Exploration of the Synergistic Effect of Chitosan Oligosaccharide and Dacarbazine (DTIC) in the Treatment of Melanoma

Dacarbazine (DTIC)-based chemotherapy remains the first-line treatment for melanoma. However, its low response rate and evident side effects limit its clinical application. The combined use of chitosan oligosaccharide (COS) and other drugs has been shown to have good anti-tumor effects. Therefore, this study aimed to investigate whether COS can be combined with DTIC for the treatment of melanoma. Methods: By constructing a tumor-bearing model, statistical analysis of tumor size, TUNEL staining, and immunohistochemical detection of CD8, F4/80, and other indicators were conducted on tumor tissue to clarify the synergistic effect and molecular mechanism of the combination therapy. Results: The tumor-bearing model showed that the combined use of COS-2 and DTIC resulted in a tumor inhibition rate of 82.28% and enhanced the therapeutic efficacy of DTIC in mice with melanoma. COS-2 promoted the polarization of macrophages toward the M1 type and induced tumor cell apoptosis. In addition, it remarkably enhanced monocyte-mediated phagocytosis, T-lymphocyte proliferation, and immune function, thereby attenuating inflammatory responses and reducing the side effects of DTIC. Discussion: This study highlighted the synergistic inhibitory effects of COS-2 and DTIC on the growth of melanoma both in vitro and in vivo. Notably, COS-2 not only enhanced the anti-tumor efficacy of DTIC but also alleviated its side effects. Conclusion: The combination therapy with COS and DTIC exhibited a synergistic effect and may be a promising therapeutic strategy for melanoma.