Biogen Advances felzartamab Program with Phase 3 TRANSCEND Trial for Late Kidney Transplant Rejection

Biogen has officially begun enrolling patients in the TRANSCEND Phase 3 clinical study, marking a pivotal moment in developing felzartamab as a potential first-in-class treatment for late antibody-mediated rejection (AMR) in kidney transplant recipients. The global trial will evaluate how felzartamab performs against placebo in approximately 120 adult patients facing this serious post-transplant complication.

The Clinical Challenge: Why This Matters

Kidney transplant rejection remains one of the leading threats to transplant success. Late AMR—occurring more than 6 months after transplantation—accounts for a substantial portion of transplant failures in the United States, with around 23,000 patients currently living with various forms of AMR. What makes late AMR particularly challenging is the limited number of effective treatment options available today. When a transplanted kidney begins to fail due to rejection, both the patient and the original donor face devastating consequences.

How felzartamab Works

The investigational drug targets CD38, a protein present on mature plasma cells—the immune cells responsible for producing the antibodies that attack the transplanted organ. By selectively depleting these CD38+ plasma cells and reducing NK cell activity, felzartamab addresses two key mechanisms driving microvascular inflammation (MVI) and rejection. MVI itself is a critical indicator of transplant damage, with higher scores strongly correlating to worse long-term kidney survival rates.

TRANSCEND Trial Design and Timeline

The 52-week study is structured in two distinct phases. In Part A (months 0-6), participants receive nine intravenous doses of either felzartamab or placebo, with efficacy assessed at 24 weeks. The primary endpoint measures whether patients achieve biopsy-confirmed resolution of AMR by month 6. Secondary endpoints track changes in MVI scores and the percentage of patients reaching an MVI score of zero—indicators of immune stabilization.

Part B extends the trial through week 52, with all participants receiving open-label felzartamab to assess longer-term safety and tolerability. This two-part design allows researchers to gather both immediate efficacy data and extended safety information.

Encouraging Preliminary Evidence

The Phase 2 results demonstrating felzartamab’s potential have provided the foundation for this Phase 3 expansion. According to researchers involved in the trial, the compound shows promise as a disease-modifying therapy—meaning it may not just manage symptoms but alter the underlying rejection process itself.

Broader Pipeline Expansion

Beyond the AMR program, Biogen plans to initiate Phase 3 trials of felzartamab in two additional kidney diseases in 2025: IgA nephropathy and primary membranous nephropathy. This portfolio expansion reflects confidence in felzartamab’s broader therapeutic potential across immune-mediated kidney conditions.

Financial Developments

As part of the Phase 3 activation, MorphoSys (now operating under Novartis following its acquisition in May 2024) will receive a one-time milestone payment of $35 million from Biogen. Biogen acquired the exclusive rights to develop and commercialize felzartamab through its purchase of Human Immunology Biosciences in July 2024.

What’s Next

The TRANSCEND trial represents a critical juncture for felzartamab’s clinical validation. For the transplant community, successful results could introduce a meaningful new option for patients facing late AMR—a condition that currently has few effective interventions. Enrollment is now underway across global sites, with results expected to inform regulatory discussions in the coming years.