MIROCALS STUDY: FilSLAN network POSITIONING

The results of the MIROCALS (Modifying Immune Responses and OutComes in ALS) clinical trial were published in May 2025 in the journal The Lancet. This study evaluated the efficacy and safety of low-dose interleukin-2 for the treatment of Amyotrophic Lateral Sclerosis (ALS).

In MIROCALS, 220 participants newly diagnosed with ALS were first treated with riluzole (standard treatment for ALS) for 3 months, then randomized to receive either interleukin-2 (IL-2) or placebo in addition to riluzole.

IL-2 showed no significant benefit on overall survival in MIROCALS participants after 21 months of follow-up. However, further analysis suggests that IL-2 may have a beneficial effect on survival in people with lower or moderate levels of neurofilaments (pNFH, phosphorylated heavy-chain neurofilaments, in cerebrospinal fluid - a marker correlated with slower disease progression) at the start of treatment.

Although the trial showed no efficacy of IL-2 on the primary survival analysis of ALS participants, this is an important advance in the search for new treatments for the disease. These results suggest that modulation of the immune system could represent an interesting avenue to explore for slowing the progression of ALS, particularly for patients with slow to intermediate progression.

The study also showed that IL-2 treatment was safe and well tolerated by patients.

More data are needed to clarify whether IL-2 can actually slow the progression of ALS, as well as the conditions under which this treatment would be effective. To this end, a phase 3 clinical trial, involving a larger group of patients, would be an essential step in addressing these issues.