Chimeric Antigen Receptor T-Cells (CART-cells) are a type of genetically engineered type of immune cell that represents one of the most promising avenues of cancer therapy. Such treatments can induce sustained remissions in patients with stubborn disease.
Studies with CART-cells have been tested in patients with relapsed and stubborn chronic lymphocytic leukemia (CLL). Now a new publication by Porter and others reports the results of a clinical trial that examined CART-cells as a treatment for blood-based cancers. This study reports that infused CART-cells were functional up to 4 years after treatment. Patients also achieved completely remission, and no patient who achieved complete remission relapsed, and no minimal residual disease was detected, suggesting that in a subset of patients, CAR T cells may drive disease eradication.
Patients enrolled in this study suffered from CLL and had a poor prognosis. The CART-cells employed in this study targeted the molecule CD19. Porter and others report the mature results of the treatment of 14 patients with relapsed and refractory CLL.
The patient’s own T-Cells were extracted from circulating blood, and genetically engineered to express a CD19-directed receptor. Patients received doses of 0.14 × 10 to 11 × 10 CTL019 cells. Patients were monitored for toxicity, response, expansion, and persistence of circulating CTL019 T cells.
The overall response rate in these heavily pretreated CLL patients was 8 of 14 (57%), and there were 4 complete remissions (CR) and 4 partial remissions (PR). The expansion of the CAR T-cells in culture correlated with clinical responses; the better the engineered T-cells grew in culture the better they performed in the Patient’s bodies. Furthermore, the CAR T-cells persisted and remained functional beyond 4 years in the first two patients achieving Complete Remission. None of the patients who experienced Complete Remission have relapsed.
All the patients who responded to the treatment developed “B cell aplastic” (abnormally low B-cell levels) and experienced cytokine release syndrome, which was part and partial of T cell proliferation.
Minimal residual disease was not detectable in patients who achieved Complete Remission, suggesting that disease eradication may be possible in some patients with advanced CLL.