Mechanism of Action
Glioma-Selective Binding
Chlorotoxin binds to a multi-protein complex on glioma cell surfaces comprising MMP-2 (matrix metalloproteinase-2), chloride channel ClC-3, and annexin A2. This complex is highly enriched on high-grade glioma cells but minimally expressed in normal brain. The binding is specific enough to detect glioma at the single-cell level in histological specimens. After binding, chlorotoxin-MMP-2 complex is internalized, concentrating imaging cargo intracellularly in glioma cells.
Tumor Paint Concept
BLZ-100 (Tumor Paint) conjugates chlorotoxin to the near-infrared fluorescent dye Cy5.5. When injected IV, BLZ-100 crosses the blood-brain barrier selectively in tumor regions and labels glioma cells with fluorescence visible during surgery. The concept is to allow neurosurgeons to visualize tumor margins intraoperatively, improving resection completeness. Phase 2 trials are evaluating safety and tumor-lighting efficacy in pediatric and adult glioma surgeries.
Research Summary
131I-TM601 Phase 2 (Historical)
Phase 2 (Completed)Radiolabeled 131I-chlorotoxin (TM601) was evaluated in Phase 2 trials for recurrent glioblastoma by TransMolecular Inc. Intracranial administration was technically challenging and the trial showed modest tumor-specific localization. The radioiodine approach was superseded by the BLZ-100 optical imaging approach. However, the Phase 2 data established chlorotoxin tumor selectivity in humans, validating the targeting concept.
BLZ-100 Optical Imaging Phase 2
Phase 2 (Active)BLZ-100 (Blaze Bioscience/Stryker) received FDA Breakthrough Device designation and is in Phase 2 trials (PINPOINT trials) across multiple pediatric and adult brain tumor types. Interim data shows fluorescent labeling of glioma with good tumor-to-background ratios. The imaging agent approach to improve surgical outcomes represents a novel paradigm distinct from radiotherapy or systemic drugs.
Calculate your Chlorotoxin dose Vial strength, BAC water, exact syringe draw in IU. Free, no signup. Open Calc →
Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| BLZ-100 tumor imaging (clinical) | 6 mg IV single dose | Single pre-surgical infusion | IV |
| In vitro glioma binding | 10-100 nM | Single treatment | Direct application |
Only investigational imaging use in clinical trials. Not approved for any indication.
Interactions
Safety Profile
BLZ-100 has been well tolerated in Phase 1/2 trials with no significant adverse events attributable to the peptide. The Cy5.5 dye component has a known safety profile. Chlorotoxin itself at low doses does not cause neurological effects in humans in the context of imaging doses. Selectivity for tumor tissue over normal brain is the key safety feature.
References
- [1]DeBin JA, et al. (1993). Purification and characterization of chlorotoxin, a chloride channel ligand from the venom of the scorpion. Am J Physiol, 264(2 Pt 1), C361-369.
- [2]Veiseh M, et al. (2007). Tumor paint: a chlorotoxin:Cy5.5 bioconjugate for intraoperative visualization of cancer foci. Cancer Res, 67(14), 6882-6888.