Radiation-induced photodynamic therapy using calcium tungstate nanoparticles and 5-aminolevulinic acid prodrug

• Published in: Biomaterials science Vol. 11; no. 18; pp. 6311 - 6324
• Main Authors: Viswanath, Dhushyanth, Shin, Sung-Ho, Yoo, Jin, Torregrosa-Allen, Sandra E, Harper, Haley A, Cervantes, Heidi E, Elzey, Bennett D, Won, You-Yeon
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 12.09.2023
• Subjects: Aminolevulinic Acid - pharmacology; Aminolevulinic Acid - therapeutic use; Animals; Calcium tungstates; Cell Line, Tumor; Ethylene glycol; Lactic acid; Mice; Nanoparticles; Nanoparticles - therapeutic use; Neoplasms - drug therapy; Penetration depth; Photochemotherapy - methods; Photodynamic therapy; Photosensitizing Agents - pharmacology; Photosensitizing Agents - therapeutic use; Polyethylene glycol; Prodrugs - pharmacology; Prodrugs - therapeutic use; Radiation; Radiation effects; Radiation therapy; Scheelite; Tumors
• ISSN: 2047-4830; 2047-4849
• DOI: 10.1039/d3bm00921a

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) prodrug is a clinically tried and proven treatment modality for surface-level lesions. However, its use for deep-seated tumors has been limited due to the poor penetration depth of visible light needed to activate the photosensitizer protoporphyrin IX (PPIX), which is produced from ALA metabolism. Herein, we report the usage of poly(ethylene glycol- b -lactic acid) (PEG-PLA)-encapsulated calcium tungstate (CaWO 4 , CWO for short) nanoparticles (PEG-PLA/CWO NPs) as energy transducers for X-ray-activated PDT using ALA. Owing to the spectral overlap between radioluminescence afforded by the CWO core and the absorbance of PPIX, these NPs can serve as an in situ visible light activation source during radiotherapy (RT), thereby mitigating the limitation of penetration depth. We demonstrate that this effect is observed across different cell lines with varying radio-sensitivity. Importantly, both PPIX and PEG-PLA/CWO NPs exhibit no significant toxicities at therapeutic doses in the absence of radiation. To assess the efficacy of this approach, we conducted a study using a syngeneic mouse model subcutaneously implanted with inherently radio-resistant 4T1 tumors. The results show a significantly improved prognosis compared to conventional RT, even with as few as 2 fractions of 4 Gy X-rays. Taken together, these results suggest that PEG-PLA/CWO NPs are promising agents for application of ALA-PDT in deep-seated tumors, thereby significantly expanding the utility of the already established treatment strategy. Poly(ethylene glycol- b -lactic acid)(PEG-PLA)-encapsulated CaWO 4 nanoparticles represent a novel tool that can enhance the applicability of 5-aminolevulinic acid(ALA)-based photodynamic therapy (PDT) from surface-level tumors to deep-seated tumors.