Cost-Effectiveness of Maintaining Higher Stem-Cell Collection Thresholds in the Chimeric Antigen Receptor T-Cell Era...

Prolonged cytopenias are a common complication after chimeric antigen receptor (CAR) T-cell therapy for multiple myeloma, increasing the risk of severe infection. Infusion of previously collected autologous stem cells may mitigate this risk, but the clinical and economic implications of proactive collection remain uncertain.

We developed an 8-year, monthly cycle Markov model simulating 10,000 patients undergoing CAR T therapy. Two strategies were compared: (1) no stem-cell boost and (2) availability of a boost for patients with prolonged cytopenias. Transition probabilities for neutropenia, infection, and infection-related mortality were derived from CARTITUDE-4 and published stem-cell boost reports. Costs included hospitalizations for severe infection and upfront stem-cell reserve collection. Deterministic and probabilistic sensitivity analyses were performed.

In the base case, universal reserve collection reduced severe infections from approximately 650 to approximately 260 per 10,000 patients and averted approximately 50 infection-related deaths. However, average per-patient costs were higher in the boost arm (approximately $19,700 US dollars [USD] v $4,500 USD), reflecting a gross reserve collection cost of $17,918 USD per patient plus lower residual infection-related hospitalization costs. Survival outcomes were similar between arms, with relapse-related mortality dominating long-term outcomes. Sensitivity analyses confirmed robustness, with hospitalization cost and reserve collection cost identified as the most influential parameters.

Proactive stem-cell collection for CAR T recipients reduces infectious complications and modestly improves infection-related survival but remains economically unfavorable when applied universally. A risk-adapted approach targeting patients at highest risk of prolonged cytopenias may better balance clinical benefit with cost-effectiveness.