GM-CSF, a cytokine produced by T cells and myeloid cells, is the most statistically significantly elevated serum marker in patients with severe neurotoxicity related to CAR T-cell therapy, Ms. Sterner told attendees.
Investigations have shown that the combination of lenzilumab plus CD19-targeted T-cell therapy did not impair CAR T-cell function in vivo or in vitro, she said.
In other studies, they investigated the impact of GM-CSF neutralization in mice engrafted with primary acute lymphocytic leukemia (ALL) blasts and treated with high doses of CD19 CAR T-cells, lenzilumab, and a murine GM-CSF blocking antibody to neutralize the mouse GM-CSF. That strategy prevented weight loss, decreased myeloid cytokines, reduced cerebral edema, and enhanced disease control, Ms. Sterner said.
Investigators also reported on CD19 CAR T-cells with reduced GM-CSF secretion due to CRISPR/Cas9 gene editing of the GM-CSF gene during the CAR T-cell manufacturing process. Xenograft model results showed a slight enhancement of disease control for those GM-CSF knockout CAR T cells versus standard CAR T cells.
More details of the investigations were recently published in Blood (2019;133:697-709).
Taken together, the investigations highlight GM-CSF inhibition as a novel approach to reducing neurotoxicity and CRS that may also enhance CAR T-cell effector functions, Ms. Sterner said.
Ms. Sterner reported having no financial disclosures related to her presentation.
SOURCE: Sterner R et al. TCT 2019, Abstract 5.