Nivolumab (Opdivo) is an anti-PD-1 antibody approved for the treatment of HCC in patients who have been previously treated with sorafenib. Nivolumab blocks the interaction between PD-1 and its ligands, reactivating T cells to target and destroy cancer cells. Pembrolizumab (Keytruda) is another anti-PD-1 antibody approved for HCC patients who have been treated with sorafenib. Pembrolizumab functions similarly to nivolumab, enhancing the immune system's ability to fight cancer by blocking the PD-1/PD-L1 interaction. Combination Therapies -Atezolizumab (Tecentriq) and Bevacizumab (Avastin): this combination has been approved for the first-line treatment of patients with unresectable or metastatic HCC. Atezolizumab is an anti-PD-L1 antibody that blocks PD-L1 from binding to PD-1, while bevacizumab is an anti-VEGF antibody that inhibits angiogenesis. The combination works synergistically to enhance immune responses and inhibit tumor blood supply. PD-1 and its ligands play a significant role in the immune evasion mechanisms of liver cancer. ICIs targeting the PD-1/PD-L1 pathway have shown promising results in treating advanced hepatocellular carcinoma, particularly in patients who have failed prior therapies. Ongoing research aims to optimize these therapies, manage associated toxicities, overcome resistance mechanisms, and expand their use to benefit a broader patient population. The integration of PD-1 inhibitors with other treatment modalities holds great promise for the future of liver cancer immunotherapy. • GATA3 | Bladder cancer GATA binding protein 3 (GATA3) is a transcription factor that plays a crucial role in the development and differentiation of various tissues, including the urothelium. In the context of bladder cancer, GATA3 has emerged as a significant biomarker with implications for diagnosis, prognosis, and potential therapeutic targeting. GATA3 regulates the expression of genes involved in cell differentiation and proliferation. Its expression is crucial for maintaining the normal function of the urothelium. Depending on the context, GATA3 can act as either a tumor suppressor or an oncogene. In bladder cancer, its role is more complex and is associated with specific molecular subtypes. GATA3 is highly expressed in urothelial carcinoma (UC), making it a useful diagnostic marker for bladder cancer. It is often used in immunohistochemistry (IHC) to confirm the diagnosis of UC. The expression level of GATA3 can also provide prognostic information. Higher levels of GATA3 are often associated with better differentiation and a less aggressive phenotype of bladder cancer. GATA3 expression is a characteristic of the luminal subtype of bladder cancer, which generally has a better prognosis and distinct therapeutic responses compared to other subtypes. GATA3 is widely used in IHC panels to diagnose urothelial carcinoma. It helps distinguish bladder cancer from other malignancies, particularly in metastatic settings where the primary origin of the tumor might be unclear. Ongoing research aims to further elucidate the role of GATA3 in bladder cancer biology and to explore its potential as a target for therapeutic intervention. Integrating GATA3 with other biomarkers and clinical parameters will enhance its utility in the management of bladder cancer. • MSI | Gastric cancer Microsatellite instability (MSI) is a condition of genetic hypermutability that results from impaired DNA mismatch repair (MMR). MSI is characterized by alterations in the length of microsatellites, which are short, repetitive sequences of DNA. MSI is a significant biomarker in various cancers, including gastric cancer, and has implications for diagnosis, prognosis, and therapeutic strategies, particularly in immuno-oncology. MSI occurs due to defects in the DNA MMR system, leading to the accumulation of mutations throughout the genome. Key MMR genes include MLH1, MSH2, MSH6, and PMS2. The accumulation of mutations results in a high mutation burden, which can produce neoantigens that are recognized by the immune system, making MSI-high (MSI-H) tumors potentially more immunogenic. MSI-H is found in approximately 10-20% of gastric cancer cases. It is more commonly observed in early-stage tumors and specific histological subtypes. MSI-H status in gastric cancer is generally associated with a better prognosis compared to microsatellite stable (MSS) tumors. MSI-H gastric cancers are more likely to respond to ICIs due to their high mutation burden and resultant neoantigen load. Diagnostic Use: MSI status can be determined using polymerase chain reaction (PCR) to analyze microsatellite markers or immunohistochemistry (IHC) to assess the expression of MMR proteins.