Inclusion Criteria:

• Age ≥ 18 years old.
• Measurable Stage IVA, Stage IVB (with or without measurable disease) or recurrent (with or without measurable disease) endometrial carcinoma.
  • NOTE: Histologic confirmation of the original primary tumor is required. Patients with the following histologic epithelial cell types are eligible: Endometrioid adenocarcinoma, serous adenocarcinoma, undifferentiated carcinoma, clear cell adenocarcinoma, mixed epithelial carcinoma, carcinosarcoma, adenocarcinoma not otherwise specified (NOS).
  • NOTE: Measurable disease is defined by RECIST (version 1.1).
• Group A only: Largest tumor diameter ≤ 5cm.
  • NOTE: Group B patients have no maximum tumor size.
• The following laboratory values obtained ≤14 days prior to registration:
  • Absolute Neutrophil Count (ANC) ≥1500/μL;
  • Platelet Count (PLT) ≥00,000/μL;
  • Hemoglobin ≥10 g/dL;
  • Creatinine ≤2.0 mg/dL;
  • AST and ALT ≤2 x upper limit of normal (ULN);
    • NOTE: If baseline liver disease, Child Pugh score not exceeding Class A.
  • Total bilirubin ≤.5 x ULN;
  • INR/PT, aPTT ≤1.4 x ULN unless on therapeutic warfarin then INR/PT≤ 5.
• Ability to provide written informed consent.
• Willingness to return to Mayo Clinic in Rochester, Minnesota for follow-up.
• Life expectancy ≥ 2 weeks.
• ECOG performance status (PS) 0, 1, or 2.
• Willingness to provide mandatory biological specimens for research purposes.
• Prior therapy:
  • Any number of prior chemotherapy regimens and/or targeted therapies and/or prior external beam radiation therapy and/or prior hormonal therapy for endometrial cancer are allowed provided the last treatment was > 4 weeks prior to registration.
  • Vaginal brachytherapy may have been administered at any time prior to registration.

Exclusion Criteria:

• Availability of and patient acceptance of curative therapy.
• Active infection, including any active viral infection, ≤ 5 days prior to registration.
• Active or latent tuberculosis or hepatitis.
• Known untreated or symptomatic brain metastases.
• Any of the following prior therapies:
  • Chemotherapy <4 weeks prior to registration;
  • Targeted biologic therapy<4 weeks prior to registration;
  • Immunotherapy <4 weeks prior to registration ;
  • Any viral or gene therapy prior to registration ;
  • External beam radiotherapy <4 weeks prior to registration.
  • NOTE: Vaginal brachytherapy may be performed at any time prior to registration.
• New York Heart Association classification III or IV, known symptomatic coronary artery disease, or symptoms of coronary artery disease on systems review, or uncontrolled current cardiac arrhythmias (atrial fibrillation or supraventricular tachycardia(SVT)).
• Active CNS disorder or seizure disorder or known CNS disease or neurologic symptomatology.
• HIV positive test result or other immunodeficiency or immunosuppression.
• History of hepatitis B or C or chronic hepatitis.
• Other concurrent chemotherapy, immunotherapy, radiotherapy, or any ancillary therapy considered investigational (used for a non-FDA approved indication and in the context of a research investigation).
• Treatment with oral/systemic corticosteroids, with the exception of topical or inhaled steroids.
• Exposure to household contacts ≤15 months old or household contact with known immunodeficiency.
• Any of the following because this study involves an investigational agent whose genotoxic, mutagenic and teratogenic effects on the developing fetus and newborn are unknown:
  • Pregnant persons or persons of reproductive ability who are unwilling to use effective contraception;
  • Nursing persons.
• Any other pathology or condition that the principal investigator deems to negatively impact treatment safety.
• Any immunotherapy-related adverse events CTCAE >Grade 1 at the time of registration.
• Receipt of a live virus vaccine ≤ 2 months prior to registration.