Inclusion Criteria:
1. The subject has a histologic or cytologic diagnosis of a variant histology renal cell carcinoma including papillary, chromophobe, Xp.11 translocation, undifferentiated, or unclassified which is treatment naïve or has previously been treated with one systemic treatment line not containing any vascular endothelial growth factor antibody or vascular endothelial growth factor receptor tyrosine kinase inhibitors. The patient may have received treatment with immune checkpoint therapy including nivolumab as a single agent or nivolumab plus ipilimumab in combination. Previous treatment with mammalian target of rapamycin agents such as temsirolimus or everolimus is acceptable.
2. Measurable disease per RECIST v1.1 as determined by the investigator.
3. The subject has had an assessment of all known disease sites eg, by computerized tomography (CT) scan, magnetic resonance imaging (MRI), bone scan as appropriate, within 28 days before the first dose of cabozantinib or sunitinib.
4. The subject is \>/=18 years old on the day of consent;
5. The subject has an Eastern Cooperative Oncology Group (ECOG) performance status of \</=2.
6. Recovery to baseline or \</= Grade 1 CTCAE v.4.0 from toxicities related to any prior treatments, unless AE(s) are clinically nonsignificant and/or stable on supportive therapy;
7. The subject has organ and marrow function and laboratory values as follows within 4 days before the first dose of cabozantinib or sunitinib: a.The ANC \>/= 1500/mm\^3 without colony stimulating factor support; b.White blood cell count \>/= 2500/mm\^3 (\>/= 2.5 GI/L). c.Platelets \>/=100,000/mm\^3; d.Hemoglobin \>/= 9 g/dL; e. Bilirubin \</= 1.5 x the ULN. For subjects with known Gilbert's disease, bilirubin \</= 3.0 mg/dL; f.Serum albumin \>/= 2.8 g/dl g.Serum creatinine \</= 2.0 X ULN or calculated creatinine clearance \>/= 30 mL/min (\>/= 0.5 mL/sec) using the Cockcroft-Gault equation: Males: (140 - age) x weight (kg)/(serum creatinine \[mg/dL\] × 72) Females: \[(140 - age) x weight (kg)/(serum creatinine \[mg/dL\] × 72)\] × 0.85 h.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. i.Urine protein/creatinine ratio (UPCR) \</= 1 mg/mg (\</= 113.2 mg/mmol);
8. The subject is capable of understanding and complying with the protocol requirements and has signed the informed consent document;
9. Sexually active subjects (men and women) must agree to use medically accepted barrier methods of contraception (eg, male or female condom) during the course of the study and for 4 months after the last dose of study drug(s), even if oral contraceptives are also used. All subjects of reproductive potential must agree to use both a barrier method and a second method of birth control during the course of the study and for 4 months after the last dose of study drug(s);
10. Female subjects of childbearing potential must not be pregnant at screening. Females of childbearing potential are defined as premenopausal females capable of becoming pregnant (ie, females who have had any evidence of menses in the past 12 months, with the exception of those who had 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. The subject has a variant histology that includes renal medullary carcinoma or collecting duct renal cell carcinoma. Any clear cell component in the tumor will lead to exclusion.
2. The subject has received any previous anti-angiogenic agent. Prior treatment with cabozantinib.
3. Radiation therapy for bone metastasis within 2 weeks, any other external radiation therapy within 4 weeks before the first dose of study treatment. Systemic treatment with radionuclides within 6 weeks before the first dose of study treatment. Subjects with clinically relevant ongoing complications from prior radiation therapy are not eligible;
4. The subject has received any other type of investigational agent within 28 days before the first dose of study treatment;
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 the first dose of study treatment. Eligible subjects must be neurologically asymptomatic and without corticosteroid treatment at the time of the start of study treatment;
6. Concomitant anticoagulation with oral anticoagulants (eg, warfarin, direct thrombin and Factor Xa inhibitors) or platelet inhibitors (eg, clopidogrel). Allowed anticoagulants are the following: o Low-dose aspirin for cardioprotection (per local applicable guidelines) is permitted. o Low-dose low molecular weight heparins (LMWH) are permitted. Anticoagulation with therapeutic doses of LMWH is allowed in subjects without known brain metastases who are on a stable dose of LMWH for at least 6 weeks before first dose of study treatment, and who have had no clinically significant hemorrhagic complications from the anticoagulation regimen or the tumor.
7. The subject has prothrombin time (PT)/INR or partial thromboplastin time (PTT) tes\>/=1.3 X the laboratory ULN within 7 days before the first dose of study treatment.
8. The subject has uncontrolled, significant intercurrent or recent illness including, but not limited to, the following conditions: Cardiovascular disorders: a.Congestive heart failure New York Heart Association Class 3 or 4, unstable angina pectoris, serious cardiac arrhythmias. b.Uncontrolled hypertension defined as sustained blood pressure (BP) \> 150 mm Hg systolic or \> 100 mm Hg diastolic despite optimal antihypertensive treatment. c.Stroke (including transient ischemic attack \[TIA\]), myocardial infarction (MI), or other ischemic event, or thromboembolic event (eg, deep venous thrombosis, pulmonary embolism) within 6 months before first dose.
9. Continuation of 8:Gastrointestinal (GI) disorders including those associated with a high risk of perforation or fistula formation: The subject has evidence of tumor invading the GI tract, active peptic ulcer disease, inflammatory bowel disease (eg, 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. Abdominal fistula, GI perforation, bowel obstruction, or intra-abdominal abscess within 6 months before first dose.
10. Continuation of 8: Clinically significant hematuria, hematemesis, or hemoptysis of \> 0.5 teaspoon (2.5 ml) of red blood, or other history of significant bleeding (eg, pulmonary hemorrhage) within 12 weeks before first dose. Cavitating pulmonary lesion(s) or known endotracheal or endobronchial disease manifestation. Lesions invading or encasing any major blood vessels. Other clinically significant disorders that would preclude safe study participation. Serious non-healing wound/ulcer/bone fracture. Uncompensated/symptomatic hypothyroidism. Moderate to severe hepatic impairment (Child-Pugh B or C).
11. Major surgery (eg, GI surgery, removal or biopsy of brain metastasis) within 8 weeks before first dose of study treatment. Complete wound healing from major surgery must have occurred 1 month before first dose and from minor surgery (eg, simple excision, tooth extraction) at least 10 days before first dose. Subjects with clinically relevant ongoing complications from prior surgery are not eligible.
12. Corrected QT interval calculated by the Fridericia formula (QTcF) \> 500 ms per electrocardiogram (ECG) within 28 days before first dose of study treatment
13. Pregnant or lactating females.
14. Inability to swallow tablets
15. Previously identified allergy or hypersensitivity to components of the study treatment formulations.
16. Diagnosis of another malignancy within 2 years before first dose of study treatment, except for superficial skin cancers, or localized, low grade tumors deemed cured and not treated with systemic therapy. Patients with Gleason 6 (3+3) prostate cancer with previous treatment or on active surveillance may also be allowed on protocol.
17. The subject requires chronic concomitant treatment with strong CYP3A4 inducers (eg, dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, rifapentine, phenobarbital, and St. John's Wort).
