Comparable survival outcomes with haploidentical stem cell transplantation and cord blood transplantation

HLA-haploidentical stem cell transplantation using post-transplant cyclophosphamide (PTCy-haplo) and umbilical cord blood transplantation (UCBT) are alternative to HLA-matched stem cell transplantation. We conducted a matched-pair analysis of PTCy-haplo and UCBT using the Japanese registry data. We identified 136 patients aged between 16 and 69 years who received PTCy-haplo as their first transplantation for acute leukemia or myelodysplastic syndromes. Control group included 408 UCBT recipients selected to match the PTCy-haplo group. Overall and relapse-free survival probabilities at 2 years were comparable between the PTCy-haplo and UCBT groups: 55% vs. 53% for overall survival (p = 0.46), and 47% vs. 48% for relapse-free survival (p = 0.79), respectively. The cumulative incidence of relapse was significantly higher (43% vs. 29%, respectively, p = 0.006), while the cumulative incidence of non-relapse mortality (NRM) was significantly lower (9% vs. 23%, respectively, p < 0.001) in the PTCy-haplo group. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) was lower in the PTCy-haplo group compared to the UCBT group (29% vs. 41%, respectively, p = 0.016), while those of grade III-IV acute GVHD and chronic GVHD were not statistically different between the two groups. Our results suggest that both PTCy-haplo and UCBT are viable alternatives to HLA-matched stem cell transplantation.