{Reference Type}: Journal Article {Title}: Preliminary preclinical study of Chol-DsiRNA polyplexes formed with PLL[30]-PEG[5K] for the RNAi-based therapy of breast cancer. {Author}: Ye Z;Abdelmoaty MM;Ambardekar VV;Curran SM;Dyavar SR;Arnold LL;Cohen SM;Kumar D;Alnouti Y;Coulter DW;Singh RK;Vetro JA; {Journal}: Nanomedicine {Volume}: 33 {Issue}: 0 {Year}: 04 2021 {Factor}: 6.458 {DOI}: 10.1016/j.nano.2021.102363 {Abstract}: RNA interference molecules have tremendous potential for cancer therapy but are limited by insufficient potency after i.v. administration. We previously found that Chol-DsiRNA polyplexes formed between cholesterol-modified dicer-substrate siRNA (Chol-DsiRNA) and the cationic diblock copolymer PLL[30]-PEG[5K] greatly increase the activity of Chol-DsiRNA against a stably expressed reporter mRNA in primary murine syngeneic breast tumors after daily i.v. dosing. Here, we provide a more thorough preliminary preclinical study of Chol-DsiRNA polyplexes against the therapeutically relevant target protein, STAT3. We found that Chol-DsiSTAT3 polyplexes greatly increase plasma exposure, distribution, potency, and therapeutic activity of Chol-DsiSTAT3 in primary murine syngeneic 4T1 breast tumors after i.v. administration. Furthermore, inactive Chol-DsiCTRL polyplexes are well tolerated by healthy female BALB/c mice after chronic i.v. administration at 50 mg Chol-DsiCTRL/kg over 28 days. Thus, Chol-DsiRNA polyplexes may be a good candidate for Phase I clinical trials to improve the treatment of breast cancer and other solid tumors.