The nucleoside analog kamuvudine-9 shows protective and therapeutic efficacy in a mouse model of multiple sclerosis

Innate immune signaling through inflammasome activation has been implicated in the pathogenesis of multiple sclerosis (MS). We previously demonstrated that nucleoside reverse transcriptase inhibitors (NRTIs), drugs approved to treat HIV and hepatitis B virus infections, and kamuvudines, safer NRTI derivatives, both inhibit inflammasome activation. Here, we report that in the experimental autoimmune encephalitis mouse model of MS, treatment with kamuvudine-9 (K-9), an NRTI derivative with an enhanced safety profile, prevented further neurological deficits and reversed preexisting paralysis and vision loss. K-9 promoted myelin and axonal preservation in the mouse spinal cord and abolished the increase in serum neurofilament light (NfL) chain. K-9 disrupted interactions between nucleotide-binding domain leucine-rich repeat (NLR) pyrin domain-containing protein 3 (NLRP3) and NIMA-related kinase 7 (NEK7) and between NLRP3 and NLR CARD domain containing 4 (NLRC4), inhibiting dual inflammasome activation. K-9 also exhibited appropriate safety and pharmacokinetic characteristics and biodistribution. In three distinct human cohorts, there was a lower incidence of MS in those individuals receiving NRTIs for HIV infection, preexposure prophylaxis for HIV, or hepatitis B virus infection. NRTI use was also associated with a reduction in relapse rate in individuals with MS. These findings provide a rationale for further investigating K-9 for treating MS.