Abstract: FR-PO1212
B-Cell Maturation Antigen-Targeted Therapy Enables HLA-Incompatible Combined Haploidentical Stem-Cell and Kidney Transplantation
Session Information
- Transplantation: Clinical - Rejection, Biomarkers, and Pharmacology
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2002 Transplantation: Clinical
Authors
- Safa, Kassem, Mass General Brigham Inc, Boston, Massachusetts, United States
- Riella, Leonardo V., Mass General Brigham Inc, Boston, Massachusetts, United States
- Yee, Andrew J., Mass General Brigham Inc, Boston, Massachusetts, United States
- Pattanayak, Vikram, Mass General Brigham Inc, Boston, Massachusetts, United States
- Chen, Yi-Bin, Mass General Brigham Inc, Boston, Massachusetts, United States
Introduction
Anti–HLA donor-specific antibodies (DSAs) remain a major barrier to solid organ transplantation. Conventional desensitization strategies often provide only transient reductions in antibody levels and are frequently followed by rebound and rejection. B-cell maturation antigen (BCMA)–targeted therapies, developed for multiple myeloma, offer a novel and effective desensitization approach.
Case Description
A 64-year-old woman presented in early 2022 with constitutional symptoms. A bone marrow biopsy confirmed multiple myeloma, and kidney biopsy demonstrated kappa light chain cast nephropathy. Despite treatment with daratumumab, bortezomib, dexamethasone, and lenalidomide, she progressed to ESKD by July 2022.
She continued daratumumab-based therapy into 2023 in addition to venetoclax, achieving a 90% reduction in light chains. Evaluation for combined peripheral blood stem cell (PBSC) and kidney transplantation (KT) from a haploidentical daughter was pursued; however, high levels of anti-HLA DSAs precluded transplantation. Therapy was transitioned to elranatamab, an anti-BCMA bispecific antibody, to deepen myeloma response and reduce DSAs. This resulted in the resolution of light chains and DSAs (from 11,100 and 4,600 MFI to <1,000 MFI).
Following this, she underwent conditioning and combined PBSC–KT. The kidney graft functioned immediately, and hematopoietic engraftment occurred with full donor chimerism. Mild acute cutaneous graft-versus-host disease developed but resolved with steroids and ruxolitinib. At 9 months, kidney function remained stable, DSAs were undetectable, and myeloma remained in remission.
Discussion
BCMA-directed agents, unlike conventional approaches, eliminate both malignant and normal plasma cells and reduce the precursor B-cell pool, resulting in sustained suppression of antibody production. The marked, durable reduction in DSAs after elranatamab enabled successful KT that was previously not feasible. This case highlights the potential of BCMA-targeted therapy in desensitization to overcome HLA incompatibility in highly sensitized candidates waiting for a transplant.
Timeline from the diagnosis of multiple myeloma, the combined kidney and stem cell transplant, and 9 months post-transplant.