[Clinical experience of leukapheresis for CD19 CAR-T cell therapy]

To perform chimeric antigen receptor T (CAR-T) cell therapy in heavily pretreated patients with progressive disease and depleted lymphocytes, an optimized leukapheresis protocol must be established. To probe the effects of patient-related parameters on the collection efficiency of CD3⁺ cells, we retrospectively analyzed patients with relapsed/refractory diffuse large B-cell lymphoma who underwent leukapheresis for tisagenlecleucel at two centers. A total of 51 patients were analyzed, with a median age at apheresis of 59 years, and precollection hemoglobin levels, CD3⁺ cell counts, and platelet counts of 9.2 g/dl, 574/µl, and 15.8×10⁴/µl, respectively. A median of 3.0×10⁹ (0.7-8.4) CD3⁺ cells were harvested with 8.7 (4.0-15.7) l apheresis volume. The collection efficiency 2 (CE2) for CD3⁺ cells was 61.0% (21.0-127.3). One-day apheresis was sufficient to obtain the designated cell numbers in all cases. Lower hemoglobin levels, higher CD3⁺ cell counts, and higher platelet counts before apheresis were significantly associated with lower CE2 for CD3⁺ cells. These results suggest a need to increase the apheresis volume in anemic, lymphocyte- or platelet-rich patients due to an expected low CE2. Erythrocyte transfusions before or during apheresis may be a reasonable option for patients with anemia.