CD93 emerged as a lung cancer biomarker tied to an immunosuppressive tumor microenvironment and reduced immunotherapy efficacy, according to integrated analyses and clinical-specimen validation. Higher CD93 expression correlated with lower CD8 infiltration, higher FOXP3-positive cells, and worse pathological response and survival trends. The study positions CD93 as a candidate predictive marker for checkpoint outcomes, suggesting that tumor-associated vascular and myeloid context may influence response. If validated prospectively, CD93 could support improved stratification of patients likely to benefit from immunotherapy. For developers, the mechanistic implication is that immune evasion may be linked to specific tumor ecosystem programs rather than broad immune markers alone.