Kidney Week

Abstract: INFO18-TH

TRANSPIRE: A Phase 2 Trial Evaluating the Efficacy and Safety of Felzartamab in Kidney Transplant Recipients with Late Isolated Microvascular Inflammation

Session Information

• Informational Posters - 1
  November 06, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• No subcategory defined

Authors

• Bohmig, Georg, Medical University of Vienna, Vienna, Austria

Georg Bohmig, MD

• Budde, Klemens, Charité Universitätsmedizin Berlin, Berlin, Germany

Klemens Budde, MD

• Cibrik, Diane Marie, University of Kansas Medical Center, Kansas City, Kansas, United States

Diane Marie Cibrik, MD

• Schinstock, Carrie A., Mayo Clinic, Rochester, Minnesota, United States

Carrie A. Schinstock, MD

• Mengel, Michael, University of Alberta, Edmonton, Alberta, Canada

Michael Mengel, MD

• Reed, Elaine F., University of California, Los Angeles, California, United States

Elaine F. Reed, PhD

• Butts, Cherie, Biogen, South San Francisco, California, United States

Cherie Butts

• Ingle, Gordon R., Biogen, South San Francisco, California, United States

Gordon R. Ingle

• Ju, Chia-Hsin, Biogen, South San Francisco, California, United States

Chia-Hsin Ju

• Kivman, Lisa, Biogen, South San Francisco, California, United States

Lisa Kivman

• Lam, Edwin, Biogen, South San Francisco, California, United States

Edwin Lam

• Manser, Paul, Biogen, South San Francisco, California, United States

Paul Manser

• Patel, Uptal D., Biogen, South San Francisco, California, United States

Uptal D. Patel, MD

• Mannon, Roslyn B., University of Nebraska Medical Center, Omaha, Nebraska, United States

Roslyn B. Mannon, MD, FASN

Description

Microvascular inflammation (MVI), the hallmark of antibody-mediated rejection (AMR) in kidney allografts, is a key predictor of disease progression and graft failure. Isolated MVI, with no evidence of donor-specific antibodies (DSA) or C4d deposition, is recognized as a distinct phenotype within the Banff 2022 MVI/AMR category. Felzartamab, a fully human IgG1 monoclonal antibody targeting CD38, has previously been shown to reduce CD38⁺ natural killer (NK) cells, which may drive both DSA-dependent and -independent MVI and subsequent graft injury.

TRANSPIRE is a randomized, double-blind, placebo-controlled, multicenter, Phase 2 study investigating the efficacy and safety of felzartamab in kidney transplant recipients with late (≥6 months after transplantation) isolated MVI without detectable DSA. Approximately 81 adults with biopsy-confirmed, late isolated MVI will be randomized to felzartamab or placebo in cohorts stratified by C4d status (positive or negative). This 52-week study consists of Part A (24 weeks, placebo-controlled) where participants receive IV felzartamab or placebo and Part B (28 weeks, open-label felzartamab) during which all participants receive IV felzartamab. Kidney biopsy histology, biopsy-based transcript molecular signatures, and donor-derived cell-free DNA (dd-cfDNA) levels will be assessed at baseline, Week 24, and Week 52. The primary endpoint for Part A is the percentage of participants who achieve biopsy-proven histologic resolution at Week 24. Secondary endpoints include changes in MVI score and estimated glomerular filtration rate. Exploratory endpoints include changes in dd-cfDNA and biopsy-based transcript composite score. Safety will be assessed throughout the study.

TRANSPIRE is the first clinical trial designed to investigate a targeted therapy in kidney transplant recipients with late isolated MVI.

Funding

• This study was sponsored by Biogen.