ZACKS·2025-12-23 16:45Core Insights - Gilead Sciences has exercised its option to exclusively license Assembly Biosciences' herpes simplex virus helicase-primase inhibitor programs, marking the first advancement under their collaboration [1][2] Licensing Agreement - Gilead entered a 12-year partnership with Assembly Biosciences in 2023 to develop novel antiviral therapies, with Assembly Bio receiving a $35 million payment upon Gilead's exercise of its option [2] - Gilead will obtain exclusive rights to ABI-5366 and ABI-1179, taking full responsibility for their clinical development and commercialization [2] Financial Milestones - Assembly Biosciences is eligible for up to $330 million in regulatory and commercial milestones, along with tiered royalties on net sales [3][7] Product Development - ABI-1179 and ABI-5366 are long-acting helicase-primase inhibitors showing strong antiviral activity and significant reduction in virus-positive lesions in interim data from early-stage studies [8][9] - Over four million people in the U.S. and some European countries suffer from recurrent genital herpes, indicating a substantial market opportunity for these new therapies [9][10] Market Context - No new HSV therapies have been approved in the U.S. or Europe in over 25 years, highlighting the potential impact of ABI-5366 and ABI-1179 if successfully developed [9][10] Gilead's HIV Portfolio - Gilead has a leading HIV franchise, with products like Biktarvy and Descovy driving top-line growth [11] - The recent FDA approval of lenacapavir for HIV prevention enhances Gilead's portfolio, especially as Truvada faces generic competition [12]