CANCER VACCINES - CHALLENGES AND POTENTIAL SOLUTIONS

Almost a century has passed since immunotherapy of cancer was first at tempted using cancer immunogens (vaccines); however, its clinical impa ct remains modest. Although initial concerns about a lack of human tum or antigens have decreased, prevailing issues include inefficient proc edures for immunization and downregulated expression of major histocom patibility complex (MHC) class I molecules in tumor cells, While immun ization can be improved, deficient MHC class I expression remains a pr oblem, because it hampers the ability of tumor cells to present antige ns for killing by CD8(+) T cells. These are the! major mediators of tu mor destruction, and they have little or no activity against antigen-n egative bystander cells, However, there are reasons to be optimistic t hat therapeutic vaccination against cancer antigens might become a rea lity at last.