• PD-L1 | Gastric cancer Gastric cancer is one of the leading causes of cancer-related deaths worldwide. The PD-1/PD-L1 pathway has emerged as a significant target in the treatment of gastric cancer due to its role in immune evasion by tumors. Gastric cancer cells can express PD-L1, which binds to PD-1 receptors on T cells, leading to the suppression of T cell activity. This interaction inhibits the immune response, allowing cancer cells to grow and proliferate unchecked. The TME in gastric cancer is often immunosuppressive, with various cells (e.g., TAMs, myeloid-derived suppressor cells) expressing PD-L1 and contributing to immune evasion. Besides as a therapeutic target, relationship has been reported between PD-L1 expression and the clinical features, molecular markers, and molecular subtypes of gastric cancer which highlights the possible prognostic role of PD-L1, especially soluble PD-L1 and exosomal PD-L1 in patients with gastric cancer. • HER2 | non-small cell lung cancer (NSCLC)