OBJECTIVE:The main objective was to use discrete event simulation (DES) to model the impact of wait-time, defined as the time between leukapheresis and chimeric antigen receptor (CAR-T) infusion, when assessing the cost-effectiveness of tisagenlecleucel in young patients with relapsed/refractory acute lymphoblastic leukaemia.
METHODS:The movement of patients through the model was determined by parametric time-to-event distributions, with the competing risk of an event determining the costs and quality adjusted life years (QALYs) assigned. Cost-effectiveness was expressed using the incremental cost-effectiveness ratio (ICER) for tisagenlecleucel compared with chemotherapy over the lifetime.
RESULTS:The base-case generated a total of 5.79 QALYs and $622,872 for tisagenlecleucel and 1.19 QALYs and $181,219 for blinatumomab, resulting in an ICER of $96,074 per QALY. An increase in mean CAR-T wait-time to 6.20 months reduced the benefit and costs of tisagenlecleucel to 2.78 QALYs and $294,478 due to fewer patients proceeding to infusion, reducing the ICER to $71,112 per QALY. Alternatively, when the cost of tisagenlecleucel was assigned pre-infusion in sensitivity analysis, the ICER increased with increasing wait-time.
CONCLUSION:Under a payment arrangement where CAR-T cost is incurred post-infusion, the loss of benefit to patients is not reflected in the ICER. This may be misguiding to decision-makers, where cost-effectiveness ratios are used to guide resource allocation. DES is an important tool for economic modelling of CAR-T as it is amenable to capturing the impact of wait-time, facilitating better understanding of factors affecting service delivery and consequently informed decision-making to deliver faster access to CAR-T for patients.