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Background Chimeric antigen receptor (CAR) T cells are a promising new immunotherapy. The first step in manufacturing is to collect autologous CD3+ lymphocytes by apheresis. Patients, however, are often leukopenic or have other disease-related complications. We evaluated the feasibility of collecting adequate numbers of CD3+ cells, risk factors for inadequate collections, and the rate of adverse events. Study Design Apheresis lymphocyte collections from patients participating in 3 CAR T cell clinical trials were reviewed. Collections were performed on the COBE Spectra by experienced nurses, with the goal of obtaining a minimum of 0.6×109 and a target of 2×109 CD3+ cells. Pre-apheresis peripheral blood counts, apheresis parameters, and product cell counts were analyzed. Results Of the 71 collections, 69 (97%) achieved the minimum and 55 (77%) achieved the target. Before apheresis, the 16 patients with yields below the target had significantly lower proportions and absolute numbers of circulating lymphocytes and CD3+ lymphocytes, and higher proportions of circulating blasts and NK cells than those who achieved the target (470 vs. 1340 lymphocytes/μL, p=0.008; 349 vs. 914 CD3+ cells/μL, p=0.001; 17.6% vs. 4.55% blasts, p=0.029). Enrichment of blasts in the product compared to the peripheral blood occurred in 4 patients, including the 2 patients whose collections did not yield the minimum number of CD3+ cells. Apheresis complications occurred in 11 patients (15%), and with one exception, were easily managed in the apheresis clinic. Conclusions In most patients undergoing CAR T cell therapy, leukapheresis is well-tolerated and adequate numbers of CD3+ lymphocytes are collected.

The Association for the Advancement of Blood and Biotherapies developed clinical practice guidelines for the appropriate use of COVID-19 convalescent plasma. This article describes the evidence and rationale for recommendations for inpatient and outpatient treatment and prophylaxis.

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