demonstration of tumor cells in the bone marrow with increased urinary catecholamines;
4. Patients must have a history of high-risk neuroblastoma, at least one measurable lesions according to the RECIST 1.1;
5. Patients who have progressed, recurrent or refractory disease after first-line treatment;
6. The residual disease biopsy must be done, if patiens who have persistent disease obtain incomplete response after first line treatment;
7. Patients must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to study registration；
8. Patients have not received enzyme-induced anticonvulsant therapy;
9. Patients have not received valproic acid within 30 days before admission;
10. ANC ≥ 1.5×10^9/L, PLT ≥75×10^9/L;TBIL≤1.5ULN, ALT and AST≤3×ULN（ALT and AST≤5×ULN if liver metastasis）;BUN and Cr≤1.5×ULN 9）LVEF ≥ 50% and QTc≤470 ms.
11. Patients' guardians must be willing and able to understand and comply with the protocol for the duration of the study.

Exclusion Criteria:

1. Patients with severe cardiovascular disease;
2. Patients who have previously received organ transplants;
3. Inability to swallow pills;
4. Female patients during pregnancy and lactation, fertile women with positive baseline pregnancy tests or women of childbearing age who are unwilling to take effective contraceptive measures throughout the trial;
5. Active HIV, hepatitis B or hepatitis C;
6. Researchers believe that patients are unsuitable for any other situation in this study.