Chemical coupling of an active/passive dual-targeting fusion protein ER(Fv)-HSA to DM1 improves its tumor-specificity and therapeutic efficacy against pancreatic cancer

Owing to the lack of early diagnosis and radio/drug-resistance, the conventional therapies can not achieve ideal therapeutic effects on pancreatic Cancer, thus targeted therapy with efficiency and specificity attracts more attention. In this study, a dual-targeting fusion protein ER(Fv)-HSA sequentially linked by anti-EGFR single-chain variable fragment, G₄S linker and human serum albumin was constructed, and then was coupled with a derivative of maytansine DM1 using succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate linker for fusion protein-drug conjugate ER(Fv)-HSA-DM1, in which the affinity to tumor was preserved. With the help of active targeting of scFv and passive targeting of HSA, ER(Fv)-HSA-DM1 showed excellent tumor-targeting that rapidly accumulated at the tumor site and retained for a long time, moreover, part of conjugate was transported into the cytoplasm. At the same molar concentration, ER(Fv)-HSA-DM1 displayed stronger cytotoxicity than DM1 on pancreatic Cancer cells, with the half-maximal inhibitory concentration value of 10^-10-10^-9 M, reflecting in microtubule networks destruction, cell cycle arrest and Apoptosis. In AsPC-1 xenograft athymic mice models, the inhibition rate of DM1 at the dosage used equivalent to human clinical dosage was only 37.3 %, while the inhibition rate of ER(Fv)-HSA-DM1 loaded molar equivalent DM1 was 53.6 %, without any body weight loss. The results revealed that ER(Fv)-HSA effectively endowed DM1 with tumor-targeting and improved its antitumor efficacy, indicating active/passive dual-targeting fusion protein might be a feasible strategy for development of new targeted drugs for pancreatic Cancer therapy.