A cancer vaccine containing PR1, a 9 amino-acid human leukocyte antigen (HLA)-A2 restricted peptide derived from proteinase 3, with potential immunotherapeutic activity. Vaccination with PR1 leukemia peptide vaccine may stimulate the host immune system to mount a cytotoxic T lymphocyte (CTL) response against tumor cells expressing proteinase 3, resulting in tumor cell lysis. Often overexpressed in leukemic cells, proteinase 3 is a serine proteinase that activates progelatinase A and is involved in angiogenesis and metastasis.