Allogeneic Hematopoietic Stem Cell Transplantation in Multiple Myeloma: A Case Series
Materials and Methods/Case Presentation/Objective:
Case 1 is a 56-year-old female diagnosed with MM on November 5, 2024, after severe back pain. She received eight cycles of bortezomib, lenalidomide, and dexamethasone, followed by four weekly doses of daratumumab. She achieved complete response, confirmed by bone marrow biopsy on February 3, 2025. She underwent full matched related allo-HSCT on June 24, 2025 and engrafted on Day +14. She developed mild chronic skin GVHD on Day +106, controlled with oral corticosteroids. Serum free light chain (SFLC) assay in June 2026 was negative for monoclonal free light chain.
Case 2 is a 54-year-old female with IgG kappa MM treated with bortezomib, cyclophosphamide, and dexamethasone in March 2022. She underwent haploidentical allo-HSCT in June 2022, complicated by HLA antibody-mediated graft rejection with autologous recovery. She subsequently received bortezomib-dexamethasone maintenance but relapsed and progressed on further therapy. She achieved complete response after daratumumab-pomalidomide-dexamethasone, which was confirmed by bone marrow aspiration on July 13, 2025. She underwent a full matched related second allo-HSCT on July 31, 2025, engrafted on Day +11, and had no GVHD. SFLC in July 2026 was negative for monoclonal free light chain.
Case 3 is a 47-year-old female presenting with back pain, anemia, renal dysfunction, lytic bone disease, and a left pleural wall mass. Diagnosis was established on March 3, 2021 by ultrasound-guided biopsy of the chest wall mass showing round cell malignancy with plasmacytoid features; immunostains were CD138-positive with lambda light chain restriction. She refused bone marrow biopsy but was treated as MM given the plasmacytic tumor, lytic disease, renal dysfunction, anemia, and lambda SFLC of 3230 mg/L. She received bortezomib, cyclophosphamide, and dexamethasone, with lambda SFLC decreasing to 17.5 mg/L and resolution of the chest mass and renal dysfunction. She underwent haploidentical allo-HSCT on November 3, 2021 and engrafted on Day +14. On Day +212, she developed moderate chronic skin and liver GVHD, controlled with oral corticosteroids. SFLC in May 2026 was negative for monoclonal free light chain.
Results/Description/Main Outcome Measure(s): Cases 1 and 2 received fludarabine 40 mg/m² for four days, melphalan 100 mg/m², total body irradiation 2 Gy, post-transplant cyclophosphamide 40 mg/kg, tacrolimus, and mycophenolate mofetil. Case 3 received fludarabine 30 mg/m² for five days, cyclophosphamide, total body irradiation 2 Gy, post-transplant cyclophosphamide 50 mg/kg, tacrolimus, and mycophenolate mofetil. All engrafted by Day +11 to +14; two developed moderate chronic GVHD responsive to oral corticosteroids. All had negative monoclonal SFLC on the latest 2026 follow-up, and are currently in remission.
Conclusion(s).: In selected MM patients, allo-HSCT may achieve timely engraftment and sustained serologic disease control, despite renal dysfunction, relapse, and prior graft rejection. Longer follow-up is needed to define durability, GVHD burden, survival, and the role of allo-HSCT in the modern myeloma era.
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