HER2-targeted therapies have become a critical treatment option for various cancers, including breast, gastric, bladder, and colorectal cancers. These therapies include monoclonal antibodies (e.g., trastuzumab, pertuzumab), tyrosine kinase inhibitors (TKIs, e.g., lapatinib, pyrotinib), and antibody-drug conjugates (ADCs, e.g., T-DM1, T-DXd). HER2 is a receptor in the EGFR family that plays a key role in tumor growth and progression. HER2 overexpression or amplification is associated with aggressive tumor behavior and poor prognosis in several cancers. Recent advancements in HER2-targeted therapies have led to the development of more effective drugs with improved efficacy and reduced toxicity. ADCs, in particular, have shown significant clinical benefits in various cancers, including breast, gastric, and bladder cancers. The emergence of ADCs has transformed the treatment landscape for HER2-positive cancers. Additionally, the concept of low HER2 expression has opened new avenues for targeted therapy, indicating that more patients may benefit from HER2-targeted approaches. Despite these advancements, challenges such as resistance and the need for standardized diagnostic criteria remain. Ongoing research aims to improve the efficacy of HER2-targeted therapies and expand their application to a broader range of cancers. The future of HER2-targeted therapy lies in the development of novel drugs, combination therapies, and improved diagnostic methods to enhance patient outcomes.HER2-targeted therapies have become a critical treatment option for various cancers, including breast, gastric, bladder, and colorectal cancers. These therapies include monoclonal antibodies (e.g., trastuzumab, pertuzumab), tyrosine kinase inhibitors (TKIs, e.g., lapatinib, pyrotinib), and antibody-drug conjugates (ADCs, e.g., T-DM1, T-DXd). HER2 is a receptor in the EGFR family that plays a key role in tumor growth and progression. HER2 overexpression or amplification is associated with aggressive tumor behavior and poor prognosis in several cancers. Recent advancements in HER2-targeted therapies have led to the development of more effective drugs with improved efficacy and reduced toxicity. ADCs, in particular, have shown significant clinical benefits in various cancers, including breast, gastric, and bladder cancers. The emergence of ADCs has transformed the treatment landscape for HER2-positive cancers. Additionally, the concept of low HER2 expression has opened new avenues for targeted therapy, indicating that more patients may benefit from HER2-targeted approaches. Despite these advancements, challenges such as resistance and the need for standardized diagnostic criteria remain. Ongoing research aims to improve the efficacy of HER2-targeted therapies and expand their application to a broader range of cancers. The future of HER2-targeted therapy lies in the development of novel drugs, combination therapies, and improved diagnostic methods to enhance patient outcomes.