Objectives: To evaluate the efficacy, safety, and tolerability of repeated NGX-4010 treatments in the open-label extension phase of a 52-week study in patients with neuropathic pain due to HIV-associated distal sensory polyneuropathy (HIV-DSP).

Methods: Patients completing the 12-week, randomized, double-blind phase of the study could enter a 40-week, open-label phase, and receive up to 3, 60-minute NGX-4010 treatments. Patients recorded their "average pain for the past 24 hours" daily using the Numeric Pain Rating Scale (NPRS). Efficacy assessment included the percentage NPRS score reduction from baseline to weeks 2 to 12 after the final treatment, and Patient Global Impression of Change (PGIC) and Clinician Global Impression of Change (CGIC) questionnaires at study termination.

Results: Of 307 patients randomized, 272 entered the open-label phase; 81, 90, 55, and 46 received 0, 1, 2, and 3 retreatments, respectively. The mean percentage decrease in NPRS score from baseline to weeks 2 to 12 after the final treatment was similar in patients receiving single or multiple NGX-4010 treatments (-25.8%, -27.1%, -24.6%, and -22.7% for 1, 2, 3, and 4 NGX-4010 treatments, respectively). PGIC and CGIC results demonstrated a benefit of NGX-4010 treatment through to the end of the study regardless of the number of treatments received. Transient local application site reactions were the most frequently reported adverse events, and were mainly mild to moderate, nonserious, and did not increase with repeated treatment.

Discussion: Repeated NGX-4010 treatments were generally well tolerated and resulted in consistent reductions in HIV-DSP-associated pain and improvement in patient-reported outcomes.