Objective:

To evaluate the association between baseline gut microbiome characteristics and clinical outcomes in patients with NSCLC and melanoma treated with immune checkpoint inhibitors (ICIs), highlighting its potential impact on treatment strategies.

Key Findings:

• Patients responding to ICIs had a more diverse gut microbiome and distinct microbial composition compared to non-responders, which may influence treatment strategies.
• Beneficial commensal bacteria were enriched in responders, while non-responders had higher levels of Bacteroidales.
• The association between gut microbiome characteristics and ICI outcomes was supported by multiple observational studies, though results were inconsistent.

Interpretation:

The gut microbiome may serve as a novel biomarker for predicting ICI efficacy, with specific microbial taxa potentially influencing treatment outcomes and immune-related adverse events, suggesting avenues for personalized therapy.

Limitations:

• Evidence is fragmented and varies across studies, leading to inconsistencies in findings, such as differences in microbiome assessment methods.
• Potential biases in study designs and reporting may affect the reliability of the results, including selection bias and publication bias.

Conclusion:

The gut microbiome is a promising area for further research to optimize patient selection for ICIs and improve therapeutic outcomes in NSCLC and melanoma, particularly in identifying specific microbial targets for intervention.