Body-mass index and metastatic melanoma outcomes - Authors' reply

Gut Microbiota, Metabolome, and Body Composition Signatures of Response to Therapy in Patients with Advanced Melanoma

Despite the recent breakthroughs in targeted and immunotherapy for melanoma, the overall survival rate remains low. In recent years, considerable attention has been paid to the gut microbiota and other modifiable patient factors (e.g., diet and body composition), though their role in influencing therapeutic responses has yet to be defined. Here, we characterized a cohort of 31 patients with unresectable IIIC-IV-stage cutaneous melanoma prior to initiation of targeted or first-line immunotherapy via the following methods: (i) fecal microbiome and metabolome via 16S rRNA amplicon sequencing and gas chromatography/mass spectrometry, respectively, and (ii) anthropometry, body composition, nutritional status, physical activity, biochemical parameters, and immunoprofiling. According to our data, patients subsequently classified as responders were obese (i.e., with high body mass index and high levels of total, visceral, subcutaneous, and intramuscular adipose tissue), non-sarcopenic, and enriched in certain fecal taxa (e.g., Phascolarctobacterium) and metabolites (e.g., anethole), which were potentially endowed with immunostimulatory and oncoprotective activities. On the other hand, non-response was associated with increased proportions of Streptococcus, Actinomyces, Veillonella, Dorea, Fusobacterium, higher neutrophil levels (and a higher neutrophil-to-lymphocyte ratio), and higher fecal levels of butyric acid and its esters, which also correlated with decreased survival. This exploratory study provides an integrated list of potential early prognostic biomarkers that could improve the clinical management of patients with advanced melanoma, in particular by guiding the design of adjuvant therapeutic strategies to improve treatment response and support long-term health improvement.

Body Mass Index and Melanoma Prognosis

Introduction

Obesity has been suggested as a risk factor in the progression of malignancies, including melanoma. Most studies defined obesity using body mass index (BMI), although the index is considered an imperfect measure of body composition.

Objective

The aim of this article is to examine whether BMI can impact on the prognosis of cutaneous melanoma, regardless of anti-tumor therapy. The relationship between BMI and specific prognostic factors in melanoma patients has been reviewed.

Methods

Literature search was conducted on PubMed using the terms "melanoma" and "body mass index" or "obesity". We selected articles, published up to 30 November 2020, examining the prognostic aspects of melanoma. Articles evaluating the risk and incidence of melanoma were excluded as well as studies regarding morbidity and complications following surgical procedures, or those performed in metastatic melanoma patients treated with anti-tumor therapies.

Results

Mixed results have emerged from studies assessing the clinical outcomes in melanoma patients in relation to BMI. More consistent data seem to support the relationship between BMI and Breslow thickness.

Conclusions

Studies that focus specifically on the link between obesity and melanoma prognosis are limited; further research is needed to deepen our knowledge on this link.

Modifiable Host Factors in Melanoma: Emerging Evidence for Obesity, Diet, Exercise, and the Microbiome

PURPOSE OF REVIEW

We discuss how potentially modifiable factors including obesity, the microbiome, diet, and exercise may impact melanoma development, progression, and therapeutic response.

RECENT FINDINGS

Obesity is unexpectedly associated with improved outcomes with immune and targeted therapy in melanoma, with early mechanistic data suggesting leptin as one mediator. The gut microbiome is both a biomarker of response to immunotherapy and a potential target. As diet is a major determinant of the gut microbiome, ongoing studies are examining the interaction between diet, the gut microbiome, and immunity. Data are emerging for a potential role of exercise in reducing hypoxia and enhancing anti-tumor immunity, though this has not yet been well-studied in the context of contemporary therapies. Recent data suggests energy balance may play a role in the outcomes of metastatic melanoma. Further studies are needed to demonstrate mechanism and causality as well as the feasibility of targeting these factors.