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Published on: September 17, 2013
Efficient Tumor-Targeted Photosensitizer Based on Nanobody-Coupled Pyropheophorbide-a for Precise Photodynamic
Henan Wang1, Yanting Liu1,2, Zongpei He1
1State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Protein Sciences, College of Life Sciences, Nankai University, Tianjin 300071, P. R. China.
Abstract:
The use of antibody-coupled photosensitizers is a promising strategy for tumor-targeted photodynamic therapy (PDT). However, some inherent disadvantages, including poor permeability into solid tumors, a long circulation half-life and random coupling of antibodies and photosensitizers, pose problems for their clinical application. In this study, we proposed an improved design for antibody-coupled photosensitizers based on microbial transglutaminase (mTGase)-catalyzed site-specific coupling of a small-sized nanobody with a stable and easily available photosensitive moiety, pyropheophorbide-a (Pyro), to obtain the NHER2-PEG-Pyro conjugate, in which the high hydrophobicity of Pyro was alleviated by introducing a hydrophilic polyethylene glycol (PEG) chain. In vitro and in vivo experiments confirmed that NHER2-PEG-Pyro had excellent binding selectivity and photodynamic activity toward highly HER2-expressing tumor cells, strongly accumulated in highly HER2-expressing tumor tissues, and eliminated highly HER2-expressing NCI-N87 tumors at a relatively low dose (20 nmol/mouse) as a single therapy. This work demonstrated the excellent therapeutic ability of this nanobody-coupled photosensitizer and highlighted the potential of Pyro as an alternative to IRDye 700DX in the development of tumor-targeted photosensitizers. The advantages of the nanobody and Pyro, along with their site-specific conjugation, confer the conjugate with good potential for clinical application.
Insights
This study developed a novel antibody-coupled photosensitizer for tumor-targeted photodynamic therapy (PDT). The improved design shows excellent selectivity and efficacy against HER2-expressing tumors, offering potential for clinical application.
Area of Science:
- Biomedical Engineering
- Oncology
- Photochemistry
Background:
- Antibody-coupled photosensitizers are promising for tumor-targeted photodynamic therapy (PDT).
- Clinical application is limited by poor tumor permeability, long circulation times, and random antibody-photosensitizer coupling.
- Site-specific conjugation strategies are needed to overcome these limitations.
Purpose of the Study:
- To design and evaluate an improved antibody-coupled photosensitizer using site-specific conjugation.
- To enhance tumor targeting and therapeutic efficacy in photodynamic therapy.
- To explore pyropheophorbide-a (Pyro) as an alternative photosensitizer.
Main Methods:
- Developed NHER2-PEG-Pyro conjugate via microbial transglutaminase (mTGase)-catalyzed site-specific coupling of a nanobody with pyropheophorbide-a (Pyro) and a polyethylene glycol (PEG) linker.
- Investigated in vitro binding selectivity and photodynamic activity against HER2-expressing tumor cells.
- Assessed in vivo tumor accumulation and therapeutic efficacy in NCI-N87 tumor models.
Main Results:
- NHER2-PEG-Pyro demonstrated excellent binding selectivity and photodynamic activity towards HER2-expressing tumor cells.
- The conjugate showed strong accumulation in HER2-expressing tumor tissues.
- A single low dose (20 nmol/mouse) of NHER2-PEG-Pyro effectively eliminated NCI-N87 tumors in vivo.
Conclusions:
- The developed nanobody-coupled photosensitizer exhibits significant therapeutic potential for HER2-expressing tumors.
- Site-specific conjugation and the choice of components (nanobody, PEG, Pyro) are crucial for improved clinical applicability.
- Pyropheophorbide-a shows promise as an alternative to IRDye 700DX for targeted photosensitizer development.
