LED-PHOTODYNAMIC THERAPY FOR CANCER
Photodynamic Therapy (PDT) is a cancer treatment modality that recently has been applied as adjuvant therapy for brain tumors. PDT consists of intravenously injecting a photosensitizer, which preferentially accumulates in tumor cells, into a patient and then activating the photosensitizer with a light source. This results in free radical generation followed by cell death. The development of more effective light sources for PDT for brain tumors has been facilitated by applications of space light-emitting diode array technology; thus permitting deeper tumor penetration of light and use of better photosensitizers. Lutetium Texaphyrin (Lutex) and Benzoporphyrin Derivative (BPD) are new, second generation photosensitizers that can potentially improve PDT for brain tumors. Lutex and BPD have major absorption peaks at 730 nm and 680 nm respectively, which gives them two distinct advantages. First, longer wavelengths of light penetrate brain tissue easily so that larger tumors could be treated; and second, the major absorption peaks mean that more of the drug is activated upon exposure to light. Tumorcidal effects of Lutex and BPD have been studied in vitro using canine glioma and human glioblastoma cell cultures. Using light-emitting diodes (LED) with peak emissions of 728 nm and 680 nm as a light source, a greater than 50 percent cell kill was measured in both cell lines by tumor DNA synthesis reduction. The effectiveness of Lutex and BPD against tumor cells in vitro thus established, we have taken the first step toward determining their in vivo efficacy by performing experiments to determine the largest doses of both Lutex, or BPD, and light that can be administered to dogs before toxicity is seen, i.e. the maximum tolerated dose (MTD). Using this dose allows us to effect maximum tumor cell destruction during in vivo studies.
For longer wavelengths of light, the improved NASA LED-technology is required. LED’s are an effective alternative to lasers for PDT. Laser conversion to near-infrared wavelengths is inherently costly and inefficient, using an argon ion or KTP/YAG laser beam that is converted by a dye module, usually to 630 nm. LEDs have been frequently used to emit longer wavelength broad spectrum near-infrared light of 25-30 nm bandwidths. LED lamps traditionally consist of an array of semiconducting LED chips. In recent years, improvements in semiconductor technology have substantially increased the light output of LED chips. A novel type of LED chip is based on the semiconductor Aluminum Gallium Arsenide (AlGaAs). These LED chips have been manufactured to emit light with peak wavelengths of 680 and 730 nm, which are optimal wavelengths for the absorption spectrum of the new photosensitizers used for cancer PDT.
Human trials have begun at the Medical College of Wisconsin, Naval Special Warfare Command and NASA-Marshall Space Flight Center.
Photodynamic Therapy with NASA LED Human Subjects
Preclinical studies of LED-photodynamic therapy were reported previously (Whelan, 1993, 1999; Schmidt, 1996, 1999)
The first patient treated with the NASA LED probe in our Photodynamic Therapy Phase II study, is a 20 year old female who underwent PDT on May 4, 1999 for a brain tumor (anaplastic ependynoma). She had had two previous PDT treatments with laser light in another area of the brain. The most recent tumor recurrence formed in a different location of the brain than the previous two sites and is thought to be the result of the laser light not being able to penetrate the tissue deep enough to prevent recurrence. LED and photofrin together allow for deeper penetration of tissue, thereby exposing surrounding tissue which may contain stray cancer cells to the LED light.
Post surgically, she experienced some edema as is expected from brain surgery, and was treated successfully, and discharged on May 14, 1999. Follow-up MRI scans do not demonstrate tumor growth. A subsequent 21 year-old male with brain tumor (glioblastoma) was treated August 25, 1999, with LED-photodynamic therapy, he tolerated the procedure well and shows no evidence residual tumor on subsequent neuro imaging.
WOUND HEALING WITH NASA LED
Preclinical LED-Wound Healing studies were reported previously (Whelan, 1999)
Type II, Diabetic Mice with excisional skin wounds were treated with LEDs at 680, 730, and 880 nm, 4J/cm2 of energy.
A repeated measures analysis was conducted using a General Linear Model with SqrtArea as the dependent variable and Treat as the independent variable. The interaction effect Day*Treat is significant (p-value=.0095), indicating there there is a significant difference between treatments on some days. This test is of primary interest in this situation, because it shows that the treatments are effective for some part of the treatment period. This analysis was carried out using the SAS statistical software package, published by the SAS Institute, Inc.
