Novel approaches to antiviral and anticancer immunotherapy.

In this review we discuss existing as well as new approaches to immunotherapy directed against infected or cancerous cells. These approaches traditionally exploit either natural components of immune system (such as cytokines, chemokines, co-stimulatory molecules and adjuvants), or monoclonal antibodies designed to target foreign agents and/or diseased cells through their molecular markers. Additional strategies in development include therapeutic vaccines, oncolytic viruses and T-cell therapies. In addition, we briefly describe a novel strategy called ReDIT (Re-Directed ImmunoTherapy), based on re-orienting the existing long-lasting immune responses (e.g. induced by measles vaccination or natural infection) towards new target molecules on the surface of infected or malignant cells. This can be principally achieved by using bi-functional protein constructs that contain an antigen carrier component and a re-directing component. The antigen carrier component can consist of the ectodomain of the measles hemagglutinin that can be recognized by antibodies and memory cells generated during previous infection or vaccination. The re-directing component consists of the specific virus- or tumor antigen-binding molecule. The fusion constructs are expected to boost existing anti-measles immunity and re-direct it against a new target, engaging the existing anti-measles immunity as an effector mechanism. Thus, ReDIT is a promising novel approach that may represent a valuable addition to immunotherapy of difficult to treat infections and tumors, as it exploits a mechanism distinct from other available therapies.