Author of

• 11515

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  P2.05 - Poster Session 2 - Preclinical Models of Therapeutics/Imaging (ID 158)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11524

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    P2.05-009 - Porphysome-enhanced bronchoscopic fluorescence detection and photothermal ablation of peripheral lung cancer: Preliminary in vivo studies (ID 1105)

    09:30 - 09:30  |  Author(s): B. Wilson
    • Abstract

    Background
    Bronchoscopic ablation of lung cancer has to date been limited to carcinoma in-situ located in the central airway or, using high-power lasers, to palliation in advanced obstructive disease . Bronchoscopic ablation of peripheral lung cancer is still under development. We are developing a new technology platform for localization (by fluorescence) and enhanced photothermal therapy (PTT) of peripheral lung lesions, based on porphysomes, which are novel, multi-functional, all-organic porphyrin-lipid nanoparticles. Even without active targeting, porphysomes accumulate within tumor through the enhanced permeability and retention (EPR) effect. In parallel, we have developed a prototype fluorescent endoscope system that allows visualization of peripheral lesions by the porphyrin fluorescence. Using this combination of novel instrumentation and nanoparticles, endoscopic PTT of lung cancer is demonstrated in preclinical lung cancer animal models in vivo.

    Methods
    The in vivo porphysome biodistribution was evaluated in both orthotopic lung tumors (A549, H460, H520) in mice and in VX2 tumors implanted directly in rabbit lung. Porphysomes were administered intravenously at a dose of 20 mg/kg, and the tumor fluorescence was imaged in vivo daily for 3 days (excised lung in the mouse model and endoscopically in the rabbit model). Ex vivo VX2 tissue was illuminated using a 670 nm diode laser to determine the optimized treatment parameters for PTT. Subsequently, in vivo bronchoscopic visualization of VX2 fluorescence and PTT was demonstrated in the rabbit model. The extent of ablation was histologically evaluated by NADH metabolic activity staining.

    Results
    The highest tumor-to-normal lung fluorescence ratio was achieved at 48 h post-injection of porphysomes(Rabbit VX2: n=4). The same trend was confirmed in the 3 kinds of orthotopic lung cancer mouse Xenografts (n=8). The ex vivo study revealed that 250 mW and 10 min of 670 nm laser irradiation raised the tumor tissue temperature by more than 20[o]C, so that this setting was used also in vivo and achieved thermal coagulation zones within the tumor of up to 13 mm diameter. In comparison, laser treatment alone without porphysomes caused minimal ablation zones of < 1.5 mm diameter.

    Conclusion
    Systemically administrated porphysomes accumulated in the lung cancer tissue with a high enough concentration to enable marked photothermal coagulation. The combination of systemically-administrated porphysomes with endoscopic near-infrared laser irradiation is a promising strategy for minimally-invasive bronchoscopic interventional therapy for peripherally-located lung cancer.