A proprietary, peptide cancer vaccine comprised of multiple peptides derived from human melanoma antigen A3 (MAGE-A3; MAGEA3), with potential immunostimulating and antineoplastic activities. Upon administration, biropepimut-S may stimulate the immune system to mount specific responses from B-cells, and CD4-positive and CD8-positive cells against tumor cells expressing MAGE-A3, resulting in tumor cell lysis. MAGE-A3, a tumor-associated antigen (TAA), is overexpressed by a variety of cancer cell types.