A Systematic Review of Health Technology Assessments of Chimeric Antigen Receptor T-Cell Therapies in Young Compared With Older Patients.

OBJECTIVES

The objective of this review was to identify sources of variability in cost-effectiveness analyses of chimeric antigen receptor T-cell (CAR-T) therapies, tisagenlecleucel and axicabtagene ciloleucel, evaluated by health technology assessment (HTA) agencies, focusing on young compared with older patients.

METHODS

HTA evaluations in pediatric acute lymphoblastic leukemia (ALL) and adult diffuse large B-cell lymphoma (DLBCL) were included from Australia, Canada, England, Norway, and the United States. Key clinical evidence, economic approach, and outcomes (costs, quality-adjusted life-years [QALYs] and incremental cost-effectiveness ratios) were summarized.

RESULTS

Fourteen HTA evaluations were identified (5 ALL, 9 DLBCL [4 tisagenlecleucel, 5 axicabtagene]). Analyses were naive comparisons of prospective single-arm studies for the CAR-Ts with retrospective cohort studies for the comparators. Key clinical evidence and economic model approaches were generally consistent by CAR-T and indication, although outcomes varied. Notably, incremental QALYs varied substantially in ALL (3.67-10.6 QALYs gained), whereas variation in DLBCL was less (1.21-1.97 [tisagenlecleucel], 1.97-3.40 [axicabtagene]). Discounting of costs and outcomes varied, with the highest QALYs generated for tisagenlecleucel in ALL (10.95) associated with the lowest discount rate (1.5%) and vice versa (4.97 QALYs; 5% discount rate). The approach to extrapolation of overall survival data varied, even where the same empirical data were used.

CONCLUSION

Modeled, long-term treatment benefit in young patients may be associated with greater uncertainty compared with adults because of potential life-long benefits with cell and gene therapies. This reflects the methodological challenges identified by HTA agencies associated with single-arm, short-term studies.