Systemically targeted cancer immunotherapy and gene delivery using transmorphic particles

Immunotherapy is a powerful tool for cancer treatment, but the pleiotropic nature of cytokines and immunological agents strongly limits clinical translation and safety. To address this unmet need, we designed and characterised a systemically targeted cytokine gene delivery system through transmorphic encapsidation of human recombinant adeno‐associated virus DNA using coat proteins from a tumour‐targeted bacteriophage (phage). We show that Transmorphic Phage/AAV (TPA) particles provide superior delivery of transgenes over current phage‐derived vectors through greater diffusion across the extracellular space and improved intracellular trafficking. We used TPA to target the delivery of cytokine‐encoding transgenes for interleukin‐12 (IL12), and novel isoforms of IL15 and tumour necrosis factor alpha (TNF α ) for tumour immunotherapy. Our results demonstrate selective and efficient gene delivery and immunotherapy against solid tumours in vivo , without harming healthy organs. Our transmorphic particle system provides a promising modality for safe and effective gene delivery, and cancer immunotherapies through cross‐species complementation of two commonly used viruses. Synopsis This study describes the characterization of a new phage‐derived gene delivery particle capable of systemic targeting (TPA), demonstrating its superiority over existing phage systemic viral vectors (AAVP), and its application in targeted cytokine gene therapy of cancer. TPA particles are targeted bacteriophage capsids that carry only an expression cassette flanked by AAV‐2 inverted terminal repeat sequences (ITRs), and a phage origin of replication. Following systemic administration in tumor‐bearing mice, the tumor‐targeted RGD4C.TPA binds to αvβ3 integrin receptor in tumors, resulting in selective expression of IL15, IL12, or TNFα cytokines in the tumor microenvironment. TPA‐guided cytokine delivery results in complete tumor eradication in 50% of the treated animals. Targeted expression of IL15 results in proliferation of the immune CD8 + T, natural killer (NK), and T helper 1 (Th1) cells in tumors. Graphical Abstract This study describes the characterization of a new phage‐derived gene delivery particle capable of systemic targeting (TPA), demonstrating its superiority over existing phage systemic viral vectors (AAVP), and its application in targeted cytokine gene therapy of cancer.