CTLA4 and neoplasm: This section states that our search included peer-reviewed articles from PubMed (2014-2025), using MeSH terms and Boolean operators combining three conceptual clusters: (“intratumoral microbiota” OR “tumor microbiome”) AND (“immune microenvironment” OR “PD-1/PD-L1” OR “CTLA-4”) AND (“immunotherapy response” OR “checkpoint blockade resistance”).