Laser immunotherapy of canine and feline neoplasia

The major cause of treatment failure in human and veterinary cancer patients is tumor invasion and metastasis. The inability of local therapy (surgery, radiation, photodynamic therapy) to eradicate a metastatic cancer presents a challenge in the therapy of residual or micrometastatic disease. Because of its local therapy limitations, chromophore-enhanced selective photothermal laser treatment has been augmented with a superimposed laser-induced systemic photobiological reaction, laser immunotherapy. Laser immunotherapy is a novel cancer treatment consisting of: (1) a laser in the infrared wavelength range (i.e. 805 nm solid state laser); (2) a photosensitizer of the corresponding absorption peak (i.e. indocyanine green [ICG]); and (3) an immunoadjuvant (i.e. glycated chitosan gel[GCG]). The intratumor injection of the photosensitizer (ICG) and immunoadjuvant (GCG) solution is followed by noninvasive laser irradiation. The laser energy causes tumor cell destruction by photothermal interaction to reduce the tumor burden and at the same time exposes tumor antigens. The immunoadjuvant concomitantly stimulates the host to mount a systemic anti-tumor immune response against the remaining cells of the tumor and to induce a long-term, tumor-specific immunity. This study investigates the feasibility of utilizing laser immunotherapy as an adjunctive therapy for the control of feline fibrosarcoma in future.