DOI: 10.1039/C6CC09624G
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ChemComm
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volume by only 39 % over the same time period (p < 0.001). Indeed, inadvertent tissue damage could have serious consequences for the
4 days after PDT treatment, the tumours reduced from their pre- patient.
treatment size by 10 %. Between days 4-7 the tumours gradually
In conclusion, we have demonstrated that the addition of iodine
increased back to their pre-treatment values but following a second atoms to the basic structural skeleton of an NIR absorbing
PDT treatment on day 8 they again reduced in volume until day 11, indocyanine dye, improves singlet oxygen production and enhances
when the experiment was terminated due to the control tumours PDT mediated cytotoxicity when compared to the non-iodinated and
reaching their maximum permissible size.
clinically-approved analogue ICG. PDT treatment of mice bearing
In the above in vivo study, an intra-tumoral injection was used to ectopic human xenograft BxPC-3 pancreatic tumours using 6a
preclude variables associated with systemic delivery and guarantee significantly reduced tumour burden and was sufficiently fluorescent
that a consistent dose of sensitiser was administered to each subject. to enable real-time NIR fluorescence imaging in vivo. Pancreatic
In the clinic however, PDT treatment of pancreatic cancer requires cancer remains one of the most recalcitrant forms of the disease in
intravenous (IV) administration of the sensitiser followed by which survival statistics haven’t changed in over 40 years, illustrating
ultrasound or MRI guided interstitial light treatment. We were a clear unmet need for alternative approaches to treat the disease. NIR
therefore interested in examining the specificity of uptake of 6a by activated PDT using 6a may provide an alternative approach to
pancreatic tumours following IV administration.18 In addition, this conventional chemotherapy as a neo-adjuvant or palliative treatment
experiment would also allow us to assess the potential of 6a as a real- for patients who present with locally advanced or metastatic disease.
time NIR fluorescence imaging agent. A solution of 6a was Since the latter represent over 70% of patients, such a treatment could
find widespread appeal as a minimally invasive treatment with limited
off-target side-effects.
Acknowledgements: JFC thanks Norbrook Laboratories Ltd for an
endowed chair.
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