Inclusion Criteria:  Voluntary written informed consent Age >18 years (maximum: 80 years) Functioning living or deceased donor allograft after ≥180 days post-transplantation eGFR ≥20 ml/min/1.73 m2 (CKD-EPI formula) HLA class I and/or II antigen-specific antibodies (preformed and/or de novo DSA). Active or chronic/active ABMR (±C4d in PTC) according to the Banff 2019 classification Molecular ABMR score (MMDx) ≥0.2  Exclusion Criteria:  Patients actively participating in another clinical trial Age ≤18 years Female subject is pregnant or lactating or not on adequate contraceptive therapy ABO-incompatible transplant Index biopsy results: T-cell-mediated rejection classified Banff grade ≥I De novo or recurrent severe thrombotic microangiopathy Polyoma virus nephropathy De novo or recurrent glomerulonephritis Acute rejection treatment ≤3 month before screening Previous treatment with other CD38 monoclonal antibodies (e.g. daratumumab) Previous treatment with other immunomodulatory monoclonal/polyclonal antibodies (e.g. CD20 Ab rituximab, IL-6/IL-6R Ab) ≤3 months before study treatment Total bilirubin >2×the upper limit of normal [ULN], alanine transaminase and aspartate aminotransferase >2·5×ULN Haemoglobin <8 g/dL Thrombocytopenia: Platelets <100 G/L Leukopenia: Leukocytes <3 G/L Neutropenia: Neutrophils < 1.5 G/L Hypogammaglobulinemia: Serum IgG <400 mg/dL Active viral, bacterial or fungal infection precluding intensified immunosuppression Active malignant disease precluding intensified immunosuppressive therapy Latent or active tuberculosis (positive QuantiFERON-TB-Gold test) Administration of a live vaccine within 6 weeks of screening History of alcohol or illicit substance abuse Serious medical or psychiatric illness likely to interfere with participation in the study