According to the results of the SUMMIT-08 LTS study published in the ‘Pain Medicine’ journal, NKTR-181, a novel mu-opioid receptor agonist can be used as a safe and effective therapy for patients suffering from moderate to severe chronic low back pain (CLBP) or other noncancer pain (CNP).

Jeffrey Gudin et al. examined the long-term safety of NKTR-181that may have decreased human abuse potential, in moderate to severe CLBP or other CNP patients. This uncontrolled, multicenter, open-label, long-term study consisted of 3 periods, namely- screening  for about ≤ 21 days, a 52 weeks treatment duration, and safety follow-up (∼14 days following the last dose of this agonist).

In the opioid-naïve and opioid-experienced patients, NKTR-181 was administered at 100–600 mg dose twice daily (BID). The patients were enrolled from initiation or following conclusion of the phase 3 efficacy study -SUMMIT-07. Adverse event citations, calculations concerning opioid withdrawal, and clinical laboratory tests were all regarded as safety evaluations. The effectiveness was assessed via the reformed Brief Pain Inventory Short Form (BPI-SF).

This study included 638 patients. At each visit, there was a decrease in mean pain intensity from 4.6 ± 2.2 (baseline) to 2.7 ± 1.8 (at the end of the dose titration period). It was found that the intensity of pain decreased after reaching a stable dose of NKTR-181. This was observed in both the opioid and non-opioid groups (see Fig. 1 Abelow). Moreover, similar dynamics were observed in the indicator of the effect of pain (Fig. 1B. After stabilizing the dose of NKTR-181, there was no significant need for OTC drugs for breakthrough pain.

As shown in the table below, the most common treatment-related adverse events (ADEs) were constipation (26%) and nausea (12%).

No mortalities or patients with respiratory depression were witnessed. A constant reduction in mBPI-SF pain intensity and pain interference from baseline to study termination was perceived during the treatment. Only 2% of patients discontinued NKTR-181 due to ineffectiveness, and 11% withdrew from the study because of treatment-related AEs. NKTR-181 dosed at 600 mg BID was normally well-tolerated, with low frequncy of opioid-related adverse events.