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A Bioengineered Peptide that Localizes to and Illuminates Medulloblastoma: A New Tool with Potential for
Shelley E Ackerman1, Christy M Wilson2, Suzana A Kahn3
1Bioengineering, Stanford University.
Abstract:
Tumors of the central nervous system are challenging to treat due to the limited effectiveness and associated toxicities of chemotherapy and radiation therapy. For tumors that can be removed surgically, extent of malignant tissue resection has been shown to correlate with disease progression, recurrence, and survival. Thus, improved technologies for real-time brain tumor imaging are critically needed as tools for guided surgical resection. We previously engineered a novel peptide that binds with high affinity and unique specificity to αVβ3, αVβ5, and α5β1 integrins, which are present on tumor cells, and the vasculature of many cancers, including brain tumors. In the current study, we conjugated this engineered peptide to a near infrared fluorescent dye (Alexa Fluor 680), and used the resulting molecular probe for non-invasive whole body imaging of patient-derived medulloblastoma xenograft tumors implanted in the cerebellum of mice. The engineered peptide exhibited robust targeting and illumination of intracranial medulloblastoma following both intravenous and intraperitoneal injection routes. In contrast, a variant of the engineered peptide containing a scrambled integrin-binding sequence did not localize to brain tumors, demonstrating that tumor-targeting is driven by specific integrin interactions. Ex vivo imaging was used to confirm the presence of tumor and molecular probe localization to the cerebellar region. These results warrant further clinical development of the engineered peptide as a tool for image-guided resection of central nervous system tumors.
Insights
A novel peptide probe accurately illuminates brain tumors in mice, offering a promising new tool for image-guided surgery. This advancement could improve tumor resection and patient outcomes in neuro-oncology.
Area of Science:
- Neuro-oncology
- Molecular Imaging
- Biotechnology
Background:
- Central nervous system tumors present significant treatment challenges due to limited efficacy and toxicity of conventional therapies.
- Surgical resection is crucial for managing brain tumors, with extent of resection correlating with patient outcomes.
- Real-time imaging technologies are essential for enhancing surgical precision and improving tumor resection rates.
Purpose of the Study:
- To develop and evaluate a novel peptide-based molecular probe for non-invasive imaging of brain tumors.
- To assess the targeting specificity and efficacy of the engineered peptide for image-guided surgery.
Main Methods:
- Engineered a peptide with high affinity for integrins (αVβ3, αVβ5, α5β1) overexpressed on brain tumor cells and vasculature.
- Conjugated the peptide to a near-infrared fluorescent dye (Alexa Fluor 680) to create a molecular imaging probe.
- Utilized the probe for non-invasive whole-body and ex vivo imaging of patient-derived medulloblastoma xenografts in mice.
Main Results:
- The peptide-dye conjugate demonstrated robust targeting and illumination of intracranial medulloblastoma in mice.
- Effective tumor visualization was achieved following both intravenous and intraperitoneal administration of the probe.
- A control peptide with a scrambled sequence showed no tumor localization, confirming specific integrin-mediated targeting.
- Ex vivo imaging confirmed probe accumulation within the tumor region.
Conclusions:
- The engineered peptide-dye conjugate serves as an effective molecular probe for non-invasive imaging of brain tumors.
- This probe shows significant potential as a tool for image-guided surgical resection of central nervous system tumors.
- Further clinical development is warranted to translate this technology into improved neurosurgical procedures.
