TAS-102 With or Without Celecoxib in ctDNA-defined Minimal Residual Disease in Colorectal Cancer After Completion of Adjuvant Chemotherapy

Inclusion Criteria:

1. Has histological confirmation of colorectal cancer

2. Received post-R0 resection of stages II, III, or IV colorectal cancer and hascompleted all planned curative intent therapies that must include ≥ 3 months ofoxaliplatin containing chemotherapy

3. Has no definitive evidence of radiographic disease per assessment by investigatorswithin 28 days (before or after) a positive ctDNA assay

4. Has minimal residual disease as defined by positive ctDNA assay (completed asstandard-of-care at MD Anderson). Patients may be identified for enrollment with anyClinical Laboratory Improvement Amendments (CLIA)-certified ctDNA assay for MRD. MRDstatus will be confirmed with the Signatera assay prior to initiation of therapy (unless the prior testing was also done with Signatera in which case this test wouldnot require confirmation)

5. Has adequate organ and marrow function as defined below:

6. absolute neutrophil count: ≥1,000/mcL

7. platelets: ≥100,000/mcL

8. total bilirubin: ≤ institutional upper limit of normal (ULN)

9. AST(SGOT)/ALT(SGPT): ≤3 × institutional ULN

10. Serum creatinine ≤ 1.5 × ULN or creatinine clearance ≥60 mL/min. Creatinineclearance (Clcr) can either be measured in a 24-hour urine collection orestimated by the Cockcroft-Gault equation as follows: Clcr (mL/min) = [(140 -age) x (weight in kg) ÷ [72 x (serum creatinine in mg/dL)] [0.85 if female]

11. Has ECOG performance status (PS) of 0 or 1

12. Is of age ≥ 18 years. Because no dosing or adverse-event data are currentlyavailable on the use of TAS-102 in patients, children <18 years of age are excludedfrom this study.

13. Is able to understand and is willing to sign a written informed consent document.

14. Is willing to utilize contraception. Female subjects agree to use highly effectivecontraception combined with an additional barrier method (eg, diaphragm, with aspermicide) while on study and for 7 months after last dose of study drug, and thesame criteria are applicable to male subjects if they have a partner of childbirthpotential. Male subject agrees to use a condom and not donate sperm while in thisstudy and for 7 months after the last treatment.

Exclusion Criteria:

1. Has other concomitant active, invasive malignancies that may interfere with ctDNAanalysis (known clonal hematopoesis of unknown potential allowed)

2. Has serum electrolytes, potassium, calcium, or magnesium levels outside of thenormal laboratory reference range which are clinically significant in theinvestigator's judgment

3. Has significant concomitant health conditions including but not limited to severeautoimmune or cardiovascular disorders that may interfere with participation in thestudy per assessment by investigators

4. Has a persistent adverse event, except alopecia and neuropathy, greater than orequal to grade 2 of the Common Toxicity Criteria for Adverse Events (CTCAE) v. 5.0

5. Has another disease, metabolic disorder, physical examination anomaly, abnormallaboratory result, or any other condition that investigators suspect may (a)prohibit use of the investigational product, (b) affect interpretation of studyresults, or (c) put the patient at undue risk of harm

6. Has known hypersensitivity to the trial drugs or their excipients or is at risk ofallergic of anaphylactic reaction to drug product according to the Investigator'sjudgement

7. Is pregnant or lactating

8. Is unable to take medication orally or has any other condition that investigatorsbelieve may affect absorption of the investigational product

9. Is receiving any other investigational agent.