Cabozantinib and Dostarlimab in Recurrent Gynecologic Carcinosarcoma

Inclusion Criteria: 1. Histologically confirmed diagnosis of carcinosarcoma (independent of organ of gynecologic origin) 2. Received at least one prior chemotherapy regimen for their cancer 3. Must have measurable or evaluable lesion defined by iRECIST 4. Recovery to baseline or ≤ Grade 1 CTCAE v5.0 from toxicities related to any prior treatments, unless AE(s) are clinically nonsignificant and/or stable on supportive therapy 5. ECOG Performance Status of 0-2 6. Age ≥ 18 years 7. Adequate organ and marrow function, based upon meeting all of the following laboratory criteria within 14 days before first dose of study treatment: 1. Absolute neutrophil count (ANC) ≥ 1500/mm3 (≥ 1.5 GI/L) without granulocyte colony-stimulating factor support. 2. White blood cell count ≥ 2500/mm3 (≥ 2.5 GI/L). 3. Platelets ≥ 100,000/mm3 (≥ 100 GI/L) without transfusion. 4. Hemoglobin ≥ 9 g/dL (≥ 90 g/L). 5. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) ≤ 3 x upper limit of normal (ULN). ALP ≤ 5 x ULN with documented bone metastases. 6. Total bilirubin ≤ 1.5 x ULN (for patients with Gilbert's disease ≤ 3 x ULN). 7. Serum albumin ≥ 2.8 g/dl. 8. Serum creatinine ≤ 2.0 x ULN or calculated creatinine clearance ≥ 30 mL/min (≥ 0.5 mL/sec) using the Cockcroft-Gault equation: \[(140 - age) x weight (kg)/(serum creatinine \[mg/dL\] × 72)\] × 0.85 i. Urine protein/creatinine ratio (UPCR) ≤ 1 mg/mg (≤ 113.2 mg/mmol). 8. Capable of understanding and complying with the protocol requirements and must have signed the informed consent document. 9. Women of childbearing potential (WOCBP) ie. sexually active fertile patients and their partners must agree to use medically accepted methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the course of the study and for 5 months after the last dose of study treatment. 10. Females should not breastfeed while receiving treatment on trial. 11. Female patients of childbearing potential must not be pregnant at screening. Females of childbearing potential are defined as premenopausal females capable of becoming pregnant (i.e., females who have had any evidence of menses in the past 12 months, with the exception of those who had a prior hysterectomy). However, women who have been amenorrheic for 12 or more months are still considered to be of childbearing potential if the amenorrhea is possibly due to prior chemotherapy, antiestrogens, low body weight, ovarian suppression, or other reasons. Exclusion Criteria: 1. Prior treatment with cabozantinib. 2. Receipt of any type of small molecule kinase inhibitor (including investigational kinase inhibitor) within 2 weeks or 5 half-lives (whichever is longer) before first dose of study treatment. 3. Receipt of any type of cytotoxic, biologic, or other systemic anticancer therapy (including investigational) within 4 weeks before first dose of study treatment. 4. Radiation therapy for bone metastasis within 2 weeks, any other radiation therapy within 4 weeks before first dose of study treatment. Systemic treatment with radionuclides within 6 weeks before the first dose of study treatment. Patients with clinically relevant ongoing complications from prior radiation therapy are not eligible. 5. Known brain metastases or cranial epidural disease unless adequately treated with radiotherapy and/or surgery (including radiosurgery) and stable for at least 4 weeks before first dose of study treatment. Eligible patients must be neurologically asymptomatic and without corticosteroid treatment at the time of first dose of study treatment. 6. Concomitant anticoagulation with coumarin agents (e.g., warfarin), direct thrombin inhibitors (e.g., dabigatran), direct factor Xa inhibitor betrixabin, or platelet inhibitors (e.g., clopidogrel). Allowed anticoagulants are the following: 1. Prophylactic use of low-dose aspirin for cardio-protection (per local applicable guidelines) and low-dose low molecular weight heparins (LMWH). 2. Therapeutic doses of LMWH or anticoagulation with direct factor Xa inhibitors rivaroxaban, edoxaban, or apixaban in subjects without known brain metastases who are on a stable dose of the anticoagulant for at least 1 week before first dose of study treatment without clinically significant hemorrhagic complications from the anticoagulation regimen or the tumor. 7. The patient has prothrombin time (PT)/INR or partial thromboplastin time (PTT) test ≥ 1.3 X the laboratory ULN within 7 days before the first dose of study treatment. 8. The patient has uncontrolled, significant intercurrent or recent illness including, but not limited to, the following conditions: a. Cardiovascular disorders: i. Congestive heart failure New York Heart Association Class 3 or 4, unstable angina pectoris, serious cardiac arrhythmias. ii. Uncontrolled hypertension defined as sustained blood pressure (BP) \> 140 mm Hg systolic or \> 90 mm Hg diastolic despite optimal antihypertensive treatment. iii. Stroke (including transient ischemic attack \[TIA\]), myocardial infarction (MI), or other ischemic event, or thromboembolic event (e.g., deep venous thrombosis, pulmonary embolism) within 6 months before first dose. b. Gastrointestinal (GI) disorders including those associated with a high risk of perforation or fistula formation: i. The patient has evidence of tumor invading the GI tract, active peptic ulcer disease, inflammatory bowel disease (e.g., Crohn's disease), diverticulitis, cholecystitis, symptomatic cholangitis or appendicitis, acute pancreatitis, acute obstruction of the pancreatic duct or common bile duct, or gastric outlet obstruction. ii. Abdominal fistula, GI perforation, bowel obstruction, or intra-abdominal abscess within 6 months before first dose. Note: Complete healing of an intra-abdominal abscess must be confirmed before first dose. c. Clinically significant hematur