ZFP36 disruption is insufficient to enhance the function of mesothelin-targeting human CAR-T cells.

Loss of inflammatory effector function, such as cytokine production and proliferation, is a fundamental driver of failure in T cell therapies against solid tumors. Here, we used CRISPR/Cas9 to genetically disrupt ZFP36, an RNA binding protein that regulates the stability of mRNAs involved in T cell inflammatory function, such as the cytokines IL2 and IFNγ, in human T cells engineered with a clinical-stage mesothelin-targeting CAR to determine whether its disruption could enhance antitumor responses. ZFP36 disruption slightly increased antigen-independent activation and cytokine responses but did not enhance overall performance in vitro or in vivo in a xenograft tumor model with NSG mice. While ZFP36 disruption does not reduce the function of CAR-T cells, these results suggest that singular disruption of ZFP36 is not sufficient to improve their function and may benefit from a multiplexed approach.