Enhancing immunotherapy efficacy against MHC-I deficient triple-negative breast cancer using LCL161-loaded macrophage membrane-decorated nanoparticles.

Current cytotoxic T lymphocyte (CTL) activating immunotherapy requires a major histocompatibility complex I (MHC-I)-mediated presentation of tumor-associated antigens, which malfunctions in around half of patients with triple-negative breast cancer (TNBC). Here, we create a LCL161-loaded macrophage membrane decorated nanoparticle (LMN) for immunotherapy of MHC-I-deficient TNBC. SIRP on the macrophage membrane helps LMNs recognize CD47-expressing cancer cells for targeted delivery of LCL161, which induces the release of high mobility group protein 1 and proinflammatory cytokines from cancer cells. The released cytokines and high mobility group protein 1 activate antitumor immunity by increasing the intratumoral density of the phagocytic macrophage subtype by 15 times and elevating the intratumoral concentration of CTL lymphotoxin by 4.6 folds. LMNs also block CD47-mediated phagocytosis suppression. LMNs inhibit the growth of MHC-I-deficient TNBC tumors, as well as those resistant to combined therapy of anti-PDL1 antibody and albumin-bound paclitaxel, and prolong the survival of animals, during which process CTLs also play important roles. This macrophage membrane-decorated nanoparticle presents a generalizable platform for increasing macrophage-mediated antitumor immunity for effective immunotherapy of MHC-I-deficient cancers.