Gemtuzumab ozogamicin (GO) combined with standard of care (SOC) chemotherapy (daunorubicin/cytarabine) is approved for newly diagnosed patients (pts) with CD33+ acute myeloid leukaemia (AML) based in part on data from the phase 3 ALFA-0701 trial (NCT00927498) of GO+SOC vs SOC in this population. We evaluated the cost-effectiveness of GO+SOC vs SOC alone for de novo AML with a UK National Health Service (NHS) and Personal Social Services perspective.
We used pt-level outcomes (response rates, relapse-free/overall survival [RFS/OS], hematopoietic stem-cell transplants [HSCTs] and adverse events [AEs]), from ALFA-0701 to inform the analysis. The base-case population was a subgroup that had a clear benefit with GO addition and excluded patients with unfavourable cytogenetics; analyses of the overall study population were also conducted. Cost data were taken from UK NHS 2016 reference costs and the literature; utility data were sourced from the literature. Long-term RFS/OS projections (pts entering with primary complete remission [CR], primary induction failure or relapse) for GO+SOC vs SOC were used to generate individual transitions in a lifetime cohort state-transition model. To capture statistical cure rates associated with AML, parametric and more complex models (flexible-spline and mixture cure models [MCMs]) were explored. MCMs provided the best fit and most reliable projections and were selected as the base-case analysis.
In the base-case deterministic analysis, higher per-pt costs (£135,545 vs £122,088) and greater life-years (LYs; 7.24 vs 5.93) and quality-adjusted LYs (QALYs; 5.29 vs 4.30) gained were seen with GO+SOC vs SOC. The incremental cost-effectiveness ratio (ICER) was £10,240/LY and £13,561/QALY gained. Higher costs of GO+SOC were mainly attributable to drug acquisition; costsavings were seen from relapse prevention and fewer HSCTs (Table). Mean probabilistic ICER was £17,956 (95% confidence interval [CI] £16,481–19,631). In the overall population, there were also higher per-pt costs (£132,245 vs £117,472) and greater LYs (6.17 vs 5.28) and QALYs (4.51 vs 3.83) gained with GO+SOC vs SOC, with an ICER of £16,492/LY and £21,819/QALY gained; mean probabilistic ICER was £23,825 (95% CI £21,530–26,568). At a willingness-to-pay threshold of £30,000/QALY gained, the probability that GO was cost-effective was 70% in the base-case analysis and 57% in the overall population.
Increased costs of adding GO to SOC were partially offset by improved outcomes. GO+SOC is a cost-effective first-line treatment option for the subgroup of pts with AML excluding those with unfavourable cytogenetics.
