B-Cell Acute Lymphoblastic Leukemia: Donor Matters in Allogeneic Stem Cell Transplant Outcomes of Hispanic Patients

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.2241-2241
• Main Authors: Ashouri, Karam, Hom, Brian, Chu, Mollee, Hwang, Jennifer, Resnick, Karen, Rahimi, Yekta, Ireland, Robert, Ginosyan, Anush Aram, Bragasin, Eljie Isaak, Chaudhary, Preet M., Woan, Karrune, Siddiqi, Imran, Ladha, Abdullah, Ali, Amir, Yaghmour, George
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-190541

Introduction: Hematopoietic stem cell transplantation (HSCT) improves long term overall survival (OS) and disease-free survival (DFS) in those with intermediate or high-risk B- cell ALL. Historically, matched related donors were the ideal choice, but with improved GVHD prophylactic regimens and supportive care, haploidentical donors are being increasingly used. Due to their increased graft-versus-leukemia (GVL) effect, they may be an option for Hispanic patients, for whom matched donation may be more challenging. Methods: This is a retrospective chart review of B- cell ALL patients that received allogeneic HSCT at Norris Comprehensive Cancer Center (NCCC) from 2012 to 2023. Mismatch-unrelated donors were excluded. For OS, DFS, and cumulative incidence of relapse (CIR), match sibling donors (MSD) and match unrelated donors (MUD) were grouped. However, for GVHD outcomes including graft-versus-host disease (GVHD)-free relapse-free survival (GRFS), incidence of grade 3-4 acute GVHD (aGVHD), and incidence of severe chronic GVHD (cGVHD) requiring immunosuppression MSD and MUD were separated. Incidence outcomes were evaluated using competing risk regression (Fine-Gray method), with death as a competing outcome, while survival outcomes were analyzed using Cox proportional hazards model. Results: One hundred eighteen B- cell ALL patients were included with a median age at transplant of 43 years (range: 21-69). Donor types included 46 (40.0%) MSD, 45 (38.1%) haploidentical, and 27 (22.9%) MUD. Most were Hispanic (N= 92, 78.0%) and our median follow-up time was 23.6 months. The majority of patients achieved CR1 (N=79, 66.9%) and MRD negativity by flow (N=106, 89.8%), pre-transplant. The 3-year OS and DFS for the cohort were 82.1% (95% CI 73.8-91.3%) and 66.2% (95% CI 57.2-76.6%), respectively, while the CR1 subgroup was 90.5% (95% CI 83.3-98.3%) and 77.1% (95% CI 67.8-87.7%) respectively. When compared to haploidentical HSCT, patients who received matched donors had significantly worse CIR (HR = 2.42; 95% CI 1.06-5.51; P = 0.036) and DFS (HR = 2.14; 95% CI 1.03-4.44; P = 0.041), along with a non-significant trend towards worse OS (HR = 2.54; 95% CI 0.83-7.80; P=0.10). Additionally, pretransplant minimal residual disease (MRD) positivity demonstrated worse OS (HR = 5.01; 95% CI 1.73-14.5; P = 0.003), DFS (HR = 3.25; 95% CI 1.48-7.16; P = 0.003), and CIR (HR = 2.05; 95% CI 0.78-5.39; P = 0.15). The 1-year GRFS, 1-year incidence of severe cGVHD, and 100-day incidence of