Full results and data from this multiple ascending dose Phase 1 study of NKTR-181 have been accepted for presentation at the 2012 American Academy of Pain Medicine's 28th Annual Meeting to be held February 23 – 26, 2012."These exciting clinical results underscore our enthusiasm for advancing NKTR-181 into Phase 2 development in chronic pain patients," said Robert Medve, MD, Chief Medical Officer at Nektar Therapeutics. "As a new mu-opioid analgesic molecule that does not rely on a formulation approach, NKTR-181 has the potential to transform the treatment of chronic pain by providing effective pain relief with less CNS-related side effects than traditional opioid therapies. Our clinical results to-date suggest that NKTR-181 exhibits a continuous analgesic effect over a 12-hour period, with a slower rate of entry into the CNS, which could greatly reduce its potential dangerous CNS-related side effects and the euphoria that leads to abuse of traditional opioids. We look forward to initiating our Phase 2 clinical study of NKTR-181 in mid-2012." Chronic pain conditions, such as osteoarthritis, back pain and cancer pain, affect at least 126 million adults in the U.S. annually and contribute to over $100 billion a year in lost productivity.(1) About the NKTR-181 Phase 1 Multiple Ascending Dose Study The Phase 1 multiple ascending dose study of NKTR-181 was conducted in the U.S. at Lifetree Clinical Research. The study enrolled a total of 60 healthy subjects over an eight-day treatment period. Four dose cohorts were evaluated with 12 subjects in each dose cohort (100, 200, 300 and 400 mg). Subjects in each cohort received oral doses of NKTR-181 (n=12) or placebo (n=3) following an overnight fast. Pharmacokinetics were determined through serial blood and urine samples. Serial opioid pharmacodynamic tests included a cold pressor test for analgesia and pupillometry as an indicator of the onset and duration of opioid effect. NKTR-181 was generally well-tolerated at all dose levels in the study: most adverse events were mild and no serious adverse events were reported. Most frequent adverse events observed at the highest doses tested were consistent with AEs characteristic of an opioid agonist, such as constipation, headache and nausea.