Anti-CLL1-based CAR T-cells with 4-1-BB or CD28/CD27 stimulatory domains in treating childhood refractory/relapsed acute myeloid leukemia

Abstract

Background: Though the efficacy of anti C-type lectin-like molecule-1 (CLL1) CAR T-cells in refractory/relapsed acute myeloid leukemia (R/R-AML) have been occasionally reported, the influence of co-stimulatory domain CAR T-cells is not investigated so far.

Method: Seven R/R-AML children treated with anti-CLL1 CAR T-cells were enrolled onto this preliminary comparison study. Among these seven patients, four received CD28/CD27-based CAR T-cells therapy, and three received 4-1BB-based CAR T-cells therapy.

Result: The overall response rates were 75% and 66.7% in CD28/CD27 and 4-1BB group respectively. All patients experienced grade 1 to 2 cytokine release syndrome, with only one patient experiencing grade 2 immune effector cell-associated neurotoxicity syndrome. The maximum CAR T-cells durations were 156 and 274 days for CD28/CD27 group and 4-1BB group respectively. The 1-yr overall survival rate was 57.1%.

Conclusions: A preliminary similar efficacy/safety index was observed in anti-CLL1-based CAR T-cells with 4-1BB or CD28/CD27 co-stimulatory elements in treating pediatric R/R-AML.

Trial registration: ClinicalTrials.gov NCT03222674.

Keywords: 4-1-BB; CD28/CD27; acute myeloid leukemia; anti-CLL1 CAR T cells; refractory/relapsed.