Work

Outcome Following CD34-Selected Stem Cell Boost for Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplant: A Single Institution Experience

Year: 2025

Type: article

Abstract: Background Poor graft function is a life-threatening complication following allogeneic hematopoietic stem cell transplantation (SCT) that occurs in 5-27% of patients and is associated with high morbidity and mortality. CD34 + -selected mobilized peripheral blood stem and progenitor cells without conditioning is used for poor graft function. The CliniMACS System (Miltenyi Biotec, Auburn, CA) is a FDA-approved Humanitarian Use Device for processing hematopoietic progenitor cells to obtain a CD34 + enriched population for use in the treatment of patients with acute myeloid leukemia in first morphologic complete remission and has also been widely used to provide CD34 + enriched grafts for other purposes. Here we describe our institutional experience performing CD34 + -selected stem cell boosts (SCB) using cells obtained from this device. Methods We conducted a single-institution, retrospective cohort review of adult patients who have undergone treatment of CD34 + -selected SCB for poor graft function after allogeneic SCT between September 2020 and September 2024 at Washington University School of Medicine. CD34 + cell selection was performed using the CliniMACS Cell Selection System. The primary objective was hematologic response rate with complete response (CR) defined as absolute neutrophil count above 2500 /μL, hemoglobin above 8.0 g/dL without transfusions, and platelet count sustained above 150,000 /μL; and partial response defined as meeting some but not all the CR criteria. Secondary objectives included transfusion independence at 30 and 60 days after SCB, incidence and severity of acute and chronic GVHD , overall survival (OS), and relapse-free survival (RFS). Results 79 patients had CD34 + -selected SCB for poor graft function. 62% were male. Median age was 59 years [1 st to 3 rd quartile: 49-64]. Median time between SCT and SCB was 105 days [61-164]. 4 pts (5%) received donor lymphocytes along with CD34 + -selected SCB for mixed chimerism or overt relapse. The overall response rate (ORR) was 75% (31% CR, 44% PR) for the 72 patients evaluable for response. The median time to response was 13 days for neutrophiles [7-24], 37 days for hemoglobin [15-63], and 25 days for platelets [14-52]. 46% and 62% of patients were transfusion independent of red blood cells at 30 and 60 days after SCB, respectively, while 58% and 63% were transfusion independent of platelets.10 patients (14%) died from disease relapse and the median OS was 12 months. Conclusions CD34 + -selected SCB without conditioning represents an effective treatment of poor graft function after allogeneic SCT . With ORR of 75%, 31% pts achieved a CR with >50% of transfusion independence by day-60.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.jtct.2025.01.103