Inclusion Criteria:

          -  Subjects must have recurrent endometrial cancer with deficient mismatch repair system.
             Mismatch repair deficiency is defined by 1. Immunohistochemistry with loss of
             expression of one of these proteins in tumor tissue as defined by standard of care:
             MLH1, MSH2, MSH6 and PMS2, 2. Microstaellite (MSI) unstable by PCR per standard of
             care, 3. MSI high by next generation sequencing using commercial platform specifically
             CARIS, TEMPUS or Foundation testing.

          -  Subjects must have histologically confirmed endometrioid, clear cell, high grade
             serous, undifferentiated carcinoma or mixed histology.

          -  Must have had prior therapy with a PD1 inhibitor, pembrolizumab.

          -  Up to 5 prior lines of therapy are allowed.

          -  Prior anti-angiogenesis therapy is not allowed. Bevacizumab if given with chemotherapy
             in primary or adjuvant setting is allowed if treatment-free interval exceeded 6
             months.

          -  Subjects must have measurable disease based on RECIST 1.1 with at least one target
             lesion.

          -  Subjects must have an ECOG performance status of 0-1.

          -  Subjects must have normal organ and marrow function as defined below within 14 days of
             enrollment unless otherwise indicated:

               -  Hemoglobin ≥ 9.0 g/dl (may have been transfused)

               -  Absolute neutrophil count ≥ 1,500/mcL

               -  Platelet count ≥ 100,000/mcL

               -  Total bilirubin ≤ 1.5 x the upper limit of normal (ULN) range

               -  AST (SGOT) and ALT (SGPT) ≤ 2.5 X ULN orAST and ALT levels ≤ 5 x ULN (for
                  subjects with documented metastatic disease to the liver).

               -  Estimated Creatinine clearance ≥ 30 mL/min according to the Cockcroft-Gault
                  formula (or local institutional standard method)

               -  TSH within normal institutional limits. If elevated, patient can be eligible if
                  evaluated by an endocrine specialist, placed on replacement therapy and deemed
                  eligible with no current or prior autoimmune disease.

          -  Subjects must have the ability to understand and the willingness to sign a written
             informed consent document.

          -  Negative serum or urine pregnancy test at screening for women of childbearing
             potential.

          -  Willing to use highly effective contraception throughout the study and for at least 30
             days after last treatment administration if childbearing potential exists

          -  Availability of an archival FFPE tumor tissue block from primary diagnosis specimen,
             metastatic, or recurrent site. If an FFPE tissue block cannot be provided then 15
             unstained slides (10 minimum) will be acceptable. Please refer to the laboratory
             manual for complete details.

          -  Urinary protein <2+ by urine dipstick. If dipstick is >2+, then 24-hour urinary
             protein <2 g per 24 hours is required.

          -  No evidence of uncontrolled hypertension as documented by 2 baseline blood pressure
             (BP) readings taken at least 1 hour apart whether same visit or different visits. The
             baseline systolic BP readings must be <140 mm Hg, and the baseline diastolic BP
             readings must be <90 mm Hg. The use of antihypertensive medications to control BP is
             allowed.

        Exclusion Criteria:

          -  Patients with sarcoma or carcinosarcoma

          -  Mismatch repair proficient tumors

          -  Patients with primary platinum refractory cancer defined as progressing during or
             within 3 months of completing primary platinum therapy.

          -  Prior anti-cancer therapy within 3 weeks prior to study enrollment.

          -  Known symptomatic brain metastases requiring steroids. Patients with previously
             diagnosed brain metastases are eligible if they have completed their treatment and
             have recovered from the acute effects of radiation therapy or surgery prior to study
             enrollment, have discontinued corticosteroid treatment for these metastases for at
             least 4 weeks and are neurologically stable.

          -  Patients having received prior therapy with PD1 or PDL1 or CTLA4 inhibitors or other
             immunotherapeutic agents except pembrolizumab.

          -  Patients having received prior anti-VEGF therapy as explained above

          -  Bowel obstruction (with or without gastrostomy tube) or inability to take oral
             medications

          -  Patients with a prior or current bowel perforation or fistula

          -  Uncontrolled hypertension defined as 140/90 or greater despite medical management with
             multiple medications

          -  ECOG performance >1

          -  Active autoimmune disease that might deteriorate when receiving an immune-stimulatory
             agent. Patients with diabetes type I, vitiligo, psoriasis, hypo- or hyperthyroid
             disease not requiring immunosuppressive treatment are eligible.

          -  Patients currently on immunosuppressive therapy except:

               -  Intra-nasal, inhaled, topical or local steroid injections (e.g., intra-articular
                  injection)

               -  Steroids as premedication for hypersensitivity reaction (e.g., CT scan
                  premedication)."

