Fenretinide in cancer therapy and chemoprevention: past, present and future

Fenretinide [N-(4-hydroxyphenyl) retinamide, 4-HPR] is a synthetic retinoid known for decades for its antitumor activity and favorable toxicological profile. In vitro and in vivo studies have demonstrated that fenretinide has broad-spectrum anticancer potential, eliciting multiple biological effects and acting as a multi-target compound that influences both tumor cells and the tumor microenvironment. However, the clinical application of fenretinide has been hampered by unfavorable physicochemical properties, such as poor solubility and low bioavailability, leading to highly variable outcomes in clinical studies. The development of novel fenretinide nanoformulations based on drug encapsulation in nanomicelles has helped overcome bioavailability limitations and improve anticancer efficacy in preclinical studies, thereby paving the way for new clinical opportunities. Moreover, recent studies have shown that fenretinide restrains the cancer stem cell compartment and promotes tumor cell dormancy, suggesting its potential use in dormancy-inducing strategies aimed at preventing and/or controlling metastatic disease. Here, we provide an overview of fenretinide's mechanisms of action in cancer cells, summarize the available clinical evidence and discuss advances achieved with novel formulations. Finally, we discuss the potential integration of fenretinide at different stages of clinical management, with particular emphasis on its prospective use as a chemopreventive strategy or as a therapeutic option for disease control.