Long-term treatment with vidofludimus calcium (IMU-838) has been tolerated well overall among people with relapsing-remitting MS (RRMS), new data from an extension study show. Findings were presented at the Consortium of Multiple Sclerosis Centers (CMSC) Annual Meeting, in a poster titled "Assessment of Long-Term Safety and Tolerability of Vidofludimus Calcium in Patients with Relapsing Remitting Multiple Sclerosis in the Open-Label Extension Period of the Phase 2 Trial (EMPhASIS)." The work was funded by Immunic Therapeutics, the company developing vidofludimus calcium. "We just published the first long-term safety and tolerability data for vidofludimus calcium, which is currently in Phase 3 clinical trials in relapsing MS and in a Phase 2 clinical trial in progressive MS," Andreas Muehler, MD, chief medical officer and co-founder at Immunic, said in an email to Multiple Sclerosis News Today. Vidofludimus calcium is an oral therapy designed to reduce MS-driving inflammation by blocking the activity of an enzyme called DHODH that is involved in the activation of inflammatory immune cells. Recent data suggest the experimental therapy also may have another target that provides nerve-protecting effects. Immunic conducted a Phase 2 trial called EMPhASIS (NCT03846219), which tested vidofludimus calcium against a placebo in 268 people with RRMS. Participants were assigned randomly to receive 10, 30, or 45 mg of vidofludimus calcium or a placebo, taken orally once per day for 24 weeks, or about six months. Trial results showed the two higher doses significantly outperformed a placebo at reducing MS brain lesions. While statistical analysis were not conducted due to the small patient sample, the therapy also showed benefits in secondary goals such as relapses and other MRI measures. Open-label extension study. After the initial six-month study, participants had the option to enter into an open-label extension study, in which all are being treated with vidofludimus calcium and monitored for long-term outcomes. All 254 patients who completed the placebo-blind portion of the study entered into the open-label extension. The CMSC poster included data collected as of October 2022. At that time, 209 patients were still in the open-label study; 193 had been treated for at least 96 weeks (about two years), and 144 patients had been treated for at least 144 weeks (nearly three years). Some patients had been on therapy for almost four years. Over the years in the extension study, the discontinuation rate was 5.3% per year, which is quite low for a long-term clinical trial. Of the 45 patients who discontinued from open-label treatment, 10 were due to MS-related clinical events, and three were related to logistical issues arising from the war in Ukraine. In four cases, discontinuation was due to treatment side effects. The specific side effects leading to discontinuation were not specified. The most common adverse events reported in the trial included COVID-19 (9.1%), the common cold (4.7%), back pain (2.8%), and urinary tract infections (2%). A total of 14 serious adverse events were documented during the open-label extension; none of these were considered related to treatment with vidofludimus calcium. Rates of liver or kidney problems also were low. "Vidofludimus calcium was once again shown to be safe and well tolerated. This was best represented by a low annual discontinuation rate of approximately 5.3%, which means that very few patients discontinued their treatment in this long-term study," Muehler said. "The overall rates of renal [kidney] and liver adverse events were low (0.023 and 0.015 per treatment year, respectively) and very few serious adverse events occurred (0.027 serious adverse events per treatment year, meaning 1 in about 37 treatment years)," he added. " Overall, this data suggests a favorable safety profile in long-term treatment with vidofludimus calcium," the researchers concluded in the poster. More trials testing vidofludimus calcium. Immunic is currently running two Phase 3 trials, ENSURE-1 (NCT05134441) and ENSURE-2 (NCT05201638), to further test vidofludimus calcium against a placebo in adults with relapsing forms of MS, including RRMS and active secondary progressive MS, ages 18 to 55. Each trial is recruiting about 1,050 patients, who will receive the 30 mg dose for 72 weeks, or about 15 months. Participants then will have the opportunity to enter an open-label extension lasting up to eight years. Another ongoing study, the Phase 2 CALLIPER trial (NCT05054140), is testing vidofludimus calcium against a placebo in adults with progressive forms of MS, ages 18 to 65. The trial will include up to 450 people with primary or secondary progressive MS who experienced no relapses in the previous two years. An interim analysis focusing on biomarkers of disease progression is expected later this year.