8 March 2013 Photodynamic therapy as a local therapeutic adjunct for the treatment of vertebral metastases
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Abstract
Metastatic cancer causes the majority of tumors in bone, most frequently detected in the spinal column. Skeletal complications cause pain and neurologic impairment. Photodynamic therapy (PDT) has been used to treat a variety of cancers. Minimally invasive surgical (MIS) strategies may allow targeted light application essential for PDT within bone structures. The purpose of this manuscript is to provide an update on pre-clinical status as well as early clinical experience of a Phase I clinical trial on vertebral PDT.

A pre-clinical (rnu/rnu rat) vertebral metastasis model of osteolytic (MT-1 breast cancer) was optimized and used to evaluate the effect of vertebral PDT. PDT alone and in combination with other standard local (radiation therapy, RT) and systemic (bisphosphonates, BP) therapies was evaluated through bioluminescence imaging, micro-CT based stereology, histology, and biomechanical testing. Single PDT treatment (photosensitizer BPD-MA, 690nm light) ablated tumor tissue in targeted vertebrae. PDT led to significant increases in bone structural properties, with greatest benefits observed from combined BP+PDT therapy: 76% and 19% increases in bone volume fraction in treated tumor-bearing and healthy untreated controls, respectively. Similar synergistic improvements (but of lesser magnitude) were found in combined PDT+RT treatments.

The safety and feasibility of MIS+PDT were evaluated in scale-up animal studies, refining surgical technique for clinical translation. Following appropriate institutional review board as well as Health Canada approval, 5 patients (light only control group) have undergone protocoled treatment to date. These patients have guided further refinement of human therapeutic application from a laser delivery and vertebral bone access perspective.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Albert Yee, Albert Yee, Shane Burch, Shane Burch, Margarete Akens, Margarete Akens, Emily Won, Emily Won, Victor Lo, Victor Lo, Lisa Wise-Milestone, Lisa Wise-Milestone, Stuart Bisland, Stuart Bisland, Aimee Theriault, Aimee Theriault, Carolyn Niu, Carolyn Niu, Brian C. Wilson, Brian C. Wilson, Cari Whyne, Cari Whyne, } "Photodynamic therapy as a local therapeutic adjunct for the treatment of vertebral metastases", Proc. SPIE 8565, Photonic Therapeutics and Diagnostics IX, 85656O (8 March 2013); doi: 10.1117/12.2019796; https://doi.org/10.1117/12.2019796
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