Establishing practical predictors of collection efficiency for optimized chimeric antigen receptor T-cell apheresis

Chimeric antigen receptor (CAR) T-cell therapy requires autologous T-cell collection via leukapheresis. Although several parameters are thought to influence optimal apheresis, no consensus exists. Collection efficiency is central to this process, yet reliable predictors remain undefined. We aimed to identify collection efficiency (CE2) predictors to support standardized approaches to apheresis optimization.

We retrospectively analyzed apheresis procedures and related data for Tisagenlecleucel (Kymriah) manufacturing between August 2022 and June 2025 at Asan Medical Center. Data included patients' diagnoses, laboratory results of pre-apheresis peripheral blood sample and collection bag sample, and procedural parameters. Pearson correlation, generalized linear model, univariate logistic regression, and stepwise multivariate logistic regression and were performed to identify CE2 predictors.

Eighty-two apheresis procedures were performed in 75 adult patients (median age, 60.5 years; range, 19-86). Most were diagnosed with diffuse large B-cell lymphoma (n = 71). Mean processed blood volume was 12.2 L, equivalent to 3.1 times total blood volume. Mean CE2 was 68.9% (range, 10.6-150.4). CE2 showed significant negative correlations with log-transformed white blood cell count (WBC), CD3 count, total blood volume (TBV) × CD3, and lymphocyte count. In univariate regression, log-transformed WBC, neutrophil count, TBV × CD3, and CD3 count were inversely associated with high CE2. In multivariate analysis, log-transformed WBC was independently associated with decreased odds of high CE2, consistent with association with low CE. (OR = 0.416, p = 0.0339).

CE2 during CAR-T apheresis is strongly influenced by pre-apheresis hematologic parameters, particularly WBC. Establishing CE2 predictors may refine estimation of processing volumes and improve planning for centers initiating CAR-T manufacturing.