Treatment of CD33-directed chimeric antigen receptor-modified T cells in one patient with relapsed and refractory acute myeloid leukemia

Abstract

We conducted a clinical trial to assess the feasibility and efficacy of CD33-directed chimeric antigen receptor-modified T cells (CART-33) for the treatment of refractory acute myeloid leukemia (AML). A 41-year-old male patient with AML was enrolled and received a total of 1.12 × 10(9) autologous CART-33 cells, of which ~38% were transduced with CAR. The CART-33 infusion alone induced rigorous chills and fevers; drastic fluctuations of his preexisting pancytopenia; elevated serum cytokine levels, including interleukin (IL)-6, IL-8, tumor necrosis factor-α, and interferon-γ; slight transient hyperbilirubinemia within 2 weeks; a subsequent intermittent moderate fever; and reversed fluctuation of the pancytopenia. A marked decrease of blasts in the bone marrow was observed on examination 2 weeks after therapy, and there was a gradual increase until florid disease progression occurred at 9 weeks after the cell infusion. These observations warrant further research on CART-33 treatment in refractory AML and may spur efforts to extend the CART-33-induced tumor burden to the preparation of other intensive strategies, such as hematopoietic stem cell transplantation. This study is registered at www.ClinicalTrials.gov as NCT01864902.

Figure 1

Expansion, transfection efficiency, and phenotypic analysis of CART-33 cells. (a) Expansion (-fold) of the control NT (no transfection T cells) and CART-33 cells generated from the patient. The cells were cultured for ~13 days. (b) Comparison of the immunophenotypic analyses of the PBMNC, NT, and CART-33 cells. (c) The verified transfection efficiency of CART-33 cells by GFP. Left panel: optical microscope photographs showing the CART-GFP cells of the patient after culture for 12 days. Right panel: expression of CAR-GFP in CART-GFP cells as assessed by FACS analysis. (d) CD33 expression on CART-33 cells as determined by FACS analysis. CART, chimeric antigen receptor-modified T cells; FACS, fluorescent-activated cell sorting; GFP, green fluorescence protein; PBMNC, peripheral blood mononuclear cell.

Figure 2

Cytotoxic activity of CART-33 and PBNMC from the patient. Cytotoxic activity of the PBMNC, NT (no transfection T cells) and CART-33 cells obtained from the patient using the following target cells: (a) K562 cell line (human chronic myelogenous leukemia cell lines, CD33⁻), (b) HL-60 cell line (human promyelocytic leukemia cells, CD33⁺), and (c) autologous blasts (primary acute myeloid leukemia cells from the patient with CD33⁺). The results are shown at effector:target (E:T) ratios of 1:1, 5:1, 10:1, 20:1, and 40:1. (d) Cytotoxic activity of the following effector cells obtained from the patient: NT and CART-33 were cultured for 12 days, the PBMNCs obtained from the PB of the patient before and after the CART-33 cell infusion, the target cells were K562 and HL-60, and the results are shown at an E:T ratios of 10:1. The cytotoxic activity was evaluated through a 24-hour carboxyfluorescein succinimidyl ester staining assay. All of the data are represented as the means of triplicate values, and the error bars represent the SEMs. CART, chimeric antigen receptor-modified T cells; PBMNC, peripheral blood mononuclear cell.

Figure 3

CART-33 copies persistent in the peripheral blood and the bone marrow as assessed by quantitative polymerase chain reaction (Q-PCR). Quantitative real-time PCR was performed on genomic DNA harvested from the patient's PBMNCs and bone marrow collected before and at the indicated serial time points after the CART-33 cell infusion. Primers specific for the transgene were used. CART, chimeric antigen receptor-modified T cells; PBMNC, peripheral blood mononuclear cell.

Figure 4

Changes in the complete blood count and body temperature during and after the CART-33 cell infusion. (a) The left panel shows the alterations in the WBC count and body temperature, and the right panel shows the changes in the platelet count, hemoglobin level, and the patient's body temperature during the first 2 weeks of cell treatment. (b) Changes in the temperature and WBC count 2 weeks later. CART, chimeric antigen receptor-modified T cells; WBC, white blood cell.

Figure 5

Changes in the various cytokine levels after CART-33 cell infusion. The serum levels of the indicated cytokines were serially measured starting on the first day of the CART-33 infusion to the indicated time point. CART, chimeric antigen receptor-modified T cells; IFN, interferon; IL, interleukin; TNF, tumor necrosis factor; VEGF, vascular endothelial growth factor.

Figure 6

FACS analysis for bone marrow aspirates. The cells in the D gate represent the blast population count corresponding to 61.66, 9.48, 28.24, 33.83, and 84.95%, respectively, of the total nucleated cells in the bone marrow aspirates collected at the indicated time points before and after the CART-33 infusions. CART, chimeric antigen receptor-modified T cells; FACS, fluorescent-activated cell sorting.