BR2 and CyLoP1 enhance in-vivo SN38 delivery using pegylated PAMAM dendrimers.

The usage of 7-Ethyl-10-hydroxy-camptothecin (SN38) as the most biologically active member of camptothecin family is restricted because of its poor solubility in pharmaceutical solvents. Polyamidoamine (PAMAM) dendrimers, can be used as suitable drug delivery carrier for poorly water soluble molecules. In this study, we prepared two cell penetrating peptides (BR2 and CyLoP1) conjugated formulations of PEGylated PAMAM containing SN38. In vitro cytotoxicity and cellular uptake were investigated on murine colon carcinoma (C26) cell line. Then in vivo antitumor efficacy and survival analysis were studied in C26 mice bearing tumor. Blood serum level in different time points and biodistribution in major organs were determined using fluorometry. In vitro evaluations revealed the IC50 range of 154.4-635 nM in two exposure times for all preparations that was much lower compared to SN38 solution. Cellular uptake studies showed a time-dependent manner and higher values for CPP conjugated dendrimers. In vivo results indicated survival improvements of all prepared formulations and significantly better tumor growth inhibition of most CPP-conjugated formulations compared to Irinotecan. Biodistribution studies confirmed higher tumor accumulations for most of formulations comparing to positive control. In conclusion; prepared CPP-targeted dendrimeric formulations of SN38 exhibited efficient characteristics in tumor inhibitory.