First-in-class opioid analgesic NKTR-181 boasts strong Phase III results


On March 20, 2017, Nektar Therapeutics announced positive results from the SUMMIT-07 Phase III study testing the efficacy of NKTR-181 in the management of moderate-to-severe chronic lower back pain. NKTR-181 is a new chemical entity (NCE) designed to relive pain without inducing high levels of euphoria, minimizing the likelihood of addiction and abuse. Due to the potential of NKTR-181 to address the urgent problem of prescription painkiller abuse, in May 2012, the FDA granted NKTR-181 a Fast Track designation for the treatment of moderate-to-severe chronic pain, giving the drug a strong playing card in an overcrowded market.

Chronic pain is associated with a plethora of conditions including cancer, fibromyalgia, rheumatoid arthritis, and osteoarthritis. According to the National Institutes of Health (NIH), it is estimated that 25.3 million Americans suffer from daily pain. Currently, opioids provide the most effective pain relief, but can cause severe adverse effects such as respiratory depression, sedation, and addiction. Pure opioid agonists, such as morphine and fentanyl, target mu receptors and are the most potent analgesics. However, due to fast rate of perfusion through the blood-brain-barrier, pure opioid agonists are associated with a high likelihood of dependence.

The SUMMIT-07 study assessed the efficacy and safety of twice-daily NKTR-181 compared with placebo in over 600 opioid-naïve patients with moderate-to-severe chronic low back pain over 12 weeks. The primary endpoint, mean change in weekly average pain score, was met, showing significantly improved pain relief with NKTR-181 (p = 0.0019). In addition, Nektar Therapeutics claims that NKTR-181 is designed to have low permeability, hence being less likely to result in addiction. The results from the study show that NKTR-181 produces a strong analgesia and has a significantly lower abuse potential than oxycodone.

Based on the review timeline for drugs with the Fast Track designation, GlobalData estimates that the earliest NKTR-181 could gain regulatory approval would be in late 2017. If approved, the new opioid will face competition from 37 other opioids currently marketed for treatment of chronic pain in the US. With that said, there is a need for novel molecular entities with a potential to address the problem of misuse and addiction. According to GlobalData, NKTR-181 has the potential to successfully occupy this niche in the chronic pain market.