As chimeric antigen receptor T (CAR-T) cell therapy targeting CD19 has shown favorable outcomes in patients with relapsed or refractory (r/r) mature B-cell lymphomas and B-cell acute lymphoblastic leukemia (B-ALL), the number of patients who are waiting to receive these treatments is increasing. Optimized protocols for T-cell collection by lymphapheresis for chimeric antigen receptor (CAR) -T cell therapy must be urgently established to provide CAR-T cell therapy for patients with refractory and progressive disease, and/or a low number of lymphocytes due to prior chemotherapies. Predicted collection efficiency of CD3 cells in apheresis can guide protocols for apheresis, but a clinically applicable model to produce reliable estimates has not been established yet. Therefore, we prospectively analyzed lymphapheresis procedures for tisagenlecleucel therapy at two centers. A total of 108 apheresis procedures included 20 procedures for patients with B-cell acute lymphoblastic leukemia, and 88 for patients with diffuse large B-cell lymphoma, with a median age at apheresis of 58 years (1-71). After lymphapheresis with a median processing blood volume of 10 L (3-16), a median of 3.2 × 10 (0.1-15.0) CD3 cells were harvested. Collection efficiency 2 (CE2) for CD3 cells was highly variable (median, 59.3%; range 11.0-199.8). Multivariate analyses revealed that lower Hgb levels, higher circulating CD3 cell counts, and higher platelet counts before apheresis significantly decreased apheresis CE2. Based on multivariate analyses, we developed a novel formula that estimates CE2 from pre-collection parameters with high accuracy (r = 0.56, p < 0.01), which also suggests the necessary processing blood volume. Our strategy in lymphapheresis should be helpful to reduce collection failure, as well as to achieve efficient utilization of medical resources in clinical practice, thereby delivering CAR-T cell therapy to more patients in a timely manner.
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