The goal of this clinical trial is to learn whether a nasal spray medicine called foralumab is safe and easy to tolerate in adults with amyotrophic lateral sclerosis (ALS). ALS is a disease that slowly damages the nerve cells that control movement, causing muscles to grow weaker over time. Foralumab is being studied as a possible way to calm the inflammation and immune system activity that are thought to play a role in ALS.
The main questions it aims to answer are:
1. Is nasal foralumab safe for people with ALS, and how well do they tolerate it over 12 and 24 weeks of treatment?
2. Does foralumab change certain markers in the blood and spinal fluid, and lower inflammation in the brain, compared with a placebo?
Researchers will compare people who take foralumab to people who take a placebo (a matching nasal spray with no medicine in it) to see how the two groups differ in safety and in these markers.
About 44 adults aged 18 to 75 with ALS will take part. For the first 12 weeks, participants will be randomly assigned so that about 3 in 4 use foralumab and about 1 in 4 use the placebo. Neither the participants nor the study staff will know who is using which during this time (this is called "double-blind"). After the first 12 weeks, everyone who continues will use foralumab for the next 12 weeks.
Participants will:
* Spray the study treatment into both nostrils 3 times a week, on alternate days, in cycles of 2 weeks on treatment followed by 1 week off
* Learn to use the nasal spray device so they or a caregiver can give most doses at home
* Take part for about 8.5 months in total, which includes screening, 24 weeks of treatment, and a safety check-in about 4 weeks after the last dose
* Attend some visits at the study clinic and complete others remotely by phone or video
* Have study tests that may include blood samples, breathing and muscle-strength checks, and - for those who agree and at certain study centers - spinal fluid samples and brain scans to measure inflammation