Nanobiopolymer for Direct Targeting and Inhibition of EGFR Expression in Triple Negative Breast Cancer

AbstractTreatment options for triple negative breast cancer (TNBC) are generally limited to cytotoxic chemotherapy. Recently, antiepidermalgrowth factor receptor (EGFR) therapy has been introduced for TNBC patients. We engineered a novelnanobioconjugate based on a poly(b-L-malic acid) (PMLA) nanoplatform for TNBC treatment. The nanobioconjugate carriesanti-tumor nucleosome-specific monoclonal antibody (mAb) 2C5 to target breast cancer cells, anti-mouse transferrinreceptor (TfR) antibody for drug delivery through the host endothelial system, and Morpholino antisense oligonucleotide(AON) to inhibit EGFR synthesis. The nanobioconjugates variants were: (1) P (BioPolymer) with AON, 2C5 and anti-TfR fortumor endothelial and cancer cell targeting, and EGFR suppression (P/AON/2C5/TfR), and (2) P with AON and 2C5 (P/AON/2C5). Controls included (3) P with 2C5 but without AON (P/2C5), (4) PBS, and (5) P with PEG and leucine ester (LOEt) forendosomal escape (P/mPEG/LOEt). Drugs were injected intravenously to MDA-MB-468 TNBC bearing mice. Tissueaccumulation of injected nanobioconjugates labeled with Alexa Fluor 680 was examined by Xenogen IVIS 200 (live imaging)and confocal microscopy of tissue sections. Levels of EGFR, phosphorylated and total Akt in tumor samples were detectedby western blotting. In vitro western blot showed that the leading nanobioconjugate P/AON/2C5/TfR inhibited EGFRsynthesis significantly better than naked AON. In vivo imaging revealed that 2C5 increased drug-tumor accumulation.Significant tumor growth inhibition was observed in mice treated with the lead nanobioconjugate (1) [P = 0.03 vs. controls;P,0.05 vs. nanobioconjugate variant (2)]. Lead nanobioconjugate (1) also showed stronger inhibition of EGFR expressionand Akt phosphorylation than other treatments. Treatment of TNBC with the new nanobioconjugate results in tumorgrowth arrest by inhibiting EGFR and its downstream signaling intermediate, phosphorylated Akt. The nanobioconjugaterepresents a new generation of nanodrugs for treatment of TNBC.