The gut microbiome and melanoma: A review

Abstract

Disturbances in the microbial ecosystem have been implemented in chronic inflammation, immune evasion and carcinogenesis, with certain microbes associated with the development of specific cancers. In recent times, the gut microbiome has been recognised as a potential novel player in the pathogenesis and treatment of malignant melanoma. It has been shown that the composition of gut microbiota in early‐stage melanoma changes from in situ to invasive and then to metastatic disease. The gut bacterial and fungal profile has also been found to be significantly different in melanoma patients compared to controls. Multiple studies of immune checkpoint inhibitor (ICI) therapies have shown that the commensal microbiota may have an impact on anti‐tumor immunity and therefore ICI response in cancer patients. When it comes to chemotherapy and radiotherapy treatments, studies demonstrate that gut microbiota are invaluable in the repair of radiation and chemotherapy‐induced damage and therapeutic manipulation of gut microbiota can be an effective strategy to deal with side effects. Studies demonstrate the oncogenic and tumor‐suppressive properties of the gut microbiome, which may play a role in the pathogenesis of melanoma. Despite this, investigations into specific interactions are still in its infancy, but starting to gain momentum as more significant and clinically relevant effects are emerging.

Role of the Microbiome in Immunotherapy of Melanoma

“…16 Factors well-established for increasing the risk of melanoma development include UV radiation and familial history of melanoma. 16 Recently, gastrointestinal microbiota has been recognized as a novel environmental factor contributing to both the pathogenesis of melanoma development and its influences on therapeutic outcomes. 16 Although the exact relationship between gut dysbiosis and melanoma is still being explored, multiple studies have yielded evidence for their interplay.…”

“…16 Recently, gastrointestinal microbiota has been recognized as a novel environmental factor contributing to both the pathogenesis of melanoma development and its influences on therapeutic outcomes. 16 Although the exact relationship between gut dysbiosis and melanoma is still being explored, multiple studies have yielded evidence for their interplay. Vitali et al 17 found that bacterial and fungal gut profiles differed drastically between melanoma and control cohorts.…”

“…Studies have noticed associations of Fusobacterium, Trueperella, and Corynebacterium genera with melanoma presence and progression. 16,21,22 There exist multifactorial contributions to the gut microbiome, such as environmental exposures, medication use, comorbid conditions, and host genetics. 23 Thus, the necessity for elucidating the exact contributions of the skin-gut axis to melanoma development and treatment has magnified in recent years with the implementation of immunotherapy as a standard of care in advanced melanoma patients.…”

New Insights into the Relationship between Gut Microbiota and Radiotherapy for Cancer

“…Preclinical data shows that radiotherapy can aggregate antitumor T cells and increase the sensitivity of refractory tumors to immune checkpoint inhibitors [ 153 ]. Recent studies on ICI therapies have shown that the changed gut microbiota may affect the antitumor immunity of tumor patients, thereby affecting the resistance to ICI, while the supplementation of different types of bacteria can restore the response to anticancer drugs [ 154 , 155 ]. It is worth mentioning that the gut microbiota can modulate antitumor immunity through small-molecule metabolites, which can disseminate from their original location in the gut to the whole body, influencing local and systemic antitumor immune responses and promoting the efficiency of ICI [ 146 ].…”

Gut Microbiota and Therapy in Metastatic Melanoma: Focus on MAPK Pathway Inhibition

“…Changes in gut microbiota from early stages to metastatic disease were described by Vitali et al, who observed an abundance of Prevotella copri and yeasts of the Saccharomycetales species in melanoma patients compared to controls [ 68 ]. A review recently published by Makaranka et al managed to describe the current evidence regarding the carcinogenic and anti-tumoral properties of GM in melanoma, emphasizing its connection with response to radiotherapy, chemotherapy and ICI and the impact that diet and probiotics may have in this scenario [ 69 ]. As an example, GM has been reported to trigger the immune system to strengthen the abscopal effect caused by radiotherapy, apart from promoting radiotherapy-adverse effects such as mucositis, colitis and bone marrow failure [ 70 ].…”