title: Myeloid cells in peripheral blood mononuclear cell concentrates inhibit the expansion of chimeric antigen receptor T cells.
abstract: Autologous chimeric antigen receptor (CAR) T-cell therapies have shown promising clinical outcomes, but T-cell yields have been variable. CD19- and GD2-CAR T-cell manufacturing records were reviewed to identify sources of variability.
  
  
  
  CD19-CAR T cells were used to treat 43 patients with acute lymphocytic leukemia or lymphoma and GD2-CAR T cells to treat eight patients with osteosarcoma and three with neuroblastoma. Both types of CAR T cells were manufactured using autologous peripheral blood mononuclear cells (PBMC) concentrates and anti-CD3/CD28 beads for T-cell enrichment and simulation.
  
  
  
  A comparison of the first 6 GD2- and the first 22 CD19-CAR T-cell products manufactured revealed that GD2-CAR T-cell products contained fewer transduced cells than CD19-CAR T-cell products (147 ± 102 × 10(6) vs 1502 ± 1066 × 10(6); P = 0.0059), and their PBMC concentrates contained more monocytes (31.4 ± 12.4% vs 18.5 ± 13.7%; P = 0.019). Among the first 28 CD19-CAR T-cell products manufactured, four had poor expansion yielding less than 1 × 10(6) transduced T cells per kilogram. When PBMC concentrates from these four patients were compared with the 24 others, PBMC concentrates of poorly expanding products contained greater quantities of monocytes (39.8 ± 12.9% vs. 15.3 ± 10.8%, P = 0.0014). Among the patients whose CD19-CAR T cells expanded poorly, manufacturing for two patients was repeated using cryopreserved PBMC concentrates but incorporating a monocyte depleting plastic adherence step, and an adequate dose of CAR T cells was produced for both patients.
  
  
  
  Variability in CAR T-cell expansion is due, at least in part, to the contamination of the starting PBMC concentrates with monocytes.
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA. Electronic address: dstroncek@cc.nih.gov.
authors.forename: David F
authors.initials: DF
authors.lastname: Stroncek
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Ren
authors.affiliation: Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Lee
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Minh
authors.initials: M
authors.lastname: Tran
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Sue Ellen
authors.initials: SE
authors.lastname: Frodigh
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Marianna
authors.initials: M
authors.lastname: Sabatino
authors.affiliation: Cell Processing Section, Department of Transfusion Medicine, National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Hanh
authors.initials: H
authors.lastname: Khuu
authors.affiliation: Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Melinda S
authors.initials: MS
authors.lastname: Merchant
authors.affiliation: Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Mackall
mesh_terms: D018941:Antigens, CD19 / Q000276:immunology / Q000378:metabolism; D049109:Cell Proliferation; D002648:Child; D006801:Humans; D007167:Immunotherapy; D007963:Leukocytes, Mononuclear / Q000166:cytology* / Q000276:immunology; D009000:Monocytes / Q000166:cytology; D022423:Myeloid Cells / Q000166:cytology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology*; D014161:Transduction, Genetic; D055815:Young Adult
chemical_list: D018941:Antigens, CD19; D011948:Receptors, Antigen, T-Cell
keywords: CD19; GD2; acute lymphocytic leukemia; adoptive cellular therapy; chimeric antigen receptor T cells; osteosarcoma