A Study to Learn About the Effects of Felzartamab Infusions in Adults With Kidney Transplants Who Have Late Isolated Microvascular Inflammation

The primary objective of the study is to evaluate the efficacy of felzartamab compared to placebo in kidney transplant recipients in Cohort 1 (Part A). The secondary objectives of the study are to evaluate the efficacy of felzartamab compared to placebo through additional clinical endpoints (Part A), summarize efficacy of felzartamab up to Week 52 in kidney transplant recipients in Cohorts 1 and 2 (Part B); evaluate safety of felzartamab in kidney transplant recipients in Cohorts 1 and 2 (Parts A and B) and to assess the pharmacokinetic (PK) profile and immunogenicity of felzartamab (Parts A and B).

• Felzartamab (Drug), also known as MOR202, MOR03087, TJ202, HIB202, BIIB148: Administered IV
• Placebo (Drug): Administered IV

Primary outcomes

• Part A: Percentage of Participants Who Achieve Biopsy-proven Histologic Resolution (BPHR) [Week 24]

Secondary outcomes

• Part A: Microvascular Inflammation (MVI) Score [Week 24]
• Part A: Percentage of Participants Who Achieve an MVI Score of 0 [Week 24]
• Part A: Change from Baseline in Estimated Glomerular Filtration Rate (eGFR) [Baseline, Week 24]
• Part A: Percentage of Participants in Cohort 2 Who Achieve BPHR [Week 24]
• Part B: Percentage of Participants Who Achieve BPHR [Weeks 24 and 52]
• Part B: MVI Score [Weeks 24 and 52]
• Part B: Percentage of Participants Who Achieve an MVI Score of 0 [Weeks 24 and 52]
• Part B: Change from Baseline in eGFR [Baseline, Weeks 24 and 52]
• Part B: Time to All-cause Allograft Loss [Up to Week 52]
• Parts A and B: Number of Participants with Adverse Events (AEs) [From first dose of study drug up to end of study follow-up (up to week 57)]
• Parts A and B: Percentage of Participants with T Cell-mediated Rejection (TCMR) by Biopsy [Weeks 24 and 52]
• Parts A and B: Number of Participants with Clinically Significant Laboratory Abnormalities [From time of first dose to end of trial visit (Up to Week 52)]
• Parts A and B: Number of Participants with Clinically Significant Vital Signs Abnormalities [From time of first dose to end of trial visit (Up to Week 52)]
• Parts A and B: Number of Participants with Clinically Significant Electrocardiogram (ECG) Abnormalities [From time of first dose to end of trial visit (Up to Week 52)]
• Parts A and B: Felzartamab Serum Concentration [Up to Week 52]
• Parts A and B: Number of Participants with Anti-drug Antibodies (ADAs) Against Felzartamab [Baseline, up to Week 52]

Sex: All, ages: 18 Years to 74 Years

Key Inclusion Criteria:

* MVI (MVI ≥2), donor specific antibody (DSA)-negative that is either complement activation (C4d) negative or C4d positive (biopsy-confirmed) without T cell-mediated rejection (TCMR) per central reading, as defined by the Banff 2022 criteria.
* Biopsy must be prior to randomization.
* For participants who received any prior treatment for antibody-mediated rejection (AMR) or MVI, the biopsy must be performed after completing (or stopping) prior treatment.
* Kidney transplant prior to Screening visit (recipients of either living or deceased donors).

Key Exclusion Criteria:

* Transplant: Blood type (ABO)-incompatible transplant.
* History of multiple organ transplants including en bloc and dual kidney transplants.
* Acute, rapid decline in renal function, defined as a participant likely to require renal replacement therapy within the next 30 days as determined by the Investigator.

Note: Other protocol-defined Inclusion/Exclusion criteria may apply.

• Medical Director, Study director, Biogen

NIH grants: 2025