NCIt definition : 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.;