C9orf72 and amyotrophic lateral sclerosis: The first clinical trial was conducted to assess the safety and tolerability of the ASO BIIB078, a phosphorothioate backbone ASO, which selectively targets C9orf72 transcript variants 1 and 3 carrying the expansion, inducing RNAse H degradation, for the treatment of adult ALS patients with C9orf72 expansion (NCT03626012).