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

IntroductionCurrent 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.ObjectivesTo assess the efficacy and safety of the novel HDAC6 inhibitor ricolinostat for the treatment of painful diabetic peripheral neuropathy.MethodsWe 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.ResultsAt the 12-week assessment, changes in average daily pain and UENS scores were not different between the ricolinostat and placebo groups.ConclusionThese 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.