Preparation and characterization of nanoliposomal bortezomib formulations and evaluation of their anti-cancer efficacy in mice bearing C26 colon carcinoma and B16F0 melanoma.

Three Bortezomib (BTZ) liposomal formulations including of HSPC/Cholesterol/DSPE-mPEG2000 (F1), HSPC/DSPG/Cholesterol (F2), and HSPC/DSPG/Cholesterol/DSPE-mPEG2000 (F3) were prepared and characterized. Results demonstrated that the size of formulations ranged 72-92 nm. The DSPE-mPEG2000 containing formulations (F1 and F3) had higher BTZ encapsulation compared to F2 formulation. The size of the liposomal formulations increased slightly when stored at 4 °C for 6 months; the zeta potential of formulations remained constant. There were no significant differences in the release properties BTZ from liposomal formulations in pH 7.0; however, in acidic pH of 5.5 the release of BTZ from F1 and F3 was higher than F2. Three formulations cytotoxicity studies demonstrated IC50 values more than free BTZ on all cell lines examined. Evaluation of antitumor activity in mice bearing C26 colon carcinoma and B16F0 melanoma tumors showed that all the designed liposomal formulations have higher efficacy compared to free BTZ. In tumor models, F2 was more effective than the F1 and F3. Our findings indicated that F2 considerably increased the therapeutic efficacy of BTZ, which promises new formulation with the potential use in clinic and merits further investigation.