Contextual reprogramming of CAR-T cells for treatment of HER2+ cancers
Zhifen Yang, Lingyu Li, Ahu Turkoz, Pohan Chen, Rona Harari-Steinfeld, Maggie Bobbin, Ofir Stefanson, Hana Choi, Violena Pietrobon, Bennett Alphson, Angshumala Goswami, Vitaly Balan, Alper Y. Kearney, Dharmesh Patel, Jin Yang, Damla Inel, Veena Vinod, Alessandra Cesano, Bing Wang, Kyung‐Ho Roh, Lei S. Qi, Francesco M. Marincola
Abstract
BACKGROUND: Adoptive transfer of chimeric antigen receptor (CAR)-engineered T cells combined with checkpoint inhibition may prevent T cell exhaustion and improve clinical outcomes. However, the approach is limited by cumulative costs and toxicities. METHODS: To overcome this drawback, we created a CAR-T (RB-340-1) that unites in one product the two modalities: a CRISPR interference-(CRISPRi) circuit prevents programmed cell death protein 1 (PD-1) expression upon antigen-encounter. RB-340-1 is engineered to express an anti-human epidermal growth factor receptor 2 (HER2) CAR single chain variable fragment (scFv), with CD28 and CD3ζ co-stimulatory domains linked to the tobacco etch virus (TEV) protease and a single guide RNA (sgRNA) targeting the PD-1 transcription start site (TSS). A second constructs includes linker for activation of T cells (LAT) fused to nuclease-deactivated spCas9 (dCas9)-Kruppel-associated box (KRAB) via a TEV-cleavable sequence (TCS). Upon antigen encounter, the LAT-dCas9-KRAB (LdCK) complex is cleaved by TEV allowing targeting of dCas9-KRAB to the PD-1 gene TSS. RESULTS: FaDu oropharyngeal cancer growth compared to the respective conventional CAR-T cell product. CONCLUSIONS: As the first application of CRISPRi toward a clinically relevant product, RB-340-1 with the conditional, non-gene editing and reversible suppression promotes CAR-T cells resilience to checkpoint inhibition, and their persistence and effectiveness against HER2-expressing cancer xenografts.