Few diseases are as cruelly debilitating as amyotrophic lateral sclerosis (ALS). But a Food and Drug Administration advisory committee this week gave patients a glimmer of hope by backing a new treatment that can slow their decline and provide precious more time to live.

ALS, or Lou Gehrig's disease, is a neurodegenerative affliction that gradually robs people of their ability to function. It afflicts about 30,000 patients in the U.S. with 5,000 new cases each year. Patients typically live only two years after a diagnosis as they lose their ability to control essential muscle movements and eventually to chew and breathe.

Scientists don't fully understand what causes the disease, and there are only two approved treatments. Neither has shown to both extend life and slow functional decline. But Amylyx Pharmaceuticals' experimental drug did both in a small Phase 2 trial. Patients treated with the drug lived on average 4.8 to 11 months longer than those who weren't and experienced 25% slower functional decline over 24 weeks.

However, an FDA advisory committee in March voted 6-4 against approving the drug. Many members wanted to wait for results from Amylyx's Phase 3 trial, which likely won't be complete until late next year or early 2024. They worried that approving the drug would give patients false hope if the Phase 3 results prove less beneficial. Our guess is that patients will take their chances on any hope.

FDA leaders appeared inclined but reluctant to approve the drug after the political lashing they took for overruling their advisory committee last year to approve Biogen's experimental Alzheimer's drug. Billy Dunn, the FDA chief of neuroscience, was pounded by the public-health left for urging regulatory flexibility amid positive but inconclusive trial results.

The FDA earlier this summer made an unusual decision to let Amylyx submit more trial data and reconvene its advisory committee for a second look. Canadian regulators in June approved the drug on condition Amylyx completes the Phase 3 trial, which prompted some patients to consider heading north to obtain the drug. What an embarrassment for the U.S.

The U.S. is the world's leading pharmaceutical innovator, and Americans typically get access to more novel treatments, and sooner, than patients in countries with government-run health systems. But the public-health left is campaigning to limit access to expensive new treatments, and Amylyx's ALS drug was nearly caught in the cross hairs.

The good news is that advisory members appeared to have been moved at their recent meeting by wrenching testimony from ALS patients and the doctors who treat them. Patients who received the drug said it helped stabilize their conditions and live independently. One could even go hiking.

Dr. Dunn rose in support of patients and urged members to show the broadest flexibility, notwithstanding an FDA staff report that was somewhat critical of Amylyx's results. Advisory members voted 7-2 in favor of approval. It's notable that one of the no votes, Johns Hopkins internist Caleb Alexander, was also a leading critic of Biogen's Alzheimer's drug.

The advisory committee's support should give FDA the political cover it was apparently seeking to approve the drug. But the battle over FDA drug approvals will continue, so patients will have to keep fighting to live another day.