Deferred Cytoreductive Nephrectomy in Synchronous Metastatic Renal Cell Carcinoma: The NORDIC-SUN-Trial

Inclusion Criteria: 1. Signed written informed consent obtained prior to any study specific procedures. 2. Patient must be willing and able to comply with the protocol. 3. Age ≥18. 4. Core needle biopsy proven metastatic renal cell carcinoma - all histologic subtypes acceptable. 5. Synchronous metastatic renal cell carcinoma with the primary tumor present in the kidney. 6. Measurable disease as per RECIST v 1.1 7. Patients for which Nivolumab/Ipilimumab or a TKI/IO-combination is considered indicated according to the recommendations by the European Medicines Agency and the national health authorities of participating countries. The prescription of nivolumab/ipilimumab or a TKI/IO-combination in the circumstances of the study is considered as a standard treatment. 8. Females with a negative serum pregnancy test unless childbearing potential can be otherwise excluded (postmenopausal, hysterectomy or oophorectomy) and not lactating. 9. Fertile women of childbearing potential (\<2 years after last menstruation) and men must use effective means of contraception (oral contraceptives, intrauterine contraceptive device, barrier method of contraception in conjunction with spermicidal jelly or surgical sterilization). 10. Karnofsky Performance status ≥70 11. Life expectancy of greater than 4 months. 12. The required laboratory values are as follows: * Adequate bone marrow function (Leucocytes \> 3.0 x 109/l, platelets \> 100 x 109/l, hemoglobin \> 6.0 mmol/l or \> 10.0 g/dL.) * International normalized ratio (INR) ≤ 1.2 x upper limit of normal (ULN) * Adequate hepatic function (bilirubin ≤ 1.5 x ULN, ALAT ≤ 2.5 x ULN or ≤ 5 x ULN if liver lesions) * Adequate kidney function (eGFR \> 35 mL/min) Exclusion Criteria: 1. Prior systemic treatment for mRCC 2. Other cancer within 3 years (except in situ basal cell carcinoma and localised prostate cancer with undetectable PSA). 3. Major surgical procedure, open surgical biopsy, or significant traumatic injury within 28 days prior to enrollment 4. Clinically significant (i.e active) cardiovascular disease for example cerebrovascular accidents (\< 6 months before inclusion), myocardial infarction (\< 6 months before inclusion), unstable angina, New York Heart Association (NYHA) grade II or greater congestive heart failure. 5. No symptomatic brain metastasis requiring systemic corticosteroids (\> 10 mg daily prednisone equivalent) 6. Recent (within the 30 days prior to inclusion) treatment with another investigational drug or participation in another investigational study. 7. Any active or recent history of a known or suspected autoimmune disease or recent history of a condition that require systemic corticosteroids (\> 10 mg daily prednisone equivalent) or other immunosuppressive medications, excluding inhaled steroids and topical steroids. Subjects with vitiligo or type I diabetes mellitus or residual hypothyroidism due to autoimmune thyroiditis only requiring hormone replacement, psoriasis not requiring systemic treatment are permitted to enroll. 8. Known hypersensitivity to monoclonal antibodies. 9. Known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS). 10. Any positive test for hepatitis B- or C-Virus indicating acute or chronic infection. 11. Oral or i.v. antibiotics administered 14 days prior to initiation of systemic therapy.