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].

Core Insights - Xilio Therapeutics announced updated Phase 2 data for vilastobart, showing deep and durable responses with a differentiated safety profile for anti-CTLA-4 combination therapy [1][5] - The company is on track to nominate its first development candidates for masked T cell engager programs in the second half of 2025 [1][12] - As of June 30, 2025, Xilio reported $121.6 million in cash and cash equivalents, providing a cash runway through the end of the third quarter of 2026 [1][13] Pipeline and Business Updates - Vilastobart is a tumor-activated, Fc-enhanced anti-CTLA-4 monoclonal antibody currently evaluated in combination with atezolizumab for advanced solid tumors and metastatic microsatellite stable colorectal cancer [3][14] - XTX301, a tumor-activated IL-12, is designed to stimulate anti-tumor immunity and is being evaluated as a monotherapy in a Phase 1 clinical trial [4][15] - Xilio's masked T cell engager programs include bispecific and tri-specific molecules designed to enhance T cell activation and are advancing through IND-enabling studies [7][9] Financial Results - Collaboration and license revenue for the quarter ended June 30, 2025, was $8.1 million, up from $2.4 million in the same quarter of 2024 [17] - Research and development expenses increased to $15.3 million in Q2 2025 from $11.2 million in Q2 2024, driven by clinical development activities [17] - The net loss for the quarter ended June 30, 2025, was $15.8 million, compared to a net loss of $13.9 million for the same period in 2024 [17][23]

Pipeline and Programs - Vilastobart (tumor-activated anti-CTLA-4) reported a preliminary Objective Response Rate (ORR) of 26% in Phase 2 for heavily pre-treated patients with microsatellite stable colorectal cancer (MSS CRC) without liver metastases[35, 41] - XTX301 (tumor-activated IL-12) is advancing in partnership with Gilead, with a potential $75 million option fee at Phase 1/2 data package[67, 69] - XTX501 (tumor-activated PD-1/IL-2 bispecific) IND submission is anticipated in mid-2026[74] - The company plans to nominate development candidates for PSMA, CLDN182, and STEAP1 masked T cell engager programs in Q3 2025, Q4 2025, and 1H 2026, respectively[24, 101] Financials and Partnerships - The company had $89.1 million in cash and cash equivalents as of March 31, 2025[120] - The company received approximately $47.2 million in estimated net proceeds from equity financing in June 2025[120] - The company anticipates a cash runway through the end of Q3 2026[21, 120] - The company is eligible to receive up to $100 million in additional gross proceeds from equity financing by 2H 2026[21, 120] - The company has a collaboration, license, and option agreement with AbbVie for tumor-activated immunotherapies, including masked T cell engagers, with up to ~$2.1 billion in total contingent payments[20, 113] Technology and Approach - The company's platform exploits dysregulated matrix metalloprotease (MMP) activity in tumors to activate molecules[12] - The company's masked T cell engagers are designed to optimize the therapeutic index by maximizing tumor exposure and minimizing peripheral activity and off-tumor cytotoxicity[98]