This study aimed to identify immunodominant epitopes from a panel of triple-negative breast cancer (TNBC)-associated proteins—MZF-1, Mucin-1, SOX-9, Keratin 5, Keratin 14, Twist1, and Progranulin (GP88)—to design multi-epitope peptide vaccines capable of eliciting robust anti-tumour immune responses. Here, SOX9 is linked to triple-negative breast carcinoma.