               -  Systemic corticosteroids at physiologic doses not exceeding 10 mg/day of
                  prednisone or equivalent

          -  Patients who are pregnant or breast feeding.

          -  Known history of testing positive for HIV or known acquired immunodeficiency syndrome.

          -  Known history of immune-mediated colitis, inflammatory bowel disease, pneumonitis,
             pulmonary fibrosis.

          -  Clinically significant (i.e., active) cardiovascular disease: cerebral vascular
             accident/stroke (< 6 months prior to enrollment), myocardial infarction (< 6 months
             prior to enrollment), unstable angina, congestive heart failure (≥ New York Heart
             Association Classification Class II), or serious cardiac arrhythmia requiring
             medication.

          -  Individuals with a history of a different malignancy are ineligible except for the
             following circumstances: Individuals with a history of other malignancies are eligible
             if they have been disease-free for at least 3 years and are deemed by the investigator
             to be at low risk for recurrence of that malignancy. Individuals with the following
             cancers are eligible if diagnosed and treated within the past 5 years: breast cancer
             in situ, cervical cancer in situ, and basal cell or squamous cell carcinoma of the
             skin.

          -  Prior organ transplantation including allogenic stem-cell transplantation.

          -  Active infection requiring intravenous systemic therapy.

          -  Known hepatitis B virus (HBV) or hepatitis C virus (HCV) infection (positive HBV
             surface antigen or HCV RNA if anti-HCV antibody screening test positive)

          -  Vaccination within 4 weeks of the first dose of treatment and while on trials is
             prohibited except for administration of inactivated vaccines.

          -  Known prior severe hypersensitivity to investigational product or any component in its
             formulations, including known severe hypersensitivity reactions to monoclonal
             antibodies (NCI CTCAE v5 Grade ≥ 3)"

          -  Persistent toxicity related to prior therapy (NCI CTCAE v. 5 Grade > 1); however,
             alopecia, sensory neuropathy Grade ≤ 2, or other Grade ≤ 2 not constituting a safety
             risk based on investigator's judgment are acceptable.

          -  Other severe acute or chronic medical conditions including immune colitis,
             inflammatory bowel disease, immune pneumonitis, pulmonary fibrosis or psychiatric
             conditions including recent (within the past year) or active suicidal ideation or
             behavior; or laboratory abnormalities that may increase the risk associated with study
             participation or study treatment administration or may interfere with the
             interpretation of study results and, in the judgment of the investigator, would make
             the patient inappropriate for entry into this study.

          -  Gastrointestinal abnormalities including:

               -  Inability to take oral medication;

               -  Requirement for intravenous alimentation;

               -  Treatment for active peptic ulcer disease in the past 6 months;

               -  Active gastrointestinal bleeding, unrelated to cancer, as evidenced by clinically
                  significant hematemesis, hematochezia or melena in the past 3 months without
                  evidence of resolution documented by endoscopy or colonoscopy;

               -  Malabsorption syndromes.

          -  Requirement of anticoagulant therapy with oral vitamin K antagonists. Low-dose
             anticoagulants for maintenance of patency of central venous access device or
             prevention of deep venous thrombosis is allowed. Therapeutic use of low molecular
             weight heparin is allowed.

          -  Evidence of inadequate wound healing.

          -  Grade >3 hemorrhage within 4 weeks of patient enrollment.

          -  Evidence of tumor involvement of the myocardium or pericardium or tumor thrombus
             extending to the heart.

          -  Ongoing known cardiac dysrhythmias of NCI CTCAE Grade >2 or prolongation of the QTc
             interval to >500 msec.

          -  Current use or anticipated need for treatment with drugs or foods that are known
             strong CYP3A4/5 inhibitors, including their administration within 10 days prior to
             patient enrollment (eg, grapefruit juice or grapefruit/grapefruit-related citrus
             fruits [eg, Seville oranges, pomelos], ketoconazole, miconazole, itraconazole,
             voriconazole, posaconazole, clarithromycin, telithromycin, indinavir, saquinavir,
             ritonavir, nelfinavir, amprenavir, fosamprenavir nefazodone, lopinavir,
             troleandomycin, mibefradil, and conivaptan). The topical use of these medications (if
             applicable), such as 2% ketoconazole cream, is allowed.

          -  Current use or anticipated need for drugs that are known strong CYP3A4/5 inducers,
             including their administration within 10 days prior to patient enrollment, eg,
             phenobarbital, rifampin, phenytoin, carbamazepine, rifabutin, rifapentin, clevidipine,
             St John's wort.