Doxorubicin’s antitumor effectiveness may be constrained with ineffective tumor penetration, systemic adverse effects, as well as drug resistance. The co-loading of immune checkpoint inhibitors and doxorubicin into liposomes can produce synergistic benefits and address problems, including quick drug clearance, toxicity, and low drug penetration efficiency. In our previous study, we modified a nanobody targeting CTLA-4 onto liposomes (LPS-Nb36) to be an extremely potent CTLA-4 signal blocker which improve the CD8⁺ T-cell activity against tumors under physiological conditions. In this study, we designed a drug delivery system (LPS-RGD-Nb36-DOX) based on LPS-Nb36 that realized the doxorubicin and anti-CTLA-4 Nb co-loaded and RGD modification, and was applied to antitumor therapy. We tested whether LPS-RGD-Nb36-DOX could targets the tumor by in vivo animal photography, and more importantly, promote cytotoxic T cells proliferation, pro-inflammatory cytokine production, and cytotoxicity. Our findings demonstrated that the combination of activated CD8⁺ T cells with doxorubicin/anti-CTLA-4 Nb co-loaded liposomes can effectively eradicate tumor cells both in vivo and in vitro. This combination therapy is anticipated to have synergistic antitumor effects. More importantly, it has the potential to reduce the dose of chemotherapeutic drugs and improve safety.

Despite the great success of CTLA-4 blocking in cancer treatment, the use of anti-CTLA-4 monoclonal antibodies still faces many limitations. Now, immune checkpoint blocking coupled with adoptive cell therapy is gaining much attention. In this paper, we reported a strategy on the basis of anti-CTLA-4 nanobody (Nb)-modified liposomes to improve these obstacles. An Nb36/liposome complex was constructed and utilized as a blocker of the CTLA-4/B7 signal pathway in a combination with dendritic cell (DC)/tumor fusion vaccine to enhance the CD8⁺ T cell cytokine secretion, activation, proliferation, as well as specific cytotoxicity. Moreover, the CD8⁺ T cells induced by LPS-Nb36 and DC/tumor fusion vaccine led to higher CD8⁺ T cell effector function in vivo, which significantly retarded tumor growth and lengthened survival of tumor-bearing mice (HepG2, A549, and MGC-803). Our data demonstrate that the anti-CTLA-4 Nb-modified liposomes in connection with DC/tumor fusion vaccines enhance the CD8⁺ T cell antitumor activity in vitro and in vivo, and is expected to be an alternative therapy for patients with malignancies that have T cell dysfunction or have poor treatment against anti-CTLA-4 mAb.

Although chimeric antigen receptor (CAR)-T cell therapy has achieved remarkable therapeutic effects in treating hematologic cancers, its effectiveness in solid tumors remains significantly restricted. the primary reason is the immunosuppression mediated by the tumor microenvironment (TME), which leads to rapid exhaustion of infiltrating CAR-T cells. To enhance CAR-T cell efficacy against solid tumors, we pursued improvements in two aspects. First, we constructed fibroblast activation protein (FAP)-directed CAR-T cells to enhance their anti-CAF capability within the TME, thereby alleviating the immunosuppressive barrier. Second, we utilized IL-15, an efficient activator of CAR-T cells that inhibits activation-induced cell death, restores effector functions, and increases the proportion of the T stem cell memory (T _SCM ) subpopulation. In this study, we report the generation of FAP/IL-15 CAR-T cells, which target FAP and autonomously synthesize and secrete IL-15. Our data demonstrate that treatment with FAP/IL-15 CAR-T cells exhibited stronger activation characteristics in a FAP antigen-dependent manner, selectively targeting CAFs within the solid TME. Moreover, endogenous IL-15 secretion enabled CAR-T cells to adopt a T _SCM -like phenotype with enhanced memory characteristics, thus improving cell survival, proliferation, activation, and therapeutic efficacy against solid tumors.