A small molecule PKCε inhibitor reduces hyperalgesia induced by paclitaxel or opioid withdrawal

The enzyme protein kinase C ε (PKCε) plays an important role in pain signaling and represents a promising therapeutic target for the treatment of chronic pain. We designed and generated a small molecule inhibitor of PKCε, CP612, and examined its effect in a rodent model of chemotherapy-induced neuropathic pain produced by paclitaxel, which does not respond well to current therapeutics. In addition, many patients with chronic pain use opiates, which over time can become ineffective, and attempts to discontinue them can increase pain thereby promoting sustained opioid use. Therefore, we also investigated if CP612 alters pain due to opioid withdrawal. We found that CP612 attenuated hyperalgesia produced by paclitaxel, and it both prevented and reversed hyperalgesia induced by opioid withdrawal. It was not self-administered and did not affect morphine self-administration. These findings suggest that inhibition of PKCε is an effective, nonaddictive strategy to treat chemotherapy-induced neuropathic pain, with the added benefit of preventing increases in pain that occur as opioid treatment is discontinued. This latter property could benefit individuals with chronic pain who find it difficult to discontinue opioids.