Chidamide + Celecoxib in Advanced Metastatic Colorectal Cancer (CCmCC)

Inclusion Criteria: 1. The patient is 20-year-old or older on the day that consent is provided. 2. With histologically or cytologically proven metastatic colorectal adenocarcinoma. 3. Have measurable lesions according to RECIST v1.1. 4. Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 to 2. 5. Adequate organ function as defined below: i. White blood cells (WBC) ≥3,000/μL ii. Absolute neutrophil count ≥1,500/μL iii. Platelets ≥1 x 105/μL iv. Hemoglobin ≥9.0 g/dL v. Total bilirubin ≤1.5 x the upper limit of normal (ULN) vi. AST(SGOT)/ALT(SGPT) ≤3 x ULN (or ≤5 x ULN if liver metastases are present) vii. Serum creatinine ≤1.5 x ULN 6. Patients who had received or were intolerant of at least 2 front-line systemic treatments. In addition, patients have failed or refused all available standard treatment, or were intolerant of such treatments. For K-ras wild type tumor, anti-EGFR therapy must have been done. For K-ras mutant tumor, antiangiogenic therapy must have been done. 7. Able to take oral medication. 8. With a life expectancy of at least 3 months. 9. Female patients of childbearing potential must have a negative urine or serum pregnancy test. 10. Patients in reproductive age must be willing to use adequate contraception (refer to Section 8.4.2 of the protocol for adequate contraception methods) during the study and 3 months after the end of the study. 11. Ability to understand and the willingness to provide a written informed consent document. Exclusion Criteria: (I) Inclusion criteria: 1. The patient is 20-year-old or older on the day that consent is provided. 2. With histologically or cytologically proven metastatic colorectal adenocarcinoma. 3. Have measurable lesions according to RECIST v1.1. 4. Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 to 2. 5. Adequate organ function as defined below: i. White blood cells (WBC) ≥3,000/μL ii. Absolute neutrophil count ≥1,500/μL iii. Platelets ≥1 x 105/μL iv. Hemoglobin ≥9.0 g/dL v. Total bilirubin ≤1.5 x the upper limit of normal (ULN) vi. AST(SGOT)/ALT(SGPT) ≤3 x ULN (or ≤5 x ULN if liver metastases are present) vii. Serum creatinine ≤1.5 x ULN 6. Patients who had received or were intolerant of at least 2 front-line systemic treatments. In addition, patients have failed or refused all available standard treatment, or were intolerant of such treatments. For K-ras wild type tumor, anti-EGFR therapy must have been done. For K-ras mutant tumor, antiangiogenic therapy must have been done. 7. Able to take oral medication. 8. With a life expectancy of at least 3 months. 9. Female patients of childbearing potential must have a negative urine or serum pregnancy test. 10. Patients in reproductive age must be willing to use adequate contraception (refer to Section 8.4.2 of the protocol for adequate contraception methods) during the study and 3 months after the end of the study. 11. Ability to understand and the willingness to provide a written informed consent document. (II) Exclusion criteria: 1. With known central nervous system (CNS) metastases, a history of CNS metastases or leptomeningeal diseases. 2. With known hypersensitivity towards chidamide, celecoxib, sulfonamides, aspirin, NSAIDs, or any other agents used in the study, including the excipient in the study agent; or with history of asthma, urticarial, or other allergic-type reactions after taking aspirin or other NSAIDs. 3. With severe systemic disease, such as renal disease (serum creatinine \>1.5 x ULN), liver disease (AST/ALT \>3 x ULN, AST/ALT \>5 x ULN if metastatic liver disease were known), active gastrointestinal hemorrhage or increased risks of gastrointestinal bleeding, uncontrolled diabetes, or uncontrolled hypertension. 4. With uncontrolled or significant cardiovascular diseases, including: i. Symptomatic congestive heart failure within 6 months prior to screening, or left ventricular ejection fraction \<50% prior to screening ii. Myocardial infarction within 12 months prior to screening iii. Severe or unstable angina within 6 months prior to screening iv. History of any significant ventricular arrhythmias (e.g., ventricular tachycardia, ventricular fibrillation, or TdP) v. History of significant QT interval prolongation, or corrected QT interval (QTc) \>450 ms prior to screening vi. History of cerebrovascular accident vii. Symptomatic coronary heart disease requiring treatment with agents 5. With the size of fluid area detected by cardiac ultrasonography in cavum pericardium ≥ 10 mm. 6. With history of organ transplantation. 7. With known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)-related illness. 8. With autoimmune disorders or history of organ transplantation who require immunosuppressive therapy. 9. Has had prior chemotherapy, targeted small molecule therapy, radiation therapy, or any NSAID within 2 weeks prior to the first dose of study medication or who has not recovered from adverse events to CTCAE v5.0 Grade 1 due to a previously administered agent. 10. Has clinical significant gastrointestinal abnormality, e.g., unable to swallow, chronic diarrhea, ileus, or bowel obstruction, which would interfere the ingestion, transportation, or absorption of oral agents. 11. With active infection \[suffered from active infection of bacteria, virus, fungi, mycobacteria, parasites, or other infections (excluding nail bed fungal infections), or require intravenous antibiotic therapy, or antiviral therapy, or hospitalization due to any significant infection events within 4 weeks\], or persistent fever within 14 days prior to study entry. 12. Had major surgery \<6 weeks prior to study entry. 13. Has known psychiatric disorder, mental deficiency, or substance abuse disorder that would limit compliance with study requirements. 14. Is currently participating and receiving study therapy, or has participated in a study of an investigational agent and received study therapy or used an investigation device within 4 weeks of the first dose of study medication. 15. Pregnant or lactating female. 16. Has a history or current evidence of any condition, therapy, or laboratory abnormality that might interfere the results of the trial or is not in the best interest of the subject to participate, in the opinion of the investigator.