Biological targeting is crucial for effective cancer treatment with reduced toxicity but is limited by the availability of tumor surface markers. To overcome this, we developed a nanoparticle-based (NP-based), tumor-specific surface marker–independent (TRACER) targeting approach. Utilizing the unique biodistribution properties of NPs, we encapsulated Ac4ManNAz (Maz) to selectively label tumors with azide-reactive groups. Surprisingly, while NP-delivered Maz was cleared by the liver, it did not label macrophages, potentially reducing off-target effects. To exploit this tumor-specific labeling, we functionalized anti–4-1BB Abs with dibenzocyclooctyne to target azide-labeled tumor cells and activate the immune response. In syngeneic B16F10 melanoma and orthotopic 4T1 breast cancer models, TRACER enhanced the therapeutic efficacy of anti–4-1BB, increasing the median survival time. Immunofluorescence analyses revealed increased tumor infiltration of CD8+ T and NK cells with TRACER. Importantly, TRACER reduced the hepatotoxicity associated with anti–4-1BB, resulting in normal serum ALT and AST levels and decreased CD8+ T cell infiltration into the liver. Quantitative analysis confirmed a 4.5-fold higher tumor-to-liver ratio of anti–4-1BB accumulation with TRACER compared with conventional anti–4-1BB Abs. Our work provides a promising approach for developing targeted cancer therapies that circumvent limitations imposed by the paucity of tumor-specific markers, potentially improving efficacy and reducing off-target effects to overcome the liver toxicity associated with anti–4-1BB.
Hyesun Hyun, Bo Sun, Mostafa Yazdimamaghani, Albert Wielgus, Yue Wang, Stephanie Ann Montgomery, Tian Zhang, Jianjun Cheng, Jonathan S. Serody, Andrew Z. Wang
TRACER improves the efficacy of anti–4-1BB in vivo.