Factors affecting lymphocyte collection efficiency for the manufacture of chimeric antigen receptor T cells in adults with B-cell malignancies.

Background: The clinical and procedural parameters that affect the optimal collection of lymphocytes for the production of chimeric antigen receptor (CAR) T cells remain undefined but are increasingly important, as commercial products are now available. We evaluated determinants of low lymphocyte collection efficiency (CE) and the rate of successful CAR T-cell manufacture in middle-aged and older adults with advanced B-cell malignancies.

Study Designs And Methods: Mononuclear cell collections using two apheresis platforms (COBE Spectra and Spectra Optia, Terumo BCT) from patients participating in a CD19-directed CAR T-cell therapy trial were reviewed. Patient- and disease-specific factors, peripheral blood counts, apheresis parameters, and product cell counts were analyzed to determine effects on lymphocyte CE.

Results: Ninety-two apheresis events from patients with acute lymphocytic leukemia (ALL) (n = 28), chronic lymphocytic leukemia (n = 18), and non-Hodgkin lymphoma (n = 46) were available for analysis. Forty-one collections (45%) had a lymphocyte CE of <40%. On multivariable analysis, age (every 10-year increase, odds ratio [OR] = 1.51; p = 0.034), disease type (chronic lymphocytic leukemia vs. ALL, OR = 0.24; p = 0.052; non-Hodgkin lymphoma vs. ALL, OR = 0.20; p = 0.009) and precollection platelets (every 10 × 10 /μL increase, OR = 1.07; p = 0.005) were appreciably associated with a lymphocyte CE of <40%. No major apheresis complications occurred.

Conclusions: Lymphocyte collection at our center was well tolerated and 100% successful in manufacturing CD19-directed CAR T cells from adult patients with B-cell malignancies despite low CE in some patients. A diagnosis of ALL, advancing age, and higher preapheresis platelet counts were observed to be associated with low CE.