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An Integrin-Targeted, Highly Diffusive Construct for Photodynamic Therapy
Oliver J Klein1, Hushan Yuan2, Nicholas H Nowell1
1Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 13th St, CNY149, Charlestown, MA, 02129, USA.
Abstract:
Targeted antineoplastic agents show great promise in the treatment of cancer, having the ability to impart cytotoxicity only to specific tumor types. However, these therapies do not experience uniform uptake throughout tumors, leading to sub-lethal cell killing that can impart treatment resistance, and cause problematic off-target effects. Here we demonstrate a photodynamic therapy construct that integrates both a cyclic RGD moiety for integrin-targeting, as well as a 5 kDa PEG chain that passivates the construct and enables its rapid diffusion throughout tumors. PEGylation of the photosensitizer construct was found to prevent photosensitizer aggregation, boost the generation of cytotoxic reactive radical species, and enable the rapid uptake of the construct into cells throughout large (>500 µm diameter) 3D tumor spheroids. Replacing the cyclic RGD with the generic RAD peptide led to the loss of cellular uptake in 3D culture, demonstrating the specificity of the construct. Photodynamic therapy with the construct was successful in inducing cytotoxicity, which could be competitively blocked by a tenfold concentration of free cyclic RGD. This construct is a first-of-its kind theranostic that may serve as a new approach in our growing therapeutic toolbox.
Insights
A novel photodynamic therapy construct targets cancer cells using cyclic RGD for integrin targeting and PEGylation for enhanced diffusion. This approach improves tumor uptake and efficacy, offering a promising new cancer treatment strategy.
Area of Science:
- Biomedical Engineering
- Oncology
- Nanotechnology
Background:
- Targeted antineoplastic agents offer specific cancer cell killing but suffer from non-uniform tumor uptake.
- Sub-lethal drug concentrations can lead to treatment resistance and off-target effects.
Purpose of the Study:
- To develop and evaluate a novel photodynamic therapy (PDT) construct for improved tumor targeting and penetration.
- To investigate the role of integrin-targeting and PEGylation in PDT efficacy.
Main Methods:
- A PDT construct was synthesized, integrating a cyclic RGD peptide for integrin targeting and a 5 kDa PEG chain for passivation.
- The construct's uptake and diffusion in large 3D tumor spheroids were assessed.
- Cytotoxicity was evaluated, and the specificity of targeting was confirmed by replacing RGD with RAD peptide.
Main Results:
- PEGylation prevented photosensitizer aggregation and enhanced the generation of reactive radical species.
- The construct demonstrated rapid cellular uptake and diffusion throughout large 3D tumor spheroids (>500 µm).
- Targeting specificity was confirmed, and PDT with the construct successfully induced cytotoxicity, which was blocked by free cyclic RGD.
Conclusions:
- The developed theranostic construct exhibits enhanced tumor penetration and specific targeting via integrins.
- This PEGylated PDT construct represents a significant advancement in cancer therapy, improving drug delivery and efficacy.
- The findings suggest a new therapeutic approach for overcoming limitations of current targeted cancer therapies.