Targeted biological therapies for pain.

Introduction: Chronic pain is often resistant to currently used drugs. The effect of these is frequently self-limiting, with increasing level of side effects caused by increased doses. Biological pain therapies provide a means to target molecules to specific types of neural cells in spatially limited areas. Targeted biological therapies utilize agents acting at specific sites, or virus or cell vectors allowing expression and secretion of transgenic substances in small anatomical compartments. Biological approaches to treatment of chronic pain may be able to provide greater analgesic efficacy, avoiding many of the limitations associated with current analgesics.

Areas Covered: The most important targets and tools for biological therapy of pain. Basic approaches, preclinical trials and the clinical studies successfully completed. The rationale and tools for biological therapies.

Expert Opinion: Biological therapy of pain holds great promise and is rapidly developing. Despite the significant numbers of preclinical studies in the last two decades only a single biological agent, the cone snail toxin ziconotide, has been advanced through all stages and licensed for clinical use. Biological therapy of pain is thus here to stay, but will need more substantial proof of efficacy and safety before being widely accepted and routinely used.