• Cohorts A and B: Histologically or cytologically confirmed advanced RCC with any clear cell or non-clear cell component. 100% sarcomatoid is permissible.

• Cohorts A and B: Patient may have had any number of prior therapies for Cohort A, but for Cohort B patients must not have received any systemic therapy in the metastatic setting

• Patients who have received prior (neo)adjuvant immunotherapy with pembrolizumab or similar are eligible for Cohort B IF they completed the adjuvant therapy \> 12 months from start of trial therapy

• Treatment naïve patients may be treated in Cohort A if deemed not candidates for nivolumab or if felt single agent cabozantinib most appropriate by the treating clinician

• Cohort C: Well differentiated NET, grades 1-3 (any primary site) who have progressed on or are not eligible for somatostatin analogs per treating physician discretion

• Cohort C: Disease progression within prior 12 months

• Cohort C: Prior or concurrent treatment with somatostatin analogue allowed but no limit on lines of therapy (stable dose of somatostatin for 2 months)

∙ All Cohorts:

• At least one measurable lesion as defined by RECIST version 1.1

• No evidence of pre-existing uncontrolled hypertension as assessed by investigator. Patients may undergo adjustments or additions to their antihypertensive regimen before or during screening to achieve optimal BP control.

• Age \> 18 years.

• ECOG performance status 0 - 2

• Patients must have normal organ and marrow function as defined below

‣ Leukocytes, \> 2,000/mcL

⁃ Absolute neutrophil count, \> 1,500/mcL

⁃ Platelets, \> 100,000/mcL

⁃ Hgb, \> 9 g/dL (\>90 g/L)

⁃ Total bilirubin, ≤ 1.5 x ULN (with the exception of of individuals with Gilberts syndrome who may have a bilirubin \<3.0 mg/dL)

⁃ AST/ALT (SGOT/SGPT)/ALP, \< 3 x ULN ALP ≤ 5x ULN with documented bone metastases.

⁃ Albumin, \> 2.8 g/dL

⁃ Creatinine clearance, \> 30 Ml/min/1.73 m2 for patients with creatinine levels above institutional normal

⁃ PT/INR or PTT, \< 1.3 x the laboratory ULN

• Ability to understand and willingness to sign a written informed consent and HIPAA consent document

• Sexually active fertile subjects 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 4 months after the last dose of study treatment