Autologous lymphapheresis for the production of chimeric antigen receptor T cells

Abstract

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.

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

“…The apheresis procedure was safe and well tolerated without any major adverse events, such as bleeding, hypotension, allergic reactions, or symptomatic hypocalcemia. Two prior studies of lymphapheresis for CAR T‐cell production reported a complication rate of 9.8% to 15%, the majority of which are minor and manageable, such as paresthesia, pain, nausea, vomiting, and headache …”

“…Only 63 collections (88%) were successful in generating sufficient quantities of CAR T cells to meet protocol dose criteria (0.3 to 3.0 × 10 6 transduced CD3+ cells). Lower CD3+ yields were significantly associated with manufacturing failures, which occurred in 5 of 16 patients (31%) with fewer than the target number of CD3+ cells, and 3 of 55 patients (5%) who met the target …”

“…The optimal parameters for hematopoietic progenitor cell collection may not be applicable to MNC collections because nonmobilized patients often have low WBC counts, making isolation of target lymphocytes challenging . MNC collections for CAR T cells more closely mimic collections for donor lymphocyte infusion wherein mature lymphocytes are the target cells of apheresis . However, in comparison with healthy donors, patients referred for CAR T‐cell therapy are heavily pretreated and frequently have lymphopenia and/or high numbers of circulating malignant cells.…”

GMP CAR-T cell production

“…A recent publication reported that the minimum T cell number was collected from 97% of apheresis donors and that 77% achieved the target dose. Apheresis complications occurred in 15% of donors, but were easily managed in the clinic [8].…”

Maintaining a fit T‐cell compartment: lymphoma treatment sequencing in the era of chimeric antigen receptor T‐cell therapies

“…note the prolonged T‐cell lymphopenia associated with bendamustine use . Production of CAR T cells requires an adequate T‐cell harvest, circulating T‐lymphocyte levels <350/μL being strongly associated with CAR T‐cell production failure . Treatments that cause prolonged T‐cell lymphopenia therefore have the potential to preclude subsequent CAR T‐cell therapy.…”