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Monoclonal antibody-mediated drug targeting to choroidal neovascularization in the rat
H Kamizuru1, H Kimura, T Yasukawa
1Department of Ophthalmology and Visual Sciences, Graduate School of Medicine, Kyoto University, Japan.
Purpose:
Active drug targeting mediated by monoclonal antibodies (mAbs) of vascular endothelial cells in tumors is a new concept in cancer therapy. Integrin alphavbeta3 has been reported to be strongly expressed in vascular endothelial cells of surgically excised choroidal neovascular membranes and is thought to be a potential antigen for mAb-mediated drug targeting of choroidal neovascularization (CNV). The objective of this study was to evaluate the efficacy of drug targeting mediated by anti-integrin alphavbeta3 mAbs in a laser-induced CNV rat model.
Methods:
The mitomycin C (MMC)-dextran (MMCD) conjugate was synthesized with a carbodiimide-catalyzed reaction. The mAb was conjugated with MMCD (MMCD-mAb). To evaluate the feasibility of mAb-mediated drug targeting in vitro, we investigated the effect of the immunoconjugates involving dextran-binding MMC on the proliferation of human umbilical vein endothelial cells (HUVECs). CNV was induced by laser photocoagulation in male Brown Norway rats. Immunolocalization of integrin alphavbeta3 in CNV lesions was assessed immunohistochemically with the anti-von Willebrand factor antibody as an endothelial cell marker. Intravenous administration of saline (n = 7), 1 mg/day mAb (n = 7), 100 microg/kg per day free MMC (n = 7), MMCD with irrelevant Ab (n = 7), unconjugated MMCD with unconjugated mAb (MMCD+mAb; n = 7), or MMCD with mAb (MMCD-mAb; n = 8) containing an equal amount of free MMC, was performed daily for 3 days from day 14 after CNV induction. CNV was assessed by fluorescein angiography 2 weeks after treatment. Fluorescein leakage was scored on a four-grade scale. The animals were killed 2 weeks after treatment, and the lesions were evaluated histologically.
Results:
The inhibition of immunoconjugates on the proliferation of HUVECs was enhanced specifically by the mediatory effect of the mAb. Endothelial cells demonstrated strong immunoreactivity of integrin alphavbeta3 in the CNV. In the vehicle-treated group, fluorescein leakage equal to that before treatment was observed 2 weeks after treatment, with an average score of 2.00 +/- 0.17 (mean +/- SEM). MMCD-mAb significantly inhibited the development of CNV in rats (P < 0.01). Moreover, the thickness of the lesions was significantly reduced in the MMCD-mAb-treated group (P < 0.01).
Conclusions:
Immunoconjugates effectively inhibited progression of CNV in this model. The results suggest that mAb-mediated drug targeting may be beneficial in the treatment of CNV.
Insights
Monoclonal antibody (mAb)-mediated drug targeting shows promise for treating choroidal neovascularization (CNV). This study demonstrated that anti-integrin alphavbeta3 mAb conjugates effectively inhibited CNV progression in a rat model.
Area of Science:
- Ophthalmology
- Oncology
- Biotechnology
Background:
- Active drug targeting using monoclonal antibodies (mAbs) is an emerging cancer therapy strategy.
- Integrin alphavbeta3 is highly expressed on vascular endothelial cells in choroidal neovascularization (CNV), making it a potential target for mAb-mediated drug delivery.
Purpose of the Study:
- To assess the efficacy of drug targeting mediated by anti-integrin alphavbeta3 mAbs in a laser-induced CNV rat model.
Main Methods:
- Synthesized a mitomycin C (MMC)-dextran (MMCD) conjugate and then conjugated it with an anti-integrin alphavbeta3 mAb (MMCD-mAb).
- Evaluated in vitro effects of immunoconjugates on human umbilical vein endothelial cell (HUVEC) proliferation.
- Induced CNV in rats via laser photocoagulation and assessed integrin alphavbeta3 expression immunohistochemically.
- Administered various treatments including MMCD-mAb, free MMC, and controls intravenously for 3 days.
- Assessed CNV by fluorescein angiography and histological evaluation 2 weeks post-treatment.
Main Results:
- In vitro studies showed enhanced inhibition of HUVEC proliferation by mAb-mediated immunoconjugates.
- Strong integrin alphavbeta3 immunoreactivity was observed in CNV lesions.
- MMCD-mAb treatment significantly inhibited CNV development and reduced lesion thickness compared to controls (P < 0.01).
Conclusions:
- Immunoconjugates demonstrated significant efficacy in inhibiting CNV progression in the experimental model.
- The findings suggest that mAb-mediated drug targeting holds therapeutic potential for treating CNV.