We studied pharmacokinetics and
tumor response to
photodynamic therapy (
PDT) using
chlorin p6 (CP6) in hamster cheek pouch model. CP6 was administered either intraperitoneally (IP) at a dose of 1.5 mg/kg
body weight or applied topically at 1.0 mg/kg
body weight and its accumulation in
tumor, normal mucosa, and abdominal skin was measured by
optical fiber-based fluorescence spectroscopy.
Photodynamic therapy was performed by superficial illumination of
tumor with 660 nm (+/-25 nm) light at a fluence rate of 100J/cm2 and
tumor response to
PDT was analyzed by histological examination. CP6 accumulation was higher in
tumors as compared to adjoining tissue and normal mucosa at 4-6h after its IP administration. For relatively large
tumors (size >8mm) topical application was observed to be more effective than IP. The level of CP6 in
tumor, surrounding tissue, normal mucosa and skin was seen to decrease rapidly within 24h after its administration and was undetectable at longer time (>72 h) intervals.
PDT of small
tumors at 4h after IP injection of CP6 resulted in complete
tumor necrosis. Whereas,
PDT of large
tumors receiving CP6 topically caused
necrosis in 300-800 microm superficial region of the
tumor. In one animal kept for follow up in each treatment group, it was observed that small
tumors disappeared completely leaving
scar tissue, while large
tumor had significant reduction in
tumor size. The use of CP6 for
PDT of
oral cancer is suggested.