Core Insights - Several small- and mid-cap biotech and medical stocks experienced significant after-hours trading activity on September 26, driven by clinical updates, investor presentations, and strategic announcements. Company Summaries - **Enanta Pharmaceuticals Inc. (ENTA)**: The stock surged 20% in after-hours trading to $9.48 after closing at $7.90, following the announcement of upcoming topline results from its Phase 2b study on zelicapavir for RSV treatment in high-risk adults [2][3]. - **Acumen Pharmaceuticals Inc. (ABOS)**: Shares rebounded 12.67% to $1.60 after closing at $1.42, driven by renewed interest in its Alzheimer's pipeline, particularly the Phase 2 candidate Sabirnetug (ACU193) [4]. - **Delcath Systems Inc. (DCTH)**: The stock gained 6.00% in after-hours trading to $11.39 after closing at $10.74, following renewed investor interest in its CHOPIN Phase 2 trial data presentation scheduled for ESMO 2025 Congress [5][6]. - **Vivos Therapeutics Inc. (VVOS)**: The stock climbed 4.81% to $3.27 after closing at $3.12, likely due to renewed interest following recent positive clinical trial results for its pediatric OSA treatment [7][8]. - **Xilio Therapeutics (XLO)**: Shares rose 4.28% to $0.83 after closing at $0.7959, driven by enthusiasm surrounding the initiation of a Phase 2 trial for its tumor-activated IL-12 candidate, which also triggered a $17.5 million payment from Gilead [9][10]. - **Nyxoah SA (NYXH)**: The stock increased 3.77% to $4.68 after closing at $4.51, supported by optimism regarding its international expansion and a recent patent infringement lawsuit against Inspire Medical Systems [11].