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Poster Display Session (ID 63)
- Event: ELCC 2017
- Type: Poster Display Session
- Presentations: 1
- Coordinates: 5/07/2017, 12:30 - 13:00, Hall 1
10P - In vivo evaluation of combertestatin A-4 phosphate for lung cancer by bioluminescence imaging and multispectral optoacoustic tomography (ID 293)
12:30 - 13:00 | Author(s): R.P. Mason
Vascular disrupting agents (VDA) promise significant therapeutic efficacy against solid tumors by selectively destroying tumor vasculature. Combretestatin A-4 phosphate (CA4P) is a well-characterized VDA that inhibits microtubule polymerization by binding to the colchicine-binding site of beta-tubulin [1,2]. This disruption causes a decrease in blood flow, leading to ischemia and cell death. Photoacoustic tomography (PAT) is a non-invasive technique which allows for high-resolution (∼100μm) spectral imaging. The iThera Multispectral Optoacoustic Tomography inVision 256-TF (MSOT) system allows for high throughput, in vivo imaging of small animals. The MSOT has access to a range of frequencies (680-980nm) with 1nm resolution and so is able to differentiate between numerous different contrasts agents simultaneously.
Female and male nude mice (each group n = 6) were implanted with 2x10 H1299 lung cancer cells subcutaneously. Ten days after implantation, the mice image were acquired in transaxial sections through the tumor region using nine wavelengths ranging from 700-880 nm by MSOT device and bioluminescence images (BLI) were taken by IVIS Spectrum at different time points. Images were reconstructed and processed using manufacturer’s software. Percentage of hemoglobin saturation (%SO~2~) was calculated as %SO~2~ = [HbO~2~/(HbO~2~+Hb)]*100.
VDA caused significant perfusion reduction and hypoxiation at 1 and 3 hours post VDA and mostly recovered at 24 hours. The %SO~2~ of tumor peripheral vessels was decreased from 42.5% at baseline to 33% and 28% at 1 and 3 hours respectively. The %SO2 of the tumor core reduced from 43% at baseline to 27% and 12% at 1 and 3 hours respectively. There was no change in %SO2 of normal tissue (spine). Similarly, BLI signal was reduced by > 90% within 3 hours after administration of CA4P indicating vascular disruption which was confirmed by histology.
We demonstrated the feasibility of MSOT to detect changes in oxyhemoglobin and deoxyhemoglobin based on their unique absorption spectra in order to further elucidate the mechanism of action. CA4P caused significant reduction of perfusion and oxygenation within the tumor. The results indicate strong rationale for further development, particularly in combination with additional therapies.
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All authors have declared no conflicts of interest.