Som et al. reviewed the physics, chemistry, and mechanics of using imaging for intratumoral (i.t.) delivery of immunotherapy/immunoadjuvants. I.t. delivery may aid in converting immune-cold tumors to a hot phenotype to improve efficacy. Ultrasound and CT imaging are the most used methods for precision drug delivery and monitoring drug distribution; delivery tracing reagents are critical. Using microparticles, hydrogels, and RNA vector carriers for drug delivery may improve local drug distribution and offer controlled sustained release. This can create higher local drug concentrations, which may improve efficacy, and, importantly, reduces the need for repeated treatment.
Contributed by Maartje Wouters
ABSTRACT: Immunotherapy has revolutionized the contemporary oncology landscape, with durable responses possible across a range of cancer types. However, the majority of cancer patients do not respond to immunotherapy due to numerous immunosuppressive barriers. Efforts to overcome these barriers and increase systemic immunotherapy efficacy have sparked interest in the local intratumoral delivery of immune stimulants to activate the local immune response and subsequently drive systemic tumor immunity. While clinical evaluation of many therapeutic candidates is ongoing, development is hindered by a lack of imaging confirmation of local delivery, insufficient intratumoral drug distribution, and a need for repeated injections. The use of polymeric drug delivery systems, which have been widely used as platforms for both image guidance and controlled drug release, holds promise for delivery of intratumoral immunoadjuvants and the development of an in situ cancer vaccine for patients with metastatic cancer. In this review, we explore the current state of the field for intratumoral delivery and methods for optimizing controlled drug release, as well as practical considerations for drug delivery design to be optimized for clinical image guided delivery particularly by CT and ultrasound.