Blinatumomab Is Cost-Effective Compared to Standard Chemotherapy for Children with High Risk Relapses of Acute Lymphoblastic Leukemia: A Cost-Effectiveness Analysis Using Population-Based Healthcare Data

Introduction: Though cure rates for childhood acute lymphoblastic leukemia (ALL) have improved significantly, outcomes for children with relapsed ALL remain poor. Novel immunotherapies have proved effective in relapsed disease. Blinatumomab, a bispecific T-cell engager targeting CD19, was recently shown to improve disease-free and overall survival among children with high-risk relapsed disease (Brown et al, 2021) prior to proceeding to stem cell transplant. Blinatumomab however also represents a significant cost burden to institutions and healthcare systems. Our objective was thus to determine the cost-effectiveness of blinatumomab vs. standard of care therapy among children with high-risk relapsed ALL.

Methods: We used a childhood ALL-specific policy simulation model previously developed using real world clinical, healthcare utilization, and cost population-based data from Ontario, Canada, and restricted it to children with B-lineage ALL who relapsed with 18 months of their original diagnosis to capture a population of patients with high-risk relapse who survived their original month of re-induction chemotherapy. This model was combined with published data from the Children's Oncology Group randomized control study AALL1331 to estimate the long-term survival, healthcare costs and quality adjusted life years associated with two courses of blinatumomab vs. two courses of standard intensive chemotherapy, followed by stem cell transplant. Combining these two sources allowed for the creation of a multi-state survival model and the estimation of the impact of blinatumomab upon relapse and survival. Healthcare costs for the administration of blinatumomab or chemotherapy were sourced from administrative data, provincial formularies, and published sources. Lifetime costs and quality-adjusted life years were calculated while Monte Carlo simulation was used to propagate parameter uncertainty in the cost-effectiveness outcomes. All costs were calculated in Canadian dollars (CAD).

Results: Blinatumomab was associated with on average higher life expectancy (43.4 years vs. 36.8 years) and a higher number of quality adjust life years [2.75 QALYs gained, 95 ^th confidence interval (95CI) -0.44 to 5.99] but higher costs (60,420 CAD, 95CI 26,794 - 94,047) compared to standard intensive chemotherapy. The incremental cost effectiveness ratio (ICER) associated with blinatumomab was 21,970 CAD/QALY gained. However, substantial uncertainty around model parameters resulted in wide confidence intervals around cost-effectiveness outcomes.

Discussion: Initial evidence indicates that the use of blinatumomab in high-risk relapse of childhood ALL as compared to standard chemotherapy is associated with a cost-effectiveness ratio that is comparable to or lower than that associated with other interventions recently introduced in pediatric ALL, and represents a cost-effective intervention for this population. However, estimates are based on limited evidence; further research is necessary to better inform several model parameters and thereby decrease uncertainty in cost-effectiveness outcomes.