A novel humanized anti-HER2 antibody conjugated with MMAE exerts potent anti-tumor activity.

Human epidermal growth factor receptor-2 (HER2) is a validated therapeutic target for breast cancer and trastuzumab (Herceptin), a humanized anti-HER2 antibody, has significant anti-cancer effects in the clinic. However, breast cancer patients often experience disease progression after prolonged Herceptin treatment. To develop a more effective therapy, we generated humanized monoclonal antibody hertuzumab and hertuzumab-drug conjugates as novel breast cancer therapies. The hertuzumab was conjugated with small molecule cytotoxic agents monomethylauristatin E (MMAE) or monomethylauristatin F (MMAF) with various linkers to generate antibody-drug conjugates (ADCs), which were evaluated for their in vitro and in vivo anti-cancer activities. Among these ADCs, hertuzumab-vc-MMAE can be effectively internalized and potently kill HER2 over-expressing tumor cells. In xenograft tumor models, hertuzumab-vc-MMAE showed a more potent anti-tumor activity than T-DM1, a FDA-approved ADC drug. More importantly, this novel ADC drug also showed superior anti-tumor activity than T-DM1 in trastuzumab- and lapatinib-resistant xenograft tumor models, suggesting its potential as an improved therapy for HER2-positive breast cancers. The novel ADC, hertuzumab-vc-MMAE, is an effective and selective agent for the treatment of HER2-positive breast tumors.

A fusion fragment from Flt-1 and KDR, acted as VEGF decoy receptor and exhibited anti-tumor function.

Angiogenesis is important in tumor development. Vascular endothelial growth factor (VEGF) is involved in this process. In this report, we constructed a recombinant protein (called FK) by fusing the second immunoglobulin-like (Ig-like) domain of a human fms-like tyrosine kinase (Flt-1) with the third Ig-like domain of human kinase insert domain-containing receptor (KDR). FK bound to VEGF(165) in a dose-dependent manner with a disocciation constant (Kd) of 2.7 pM. In addition, FK specifically inhibited the proliferation of human microvascular endothelial cell (HMEC) and human umbilical vein endothelial Cell (HUVEC) stimulated by VEGF(165). Subsequent studies also demonstrate that FK efficaciously suppresses growth of a variety of tumors, which could make FK a potential drug candidate in anti-tumor therapy.

Monomethyl auristatin E-conjugated anti-EGFR antibody inhibits the growth of human EGFR-positive non-small cell lung cancer.

PURPOSE: Epidermal growth factor receptor (EGFR) is highly expressed on non-small cell lung cancers (NSCLC) and a valuable therapeutic target. This study aimed at producing and characterizing monomethyl auristatin E (MMAE)-conjugated anti-EGFR antibody as a novel EGFR-targeting therapy for NSCLC. METHODS: A humanized anti-EGFR monoclonal antibody (named RC68) was purified and conjugated with MMAE using a MC-VC-PAB or PY-VC-PAB linker. The in vitro and in vivo antitumor activity of RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE were characterized. RESULTS: The RC68 was generated from RC68-expressing cells and had a purity of > 99.0%. The RC68 recognized EGFR on tumor cells, particularly for higher EGFR expressing H125, A431, HCC827 and H1975 cells. The RC68 was conjugated with an average of 4 MMAE molecules to generate RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE, respectively. The RC68-MC-VC-PAB-MMAE, RC68-PY-VC-PAB-MMAE and RC68 displayed similar binding affinity to EGFR on tumor cells, and RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE were effectively internalized by H125 cells. The RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE inhibited the growth of H125 cells in vitro with an IC50 7.37-8.04 ng/mL and implanted H125 tumors in vivo, but did not affect body weights of mice. The antitumor effect of RC68-MC-VC-PAB-MMAE was stronger than RC68-PY-VC-PAB-MMAE, which was also stronger than docetaxel in vivo. CONCLUSIONS: These novel antibody-drug conjugates, particularly for RC68-MC-VC-PAB-MMAE, may be a potential candidate for treatment of EGFR + NSCLC.

Development of a Novel EGFR-Targeting Antibody-Drug Conjugate for Pancreatic Cancer Therapy.

BACKGROUND: Overexpression of epidermal growth factor receptor (EGFR) is common in pancreatic cancer and associated with the poor prognosis of this malignancy. OBJECTIVE: To develop anti-EGFR antibody-drug conjugates (ADCs) for use in a novel EGFR-targeting approach to treat pancreatic cancer. METHODS: A humanized anti-EGFR monoclonal antibody (RC68) was generated by mouse immunization and complementary-determining region grafting technology. Two RC68-based ADCs, RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE, were synthesized by conjugating monomethyl auristatin E (MMAE), a small-molecule cytotoxin, to RC68 through two distinct linkers (MC and PY). Internalization of the RC68-based ADCs was examined by flow cytometry. The in vitro and in vivo antitumor activities of RC68-based ADCs were evaluated in human pancreatic cancer cells and in a BXPC-3 xenograft nude mouse model, respectively. RESULTS: The RC68-based ADCs bound to EGFR on the surface of tumor cells and were effectively internalized, resulting in the death of EGFR-positive cancer cell lines. The RC68-based ADCs (at 5 or 10 mg/kg) were more potent than gemcitabine hydrochloride (60 mg/kg) at inhibiting the growth of BXPC-3 xenografts. Moreover, RC68-PY-VC-PAB-MMAE was found to have superior stability in human plasma compared with RC68-MC-VC-PAB-MMAE. CONCLUSION: A novel EGFR-targeting ADC, RC68-PY-VC-PAB-MMAE, shows promise as an effective, selective, and safe therapeutic agent for EGFR-positive pancreatic cancer.

Development of novel anti-CD19 antibody-drug conjugates for B-cell lymphoma treatment.

B-cell lymphoma remains one of the most refractory tumors, and as such the development of novel treatment approaches, such as antibody-drug conjugates (ADCs), is required. To improve the stability and homogeneity of the ADCs, a humanized anti-CD19 monoclonal antibody (RC58) was developed in the present study. RC58 was based on the CD19 antigen as a potential molecular target of human B-cell lymphomas. RC58 has high CD19-binding affinity and can be internalized in CD19-positive cells through endocytosis. Furthermore, three types of RC58-based ADCs (ADC-1, ADC-2, and ADC-3) were generated using three kinds of Maleimide-PEG-based linkers with two different cytotoxins. The anti-tumor activities of the ADCs were confirmed by in vitro and in vivo experiments. The stability of the ADCs was also evaluated by incubation in human plasma for 10 days. In vitro experiments showed that the three ADCs had distinct inhibitory effects on several B-lymphoma cell lines. Meanwhile, a close correlation between efficacy and drug concentration was found in a nude mouse xenograft model of human B-cell lymphoma, after treatment with RC58-based ADCs. Our results suggest that ADC-1, with high efficiency, could be used as a potential therapeutic agent for human B-cell malignancies.

[Optimization of fermentation of recombinant human Endostatin (rh-Endostatin) expression in Escherichia coli].

The fermentation process of recombinant human Endostatin expression in Escherichia coli BL21 (DE3) was studied. The effects of factors such as concentration of IPTG, induction time, cultivation temperature and feeding strategies were investigated. Beside that, by changing the temperature to 40 degrees C after induction, the high-density cultivation finished in a much shorter period. After 9 hours cultivation, the optical density (OD) at 600 nm reached 140 and the yield of inclusion body was 3 g/L. While E. coli system was used, protein with better activity and stability was obtained. The cost was much lower and the producing process was much steadier. It will meet the demands of the industrial production.