The Current Landscape of Nanopaclitaxel Formulations and the Benefits of Polymeric Micellar Paclitaxel in Solid Tumors

Abstract The tumor microenvironment (TME) creates a complex biochemical and physical barrier affecting the penetration of chemotherapeutic agents into the tumor. Nanotherapy, which allows targeted drug delivery, has generated considerable interest in recent times to overcome the limitations of conventional chemotherapeutics and target the TME. The therapeutic efficacy of nanoformulations is significantly influenced by the particle size. Paclitaxel (PTX) is one of the most effective chemotherapeutic drugs for solid tumors, but its major limitation is its low water solubility. Its organic solvent formulation (Taxol) is known to cause severe toxicity. Therefore, various PTX nanoformulations have been developed using carriers, such as albumin, liposomes, and polymeric micelles. Each carrier has specific characteristics that offer some advantages and also lead to some limitations. There is scarce literature on the comparative profiles of the various types of PTX nanoformulations. Polymeric micelles that are smaller than 100 nm have acquired considerable attention due to their unique structure and high-loading capacity. Currently, there is only one approved and marketed formulation of polymeric micellar PTX (Genexol-PM). Over the years since preclinical evaluation, 22 studies on Genexol-PM in various solid tumors have been published, making it the most widely studied polymeric micellar PTX, demonstrating its safety, efficacy, and higher maximum tolerated dose compared to the conventional formulations. However, many of these were phase 2 trials, and studies on the available liposomal PTX formulations are scarce. There is a need for more PTX nanoformulations with different carriers, and more phase 3 and phase 4 studies on the available PTX nanoformulations. Moreover, head-to-head studies comparing the outcomes of various PTX nanoformulations are necessary to help clinicians make an informed decision when choosing nano PTX for their patients.