Abstract
Revolutionary CART therapy still faces the challenge of severe cytokine release syndrome (CRS). While IL6 and IL1 have been demonstrated as essential contributors, GM-CSF is one of the most abundant inflammatory cytokines secreted by CART and has also been suggested in contributing to CRS. To minimize GM-CSF production from CART to reduce its associated toxicity, we conducted a pilot study (ChiCTR2000032124) of CRISPR-edited GM-CSF knockout (KO) in CART secreting anti-IL6 scFv and IL1RA, with additional TCR KO for tracing edited CART. The initial results of three patients (1 Non-Hodgkin lymphoma (NHL) and 2 multiple myelomas (MMs)) are summarized as: 3/3 complete response, 2/3 none CRS, 1/3 grade 2 CRS, and 0/3 neurotoxicity. The analysis revealed low levels of GM-CSF, IL6 and IL1B at the time of interferon-gamma (IFNG) peaks, and elevated IL1RA. We also observed significant expansion of CD3- CART during treatment and no aberrant expansion of CD3- CART in the follow-up. Re-expansion of CD3- CART was observed in two patients while recurring CD19+ cells were eradicated in the patient with NHL. In summary, our study supported the safety and durable potency of CRISPR-edited CART in patients, providing a novel platform for developing autologous or allogeneic CART to minimize GM-CSF-associated toxicity in addition to autonomous IL6/IL1 blockade.