Therapeutic induction of ferroptosis in tumors using PD-L1 targeting antibody nanogel conjugates

Abstract

Although programmed cell death ligand 1 (PD-L1) is best known for its role in immune suppression, tumor-intrinsic functions are emerging. Here, we report that tumor cells that express PD-L1 are sensitive to ferroptosis inducers such as imidazole ketone erastin (IKE). PD-L1 promotes ferroptosis sensitivity because it suppresses SLC7A11 expression and diminishes glutathione levels. Although the use of anti-PD-L1 antibody drug conjugates (ADCs) could be effective for the delivery of ferroptosis inducers to specific tumor populations, the chemistry of most ferroptosis inducers precludes their incorporation in ADCs. To overcome this challenge, we synthesized an antibody nanogel conjugate (ANC) comprised of an anti-PD-L1 antibody conjugated to a nanogel encapsulated with IKE. This ANC targets PD-L1-expressing cells in vitro and in vivo and induces ferroptosis, resulting in tumor suppression. Importantly, this approach is superior to systemic administration of IKE because it enables enhanced delivery of IKE specifically to tumor cells and it requires lower drug doses for efficacy.