Low-dose interleukin-2

MIROCALS was an academic trial sponsored by the University Hospital of Nîmes (France) and run by a European consortium, with funding from the EU and the UK MND Association. The Paris company ILTOO Pharma holds exclusive rights to the trial data and makes the IL-2 product (ILT-101), so any approval application would likely come from ILTOO.

In ALS, immune cells in the nervous system can become overactive and add to nerve damage. Regulatory T cells normally keep this in check, and they tend to be weaker in faster progressing ALS. Small doses of IL-2 selectively increase regulatory T cells without strongly activating other immune cells.

MIROCALS was a Phase 2b placebo-controlled trial and reported in The Lancet in May 2025. UK ALS experts said a Phase 3 trial (or a funded early access programme) would be needed before the drug could be recommended. As of November 2026 we found no announced confirmatory trial, though the programme has not been formally stopped.

For everyone in the trial, 41 people on IL-2 (37%) and 49 on placebo (45%) had died by 21 months, a difference that was not statistically significant (hazard ratio 0.81, p=0.33), so the main goal was missed. In the 70% of people with lower levels of a nerve-damage marker (pNFH) in their spinal fluid, the risk of death was 48% lower with IL-2 (hazard ratio 0.52, p=0.016), and there was no benefit in people with high levels. This subgroup was planned in advance, but it still needs to be confirmed in a new trial.

This is the most favourable result reported. See all key studies for the full picture.

MIROCALS enrolled people early after diagnosis who were already taking riluzole. Treatment was a small injection under the skin on five days in a row, repeated every 28 days for 18 months. The apparent benefit was in people with lower pNFH, which requires a spinal fluid test.

In 2025 ILTOO said it was talking with European and US regulators about faster access, and UK experts called for a Phase 3 trial. As of November 2026 we could not find a public plan, date or funding for either. A UK patient campaign said in February 2026 it had seen no new activity.

MIROCALS has finished. ILTOO Pharma has run a managed access programme in some countries, including France, the UK and Austria, but in the UK it has been limited to former MIROCALS participants, and the drug is not available on the NHS. Ask your neurologist whether any access route exists where you live.

• MIROCALS (NCT03039673) completed · France, UK, other European sites