Donor Age as an Independent Predictor of Inferior Outcomes After Haploidentical Hematopoietic Cell Transplantation in Acute Myeloid Leukemia. Study Conducted on Behalf of GETH-TC

Daniel Munárriz¹Estefanía Pérez-López²Carlos Martín Rodríguez²Marta Luque³Albert Esquirol⁴Carmen Martín⁵Clara Aparicio Pérez⁵Felipe Peña-Muñóz⁶Inmaculada Heras⁷Itziar Oiartzabal Ormtegi⁸Adolfo Jesús Sáez-Marín⁹Sara Fernández-Luis¹⁰Juan José Domínguez-García¹⁰Sara Villar Fernandez¹¹Jose Luis Lopez Lorenzo¹²Cynthia Acosta Fleitas¹³Ana Pilar Gonzalez-Rodriguez¹⁴Lucía García¹⁵Tamara Torrado¹⁶Silvia Filaferro¹⁷Pascual Balsalobre¹⁷María Jesús Pascual Cascon³Montserrat Rovira¹Maria Queralt Salas^1,18*Maria Queralt Salas^1,18*

• ¹Hospital Clinic of Barcelona, Barcelona, Spain
• ²Hospital Universitario de Salamanca, Salamanca, Spain
• ³Hospital Regional Universitario de Malaga, Málaga, Spain
• ⁴Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
• ⁵Hospital Universitario Reina Sofia, Córdoba, Spain
• ⁶Institut Catala d'Oncologia, L'Hospitalet de Llobregat, Spain
• ⁷Hospital General Universitario Jose M Morales Meseguer, Murcia, Spain
• ⁸Hospital Universitario de Donostia, San Sebastián, Spain
• ⁹Hospital Universitario 12 de Octubre servicio de Hematologia y Hemoterapia, Madrid, Spain
• ¹⁰Hospital Universitario Marques de Valdecilla, Santander, Spain
• ¹¹Clinica Universidad de Navarra, Pamplona, Spain
• ¹²Hospital Universitario Fundacion Jimenez Diaz, Madrid, Spain
• ¹³Hospital Universitario de Gran Canaria Dr Negrin, Las Palmas de Gran Canaria, Spain
• ¹⁴Hospital Universitario Central de Asturias, Oviedo, Spain
• ¹⁵Hospital Universitario Son Espases, Palma, Spain
• ¹⁶Complexo Hospitalario Universitario A Coruna, A Coruña, Spain
• ¹⁷Grupo Espanol de Trasplante Hematopoyetico y Terapia Celular, Madrid, Spain
• ¹⁸Universitat de Barcelona, Barcelona, Spain

This study evaluated the impact of donor age on clinical outcomes in 274 patients with acute myeloid leukemia (AML) haplo-HCT using PTCY-based prophylaxis. Median patient age was 53 years, with 42.6% classified as high-risk AML. The median donor age of 38 years; 31% were under 30. An optimal donor age cut-off of 30 years was identified through ROC analysis. Patients receiving grafts from younger donors (<30 years) showed lower rates of aGVHD grade II–IV (3.0% vs. 19.9%, p < 0.001) and grade III–IV (1.5% vs. 10.2%, p = 0.034), with no differences in cGVHD or relapse rates. Overall survival (OS) was higher in the younger donor group (2-year: 80.6% vs. 64.3%, p = 0.011), along by lower non-relapse mortality (NRM) (2-year: 11.1% vs. 23.2%, p = 0.031). Multivariate analysis confirmed donor age ≥30 years as an independent adverse factor for OS (HR: 1.88, p = 0.019) and NRM (HR: 2.06, p = 0.049), along with older recipient age, higher HCT-CI score, and high-risk AML. These findings suggest that younger donor age contributes to improved survival, primarily through reduced NRM and aGVHD, supporting prioritization of younger donors when multiple haploidentical options are available to optimize transplant outcomes.