Gilead, GSK/ViiV, Merck Present New HIV PrEP Frontiers at IAS25

At IAS 2025, major pharmaceutical players unveiled significant advancements in long-acting HIV prevention (PrEP) and treatment, signaling intensified competition and expanded market opportunities. Gilead presented new Phase III data for its recently approved twice-yearly injectable PrEP, Yeztugo, confirming efficacy in vulnerable populations and detailing a no-profit global access strategy. ViiV Healthcare showcased real-world data reinforcing patient preference for its established long-acting injectable PrEP, Apretude, and its HIV treatment, Cabenuva. Meanwhile, Merck re-entered the late-stage PrEP arena, advancing its once-monthly oral candidate, MK-8527, into Phase III, collectively highlighting a market shift towards more convenient, less frequent dosing regimens poised to reshape HIV care and prevention.

Analysis

The long-acting HIV prevention (PrEP) market is entering a phase of intensified competition and innovation, driven by a clear trend towards less frequent, more convenient dosing regimens. Gilead (GILD) has established a formidable position with the recent landmark approval of Yeztugo, a twice-yearly injectable that analysts from Mizuho suggest could 'redefine' the PrEP market. This competitive advantage is being reinforced by new Phase III data from the PURPOSE program confirming efficacy and safety in critical populations, including pregnant women and adolescents, alongside a strategic no-profit agreement with the Global Fund to accelerate access in low- and middle-income countries. In response, incumbent ViiV Healthcare (a GSK and PFE venture) is defending its market share by presenting real-world evidence for its every-two-month injectable, Apretude, demonstrating high patient satisfaction (95% happy to switch from oral PrEP) and feasibility. Concurrently, Merck (MRK) is making a significant re-entry into the late-stage PrEP field by advancing its once-monthly oral candidate, MK-8527, into a large Phase III program, representing a comeback after the 2022 discontinuation of its previous candidate, islatravir. This move introduces a differentiated oral option that will compete directly with the injectable offerings from Gilead and ViiV, setting up a dynamic three-way contest for market dominance.

Key Decisions for Investors

• Investors should recognize Gilead's strengthened leadership position, as the superior convenience of its twice-yearly Yeztugo injectable, backed by strong new clinical data, presents a significant commercial advantage over competitors.
• For ViiV Healthcare (GSK, PFE), the key consideration is its ability to leverage strong real-world patient preference data to defend its market share for Apretude against the more convenient dosing of Gilead's Yeztugo.
• Merck's advancement of its once-monthly oral PrEP candidate to Phase III is a notable de-risking event; its success could disrupt the injectable-dominated market and represents a key long-term catalyst to monitor.
• The competitive landscape in HIV PrEP is now clearly defined by dosing frequency and delivery method, warranting a portfolio view that assesses how Gilead's convenience, ViiV's incumbency, and Merck's oral alternative will capture distinct patient segments.