Co-delivery nanoparticle targeting CAF for simultaneous activating T cell plus NKT cell attack in solid tumor

• A precise fibroblast-activated protein-α (FAP-α) responsive nanoparticle delivery system was developed. • This FAP-α-responsive delivery system achieves tumor-targeted drug delivery and promotes rapid payload release, enhancing payload penetration within the tumor. • Combining cancer-associated fibroblast (CAF) depletion with natural killer T (NKT) cell activation is a potential strategy for the effective solid tumor immunotherapy. Tumor fibrosis promotes immunosuppression by creating physical barrier that limits immune cell infiltration, posing challenges for immunotherapy. Therefore, it is essential to design a reasoned therapeutic strategy to surmount the tumor immune privilege by activating antitumor immunity and simultaneously destroying the physiological barriers of tumor microenvironment. Aim to develop a fibroblast-activated protein-α (FAP-α) responsive nanoparticle delivery system, (α-GC/NAV)-CPC, which encapsulates navitoclax (NAV) and alpha-galactosylceramide (α-GC). Upon reaching tumor site, the nanoparticles would be disassembled by FAP-α in tumor. The released α-GC activates natural killer T (NKT) and in parallel, the released NAV eliminates cancer associated fibroblasts (CAFs), ultimately breaking down physical barrier and realizing potent anti-tumor activity. To maintain the self-assembly ability and FAP-α responsiveness, the designed amphiphilic block polymers consist of PEG chain as the hydrophilic domain, terminal cholesterol as the hydrophobic domain and FAP-α degradable amino acid residue sequence linkage (Ala-Thr-Gly-Pro-Ala). At the tissue level, the tumor specific fibrosis barrier destroying ability of (α-GC/NAV)-CPC was investigated. Subsequently, the NAV and α-GC were co-encapsulated into nanoparticles. The tumor accumulation, tumoricidal and anti-metastasis efficacy were validated in triple negative breast cancer-bearing models. This strategy can efficiently break down the cancer associated fibroblast based physical barrier. Encapsulated NAV can significantly decrease tumor interstitial fluid pressure (IFP), indicating as 4.9-fold lower than saline control group. Consequently, enhanced tumor infiltration and penetration of immune cells were observed. By quantitative flow-cytometry analysis, the abundances of NKT and T cells in tumors after (NAV/α-GC)-CPC treatment increased over 5 times and 4 times respectively, compared with saline treatment. Encouragingly, in in vivo models, (α-GC/NAV)-CPC treatment even led to 66.7% of mice achieving tumor eradication without recurrence. In further pulmonary metastasis challenge, mice treated with (α-GC/NAV)-CPC rarely displayed lung metastatic nodules.