Impact of U.S. most-favored-nation (MFN) drug pricing on global oncology access.

11056 Background: U.S. cancer drug prices substantially exceed those in other OECD countries. In May 2025, a U.S. Presidential Executive Order mandated adoption of a Most-Favored-Nation (MFN) pricing policy, linking U.S. drug prices to those of economically comparable countries. In December 2025, the Centers for Medicare & Medicaid Services (CMS) proposed two MFN-based frameworks: the Global Benchmark for Efficient Drug Pricing (GLOBE) for Medicare Part B drugs and Guarding U.S. Medicare Against Rising Drug Costs (GUARD) for Part D drugs. Both require manufacturer rebates when U.S. prices exceed GDP-adjusted international benchmarks, creating potential incentives for manufacturers to alter global oncology pricing and launch strategies. This study assesses which international markets may face pricing pressure or delayed access to new oncology therapies following MFN implementation. Methods: The top 50 best-selling U.S. drugs in 2024 were reviewed, and 12 oncology drugs without generic or biosimilar competition were selected. List prices were collected from the 19 OECD reference countries included in GLOBE and GUARD. Prices were adjusted for GDP per capita using purchasing power parity (PPP). For each drug, the two lowest GDP-adjusted international prices were identified and compared with U.S. prices, using January 2026 Medicare Average Sales Price (ASP) data for Part B drugs and December 2025 Federal Supply Schedule (FSS) prices for Part D drugs. Results: Across all 12 drugs, GDP-adjusted benchmark prices were 48% to 90% lower than U.S. prices. Pembrolizumab, the top-selling oncology drug in 2024, had a U.S. Medicare price of $5,972 per 100 mg; the lowest adjusted prices were observed in South Korea ($2,116) and Japan ($2,271), representing reductions of 65% and 62%, respectively. Daratumumab, the second top-selling oncology drug, was priced at $2,831 per 400 mg in the U.S., compared with $1,467 in South Korea and $1,603 in the Netherlands (48% and 43% lower). The lowest benchmark prices most frequently originated from South Korea (n=5) and the Netherlands (n=4). Norway, Germany, and Japan each provided the lowest benchmark for one drug. Second-lowest benchmark prices were observed in Japan (n=4), South Korea (n=3), the Netherlands (n=2), Germany (n=2), and Norway (n=1). Conclusions: Countries serving as the lowest-price benchmarks- particularly South Korea, Japan, the Netherlands, Norway, and Germany- may face increased risk of upward pricing pressure or delayed access to innovative oncology therapies as manufacturers seek to limit U.S. MFN rebate exposure. Expanded use of confidential discounts, confidential rebates and other managed-entry agreements may help preserve access while reducing MFN benchmark risk.