Human Trials of HSV-mediated Gene Transfer
In April 2011 we reported the results of the first clinical trial of gene therapy for the treatment of pain (Annals of Neurology, 2011).
NP2, a replication defective HSV-based vector expressing human preproenkephalin (PENK) in subjects with intractable focal pain caused by cancer. NP2 was injected intradermally into the dermatome(s) corresponding to the radicular distribution of pain. The primary outcome was safety. As secondary measures, efficacy of pain relief was assessed using a numeric rating scale (NRS), the Short Form McGill Pain Questionnaire (SF-MPQ) and concurrent opiate usage.
Ten subjects with moderate to severe intractable pain despite treatment with more than 200 mg/day of morphine (or equivalent) were enrolled into the study. Treatment was well tolerated with no study agent-related serious adverse events (SAE) observed at any point in the study. Subjects receiving the low dose of NP2 reported no substantive change in pain. Subjects in the middle and high dose cohorts reported pain relief as assessed by NRS and SF-MPQ. Treatment of intractable pain with NP2 was well tolerated. There were no placebo controls in this relatively small study, but the dose-responsive analgesic effects suggest was encouraging, and a Phase 2 placebo-controlled trial has been initiated.
The study was sponsored by Diamyd Medical, and the human-grade vector produced by Diamyd, Inc.