To evaluate the efficacy and safety of LX9211 in postherpetic neuralgia (PHN)

PHN is a debilitating complication associated with Varicella zoster. The pain associated with PHN can last for months or years after the zoster rash has cleared. Often the available treatment options do not provide adequate pain relief, and these treatment options are associated with undesirable side effects including somnolence and peripheral edema.

LX9211 is a potent, small molecule inhibitor of adaptor-associated protein kinase 1 (AAK1) which is a novel, non-opioid target for the treatment of neuropathic pain (NP). In a recent Phase 2 study, RELIEF-DPN 1, once-daily oral administration of LX9211 significantly reduced NP in patients with painful diabetic peripheral neuropathy.

A multicenter, Phase 2, double-blind, randomized, placebo-controlled, parallel-group study was conducted evaluating the efficacy and safety of LX9211 in the treatment of PHN. Adults (≥18 years of age) with prior Varicella zoster skin rash and PHN pain persisting for ≥3 months after healing of the Varicella zoster skin rash who met all inclusion and no exclusion criteria were eligible for enrollment in this study. The primary outcome was change from baseline in Average Daily Pain Score (ADPS) based on the 11-point numerical rating scale.

Treatment with LX9211 resulted in consistent reduction in ADPS, compared to placebo, throughout the 6-week dosing period. This was statistically significant when measured across dosing period but did not reach significance at Week 6 primary endpoint. The adverse event profile in this study was consistent with that observed in the prior study in patients with DPN with dizziness reported as the most common adverse event. There were no serious adverse events or deaths reported in the study.

Together with the successful RELIEF-DPN 1 study, this study supports further clinical evaluation of LX9211 as a novel, non-opioid treatment option for multiple neuropathic pain conditions.