Evaluation of a novel chemokine receptor 2 (CCR2)-antagonist in painful diabetic polyneuropathy.

Background and aims Preclinical data suggest that the chemokine receptor 2 (CCR2) is involved in the pathophysiology of neuropathic pain through modulation of neuronal excitability, synaptic transmission and activation of spinal cord microglia. CCR2-antagonists have shown to be effective in preclinical models of neuropathic pain. The aim of this study was to evaluate the analgesic efficacy, safety and tolerability of a novel CCR2-antagonist, AZD2423, in patients with painful diabetic neuropathy (PDN). Methods This was a double-blind, randomized, parallel-group, multi-center study in patients with symmetric distal sensory polyneuropathy due to type 1 or 2 diabetes and duration of neuropathic pain between 3 months and 5 years. Concomitant treatment with neuropathic pain medications (e.g. anticonvulsants, tricyclic antidepressants, serotonin-noradrenaline uptake inhibitors, opioids, topical lidocaine or capsaicin) was not allowed. 134 patients with PDN were equally randomized to 28 days oral administration of 20 mg AZD2423,150 mg AZD2423, or placebo. The primary efficacy variable was the change of average pain score from 5-days baseline to the last 5 days of treatment, measured with numerical rating scale (NRS, 0-10). The secondary efficacy measures included NRS worst pain scores, patient global impression of change, pain interference on sleep and activity, and neuropathic pain symptom inventory (NPSI). Results The change of NRS average pain score was not significantly different between treatment groups (AZD2423 20mg: -1.50; AZD2423 150 mg: -1.35; placebo: -1.61). The NPSI total score and three out of five subscores (evoked pain, pressing/deep pain and paresthesia/dysesthesia) tended to be reduced more by AZD2423 150 mg than by placebo. No other secondary efficacy variables differed between treatment groups. The frequency and type of adverse events for AZD2423 were similar to placebo. The achieved plasma levels of AZD2423 in the two dose groups were in line with predictions from pharmacokinetic data previously obtained in healthy volunteers. Dose-dependent increase of plasma levels of the ligand of CCR2 (CCL2; chemokine ligand 2) and decrease of the mean levels of monocytes (-27% by AZD2423 150 mg) suggested that the administrated doses of AZD2423 interacted with the CCR2 target. Conclusion The CCR2-antagonist AZD2423 showed no analgesic efficacy in PDN based on NRS average pain scores and global and functional pain outcome measures. The NPSI data suggested possible effects on certain sensory components of pain. There were no major safety or tolerability concerns. Implications Treatment with a CCR2-antagonist does not have a clinically important analgesic effect in an overall PDN population.