A randomized, double-blind, placebo-controlled study of histone deacetylase type 6 inhibition for the treatment of painful diabetic peripheral neuropathy

INTRODUCTION: Current treatments for painful diabetic peripheral neuropathy (DPN) are insufficiently effective for many individuals and do not treat nonpain signs and symptoms. The enzyme histone deacetylase type 6 (HDAC6) may play a role in the pathophysiology of painful DPN, and inhibition of HDAC6 has been proposed as a potential treatment. OBJECTIVES: To assess the efficacy and safety of the novel HDAC6 inhibitor ricolinostat for the treatment of painful diabetic peripheral neuropathy. METHODS: We conducted a 12-week randomized, double-blind, placebo-controlled phase 2 study of the efficacy of ricolinostat, a novel selective HDAC6 inhibitor, in 282 individuals with painful DPN. The primary outcome was the change in the patient-reported pain using a daily diary, and a key secondary outcome was severity of nonpain neuropathic signs using the Utah Early Neuropathy Scale (UENS) score. RESULTS: At the 12-week assessment, changes in average daily pain and UENS scores were not different between the ricolinostat and placebo groups. CONCLUSION: These results do not support the use of the HDAC6 inhibitor ricolinostat as a treatment for neuropathic pain in DPN for periods up to 12 weeks.