Felzartamab in Late Antibody-Mediated Rejection

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 intensi…