Evaluation of cell collection efficiency in non-mobilized adult donors for autologous chimeric antigen receptor T-cell manufacturing.

Background And Objectives: Data about collection efficiency 1 (CE1), which takes into account blood cell counts before and after collection, thus providing a more accurate estimate, in the collection of autologous T lymphocytes by apheresis for chimeric antigen receptor (CAR) T-cells remain scarce. We evaluated donor- and procedure-related characteristics that might influence the CE1 of lymphocytes.

Materials And Methods: We retrospectively reviewed all mononuclear cell (MNC) collections) performed for CAR T-cell manufacturing in our institution from May 2017 to June 2021 in adult patients. Age, gender, weight, total blood volume (TBV), prior haematopoietic cell transplant, diagnosis, days between last treatment and apheresis, pre-collection cell counts, duration of apheresis, TBV processed, vascular access, inlet flow and device type were analysed as potential factors affecting CE1 of lymphocytes.

Results: A total of 127 autologous MNC collections were performed on 118 patients diagnosed with acute lymphoblastic leukaemia (n = 53, 45%), non-Hodgkin lymphoma (n = 40, 34%), multiple myeloma (n = 19, 16%), and chronic lymphocytic leukaemia (n = 6, 5%). The median CE1 of lymphocytes was 47% (interquartile range: 32%-65%). In multiple regression analysis, Amicus device was associated with higher CE1 of lymphocytes (p = 0.01) and lower CE1 of platelets (p < 0.01) when compared with Optia device.

Conclusion: The knowledge of the MNC and lymphocyte CE1 of each apheresis device used to collect cells for CAR T therapy, together with the goal of the number of cells required, is essential to define the volume to be processed and to ensure the success of the collection.