Pilot Window of Opportunity Trial (POET)

Inclusion Criteria: 1. Written informed consent signed and dated by the patient prior to the performance of any study- specific procedures. 2. At least 18 years of age at the time of signature of the informed consent form (ICF) 3. Histologically confirmed endometrial cancer or colorectal cancer of any stage; either newly diagnosed or recurrent cancer, however no prior chemotherapy or radiation will be allowed. 4. Must be candidates for surgical therapy. 5. Male or female patients. Male patients with female partners of childbearing potential and female patients of childbearing potential are required to use two highly effective methods of contraception during the study treatment and for 3 months after the treatment termination visit. In addition, women of childbearing potential are required to undergo serum pregnancy testing at screening, and at the treatment termination visit. Male study participants should refrain from sperm donation during study treatment and up to 3 months following the last dose of TPST-1495 6. To have archival tumor tissue specimen available. Otherwise, patients should agree to have tumor biopsy to obtain sufficient tissue for histological assessment. 7. Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1. 8. Life expectancy estimated to be \> 12 weeks. 9. Adequate organ and marrow function as defined in protocol. Exclusion Criteria: 1. Concurrent enrollment in another clinical study, unless it is an observational clinical study, a specimen-collection study, or the follow-up period of an interventional study. 2. Patients who used NSAID or COX-2 inhibitors with duration of 4 days or longer within 2 weeks prior to study treatment initiation. 3. Patients with past medical history (PMH) of allergy or hypersensitivity, GI bleed, or ulceration secondary to NSAID's or COX-2 inhibitors. 4. PMH of GI ulcer within one year of treatment initiation or history of untreated helicobacter's pylori infection. Subjects with history of treated helicobacter's pylori infection with confirmation of eradication are eligible. 5. PMH of diverticulitis or any GI bleed within 2 years of treatment initiation. 6. Heart failure is classified by New York Heart Association as Classification II, III or IV. 7. Patients with history of MI or TIA/CVA will be excluded. 8. Active autoimmune disease or inflammatory disorders including inflammatory bowel disease (e.g., ulcerative colitis or Crohn's disease) requiring systemic treatment (i.e., with use of disease modifying agents, systemic corticosteroids, or immunosuppressive drug) within 2 years prior to treatment initiation. 9. Uncontrolled intercurrent illness, including but not limited to, ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, cardiac arrythmia, serious chronic gastrointestinal conditions associated with diarrhea, or psychiatric illness/social situations including a history of substance abuse that would limit compliance with study requirement, substantially increase risk of incurring AEs or compromise the ability of the patient to give written informed consent. 10. Subjects who are receiving anticoagulant therapy or considered to be at increased risk of bleeding (i.e., bleeding disorder or coagulopathy). 11. Psychological, familial, sociological, or geographical conditions that do not permit compliance with the protocol and/or follow-up procedures outlined in the protocol. 12. Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen should be included.