Post-Transplant Cyclophosphamide (PTCy)-Based Haploidentical (Haplo) Donor Vs. Calcineurin-Inhibitor (CNI)-Based Matched Related Donor (MRD) Reduced-Intensity Conditioning (RIC) Allogeneic Hematopoietic Cell Transplantation (alloHCT) for Classical Hodgkin Lymphoma (cHL)

Abstract

Introduction Classical HL patients with relapsed or refractory disease may benefit from alloHCT, but many will be heavily pre-treated and not eligible for myeloablative conditioning and/or may not have an available MRD graft source. Herein, we compare the outcomes of two RIC-HCT platforms in cHL: haplo-PTCy-based approaches compared to MRD/CNI-based approaches. Methods Using CIBMTR registry, included are 596 adult patients who underwent first alloHCT for cHL between 2008-2016, using RIC with either haplo/PTCy-based (n=139) or MRD/CNI-based (n=457) approaches. The primary endpoint was overall survival (OS). Secondary endpoints included acute (a) and chronic (c) GVHD, non-relapse mortality (NRM), relapse/progression and progression-free survival (PFS). Results Baseline characteristics are shown in Figure 1. On multivariate analysis, haplo/PTCy was associated with significantly higher risk of grade 2-4 aGVHD (odds ratio [OR] 1.73, 95% CI 1.16-2.59, p=0.01), but the risk of grade 3-4 aGVHD was not significantly different between the two cohorts (OR 0.61, 95% CI 0.29-1.27, p=0.19). The haplo/PTCy platform showed a significant reduction in cGVHD (hazard ratio [HR] 0.45, 95% CI 0.32-0.64, p Conclusion Haplo/PTCy-based approaches are associated with lower incidence of cGVHD and relapse, with PFS and OS outcomes comparable to MRD/CNI-based approaches. These data support that haplo/PTCy-based approaches can result in outcomes for cHL patients that are equivalent to MRD/CNI-based approaches and that HCT should be considered for patients with relapsed/refractory cHL regardless of donor options. Novel approaches to promote immune reconstitution, mitigate organ toxicity, and decrease post-HCT relapse risk may improve outcomes.