Self-targeted, bacillus-shaped, and controlled-release methotrexate prodrug polymeric nanoparticles for intratumoral administration with improved therapeutic efficacy in tumor-bearing mice

Poor drug distribution and inefficient drug concentrations within the tumor intracellular environment still limit the therapeutic efficacy of drugs for cancer chemotherapy. Local drug delivery (physical targeting) combined with receptor-mediated drug delivery (chemical targeting) and assistance by a novel shape design is a promising strategy to treat the infiltrating tumor (even those that persist post surgery). In this paper, we prepared dye and methotrexate (MTX) functionalized nanobacilli (MPEG–PLA–MTX–Cy5.5 NB) by a self-assembly technique combined with extrusion through a SPG membrane for intratumoral administration, in which the bacillus-shaped MPEG–PLA–MTX–Cy5.5 NB were armed with a dual-acting MTX that can specifically and efficiently enhance their cellular uptake, while avoiding their dispersion from tumor sites. After intratumoral administration to a H22 xenograft mouse model, the MPEG–PLA–MTX–Cy5.5 NB delivered the drug more effectively to the tumor compared to the MPEG–PLA–Cy5.5 nanospheres (MPEG–PLA–Cy5.5 NSs) and MPEG–PLA–MTX–Cy5.5 nanospheres (MPEG–PLA–MTX–Cy5.5 NSs). Compared to the free MTX and MPEG–PLA–MTX–Cy5.5 NSs, the controlled-release MPEG–PLA–MTX–Cy5.5 NB also significantly inhibited the tumor growth and improved therapeutic efficacy. The platforms are highly convergent, flexible and simplified systems that may serve as guides in the further design of nanoparticles with a revolutionary new shape and function for clinical applications.