Indication: Treatment of moderate to severe chronic low back pain

Discovered and Wholly Owned by Nektar


Phase 3

NKTR-181 is a first-in-class, mu-opioid analgesic investigational drug candidate with a novel molecular structure designed to provide potent pain relief with a slow rate of entry into the brain. This slow rate of entry is designed to reduce the euphoria that can lead to the abuse of current opioid analgesics.1

About Opioids and Pain Management

Pain is one of the most common reasons people seek medical treatment.2 A study published in the American Pain Society's The Journal of Pain in October 2014 estimated that 19 percent of the U.S. population, or 39 million people, suffer from persistent pain.3

Opioids are considered the most effective therapeutic option for pain but can cause serious side effects such as respiratory depression and sedation and have the potential for addiction, abuse and misuse.4,5 In 2014, nearly two million Americans either abused or were dependent on prescription opioid pain relievers.6 According to a 2011 Institute of Medicine Report, pain is a significant public health problem that costs society at least $560-$635 billion annually. This includes the total incremental cost of health care due to pain from ranging between $261 to $300 billion and $297-$336 billion due to lost productivity (based on days of work missed, hours of work lost, and lower wages).7

NKTR-181 is a new chemical entity (NCE) that Nektar Therapeutics created using its proprietary small molecule polymer conjugate technology. NKTR-181 has several potential differentiating properties which are designed as part of the structure of the molecule, including a slow rate of entry into the central nervous system (CNS) as measured by pupillometry (contraction of the pupils) and a pharmacokinetic profile that will allow it to be administered to chronic pain patients twice-a-day to allow for around the clock pain control. NKTR-181 is not a reformulation of an approved opioid, which is a commonly-used method to attempt to prevent the manipulation of existing long-acting opioid drugs into more abusable forms. The U.S. Food and Drug Administration (FDA) has granted NKTR-181 Fast Track designation for the treatment of moderate to severe chronic pain.

SUMMIT Phase 3 Program

The SUMMIT Phase 3 program for NKTR-181 includes two efficacy and safety studies and a 52-week long-term safety study (SUMMIT-LTS). Enrollment is complete in the first Phase 3 efficacy study (SUMMIT-07) which will evaluate NKTR-181 versus placebo in opioid-naïve patients with chronic low back pain. The SUMMIT Phase 3 program will also include a Phase 3 efficacy and safety trial in people who are opioid-experienced (SUMMIT-12). Information about the SUMMIT studies can be found on clinicaltrials.gov.


1Hyman, Steven E., Harvard Review of Psychiatry. 2(1):43-46, May/June 1994.

22011 National Academy of Sciences. Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education and Research, 2010 Decision Resources, and Harstall, C. How prevalent is chronic pain? Pain Clinical Updates X, 1-4 (2003).


4IMS, NSP, NPA and Defined Health 2013 Estimates.

5Melnikova, I, Pain Market, Nature Reviews Drug Discovery, Volume 9, 589-90 (August 2010).

6Substance Abuse and Mental Health Services Administration, National Survey on Drug Use and Health, 2014.

7Institute of Medicine Report from the Committee on Advancing Pain Research, Care, and Education: Relieving Pain in America, A Blueprint for Transforming Prevention, Care, Education and Research. The National Academies Press, 2011.