Closed-system manufacturing of CD19 and dual-targeted CD20/19 chimeric antigen receptor T cells using the CliniMACS Prodigy device at an academic medical center

Background aims

Multiple steps are required to produce chimeric antigen receptor (CAR)-T cells, involving subset enrichment or depletion, activation, gene transduction and expansion. Open processing steps that increase risk of contamination and production failure are required. This complex process requires skilled personnel and costly clean-room facilities and infrastructure. Simplified, reproducible CAR-T-cell manufacturing with reduced labor intensity within a closed-system is highly desirable for increased availability for patients.

Generation of alloreactivity-reduced donor lymphocyte products retaining memory function by fully automatic depletion of CD45RA-positive cells

Background aims

For patients needing allogeneic stem cell transplantation but lacking a major histocompatibility complex (MHC)-matched donor, haplo-identical (family) donors may be an alternative. Stringent T-cell depletion required in these cases to avoid lethal graft-versus-host disease (GVHD) can delay immune reconstitution, thus impairing defense against virus reactivation and attenuating graft-versus-leukemia (GVL) activity. Several groups reported that GVHD is caused by cells residing within the naive (CD45RA⁺) T-cell compartment and proposed use of CD45RA-depleted donor lymphocyte infusion (DLI) to accelerate immune reconstitution. We developed and tested the performance of a CD45RA depletion module for the automatic cell-processing device CliniMACS Prodigy and investigated quality attributes of the generated products.

Manufacturing chimeric antigen receptor T cells: issues and challenges

Clinical trials of adoptively transferred CD19 chimeric antigen receptor (CAR) T cells have delivered unprecedented responses in patients with relapsed refractory B-cell malignancy. These results have prompted Food and Drug Administration (FDA) approval of two CAR T-cell products in this high-risk patient population. The widening range of indications for CAR T-cell therapy and increasing patient numbers present a significant logistical challenge to manufacturers aiming for reproducible delivery systems for high-quality clinical CAR T-cell products. This review discusses current and novel CAR T-cell processing methodologies and the quality control systems needed to meet the increasing clinical demand for these exciting new therapies.     

Depletion of T-cell receptor alpha/beta and CD19 positive cells from apheresis products with the CliniMACS device

Background aimsThe CliniMACS device (Miltenyi Biotec, Bergisch Gladbach, Germany) was used for depletion of T-cell receptor alpha/beta positive (TCRαβ⁺) and CD19 positive (CD19⁺) cells from apheresis products.MethodsInvestigators performed 102 separations. Apheresis products with a median 5.8 (minimum to maximum, 1.2–10.4) × 10¹⁰ mononuclear cells were used with a median 358 (92–1432) × 10⁶ CD34⁺ cells. There were 24.8% (6.1–45.7%) median TCRαβ⁺ cells and 4.4% (1.2–11.7%) median B cells in the apheresis product.ResultsAfter depletion, a median 0.00097% (0.00025–0.0048%) of TCRαβ⁺ cells could be detected, and B cells, as determined as CD20⁺ cells, were reduced to 0.0072% (0.0008–0.072%). TCRαβ⁺ cells were depleted by log 4.7 (3.8–5.5), and B cells were depleted by log 4.1 (3.0–4.7). Recovery of mononuclear cells was 55% (33–77%), and recovery of CD34⁺ cells was 73% (43–98%). Recovery of CD56⁺/3^? natural killer cells was 80% (35–142%), recovery of TCR gamma/delta positive (TCRγδ⁺) T cells was 83% (39–173%) and recovery of CD14⁺ cells was 79% (22–141%). Viability of cells was 98% (93–99%) after separation (all values median).ConclusionsProfound depletion of TCRαβ⁺ T cells can be achieved with the CliniMACS system. Recovery of CD34⁺ stem cells is in the same range than after CD34⁺ enrichment and CD3/CD19 depletion. Transplantation with >4 × 10⁶ CD34⁺ cells/kg can be performed for every patient with 1–5 × 10⁴ TCRαβ⁺ cells/kg and about 5–10 × 10⁶ TCRγδ⁺ cells/kg with two rounds of apheresis.     

Clinical-scale isolation of ‘minimally manipulated’ cytomegalovirus-specific donor lymphocytes for the treatment of refractory cytomegalovirus disease

Background aimsReactivation of cytomegalovirus (CMV) after hematopoietic stem cell transplantation remains a major cause of morbidity despite improved antiviral drug therapies. Selective restoration of CMV immunity by adoptive transfer of CMV-specific T cells is the only alternative approach that has been shown to be effective and non-toxic. We describe the results of clinical-scale isolations of CMV-specific donor lymphocytes with the use of a major histocompatibility (MHC) class I peptide streptamer-based isolation method that yields minimally manipulated cytotoxic T cells of high purity.MethodsEnrichment of CMV-specific cytotoxic T lymphocytes (CTLs) was performed by labeling 1 × 10¹⁰ leukocytes from a non-mobilized mononuclear cell (MNC) apheresis with MHC class I streptamers and magnetic beads. Thereafter, positively labeled CMV-specific CTLs were isolated through the use of CliniMACS (magnetic-activated cell sorting), and MHC streptamers were released through the use of d-biotin. The purity of enriched CMV-specific CTLs was determined on the basis of MHC streptamer staining and fluorescence-activated cell sorting.ResultsA total of 22 processes were performed with the use of five different MHC class I streptamers. The median frequency of CMV-specific CTLs in the starting apheresis product was 0.41% among CD3+ T cells. The isolation process yielded a total of 7.77 × 10⁶ CMV-specific CTLs, with a median purity of 90.2%. Selection reagents were effectively removed from the final cell product; the CMV-specific CTLs displayed excellent viability and cytotoxicity and were stable for at least 72 h at 4°C after MNC collection.ConclusionsClinical-scale isolation of “minimally manipulated” CMV-specific donor CTLs through the use of MHC class I streptamers is feasible and yields functional CTLs at clinically relevant dosages.