PTCy-based GvHD prophylaxis following MMUD peripheral blood stem cell transplantation: Results from the phase II ACCESS trial

The ongoing phase II ACCESS trial (NCT04904588) is assessing the impact of post-transplant cyclophosphamide (PTCy)-based graft-versus-host disease (GvHD) prophylaxis on overall survival (OS) in adult and pediatric patients with hematological malignancies undergoing a mismatched unrelated donor (MMUD) transplantation.¹ Results from the first 70 adult patients who received reduced-intensity condition (RIC) MMUD peripheral blood stem cell (PBSC) transplantation were presented during the European Hematology Association (EHA) 2024 Hybrid Congress by Jimenez.¹ Results were compared with the phase II 15-MMUD trial (NCT02793544) of RIC MMUD bone marrow transplantation with PTCy prophylaxis.¹

In the phase II ACCESS trial, with a median follow-up of 12.1 months, the 1-year OS rate was 79% and was not impacted by match grade (7/8 vs <7/8; p = 0.580); this was similar to the 1-year OS rates in the 15-MMUD trial (RIC cohort, 79%; overall, 76%).

The 1-year GvHD-free, relapse-free survival and non-relapse mortality rates were 51% and 13%, respectively. 

The rates of acute GvHD Grade III–IV and moderate/severe chronic GvHD were 9% for both. 

With comparable OS rates to bone marrow transplantation and comparable GvHD rates to matched donor transplantation, these results suggest that RIC MMUD PBSC transplantation with PTCy-based GvHD prophylaxis could expand access to HSCT for patients with hematological malignancies without a matched donor available.