A11, a cell-penetrating peptide, integrates the HIV-1 Tat protein transduction domain with an 11-amino acid segment from the annexin A1 N-terminus (residues 20-30). This compound disrupts the interaction between annexin A1 and the Eph receptor tyrosine kinase A2 (EphA2), leading to enhanced EphA2 ubiquitination in HK1 nasopharyngeal carcinoma (NPC) cells. At a concentration of 10 µM, A11 curtails proliferation, migration, and invasion of HK1 and 5-8F NPC cells. Furthermore, A11 demonstrably diminishes tumor volume in mouse xenograft models of 5-8F and HK1 NPC in vivo.