Antitumor activity of raloxifene-targeted poly(styrene maleic acid)-poly (amide-ether-ester-imide) co-polymeric nanomicelles loaded with docetaxel in breast cancer-bearing mice

Purpose Raloxifene (RA) receptors have over-expressed GPER-positive breast cancer tumors. The purpose of this work was to evaluate the antitumor activity and pharmacokinetic behavior of docetaxel (DTX), loaded in RA-targeted nanomicelles, which were designed to overcome a lack of specific distribution and inadequate DTX concentration in tumor tissues, as well as its cytotoxicity and damage to normal tissues. Methods DTX-loaded RA-targeted poly(styrene maleic acid) (SMA)- poly(amide-ether-esterimide)-poly(ethylene glycol) (PAEEI-PEG) nanomicelles were prepared; then, their antitumor activity and survival rate were studied in MC4-L2 tumors induced in BALB/c mice. The pharmacokinetics of DTX-loaded SMA-PAEEI-PEG-RA micelles was also investigated in comparison with free DTX. Results DTX-loaded SMA-PAEEI-PEG-RA micelles inhibited tumor growth considerably and increased animal survival as compared to free DTX and non-targeted micelles. SMA-PAEEIPEG-RA micelles enhanced significantly the area under the curve (AUC0-∞) 1.3 times as compared to free DTX and reduced clearance (CL) from 410.43 ml/kg.h (for free DTX) to 308.8 ml/kg.h (for SMA-PAEEI-PEG-RA micelles). Volume of distribution (Vdss) was also reduced 1.4 times as compared to free DTX. RA-targeted micelles increased tumor inhibition rate (TIR) 1.3 times and median survival time (MST) >1.5 times compared to free DTX. Percentage increase in life span (%ILS) was also enhanced significantly from 41.66% to >83.33% in MC4-L2 tumor-bearing BALB/c mice. Discussion All studies in this work showed the potential of DTX-loaded SMA-PAEEI-PEG-RA micelles in the treatment of GPER-positive receptor breast cancer tumors.