Abstract: INFO22-TH
TRANSTELLAR: An Open-Label, Long-Term Extension Study of Felzartamab in Kidney Transplant Recipients with Antibody-Mediated Rejection or Microvascular Inflammation
Session Information
- Informational Posters - 1
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- No subcategory defined
Authors
- Budde, Klemens, Charité Universitätsmedizin Berlin, Berlin, Germany
- Bohmig, Georg, Medical University of Vienna, Vienna, Austria
- Cibrik, Diane Marie, University of Kansas Medical Center, Kansas City, Kansas, United States
- Schinstock, Carrie A., Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Mengel, Michael, University of Alberta, Edmonton, Alberta, Canada
- Reed, Elaine F., University of California, Los Angeles, Los Angeles, California, United States
- Ingle, Gordon R., Biogen, South San Francisco, California, United States
- Liverman, Rochelle, Biogen, South San Francisco, California, United States
- Helmi, Haytham, Biogen, South San Francisco, California, United States
- Ju, Chia-Hsin, Biogen, South San Francisco, California, United States
- Lam, Edwin, Biogen, South San Francisco, California, United States
- Holt, Curtis D., Biogen, South San Francisco, California, United States
- Manser, Paul, Biogen, South San Francisco, California, United States
- Kalapala, Sundeep, Biogen, South San Francisco, California, United States
- Patel, Uptal D., Biogen, South San Francisco, California, United States
- Mannon, Roslyn B., University of Nebraska Medical Center, Omaha, Nebraska, United States
Description
Microvascular inflammation (MVI) is a hallmark manifestation of antibody-mediated rejection (AMR), a major cause of kidney allograft failure in kidney transplant recipients. Felzartamab is a human monoclonal antibody targeting CD38+ plasmablasts, plasma cells, and NK cells, thereby targeting multiple cellular drivers of AMR and MVI. Two ongoing 52-week, randomized, double-blind, placebo-controlled, multicenter studies are assessing the efficacy and safety of felzartamab in kidney transplant recipients ≥6 months post-transplant. TRANSCEND (NCT06685757) is a Phase 3 trial in active or chronic active AMR, and TRANSPIRE (NCT07219043) is a Phase 2 trial in MVI without detectable donor-specific antibodies (C4d-negative or -positive).
TRANSTELLAR (TRANSCEND/TRANSPIRE LTE; NCT07444489) is an open-label long-term extension (LTE) study with rolling enrollment of participants who completed either TRANSCEND or TRANSPIRE (estimated enrollment: ≈201). Those who completed a Phase 2 investigator-initiated trial (EU-2024-511764-86-00) will be analyzed as part of a separate subprotocol. Participants who did not discontinue felzartamab (ongoing treatment) or who did not receive felzartamab at the Week 44 visit (treatment interrupted) in the parent studies will continue to receive felzartamab every 8 weeks in the LTE. Those who discontinued felzartamab in the parent studies or the LTE will continue to be followed up off treatment (Figure). The primary endpoint is the long-term safety of felzartamab (adverse events [AEs], serious AEs, AEs of special interest, AEs leading to treatment discontinuations, and clinically significant laboratory, vital signs, and electrocardiogram abnormalities). Secondary endpoints include the percentage of participants with biopsy-proven histologic resolution, MVI score, percentage of participants with an MVI score of 0, change from baseline in estimated glomerular filtration rate and proteinuria, time to all-cause and death-censored allograft loss, pharmacokinetics, and immunogenicity.
TRANSTELLAR will evaluate the long-term safety and durability of felzartamab, further informing its therapeutic potential in AMR and MVI.
Funding
- This study is sponsored by Biogen.