PCN179 TREOSULFAN-BASED CONDITIONING VS BUSULFAN-BASED CONDITIONING FOR ALLOGENEIC HAEMATOPOIETIC STEM CELL TRANSPLANTATION IN PATIENTS WITH AML OR MDS — A UK COST-UTILITY ANALYSIS

Abstract

Cost-utility analyses comparing alternative conditioning regimens for patients undergoing allogeneic haematopoietic stem cell transplantation (alloHSCT) have not previously been conducted. A cost-utility analysis was developed to compare a treosulfan and fludarabine conditioning regimen (Tr-Fl) versus busulfan with fludarabine based conditioning (Bu-Fl) prior to alloHSCT, for patients with acute myeloid leukaemia (AML) or myelodysplastic syndrome (MDS) considered ineligible to receive standard conditioning regimens. A partitioned survival model was developed to compare Tr-Fl with Bu-Fl from a UK National Health Service and Personal Social Services perspective. Patients started in the induction/alloHSCT health state, before transitioning to alloHSCT recovery (remission), relapse/progression and death after the first model cycle. Data on patient characteristics, overall survival (OS), event-free survival (EFS) and adverse events were collected from a head to head phase III clinical trial. OS and EFS were extrapolated beyond the trial duration using parametric survival models. A functional cure assumption was applied at 5 years based on clinical expert opinion, with subsequent mortality defined using a hazard ratio for long-term post-HSCT patients applied to UK life table data. Utilities and mapping algorithms were identified through systematic and targeted literature review and were adjusted for age and sex using a published model for general population utility. Costs of treatment, adverse events, inpatient/outpatient care, and mortality were included in the analysis. Tr-Fl dominated Bu-Fl, with incremental quality-adjusted life-years (QALYs) and costs of 0.78 and -£17,689, respectively. Probabilistic sensitivity analysis indicated that Tr-FL had an 94.1% probability of cost-effectiveness at a £30,000 per QALY threshold. Tr-Fl also dominated Bu-Fl for each indication subgroup, with incremental QALYs of 0.71 and 1.03 and incremental costs of -£24,138 and -£2,570 for AML and MDS, respectively. Tr-Fl is a highly cost-effective conditioning treatment for alloHSCT patients with AML or MDS ineligible for standard conditioning regimens, compared with Bu-Fl.