Results from the prospective phase 2 multicentre <scp>UK PBSC</scp> haplo trial using <scp>PTCy</scp> pre‐ or post‐stem cells

This prospective phase 2 multicentre non-randomised parallel arm study of haploidentical peripheral blood stem cell (PBSC) transplantation with post-transplant cyclophosphamide (PTCy) recruited 77 patients: 50 received reduced-intensity conditioning (RIC) with PTCy post stem cell infusion while 27 underwent myeloablative conditioning (MAC) with PTCy given after lymphocyte but prior to infusion of CD34 selected stem cells. The primary end-point 1-year overall survival (OS) was 86% for RIC and 78% for MAC, meeting the pre-specified targets for efficacy. At 4 years, OS was 63% for RIC and 60% for MAC with low non-relapse mortality of RIC 18% and MAC 4%. Engraftment was faster in the MAC arm (median time to neutrophil and platelet engraftment 11 and 15 days; 21 and 24 days in the RIC arm). The economic analysis showed that MAC had higher initial transplant costs, RIC incurred greater post-transplant monitoring costs, resulting in higher overall costs (RIC £156 711, MAC £131 092). Quality of life (QoL) outcomes in both indicated significant post-transplant declines at 3 months but returned to baseline by 12 months. This study confirms the long-term safety of using PBSC with PTCy in haploidentical transplants, with a good quality of life and reasonable costs.