Moderna became a household name by turning mRNA into vaccines. The next frontier the company has chased is using that same molecular technology to treat established disease, and one of its more ambitious targets is an autoimmune disorder of the brain and spinal cord. Trial NCT06735248 is a Phase 2 study of mRNA-1195, an investigational mRNA therapeutic that Moderna is testing for relapse prevention in multiple sclerosis. The study, sponsored by ModernaTX, was last updated on June 15, 2026, and is recruiting 180 participants between 18 and 55 years old.
The short version: this is an early, carefully controlled trial whose main job is to establish that mRNA-1195 is safe and well tolerated and to compare two dose levels, rather than to prove it prevents relapses outright. That distinction is the single most important thing to understand about the study, and the design makes it explicit.
What multiple sclerosis is, and why an mRNA approach is intriguing
Multiple sclerosis is an autoimmune disease in which the immune system mistakenly attacks myelin, the protective insulation around nerve fibers in the brain and spinal cord. When myelin is stripped away, electrical signals along those nerves slow or fail, producing the relapses that define the disease: episodes of vision loss, weakness, numbness, balance problems, and cognitive difficulty. Think of myelin as the rubber coating on an electrical wire; once the immune system chews through it, the signal short-circuits.
Most existing MS drugs work by broadly suppressing or depleting parts of the immune system, which dampens the attacks but also raises infection risk and other complications. The intriguing promise of an mRNA therapeutic is the possibility of a more targeted intervention, instructing the body's own cells to retrain or rebalance the immune response toward myelin rather than blunting immunity wholesale. Whether mRNA-1195 actually delivers on that promise is exactly what the broader program will eventually have to demonstrate; this Phase 2 trial is the first rigorous human step.
How the trial is built
NCT06735248 is described as a Phase 2, randomized, observer-blind, placebo-controlled, dose-ranging study. Each of those words carries weight. Randomized means participants are assigned to groups by chance to avoid bias. Observer-blind means the people assessing outcomes do not know who received drug versus placebo. Placebo-controlled means a comparison group receives inactive injections. And dose-ranging means the trial is explicitly comparing more than one dose to learn which level is best to carry forward.
There are three arms. One group receives mRNA-1195 at dose level 1, the low dose; a second receives dose level 2, the high dose; and a third receives placebo. All three groups follow the same schedule: three intramuscular injections given at months 0, 2, and 6. The trial is listed as triple-masked, a strong blinding standard. The 180-participant enrollment is modest, which is consistent with a study designed to characterize safety and dose response rather than to power a definitive efficacy claim.
What the trial measures
The primary endpoints make the study's intent unmistakable: they are about safety, not efficacy. The registry lists the number of participants with solicited local and systemic adverse reactions in the seven days after each injection, the number with unsolicited adverse events within 28 days of each injection, the number with medically attended adverse events out to six months after the last dose, and a composite of adverse events of special interest, serious adverse events, and events leading to discontinuation, tracked all the way to the end of the study at roughly day 887. In short, the trial is methodically cataloging what happens to the body after each of the three shots and over the long follow-up.
That heavy emphasis on reactogenicity, the local soreness, fever, and systemic reactions that can follow an injection, is the signature of an mRNA program importing the rigorous tolerability framework Moderna built in its vaccine work. Before any company asks whether a novel mRNA therapeutic stops MS relapses, it has to show the injections themselves are safe to give repeatedly.
The three-dose schedule at months 0, 2, and 6 is itself informative. Spacing injections this way, rather than giving them days apart, is consistent with a regimen meant to build and then reinforce a sustained immunological effect over months rather than to provoke a rapid acute response. It also lengthens the safety observation: with the final dose at month 6 and follow-up running to roughly day 887, participants are monitored for well over a year after their last injection. That extended tail is deliberate, because adverse events of special interest in an immunomodulatory therapy can emerge long after dosing ends, and a study designed to support a chronic autoimmune indication has to look for them across a long horizon rather than just in the days after each shot.
What a clean readout would mean
The study started on April 16, 2025, with an estimated primary completion date of January 8, 2029. A successful outcome at this stage is more modest than a typical pivotal trial: it would mean mRNA-1195 proved acceptably safe and tolerable across both dose levels, with a manageable reactogenicity profile and no concerning adverse events of special interest, and it would identify a dose worth advancing. Encouraging early signals on relapse-related measures would be a bonus, but they are not the bar this trial is set to clear.
The honest framing matters. This is a foundational, foothold study. mRNA therapeutics for autoimmune disease remain unproven, and the long road from a 180-person Phase 2 safety trial to an approved MS therapy is littered with programs that looked promising early. The right way to read NCT06735248 is as evidence of Moderna's strategic intent to push mRNA well beyond vaccines, and as the gating safety-and-dose checkpoint that determines whether mRNA-1195 earns a larger, efficacy-focused trial. The answer to that first question is due in early 2029.