FDA gives conditional approval to Biogen drug for rare form of ALS

The Food and Drug Administration on Tuesday granted conditional approval to a new Biogen treatment for a rare, genetic form of ALS — basing its decision for the first time on preliminary evidence that may also speed the development of future medicines for the fatal, neurodegenerative disease. The drug, called Qalsody, is administered by a monthly injection into the spine, and is intended to treat people with ALS caused by inherited mutations in a gene called SOD1. Cambridge-based Biogen estimates approximately 330 people in the United States have this form of ALS, with 120 new cases each year. Globally, SOD1 mutations are responsible for approximately 2 percent of all ALS cases. The FDA cleared the use of Qalsody through a regulatory pathway called accelerated approval, which allows drugs to reach the market based on early evidence from so-called surrogate biomarkers, but before more definite patient benefit is confirmed. It’s the first time accelerated approval has been used by the FDA for a medicine to treat ALS. In this case, Qalsody reduces levels of a protein called neurofilament light chain that leaks into the blood and spinal fluid of ALS patients as nerves are damaged. Scientists believe decreases in neurofilament levels will lead to a slowing of neurologic and functional decline in ALS patients, although Biogen will need to confirm the benefit in another clinical trial. Results from a Phase 3 study showed Qalsody, after six months, was able to reduce SOD1 protein levels, as expected, but that only led to a modest slowing of neurologic and functional decline in ALS patients compared to a placebo — not enough to reach statistical significance or achieve the study’s main efficacy goal. But Biogen sought accelerated approval anyway, arguing that reductions in neurofilament were reasonably likely to lead to a benefit for patients, even though, due to, limitations and flaws, its Phase 3 study failed to confirm that.