Metformin encapsulating immunoliposomes conjugated with anti-TROP 2 antibody fragments for the active targeting of triple negative breast cancer

Abstract

Trophoblast Cell-Surface Antigen 2 (TROP 2) has re-emerged as a promising biomarker in Triple Negative Breast Cancer (TNBC), with high overexpression in many TNBC cases. Despite its potential and the approval of an antibody-drug-conjugate for TNBC treatment, TROP 2 targeted delivery systems are currently under-explored. Therefore, this study aimed to exploit the potential of TROP 2 targeting by encapsulating metformin (Met), an antidiabetic drug associated with tumor growth inhibitory properties, inside liposomes decorated with TROP 2 targeting single-chain variable fragments (scFvs). The optimization of scFv grafting resulted in Met-Immunoliposomes with an average diameter below 200 nm, low polydispersity index (~ 0.1), negative surface charge (less than -10 mV), high Met drug loading (greater than 150 mg/g), and high affinity towards TROP 2 binding. Met-Immunoliposomes were reproducible, the scFv conjugation was stable in the presence of serum during five days, and the cellular uptake was increased 4-fold on two-dimensional and 9-fold on three-dimensional TNBC models due to the high affinity towards TROP 2 binding. Finally, the Met therapeutic effect to suppress cancer cell growth and proliferation was superior with anti-TROP 2 scFv-grafted Met-Immunoliposomes, which completely stopped the spheroid growth and inhibited the expression of adenosine triphosphate. This study is among the first reports to explore the combination of nanoparticle-based drug delivery system to target TROP 2 protein in TNBC, and to the best of our knowledge this is the first report to specifically combine the use of scFvs in TROP 2 targeting to deliver therapeutics for TNBC treatment.