American Association for Cancer Research
crc-23-0269_fig2.png (707.56 kB)

FIGURE 2 from Nanoparticle-mediated Photodynamic Therapy as a Method to Ablate Oral Cavity Squamous Cell Carcinoma in Preclinical Models

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posted on 2024-03-15, 14:20 authored by Axel Sahovaler, Michael S. Valic, Jason L. Townson, Harley H.L. Chan, Mark Zheng, Sharon Tzelnick, Tiziana Mondello, Alon Pener-Tessler, Donovan Eu, Abdullah El-Sayes, Lili Ding, Juan Chen, Catriona M. Douglas, Robert Weersink, Nidal Muhanna, Gang Zheng, Jonathan C. Irish

Photophysical and photochemical characterization of PS nanoparticles. A, Structure and composition of PS: PEGylated porphyrin-lipid conjugate-containing nanoparticles. B, Transmission electron microscopy of negatively stained PS nanoparticle morphology. Scale bar, 0.1 µm. C, Molar attenuation coefficient (ε) profile of intact and disassembled PS in aqueous media. Intact PS are suspended in 1x PBS and disassembled PS are treated with a non-ionic surfactant (Triton X-100). Note ε reported here on basis of mols of porphyrin-lipid conjugate. D, Fluorescence spectra of intact and disassembled PS nanoparticles in aqueous media at excitation wavelength 416 nm. Note the 100-fold increase in fluorescence intensity in the disassembled PS versus the intact PS at 675-nm wavelength. E, Singlet oxygen (1O2) generation of intact and disassembled PS nanoparticles in aqueous media with increasing light dose. Note the approximately 4-fold increase in 1O2 generation in the disassembled PS versus the intact PS using 671-nm excitation wavelength (50 mW). Mean ± SD. N = 5 samples/light dose. Additional material characterizations of PS described in Supplementary Fig. S1 and Supplementary Table S1.


Terry Fox Research Institute (TFRI)

Princess Margaret Cancer Foundation (PMCF)



Photodynamic therapy (PDT) is a tissue ablation technique able to selectively target tumor cells by activating the cytotoxicity of photosensitizer dyes with light. PDT is nonsurgical and tissue sparing, two advantages for treatments in anatomically complex disease sites such as the oral cavity. We have previously developed PORPHYSOME (PS) nanoparticles assembled from chlorin photosensitizer–containing building blocks (∼94,000 photosensitizers per particle) and capable of potent PDT. In this study, we demonstrate the selective uptake and curative tumor ablation of PS-enabled PDT in three preclinical models of oral cavity squamous cell carcinoma (OCSCC): biologically relevant subcutaneous Cal-33 (cell line) and MOC22 (syngeneic) mouse models, and an anatomically relevant orthotopic VX-2 rabbit model. Tumors selectively uptake PS (10 mg/kg, i.v.) with 6-to 40-fold greater concentration versus muscle 24 hours post-injection. Single PS nanoparticle–mediated PDT (PS-PDT) treatment (100 J/cm2, 100 mW/cm2) of Cal-33 tumors yielded significant apoptosis in 65.7% of tumor cells. Survival studies following PS-PDT treatments demonstrated 90% (36/40) overall response rate across all three tumor models. Complete tumor response was achieved in 65% of Cal-33 and 91% of MOC22 tumor mouse models 14 days after PS-PDT, and partial responses obtained in 25% and 9% of Cal-33 and MOC22 tumors, respectively. In buccal VX-2 rabbit tumors, combined surface and interstitial PS-PDT (200 J total) yielded complete responses in only 60% of rabbits 6 weeks after a single treatment whereas three repeated weekly treatments with PS-PDT (200 J/week) achieved complete ablation in 100% of tumors. PS-PDT treatments were well tolerated by animals with no treatment-associated toxicities and excellent cosmetic outcomes. PS-PDT is a safe and repeatable treatment modality for OCSCC ablation. PS demonstrated tumor selective uptake and PS-PDT treatments achieved reproducible efficacy and effectiveness in multiple tumor models superior to other clinically tested photosensitizer drugs. Cosmetic and functional outcomes were excellent, and no clinically significant treatment-associated toxicities were detected. These results are enabling of window of opportunity trials for fluorescence-guided PS-PDT in patients with early-stage OCSCC scheduled for surgery.

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