Genetically modified Ferritin nanoparticles have been used to selectively deliver a photosensitizer to tumors and prevent the traditional pitfalls of using Photodynamic Therapy (PDT) (ACS Nano 2013, DOI:10.1021/nn402199g). Given the versatility of the ferritin particles, this technique could be extended to treat a broad range of cancers with high efficacy of drug delivery and minimal side effects. Despite decades of research and vast sums of money, cancer remains one of the highest causes of mortality worldwide. This investment has yielded powerful new therapeutics, but issues with biocompatibility, immunogenicity, and toxicity have prevented the widespread use of many of these drugs. While nanotechnology was purported to revolutionize drug delivery, it has failed to make many clinically significant gains over previous drugs. Postdoctoral researcher Zipeng Zhen and assistant professor Jin Xie have recently developed a ferritin-based PDT drug delivery platform that can deliver large amounts of a hydrophobic PDT agent to tumors with meager concerns from the above issues or other side effects. Ferritin, with the primary function of iron storage, is a nearly ubiquitous iron storage protein found in most living organisms. When grown in an iron deficient system, ferritin has a hollow core that can be filled with various therapeutics or imaging agents. Taking advantage of the loading potential, the researchers were able to load several times more of a PDT agent by weight into the ferritin particles compared with other reported PDT agent nanocarriers. This work has received wide attention and was reported by C&EN. Tumor targeting molecules were imparted onto the ferritin surface by genetic modification. This allowed the efficient localization of the ferritin particles to the tumor and limited collateral damage from the PDT agent. With traditional PDT therapy, patients are required to avoid powerful sources of light for up to two months after the initial treatment. Failure to do so can result in serious toxicity to the skin. Due to encapsulation by the targeted ferritin particles, no skin toxicity was observed, even with a high tumor inhibition rate. Given the favorable compatibility profiles of the ferritin particles and the excellent therapeutic results of PDT, there is potential for this targeted ferritin mediated delivery to be clinically evaluated.
