Nanoscintillators-induced photodynamic therapy : towards overcoming the low penetration depth of light in tissue

Orateur : Anne-Laure BULIN (Rayonnement Synchrotron et Recherche Médicale, ESRF)

Photodynamic therapy (PDT) is a cancer therapy that demonstrates promising results for the treatment of several cancer types that have dismal prognoses, including brain, gastrointestinal and ovarian cancers. The PDT efficacy stems from non-toxic molecules (photosensitizers) that generate reactive oxygen species in tumor tissues upon light irradiation, inducing cytotoxicity. Although promising, PDT is limited by the shallow penetration of light in tissue and its application remains restricted to small and/or superficial tumors. Recently, technological advances on nanoscintillators have opened the door towards deep tissue PDT. Nanoscintillators are down-converting nanoparticles that absorb high energy X-ray photons and emit visible light, that can subsequently excite nearby photosensitizers and induce PDT in deep tissue embedded tumors and throughout large tumor volumes. Through this mechanism, the RT/PDT combination treatment benefits from three therapeutic components : (1) the RT, (2) the PDT and (3) the radiation dose enhancement effect caused by the accumulation of nanoscintillators with high-Z elements in the tumor tissue. Since the introduction of this idea, proofs of concept have been reported, yet many questions remain to be answered.

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