The use of several different drugs and different treatment modalities often leads to synergistic effects in treating diseases, such as cocktail
therapy in
AIDS treatment and combination
therapy in
chemotherapy treatment of
cancer patients. With the wide application of
lasers in the treatment of
cancers, can the synergistic effect manifest itself in the combination application of
lasers and other treatment components, particularly those related to immunological stimulation? Selective photothermal interactions using a
laser and a light-absorbing
dye have been used in combination with immunological interactions using an in situ
immunoadjuvant in treating metastatic
tumors. Three components were used in this method: a near-infrared
laser, a ligh-tabsorbing
dye and an
immunoadjuvant. This new method -
Laser Immunotherapy - has achieved the synergistic effect. This novel approach has been applied in treating metastatic mammary
tumors in rats. In our animal studies, when the components were applied individually, or in two-component combinations, the long-term effect of
cancer treatment was almost negligible. However, when the three components were used at the same time, the treatment effect improved significantly. In this study, we show the synergistic effect using an 805 nm
laser,
indocyanine green (ICG) as the light-absorbing
dye, and
glycated chitosan, a novel compound, as the
immunostimulant. Furthermore, optimization of the
laser-dye photothermal interaction using different
laser and
dye parameters in an in vitro study using tissue-simulating gel phantoms was performed. Our results showed that the optimal photothermal effect could be achieved using 1.8 watts and 0.5 cm beam radius, and an ICG concentration between 0.08 to 0.14% in the target gel. To study the effect of
immunoadjuvant, three additional adjuvants, complete
Freund's adjuvant,
incomplete Freund's adjuvant, and C-parvum were also used in
laser immunotherapy.
Glycated chitosan appeared to be the most effective. The complete
Freund's adjuvant at a dose of 200 μl and 50% concentration resulted in a cure rate comparable to that using
glycated chitosan.
Incomplete Freund's adjuvant and C-parvum showed relative weak effects in treating the metastatic
tumors.