Objective:

To delineate immune reprogramming following liver resection in colorectal cancer liver metastases (CRLM) patients.

Approach:

• Sample Collection: Peripheral blood samples were collected from CRLM patients before and after liver resection.
• Analysis Methods: Peripheral blood mononuclear cells were analyzed using multiparameter flow cytometry with adaptive and innate immunity panels.
• Tumor Immune Microenvironment Assessment: The tumor immune microenvironment (TIME) was assessed by H&E, immunohistochemistry, and immunofluorescence.

Key Findings:

• Postoperative analysis revealed remodeling of T cell composition with increased CD4+ T cells among circulating CD3+ T cells.
• The overall proportion of CD8+ T cells among circulating CD3+ T cells was reduced.
• Patients with recurrence had a higher postoperative proportion of S100A9+ monocytic myeloid-derived suppressor cells (M-MDSCs).
• KRAS-mutated tumors may be associated with distinct postoperative immune profiles.

Interpretation:

Liver metastasis resection is associated with CD4+ T cell-dominant systemic immune remodeling and changes in exhaustion-associated markers, suggesting a potential postoperative window for future immunotherapeutic interventions.

Limitations:

• Findings are speculative and require further functional validation.
• The study does not provide direct evidence for clinical implications of the altered immune landscape.

Conclusion:

The altered CD4+ T cell landscape warrants further investigation regarding its potential relevance to adoptive cellular therapies or immune checkpoint inhibition.