Heat-shock proteins (HSPs) are a group of
proteins whose expression is increased when the cells are exposed to elevated temperatures or other stressful conditions. This increase in expression is transcriptionally regulated. The function of HSPs is similar in virtually all living organisms, from bacteria to humans. Their expression also occur under non-stressful conditions, simply 'monitoring' the cell's
proteins, i.e., they carry old
proteins to the cell's 'recycling bin' and they help newly synthesized
proteins fold properly. These activities are part of a cell's own repair system. HSPs are
molecular chaperones for
protein molecules. They are usually cytoplasmic
proteins and they perform functions in various intracellular processes. Tumour-derived HSP-
peptide complexes (HSPPCs) can be used for vaccination against
malignancies. In particular, HSPPC-96 complex, called Vitespen (formerly
Oncophage) is a HSPs-based
vaccine made from individual patients' tumours with a promising role in
cancer management. This
vaccine has been extensively studied in Phase I and II clinical trials, showing activity on different
malignancies, including
gastric cancer,
colorectal cancer,
pancreatic cancer,
non-Hodgkin's lymphoma and chronic myelogenous leukaemia. The
vaccine has also been studied in Phase III clinical trials in
melanoma and
kidney cancer, showing an excellent safety profile with essentially no toxicity. Thus, HSP-based
vaccines are a novel therapeutic approach with a promising role in
cancer management.