Development of a novel multi-functional integrated bioconjugate effectively targeting K-Ras mutant pancreatic cancer / 药物分析学报

Folate receptor(FR)overexpression occurs in a variety of cancers,including pancreatic cancer.In addi-tion,enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer.Furthermore,the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer.In this study,a novel FR-directed,macropinocytosis-enhanced,and highly cytotoxic bioconjugate folate(F)-human serum albumin(HSA)-apoprotein of lidamycin(LDP)-active enediyne(AE)derived from lidamycin was designed and prepared.F-HSA-LDP-AE consisted of four moieties:F,HSA,LDP,and AE.F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells.Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells.By in vivo optical imaging,F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice,showing clear and lasting tumor localization for 360 h.In the MTT assay,F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines.It also induced apoptosis and caused G2/M cell cycle arrest.F-HSA-LDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice.At well-tolerated doses of 0.5 and 1 mg/kg,(i.v.,twice),the inhibition rates were 91.2％and 94.8％,respectively(P＜0.01).The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

Preparation and anti-tumor activity of a novel antibody-drug conjugate 607-LDM / 药学学报

Antibody-drug conjugates (ADCs) are one of the most important classes of anticancer therapeutics. Human epidermal growth factor receptor-2 (HER2), which is highly expressed in many types of aggressive cancers including breast and ovarian cancer, has been approved as an ideal target for ADCs. Lidamycin (LDM), developed by Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, is an enediyne-containing antibiotic with potent anti-tumor activity. LDM is a promising payload for ADCs. In the present research, using a special site-directed conjugating technology, we made a novel ADC (607-LDM) with a drug-to-antibody ratio (DAR) of 2 and composed of the anti-HER2 antibody 607 and LDM. The new ADC exhibited potent antitumor activity against human ovarian cancer SKOV3 and breast cancer BT-474 cells. It also induced apoptosis and G2/M arrest. In nude mice with SKOV3 xenografts and a tumor volume of 150-200 mm3, a single intravenous injection 607-LDM at 1 mg·kg-1 induced tumor growth inhibition of 72.4%, which was significant compared to either LDM (50.6%) or antibody (30.2%) treatment alone, or both in combination (50.1%, P < 0.05). All animal experiments were performed in accord with National Regulations and approved by the Animal Experiments Ethical Committee of College of Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences. The novel ADC designed in this study, 607-LDM, is a promising candidate for the treatment of HER2-positive cancers.

An overview of antibody-based cancer therapy / 药学学报

The use of monoclonal antibodies (mAbs) for cancer therapy has achieved considerable success in recent years. Approximate 17 monoclonal antibodies have been approved as cancer therapeutics since 1997. Antibody-drug conjugates (ADC) are powerful new treatment options for cancer, and naked antibodies have recently achieved remarkable success. The safety and effectiveness of therapeutic mAbs in oncology vary depending on the nature of the target antigen and the mechanisms of tumor cell killing. This review provides a summary of the current state of antibody-based cancer therapy, including the mechanisms of tumor cell killing by antibodies, tumor antigens as antibody targets, clinical effectiveness of antibodies in cancer patients and nanoparticles-based ADCs.

Construction and screening of phage antibody libraries against epidermal growth factor receptor and soluble expression of single chain Fv / 药学学报

Recent studies have shown that epidermal growth factor receptor (EGFR) is an important target for cancer therapy. The present study prepared single chain Fv (scFv) directed against EGFR. Balb/c mice were immunized by human carcinoma A431 cells, and total RNA of the splenic cells was extracted. VH and VL gene fragments were amplified by RT-PCR and further joined into scFv gene with a linker, then scFv gene fragments were ligated into the phagemid vector pCANTAB 5E. The phagemid containing scFv were transformed into electro-competent E. coli TG1 cells. The recombinant phage antibody library was constructed through rescuing the transformed cells with help phage M13K07. The specified recombinant phages were enriched through 5 rounds of affinity panning and the anti-EGFR phage scFv clones were screened and identified with ELISA. A total of 48 clones from the library were selected randomly and 45 clones were identified positive. After infecting E. coli HB2151 cells with one positive clone, soluble recombinant antibodies about 27 kD were produced and located in the periplasm and the supernatant. The result of sequencing showed that the scFv gene was 768 bp, which encoded 256 amino acid residues. VH and VL including 3 CDRs and 4 FRs, respectively, were all homologous to mouse Ig. The soluble scFv showed the specific binding activity to purified EGFR and EGFR located in carcinoma cell membrane. The successful preparation of anti-EGFR scFv will provide an EGFR targeted molecule for the development of antibody-based drugs and biological therapy of cancer.