Biogen Inc. and Ionis Pharmaceuticals, Inc. announced topline results from the Phase 1 study of BIIB078 (IONIS-C9Rx), an investigational antisense oligonucleotide (ASO) for people with C9orf72-associated amyotrophic lateral sclerosis (ALS). In this Phase 1 study, BIIB078 was generally well-tolerated. The adverse events (AEs) were mostly mild to moderate in severity and occurred at a similar rate across BIIB078 and placebo groups.

The most common AEs were fall, procedural pain and headache. BIIB078 did not meet any secondary efficacy endpoints and it did not demonstrate clinical benefit. In the dose cohorts up to 60 mg there were no consistent differences between the BIIB078 group and the placebo group.

Participants in the BIIB078 90 mg dose cohort trended toward a greater decline than those in the placebo group across secondary endpoints. Based on these results, the BIIB078 clinical development program will be discontinued, including its ongoing open-label extension study. This Phase 1 study was a randomized, placebo-controlled, dose-escalating trial to evaluate BIIB078 administered intrathecally to adults (n=106) with C9orf72-associated ALS.

Within each of the six study treatment cohorts, participants were randomized to receive BIIB078 or placebo (3:1 ratio). The primary objective of the study was to assess safety and tolerability. Secondary efficacy endpoints included ALS Functional Rating Scale–Revised, Slow Vital Capacity, Hand-Held Dynamometry, and the Iowa Oral Pressure Instrument.

The companies will present the BIIB078 Phase 1 data at a future scientific forum.