Treating B-cell cancer with T cells expressing anti-CD19 chimeric antigen receptors

Abstract

Most B-cell malignancies express CD19, and a majority of patients with B-cell malignancies are not cured by current standard therapies. Chimeric antigen receptors (CARs) are fusion proteins consisting of antigen recognition moieties and T-cell activation domains. T cells can be genetically modified to express CARs, and adoptive transfer of anti-CD19 CAR T cells is now being tested in clinical trials. Effective clinical treatment with anti-CD19 CAR T cells was first reported in 2010 after a patient with advanced-stage lymphoma treated at the NCI experienced a partial remission of lymphoma and long-term eradication of normal B cells. Additional patients have subsequently obtained long-term remissions of advanced-stage B-cell malignancies after infusions of anti-CD19 CAR T cells. Long-term eradication of normal CD19(+) B cells from patients receiving infusions of anti-CD19 CAR T cells demonstrates the potent antigen-specific activity of these T cells. Some patients treated with anti-CD19 CAR T cells have experienced acute adverse effects, which were associated with increased levels of serum inflammatory cytokines. Although anti-CD19 CAR T cells are at an early stage of development, the potent antigen-specific activity observed in patients suggests that infusions of anti-CD19 CAR T cells might become a standard therapy for some B-cell malignancies.

Figure 1 |

Chimeric antigen receptors. a | CARs usually include a T-cell activation domain, one or more co-stimulatory domains, a hinge region, a cell membranespanning transmembrane domain, and an antigen-recognition moiety that is usually derived from an antibody. b | A schematic of an anti-CD19 CAR-expressing T cell recognizing a CD19+ malignant cell is shown. Abbreviation: CAR, chimeric antigen receptor.

Figure 2 |

Eradication of bone marrow lymphoma and normal B cells occurred after anti-CD19 CAR T cell infusion. a | A patient with follicular lymphoma (patient 1 in Table 1) had extensive bone marrow involvement with lymphoma before treatment with chemotherapy followed by anti-CD19 CAR T cells and IL-2. The lymphoma cells expressed the B-cell markers CD19, CD79a, and CD20. b | 14 weeks after treatment, the lymphoma as well as normal B cells were absent. Abbreviations: CAR, chimeric antigen receptor; H&E, haematoxylin and eosin; IL, interleukin. The CD19 and CD79a panels of part a are reproduced with permission from American Society of Hematology © Kochenderfer, J. N. et al. Blood 116, 4099–4102 (2010).

Figure 3 |

Eradication of bone marrow and blood CLL cells occurred in a patient treated with chemotherapy followed by anti-CD19 CAR T cells and IL-2. a | Before treatment almost all bone marrow CD19⁺ B-lineage cells also expressed CD5. Expression of CD5 together with CD19 is an aberrant phenotype that is typical for CLL. 14 months after treatment, the aberrant CD19⁺, CD5⁺ population is absent. b | Blood B cells, most of which were CLL cells, were eliminated after treatment. B cells, which were defined as CD19⁺ cells, were assayed by flow cytometry. The results are from patient 3 from Table 1. Abbreviations: CAR, chimeric antigen receptor; CLL, chronic lymphocytic leukaemia; IL, interleukin. Reproduced with permission from American Society of Hematology © Kochenderfer, J. N. et al. Blood 119, 2709–2720 (2012).

Figure 4 |

Regression of adenopathy occurred in a patient with CLL after treatment with chemotherapy followed by an infusion of anti-CD19 CAR T cells and IL-2. The arrow indicates the adenopathy. The CT scans are of patient 7 in Table 1: a | Before treatment, b | 32 days after the anti-CD19 CAR T cell infusion, c | 132 days after infusion, and d | 645 days after infusion. Abbreviations: CAR, chimeric antigen receptor; IL, interleukin. Parts a, b and c reproduced with permission from American Society of Hematology © Blood 119, 2709–2720 (2012).

Figure 5 |

A schematic of our current approach to anti-CD19 CAR T cell therapy is shown. The ex vivo cell processing takes 10 days. The lymphocyte-depleting chemotherapy regimen consists of fludarabine and cyclophosphamide. All patients receive 25 mg/m² of fludarabine daily for 5 days. The cyclophosphamide dose depends on the patient’s platelet count. A cyclophosphamide dose of 60 mg/kg daily for 2 days is administered to patients with a blood platelet count of 100,000/μl or more. A cyclophosphamide dose of 30 mg/kg daily for 2 days is administered to patients with a blood platelet count between 75,000 and 99,000/μl. Patients with platelet counts less than 75,000/μL are not eligible for the clinical trial. Abbreviations: CAR, chimeric antigen receptor; PBMC, peripheral blood mononuclear cell.