PHOTO REACTIVE THERAPY

Our proprietary Photo Reactive Therapy involves the application of a photosensitizing drug such as 5-aminolevulinic acid (5-ALA) followed by activation with light to produce a photodynamic effect. The most commonly used wavelengths are 640nm (red light) and 400-450nm (blue light). After topical application, the thermo photosensitizing drug preferentially accumulates in the tumor and dysplastic cells, and is converted into the photosensitizer protoporphyrin IX (PpIX.) When activated by light, PpIX generates cytotoxic reactive oxygen species that selectively destroy cells, and may cause malignant and nonmalignant hyperproliferative tissue to be destroyed or to decrease in size. 

MITI's pulsed light source provides a simple and efficient light source for the activation of photodynamic diagnostic dyes. This light source is extremely rich in UV, and can generate sufficient narrow-band wavelengths to activate these dyes, while providing visual imaging capability simultaneously through a single device. Initial laboratory tests demonstrated Pulsed Xenon’s ability to not only excite these dyes, but to obtain high quality digital images as well. The photo below illustrates a diagnostic monochrome visual image of fluorescein, a photo reactive dye, after injection into human tissue, as viewed through an endoscope. 

 Visual Image of Human Tissue Exposed to MITI UV Lightwaves

According to the American Cancer Society, recent studies of laparoscopic fluorescence suggest that in vivo fluorescence may improve the early detection of intra-peritoneal ovarian carcinoma micro metastases. In vivo fluorescence has also been used to detect occult gastrointestinal tumors, as well as peritoneal colon carcinoma metastases that were, previously, undetected. Fluorescence-based laparoscopy has also provided improved diagnostic accuracy in the staging of hepato-cellular carcinoma, particularly in patients potentially suitable for partial liver resection or transplantation. It has also been used for in vivo detection of metastatic ovarian cancer in a rat model. In this study, tumor-free peritoneum did not show fluorescence, and was significantly distinguishable from cancer nodules.

The use of the TheraScope for closed endoscope procedures that employ photo fluorescence represents a new capability of viewing tissue and blood vessels that cannot be seen with current endoscopes. The use of these dyes for diagnosis has only been available in open surgical procedures using a “Woods Light.” TheraScope will be used in such procedures to identify tumors, blood restrictions, and major arteries and other images that can only be seen as topographical images in the visible spectrum. MITI will develop specialized rigid and flexible endoscopes that, harnessing the ultraviolet spectra, will activate photo reactive anti-cancer agents and diagnostic dyes that show differential adhesion to tumors. We expect to seek FDA approval in late 2008.