Publication Date:
2015-12-03
Description:
Introduction Progressive malignancy is the leading cause of death after allogeneic hematopoietic stem cell transplantation (alloHSCT). After alloHSCT, B-cell malignancies are often treated with infusions of unmanipulated donor lymphocytes (DLIs) from the transplant donor. DLIs are frequently not effective at eradicating malignancy, and DLIs often cause graft-versus-host disease (GVHD), which is a potentially lethal allogeneic immune response against normal recipient tissues. Methods We conducted a clinical trial of allogeneic T cells that were genetically engineered to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. The CAR was encoded by a gamma-retroviral vector and included a CD28 costimulatory domain. Patients with B-cell malignancies after alloHSCT received a single infusion of CAR T cells. No chemotherapy or other therapies were administered. The T cells were obtained from each recipient's alloHSCT donor. Findings Eight of 20 treated patients obtained remissions, including 6 complete remissions (CR) and 2 partial remissions. The response rate was highest for acute lymphoblastic leukemia with 4/5 patients obtaining minimal-residual-disease-negative CRs, but responses also occurred in chronic lymphocytic leukemia (CLL) and lymphoma. The longest ongoing CR is 30+ months in a patient with CLL. No patient developed new-onset acute GVHD after CAR T-cells were infused. Toxicities included fever, tachycardia, and hypotension. Median peak blood CAR T-cell levels were higher in patients who obtained remissions (39 CAR+ cells/mL) than in patients who did not obtain remissions (2 CAR+ cells/mL, P=0.001). Presence of endogenous normal or malignant blood B lymphocytes before CAR T-cell infusion was associated with higher post-infusion median blood CAR T-cell levels (P=0.04). Compared to patients who did not obtain a remission of their malignancies, patients obtaining remissions had a higher CD8:CD4 ratio of blood CAR+ T cells at the time of peak CAR T-cell levels (P=0.007). The mean percentage of CAR+CD8+ T cells expressing the programmed cell death-1 (PD-1) protein increased from 12% at the time of infusion to 82% at the time of peak blood CAR T-cell levels (P
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine