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Gregory Szeto1 2

1, University of Maryland Baltimore County, Baltimore, Maryland, United States
2, University of Maryland, Baltimore, Maryland, United States

Adoptive cell therapies (ACT) using ex vivo-modified lymphocytes to enhance anti-tumor immunity is rapidly gaining FDA approval for multiple cancer types. ACT has been promising in blood cancers, but poor efficacy persists in many solid tumors. Further, the complex requirements of genetic manipulation and occurrence of immune-related adverse effects remain outstanding challenges for implementing ACT in the clinic. Combining ACT with other therapies such as immune-enhancing drugs can also be limited by inefficient trafficking and activity of drugs to the immunosuppressive tumor microenvironment, and low colocalization of drug with ACT. To address these challenges, we have engineered molecular conjugates using lipid-based tails coupled to TLR agonists (lipo-TLRa) that rapidly and densely insert into the plasma membrane of immune cells. Murine T-cells coated with lipo-CpG-DNA (TLR9a) and Pam2CSK4 (TLR2a) can signal by both autocrine and paracrine mechanisms to enhance therapeutic outcomes while reducing unwanted side effects by tightly colocalizing drugs with cells. Our data showed that lipo-TLRa functionalize immune cell surfaces in a dose and time-dependent manner. Signals loaded for up to 1 h can functionally persist on cell surfaces for multiple days. Lipo-TLRa were shown to 1) activate lipid—inserted cells along with nearby bystander immune cells by co-delivering danger signals, 2) efficiently deliver prolonged signaling to both intracellular and surface TLR receptors, and overcome tumor immunosuppression by 3) recovering proliferative function and 4) enhancing cytokine production in vitro when T-cells were co-cultured with immunosuppressive tumor cells. Further, membrane-inserted lipo-TLRa was equivalent or superior to soluble drug at higher concentrations. These results demonstrate the unique properties and abilities of lipo-TLRa’s to enhance the function of T cells for adoptive transfer.

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