Development and evaluation of oxaliplatin and irinotecan co-loaded liposomes for enhanced colorectal cancer therapy.

Drug combinations are widely employed in chemotherapy for colorectal cancer treatment. However, traditional cocktail combination in clinic causes the uncertainty of the treatment, owing to varying pharmacokinetics of different drugs. The aim of this study was to design co-loaded liposomes to achieve the synchronised delivery and release. Oxaliplatin and irinotecan hydrochloride, as one of recommended combination schemes for the treatment of colorectal cancer in clinic, were co-loaded into the liposomes. The particle sizes of the liposomes were <200nm with uniform size distribution. In vitro release study showed that both drugs could be synchronously released from the liposomes, which means the optimized synergistic ratio of two drugs could be achieved. In vitro cellular uptake revealed that co-loaded liposomes could efficiently deliver different drugs into the same cells, indicating their potential as carriers for enhancing the cancer therapy. CLSM images of cryo-sections for in vivo co-delivery study also revealed that co-loaded liposomes had superior ability to co-deliver both the cargoes into the same tumor cells. Besides, in vivo NIRF imaging indicated that the liposomes could increase the drug accumulation in tumor compared with free drug. In vitro cytotoxicity evaluation demonstrated that co-loaded liposomes exhibited higher cytotoxicity than the mixture of single loaded liposomes in both CT-26 and HCT-116 cells. Furthermore, co-loaded liposomes also presented superior anti-tumor activity in CT-26 bearing BALB/c mice. In vivo safety assessment demonstrated that liposomes had lower toxicities than their solution formulations. These results indicated that oxaliplatin and irinotecan hydrochloride co-loaded liposomes would be an efficient formulation for improving colorectal cancer therapy with potential clinical applications.