Launching triple-hit chemo attack on TNBC through nanoparticle-mediated codelivery of cisplatin-chlorambucil conjugate and venetoclax

The BRCA1 dysfunction and HR deficiency in TNBC are responsible for high effectiveness of DNA-damaging agents in TNBC treatment. Preclinical and clinical studies confirmed the effectiveness of cisplatin in TNBC treatment. Nevertheless, the clinical utility of cisplatin is inadequate due to severe systemic side effects and resistance development. Dual-action cisplatin (IV) prodrugs provide an excellent opportunity to improve anticancer activity, reduce toxicities and minimize chance of resistance development. Therefore, in this investigation we have synthesized cisplatin-chlorambucil (CP-CBL) prodrug and loaded it with venetoclax (VTX) in phenylboronic acid conjugated TPGS-lactide nanoparticles (TNPs) to achieve tumor-targeted drug delivery thereby reducing the therapeutic dose as well as increasing the efficacy of free cisplatin, chlorambucil and venetoclax. The TNPs possessed particle size of 143 nm, PDI 0.186 and entrapment efficiency of 63.5 % and 56.4 % for VTX and CP-CBL. The TNPs followed Higuchi release kinetic model and represented biphasic release behaviour with early burst release of drug within 2 h succeeded by sustained drug release till 72 h. Further, the TNPs showed ∼ 42 folds and ∼ 19 folds reduction in the IC₅₀ values compared to free CP. Also, higher cellular uptake and therefore greater apoptotic index was observed for the TNPs in comparison to the untargeted nanoparticles. The TNPs further showed higher ROS generating potential, enhanced mitochondrial membrane depolarization, higher intensity of nuclear condensation and highest level of caspase-3 expression. Moreover, a noteworthy decrease in the tumor volume was noticed in the mice treated with TNPs along with lower serum toxicity biomarker levels compared to the free drugs. Overall, the developed TNPs proved to be a promising and safer strategy for inducing triple-hit action in TNBC management.