MC-Sq-Cit-PAB-Gefitinib is primarily utilized in the field of targeted cancer therapy, specifically in the development of antibody-drug conjugates (ADCs). This compound acts as a linker-payload, where the Gefitinib component serves as a potent tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR). The MC-Sq-Cit-PAB segment functions as a cleavable linker, enabling the controlled release of Gefitinib at the tumor site. This targeted approach enhances the efficacy of the drug while minimizing off-target effects, making it a valuable tool in treating EGFR-positive cancers such as non-small cell lung cancer (NSCLC). Its application in ADCs represents a significant advancement in precision medicine, offering improved therapeutic outcomes for patients.