Advancing cancer immunotherapy through emerging intratumoral delivery and biomedical imaging technologies

Intratumoral delivery of cytotoxic or immunomodulating compounds is a promising approach for cancer therapy. When a primary tumor or its metastases can be accessed through minimally invasive or conventional surgery, the direct administration of therapeutic agents may serve to not only eradicate local tumors but also reduce systemic tumor burden. Currently, numerous conventional and novel agents are under investigation as intratumoral-based therapies, including immunomodulators that target specific biological pathways and nanomaterials such as high-Z nanoparticle radiosensitizers. While the shift from systemic to intratumoral therapy has been actively investigated in preclinical and clinical research, the adoption of intratumoral drug delivery remains unclear, necessitating the development of new techniques to validate the feasibility and safety of this delivery route. Here, we review and assess recent advances in immunotherapy in terms of biomaterials and delivery platform development and discuss clinically relevant imaging technologies for guiding intratumoral delivery.