This project is a combination of a clinical trial of infusions of autologous anti-CD19 chimeric-antigen-receptor-transduced T cells and laboratory experiments performed on cells obtained from patients that received infustions of the chimeric-antigen-receptor-transduced T cells. During 2010 this project resulted in one publication in Blood entitled """"""""Eradication of B-lineage cells and regression of lymphoma in a patient treated with autologous T cells genetically-engineered to recognize CD19"""""""". The project also resulted in 2 abstracts that were presented at major international meetings. The rest of this section summarizes the project. New therapies are needed for chemotherapy-resistant B-cell malignancies. Adoptive transfer of T cells genetically-engineered to express chimeric antigen receptors (CARs) that specifically recognize the B-cell antigen CD19 is a promising new approach for treating B-cell malignancies. We are conducting a clinical trial in which patients receive infusions of autologous T cells that are transduced with gamma-retroviruses encoding an anti-CD19 CAR. The CAR is made up of the variable regions of an anti-CD19 antibody, a portion of the CD28 molecule, and a portion of the CD3-zeta molecule. Our clinical protocol consists of cyclophosphamide plus fludarabine chemotherapy followed by an infusion of anti-CD19-CAR-transduced T cells and a course of high-dose IL-2. We have treated 8 patients on this clinical trial. Four of the patients had chronic lymphocytic leukemia (CLL), and 4 patients had B-cell lymphoma. Anti-CD19-CAR-transduced T cells that specifically recognized CD19-expressing target cells were produced for all patients. The total number of cells administered to each patient ranged from 0.5x10e7 to 5.5x10e7 cells per kg of bodyweight. A mean of 54 percent of the administered cells expressed the anti-CD19 CAR. One patient with CLL obtained a complete remission that is ongoing 15 months after treatment. Five patients obtained partial remissions that are ongoing in 3 patients. One patient with CLL had stable disease. One patient with lymphoma died of culture-proven influenza A pneumonia and is not evaluable for lymphoma response. A striking depletion of CD19+ B-lineage cells occurred in 4 of 8 patients. This B-cell depletion lasted for up to 15 months, and it is ongoing in 3 of 4 patients. Because of the long duration of B-cell depletion, it cannot be attributed to the chemotherapy that the patients received. For example, a patient with follicular lymphoma had a normal level of polyclonal blood B cells before treatment on our protocol. Six months after treatment, he had a blood B cell count of 1 per microliter (normal range 61-321 B cells per microliter). A patient with CLL had a regression of adenopathy in the first 32 days after chemotherapy and CAR-transduced T cell administration. CAR-transduced cells were detected in the blood of all 8 patients by quantitative PCR. The percentage of peripheral blood mononuclear cells (PBMC) containing the CAR gene varied widely, but in 2 patients the CAR gene was detected in greater than 0.1 percent of PBMC more than 90 days after infusion. At early time-points after infusion, CAR-expressing T cells constituted up to 20 percent of all blood T cells. Patients had significant toxicity during the first 10 days after CAR-transduced T cell infusion. The most prominent toxicity was hypotension. CAR-transduced cells were detected in the blood of all 8 patients by quantitative PCR. The percentage of peripheral blood mononuclear cells (PBMC) containing the CAR gene varied widely, but in 2 patients the CAR gene was detected in greater than 0.1 percent of PBMC more than 90 days after infusion. At early time-points after infusion, CAR-expressing T cells constituted up to 20 percent of all blood T cells. Patients had significant toxicity during the first 10 days after CAR-transduced T cell infusion. The most prominent toxicity was hypotension.These results demonstrate that CAR-expressing T cells can specifically eliminate targeted cells and cause significant cytokine-mediated toxicity in humans.
