A
chitosan derivative,
glycated chitosan (GC), has been used as an
immunostimulant for
cancer treatment in
laser immunotherapy. The function of GC is to enhance the host immune response after direct
cancer cell destruction by a selective
laser photothermal interaction. To further test its effects,
laser immunotherapy was extended to include several different adjuvants for immunological stimulation and to include
photodynamic therapy (
PDT) as a different
tumor-destruction mechanism. Complete Freund (CF) adjuvant, incomplete Freund (IF) adjuvant and Corynebacterium parvum (CP) were selected for treatment of metastatic mammary
tumors in rats, in combination with a selective photothermal interaction. The
solution of the
immunoadjuvants admixed with
indocyanine green (ICG), a light-absorbing
dye, was injected directly into the
tumors, followed by noninvasive irradiation of an 805 nm
laser. Combined with
PDT, in the treatment of
tumors in mice, GC was administered peritumorally immediately after
laser irradiation. The survivals of treated animals were compared with untreated control animals. In the treatment of rat
tumors, CF, IF and CP raised the cure rates from 0% to 18%, 7% and 9%, respectively. In comparison, GC resulted in a 29% long-term survival. In the treatment of EMT6 mammary
sarcoma in mice, GC of 0.5% and 1.5% concentrations increased the cure rates of
Photofrin-based
PDT treatment from 38% to 63% and 75%, respectively. In the treatment of Line 1
lung adenocarcinoma in mice, a 1.67% GC
solution enabled a noncurative meso-substituted tetra(meta-hydroxy-phenyl)
chlorin-based
PDT to cure 37% of the
tumor-bearing mice. The experimental results of this study confirmed our previous studies, showing that
immunoadjuvants played an active role in
laser-related
cancer treatment and that GC significantly enhanced the efficacy of
laser cancer treatment.