Allogeneic stem cell transplantation for mantle cell lymphoma can achieve durable remission and myeloablative conditioning is associated with inferior survival: an Australian and New Zealand Transplant & Cellular Therapies registry study

BACKGROUND: Allogeneic stem cell transplantation (AlloSCT) has established curative potential in mantle cell lymphoma (MCL). As therapies for MCL evolve, outcomes with AlloSCT require reassessment. AIM: This study aimed to report the outcomes of AlloSCT for MCL across Australia and New Zealand. METHODS: Data were collected through the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) for all patients undergoing AlloSCT for MCL between January 2009 and December 2019. RESULTS: Forty-six patients underwent AlloSCT for MCL between 2009 and 2014 and 40 between 2015 and 2019. The median patient age was 56 years (range 32-72), nine of 15 patients tested (60%) had TP53 mutation, and 14% of patients underwent myeloablative conditioning (MAC). A higher proportion of patients in the 2015-2019 period were BTKi-exposed (68% vs. 0%, P = 0.00). Non-relapse mortality (NRM) at 1 year and 5 years was 23% (95% confidence interval (95% CI) 14-32) and 31% (95% CI 21-42) respectively. The 100-day cumulative incidence of grade II to IV acute graft-versus-host disease (GVHD) was 21% (95% CI 13-30), and the 3-year cumulative incidence of chronic GVHD was 31% (95% CI 22-41). At 5 years, overall survival (OS) was 48% (95% CI 36-59) and progression free survival (PFS) was 38% (95% CI 27-50). The use of MAC was independently associated with inferior PFS (hazard ratio [HR] 2.33, 95% CI 1.05-5.17, P = 0.038) and OS (HR 3.11, 95% CI 1.39-7.00, P = 0.006). There was no difference in outcomes for patients transplanted between 2009 and 2014 versus 2015 and 2019. CONCLUSION: AlloSCT can achieve durable remissions for MCL in the modern era, and the use of MAC is associated with inferior outcomes.