Pt #1 is a 31 year-old white female insulin dependent diabetic (type 1) with end-stage renal disease status post renal transplant failure and bilateral below knee amputations. Her left amputation site has poor healing compared to the right. She was receiving Hyperbaric Oxygen therapy because of bilateral arterial insufficiency ulcers on her hands. In January of 1999 she had a hangnail on her right third finger and sores developed at the tip. Multiple fissures and sores on both hands further occurred. Sores covered with black eschar developed and her hands are dry with very limited range of motion. She has similar processes on both hands and had similar processes developing on her feet prior to undergoing bilateral below the knee amputations. At that time she complained of cold-induced cyanosis of the fingers and has been developing fissuring of the skin on her hands and some small spots on her fingers. She is a nonsmoker and has been on dialysis for her renal failure. The renal failure and the arterial insufficiency ulcers of her extremities have been felt to be due to vasculitis She does not use alcohol and has no drug allergies. She had renal transplant for renal failure in 1996 with removal of the transplanted kidney in 1998. She has received Prednisone and Cytoxan for her vasculitis and she also takes Synthroid for hypothyroidism. She has had problems in the past with gastroparesis and had a temporary percutaneous endoscopic gastrostomy tube in place, but has never had a diagnosis of gastroesophageal dysmotility. She has no history of calcinosis and she is anuric because of renal failure. A renal biopsy performed December 5, 1997 of her transplanted kidney showed “focal necrotizing glomerular nephritis, no evidence of acute rejection, no evidence of recurrent diabetic nephopathy”. She received 20 treatments of 8 J/cm2 NASA LED light therapy to all surfaces of both hands. Prior to starting treatment her hands were cold and dusky, lacking sensation. They had many eschar ulcerations. After light treatment we noted an improvement in color and hands were warm to the touch. Her complaints of pain and itching indicated a return of sensation.
PT #2 is a 76 year-old white mail, borderline diabetic with two open sores on his right medial malleolus. These wounds were traumatic, caused when he was wounded by mortar fire during World War II in the Battle of the Bulge. He has had open sores in that area since that time. These wounds have required two split thickness grafts. One was performed in 1945 and another in 1965. Both grafts have been of questionable success. Mr. Marek has been treated with 52 Hyperbaric Oxygen Treatments to date and has received 19 treatments of 8 J/cm2 of NASA LED therapy to his ankle wound. At the start of NASA LED treatment the area had opened into one large 2cm X 3cm wound draining sanguinous fluid. Since treatment we have seen an increase in tissue granulation from the inside towards the outer edges of the wound. Area has decreased to 1.5cm X 2.8cm and there is a significant decrease in drainage. Transcutaneous Oxygen Measurement (T.C.pO2) readings have shown an improvement in vasculature to the area.
Further In Vitro LED Cell Growth Studies
In-vitro studies continue with the 3T3 Fibroblasts, and L6 Rat Skeletal Muscle cell line. Stimulation with LEDs clearly shows proliferation of both cell lines with the DNA synthesis assay. The studies indicate the 3T3 Fibroblasts with stimulation of 4 J/cm2, 8 J/cm2 and 12 J/cm2 of energy show proliferation of cells within 3 hours after exposure to LED. Studies on the L6 Skeletal Muscle depict growth over a period of 48 hours after exposure to 4 J/cm2 of energy. This data demonstrates immediate benefit of LED exposure in-vitro, as in the 3T3 Fibroblasts, but also over a period of time, over 48 hours with the L6 Muscle Cells.
We wish to thank Karen Zeqiri for assistance in manuscript preparation. The LED arrays were provided by Quantum Devices, Inc., Barneveld, WI. We also gratefully acknowledge the Department of Defense, Air Force Material Command, Armstrong Laboratories, Davis Hyperbaric Laboratory, Brooks Air Force Base, TX for providing the hyperbaric chamber used in this research. The hyperbaric oxygen treatments of our human subjects were performed by Estelle Woodard, C.R.T., C.H.T. This work was supported by the National Aeronautics and Space Administration, Marshall Space Flight Center SBIR grants: NAS8-99015 and NAS8-97277, Children’s Hospital Foundation, the MACC Fund and Quantum Devices, Inc.
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