Nektar Therapeutics, a biopharmaceutical company developing novel therapeutics based on its PEGylation and advanced polymer conjugation technology platforms, has received the fast track designation for its NKTR-181 from the US Food and Drug Administration (FDA) for the treatment of moderate to severe chronic pain.

NKTR-181 is a novel mu-opioid agonist molecule, which is designed to have a slow rate of entry into the brain to reduce the attractiveness of the molecule as a target of abuse and to reduce its CNS-mediated side effects.

NKTR-181 was created using Nektar's proprietary polymer conjugate technology and its potential differentiating properties are inherent to the design of the new molecule. NKTR-181 is an NCE and as a new molecular structure does not rely on a formulation approach to prevent its conversion into an abusable form of an opioid.

“We are very pleased that the NKTR-181 development programme has been granted Fast Track designation and we look forward to working closely with the FDA on this programme,” said Robert Medve, MD, Chief Medical Officer of Nektar Therapeutics. “NKTR-181 could have significant advantages over currently-available opioids, including reduced attractiveness for abuse and reduced CNS-mediated side effects, such as sedation and respiratory depression. As a new chemical entity with these properties, we believe NKTR-181 has the potential to transform the treatment of chronic pain. We are excited about advancing NKTR-181 into phase II development in July of this year.”

Nektar requested Fast Track designation from the FDA for NKTR-181 based upon what is known about its safety and efficacy profile to-date from both preclinical and phase I clinical studies, as well as NKTR-181's potential to treat chronic pain conditions with an improved safety profile over existing therapies. Given the properties and potential of NKTR-181 in the treatment of chronic pain, Nektar believes that this promising therapy could provide a unique solution to pain management with its intrinsic abuse deterrent design.

NKTR-181 has completed a phase I clinical development programme, which evaluated its pharmacokinetics, pharmacodynamics and safety in more than 180 healthy subjects. The phase II development programme for NKTR-181 will use a standard, randomized, placebo-controlled withdrawal design to evaluate the efficacy and safety of this new opioid molecule in up to 200 patients with chronic pain from osteoarthritis of the knee. A human abuse liability study is also planned as part of NKTR-181's phase II development.

Under the FDA Modernization Act of 1997, the Fast Track programme facilitates interactions with the FDA before and during the submission of a New Drug Application (NDA) for therapeutics being investigated as a treatment for serious or life-threatening conditions, which demonstrate the potential to address an unmet medical need for such a condition. The Fast Track programme enables a company to file sections of an NDA on a rolling basis as data becomes available. This permits the FDA to review portions of the NDA as they are received, rather than waiting for the entire NDA filing prior to commencing the review process. With a Fast Track designation, there is an opportunity for more frequent interactions with the FDA and the possibility of a priority review, which could decrease the typical development time and review period.

Pain is the most common symptom for which patients seek medical attention. According to the American Pain Society, the prevalence of chronic pain in the United States is estimated to be 35.5 per cent or 105 million people.  Chronic pain conditions, such as osteoarthritis, back pain and cancer pain, affect at least 126 million adults in the US annually and contribute to over $100 billion a year in direct health-care expenditures and lost work time. Opioids are considered to be the most effective therapeutic option for pain and have over $10 billion a year in sales in the US alone. However, opioids cause significant problems for physicians and patients because of their serious side effects such as respiratory depression and sedation, as well as the risks they pose for addiction, abuse, misuse, and diversion. The US Food and Drug Administration has cited prescription opioid analgesics as being at the centre of a major public health crisis of addiction, misuse, abuse, overdose and death. A 2010 recent report from the Centres for Disease Control and Prevention (CDC) notes that emergency room visits tied to the abuse of prescription painkillers is at an all-time high, having increased 111 per cent over a five-year period.