Herpes vector-mediated expression of proenkephalin reduces bone cancer pain

We examined whether a herpes simplex virus vector that expresses human proenkephalin could be used to attenuate nociception in a model of bone cancer pain in mice. Osteolytic sarcoma cells were implanted into the medullary space of the right femur, followed by a subcutaneous inoculation of a replication‐defective herpes simplex virus vector expressing human proenkephalin (vector SHPE) or a lacZ‐expressing control vector (vector SHZ). SHPE‐inoculated mice demonstrated a significant, naltrexone‐reversible decrease in pain‐related behavior assessed during open‐field motor activity. These results suggest that gene transfer with an enkephalin‐expressing vector may be used to treat pain resulting from cancer in bone.