WESTON (dpa-AFX) - Biogen Inc. (BIIB) announced positive results from Part A of the AMETHYST Phase 2/3 study of litifilimab in people living with cutaneous lupus erythematosus (CLE). Litifilimab is the first humanized IgG1 monoclonal antibody targeting blood dendritic cell antigen 2 (BDCA2), with the potential to become the first innovative therapy for CLE in 70 years. The Phase 2 portion of AMETHYST evaluated efficacy and safety through week 24, showing reductions in skin disease activity across several measures, consistent with earlier findings from the Phase 2 LILAC study. These results supported litifilimab's recent U.S. FDA Breakthrough Therapy Designation.
The company noted that AMETHYST Part A met its primary endpoint, with litifilimab demonstrating a statistically significant 11.8% higher reduction in disease activity compared to placebo at Week 16, as measured by the Cutaneous Lupus Activity Investigators' Global Assessment Revised erythema score of 0-1 (clear/almost clear).
Secondary endpoints were not adjusted for multiplicity, so statistical significance cannot be claimed, but litifilimab showed rapid and sustained improvement in skin disease activity, with separation from placebo observed as early as Week 4. More participants receiving litifilimab achieved CLASI-50 and CLASI-70 responses-defined as 50% and 70% improvements from baseline in CLASI-A scores-through Week 24. Additionally, one in six participants on litifilimab achieved a CLASI 0-3 score, indicating no or minimal disease activity, compared to placebo.
Litifilimab was generally well tolerated, with a safety profile consistent with prior studies, including LILAC. Adverse events occurred in 74.6% of participants receiving litifilimab and 64.7% of those on placebo over 24 weeks, most of which were mild to moderate. Serious adverse events were reported in 6.8% of litifilimab participants compared to 2.9% in the placebo group.
BIIB closed at $183.84, down $7.22 or 3.78% on March 27. However, in overnight trading at 9:42:44 PM EDT, the stock showed signs of recovery, rising to $185.01, increase of $1.17 or 0.64%.
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