No abstract

Breast cancer (BC) is the most common type of malignancy which covers almost one-fourth of all the cancers diagnosed in women. Conventionally, chemo-, hormonal-, immune-, surgery, and radiotherapy are the clinically available therapies for BC. However, toxicity and other related adverse effects are still the major challenges. A variety of nano platforms have been reported to overcome these limitations, among them, exosomes provide a versatile platform not only for the diagnosis but also as a delivery vehicle for drugs. Exosomes are biological nanovesicles made up of a lipidic bilayer and known for cell-to-cell communication. Exosomes have been reported to be present in almost all bodily fluids, viz., blood, milk, urine, saliva, pancreatic juice, bile, peritoneal, and cerebrospinal fluid. Such characteristics of exosomes have attracted immense interest in cancer diagnosis and therapy. They can deliver bioactive moieties such as protein, lipids, hydrophilic as well as hydrophobic drugs, various RNAs to both distant and nearby recipient cells as well as have specific biological markers. By considering the growing interest of the scientific community in this field, we comprehensively compiled the information about the biogenesis of exosomes, various isolation methods, the drug loading techniques, and their diverse applications in breast cancer diagnosis and therapy along with ongoing clinical trials which will assist future scientific endeavors in a more organized direction.

Paclitaxel (PAC) has been approved by FDA for clinical use (Taxol®), yet dose-dependent severe toxicity due to the adjuvant Cremophor EL® in combination with ethanol is a major drawback. The drawbacks of the current therapy can be overcome by (i) finding a suitable vehicle that cannot only bypass the above adjuvant but also be used to deliver drugs orally and (ii) combining the PAC with some other chemotherapeutics to have the enhanced therapeutic efficacy. In the current work, we have used folic acid (FA) functionalized bovine milk-derived exosomes for oral delivery of PAC in combination with 5-fluorouracil (5-FU). Exosomes before and after the drug loading were found to have a particle size in the range of 80–100 nm, polydispersity index (PDI ~0.20), zeta potential (~−25 mV), entrapment efficiency (~82%), practical drug loading (~28%) and sustained drug release for 48 h. Significant decreases in IC50 were observed in the case of exosomes loaded drugs which further improved following the FA functionalization. FA functionalized coumarin-6-loaded exosomes showed remarkably higher cellular uptake in comparison with free coumarin-6. Moreover, FA-functionalized drug-loaded exosomes showed a higher apoptotic index with better control over cell migration. Collectively, data suggested the enhanced efficacy of the combination following its loading to the folic acid functionalized exosomes against breast cancer.

Triple-negative breast cancer is considered the most aggressive type of breast cancer among women and the lack of expressed receptors has made treatment options substantially limited. Recently, various types of nanoparticles have emerged as a therapeutic option against TNBC, to elevate the therapeutic efficacy of the existing chemotherapeutics. Among the various nanoparticles, lipid-based nanoparticles (LNPs) viz. liposomes, nanoemulsions, solid lipid nanoparticles, nanostructured lipid nanocarriers, and lipid–polymer hybrid nanoparticles are developed for cancer treatment which is well confirmed and documented. LNPs include various therapeutic advantages as compared to conventional therapy and other nanoparticles, including increased loading capacity, enhanced temporal and thermal stability, decreased therapeutic dose and associated toxicity, and limited drug resistance. In addition to these, LNPs overcome physiological barriers which provide increased accumulation of therapeutics at the target site. Extensive efforts by the scientific community could make some of the liposomal formulations the clinical reality; however, the relatively high cost, problems in scaling up the formulations, and delivery in a more targetable fashion are some of the major issues that need to be addressed. In the present review, we have compiled the state of the art about different types of LNPs with the latest advances reported for the treatment of TNBC in recent years, along with their clinical status and toxicity in detail.