Safety, Tolerability and Efficacy of AntiBKV as Treatment of BKV Infection in Kidney Transplant Recipients (SAFE KIDNEY II)

Inclusion Criteria: Male or female aged 18 years or older Kidney transplantation within 24 months prior to enrollment Kidney transplant recipient with first-time BK viremia (evaluated during routine clinical monitoring by the local laboratory and acknowledged by a physician within 35 days prior to day 1). BK viremia either defined by BK virus (BKV)-DNAemia of >1,000 copies/mL sustained for three weeks (confirmed by 2 consecutive measurements 3 weeks apart), or one time >10,000 copies/mL) Kidney transplant recipients with adequate and/or stable allograft function as indicated by estimated glomerular filtration rate ((e)GFR) ≥ 30 mL/min Female subjects (if of childbearing potential) must agree to use adequate and reliable contraceptive measures throughout their participation in the trial. Contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies Ability to provide written informed consent Exclusion Criteria: Patients with previous diagnosis of BK viremia (defined as >1,000 copies/mL sustained for three weeks (confirmed by 2 consecutive measurements 3 weeks apart), or one time >10,000 copies/mL since last kidney transplant Known hypersensitivity to any component of the investigational medicinal product (IMP) Participants with combined or multi-organ transplants Transplanted kidney disease with an estimated glomerular filtration rate ((e)GFR) < 30 mL/minute at screening Uncontrolled acute or chronic infection other than BK virus (BKV) infection at screening which might interfere with study participation at the discretion of the investigator Recipients who are treated or planned to be treated with a mammalian Target of Rapamycin (mTOR) inhibitor or belatacept as part of their immunosuppression regimen post-transplantation at the time of enrollment and during the study period. Recipients who are treated or planned to be treated during study participation with leflunomide at the time of enrollment and during the study period. Recipients who in the opinion of the investigator are likely to require antibody-depletion therapy during trial participation. Antibody-depleting therapies include but are not necessarily limited to plasmapheresis, immunoadsorption, and intravenous immunoglobulins (IVIg) Recipients with kidney transplant rejection or focal segmental glomerulosclerosis (FSGS) shown by renal biopsy Recipients who have medical conditions that prevent the recipient from undergoing allograft biopsy due to chronic anticoagulation or antiplatelet agents (except for low dose aspirin) Recipients with known donor-specific antibodies (DSA) (de novo or pre-transplantation). Kidney transplant recipients with low-level pretransplant DSAs (<1000 mean fluorescence intensity (MFI) can be includred if no impact on the study assessments is expected by the discretion of the investigator Recipients who are receiving a monoclonal antibody treatment for another indication (e.g. rituximab, infliximab etc.) Recipients with extremely high BK virus (BKV)-DNAemia (>10,000,000 copies/mL) or hemorrhagic cystitis Recipients who in the opinion of the investigator are likely to develop recurrent native kidney disease (e.g. immunoglobulin A [IgA] nephritis, focal segmental glomerulosclerosis [FSGS], C3 glomerulonephritis) Recipients with a functionally significant ureteral stricture Pregnant or nursing (lactating) women Current clinical, radiographic, or laboratory evidence of active or latent tuberculosis (TB) or any history, in the opinion of the investigator, that confers a risk of reactivation of latent tuberculosis (TB) and precludes the use of conventional immunosuppression History of splenectomy or asplenia Any condition, that in the opinion of the investigator, would interfere with the evaluation of the investigational product or interpretation of the participant safety data or study results History of malignancy within the past 5 years, except completely excised basal cell or squamous cell carcinoma of the skin, or cervical carcinoma in situ at least 2 years prior to screening Participation in another interventional clinical trial during trial participation or within 30 days prior to the investigational medicinal product (IMP) dosing or planned dosing History of alcoholism or drug addiction within 1 year of screening. Substance use disorder will be an exclusion criterion, at investigators discretion