ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATION FOR PERIPHERAL T‐CELL LYMPHOMA: COMPARABLE OUTCOMES OF HAPLO‐IDENTICAL VS. MATCHED DONORS. A CIBMTR & EBMT ANALYSIS

Abstract

Introduction: The advent of immunosuppression with post-transplant cyclophosphamide (ptCY) has facilitated allogeneic hematopoietic cell transplantation (alloHCT) from haplo-identical donors in patients lacking a matched donor. The aim of this study was to compare the outcomes of ptCY haplo-identical transplantation (haploHCT) with that of alloHCT from matched sibling donors (msdHCT), matched unrelated donors with in-vivo T-cell depletion (mudHCT-TCD), and matched unrelated donors without T-cell depletion (mudHCT-TRD) in patients with peripheral T-cell lymphoma (PTCL). Methods: Eligible for this retrospective registry study were patients aged 18 or older who had undergone alloHCT for anaplastic large cell lymphoma(ALCL), angioimmunoblastic T-cell lymphoma (AITL), or PTCL-not other specified (PTCL-NOS) from the 4 donor types described between 2008 and 2018 and were registered with the CIBMTR or the EBMT. Co-primary endpoints were overall survival (OS) and progression-free survival (PFS); secondary endpoints included engraftment, acute and chronic GVHD, non-relapse mortality (NRM), and relapse/progression incidence (RI). Results: Altogether 1942 patients were eligible (haploHCT 237; msdHCT 911; mudHCT-TCD 468; mudHCT-TRD 326). HaploHCT and matched aloHCT recipients were comparable for histology, age, gender, comorbidity score, pretreatment lines, prior autoHCT, and disease status at HCT. However, haploHCT patients were more likely to have a Karnofsky score of 90-100, and had more often received reduced intensity conditioning as well as bone marrow grafts (31% vs 6%). On univariate and multivariate comparisons, OS and PFS, RI, and NRM were not significantly different between haploHCT, msdHCT, mudHCT-TCD, and mudHCT-TRD with 3-year estimates for OS and PFS of 60%, 63%, 59%, and 64; and 50%, 50%, 48%, and 52%, respectively. Engraftment was significantly delayed after haploHCT (neutrophils >0.5/nl at d +28 86% vs 95%, 94%, 97%, respectively, p < 0.001; platelets >20/nl at d +100 80% vs 96%, 93%, 96%, respectively, p < 0.001). Whilst risk of acute GVHD was comparable between haploHCT, msdHCT, and mudHCT-TCD, there was a lower 1-year cumulative incidence of chronic GVHD after haploHCT (28% vs 41%, 35%, and54%; p < 0.001); retaining significance after multivariate adjustment for confounders. Factors significantly impairing both OS and PFS on multivariate analysis were advanced disease status at alloHCT, age >50, and poor Karnofsky score. Patients undergoing alloHCT in 1st line had significantly better OS than patients allografted later. Conclusions: These data, the largest study to date, confirm that alloHCT can result in durable PFS in a sizable proportion of patients with ALCL, AITL, and PTCL-NOS. The outcome of haploHCT in PTCL is comparable to that of matched donor alloHCT, suggesting that haploHCT might be a valid alternative in this setting. Keywords: Stem Cell Transplant Conflicts of interests pertinent to the abstract P. Dreger Consultant or advisory role: Gilead, Novartis, BMS, Bluebird Bio, Takeda