Cost-Effectiveness of KTE-X19 for Adults with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia in the United States

Introduction Despite currently available treatments for adults with relapsed/refractory acute lymphoblastic leukemia (R/R ALL), survival outcomes remain poor, highlighting the need for new therapeutic strategies. This study estimates the cost-effectiveness of KTE-X19 to treat adults with R/R ALL from a US payer perspective. Methods The model had two components: a decision-tree, where pre-infusion costs for patients who ultimately did not receive KTE-X19 are accounted for, followed by a partitioned survival analysis, where all KTE-X19 infused patients would enter the three-state (pre-progression, progressed disease, death) model. Comparators included current standard of care treatments, i.e., blinatumomab (BLIN), inotuzumab ozogamicin (INO), and salvage chemotherapy (CHEMO). Both standard parametric and mixture cure models were used to model survival. Efficacy, safety, healthcare resource utilization, and health state utility inputs were derived from the ZUMA-3 trial (NCT02614066) and literature. Cost inputs were derived from literature or publicly available sources. Outcomes and costs were discounted 3% annually. Results of KTE-X19 versus comparators are reported as total and incremental life-years (LYs), quality-adjusted life-years (QALYs), costs, and resulting incremental cost-effectiveness ratio (ICER). Deterministic and probabilistic sensitivity analyses (PSA) and key scenario analyses were also performed. Results In the base case, incremental QALYs for KTE-X19 were 2.44, 3.26, and 4.61 versus BLIN, INO, and CHEMO, respectively. Incremental costs were $50,913, $251,532, and $432,027, respectively, resulting in ICERs of $20,843/QALY (versus BLIN), $77,271/QALY (versus INO), and $93,768/QALY (versus CHEMO). Deterministic sensitivity analysis results were most sensitive to subsequent allogeneic stem cell transplant rates and post-progression utilities. PSA found that KTE-X19 is 78.4%, 74.0%, and 75.4% likely to be cost-effective versus BLIN, INO, and CHEMO, respectively. Across most scenarios, at a willingness-to-pay (WTP) threshold of $150,000/QALY, KTE-X19 was cost-effective versus all treatments. Conclusions Compared to current options for adults with R/R ALL, KTE-X19 is cost-effective, driven primarily by improved survival.