Real-world evidence and multi-omics insights into differential immunotherapy responses between primary and metastatic sites

This study examines how tumors in different metastatic organs respond to immune checkpoint inhibitor (ICB) therapy in real-world clinical practice. ICB therapy helps the immune system recognize and attack cancer cells, but treatment responses may vary depending on where the cancer has spread. Common metastatic sites such as the liver, brain, lung, and bone each have unique immune environments that may influence treatment outcomes. The investigators will review the medical records of approximately 1,000 adults with solid tumors who received ICB therapy at Sun Yat-sen Memorial Hospital, the Third Affiliated Hospital of Sun Yat-sen University, and the First Affiliated Hospital of Chongqing Medical University since 2016. The study will compare treatment response, time until disease progression, and overall survival among patients with different metastatic sites. Additional outcomes include disease control, immunotherapy-related side effects, and concordance between primary and metastatic tumor responses. The study will also analyze available molecular and immune-profiling datasets to explore biological mechanisms that may explain organ-specific differences in ICB response. The goal is to improve understanding of how metastatic sites influence immunotherapy effectiveness and to support future treatment decision-making.