Biosimilar Race for the 'King of Drugs': FDA Accepts First Keytruda Biosimilar BLA — Without a Comparative Phase III
On October 13, Zydus Lifesciences and Formycon announced FDA acceptance of the FYB206 BLA — a pembrolizumab (Keytruda) biosimilar and, to the companies' knowledge, the first publicly announced Keytruda biosimilar filing accepted in the US. Developed without a comparative Phase III efficacy trial under a February 2025 FDA agreement, FYB206 could see a decision by Q3 2027. Keytruda posted US$8.4B in Q2 2026 quarterly sales, putting the industry's largest patent cliff on the clock.
The world's biggest-selling oncology drug has entered its imitation window. On October 13, India's Zydus Lifesciences and Germany's Formycon jointly announced that FDA accepted the Biologics License Application (BLA) for FYB206, a proposed biosimilar to pembrolizumab (Keytruda). To the companies' knowledge, it is the first publicly announced US acceptance of a Keytruda biosimilar filing; the BLA was submitted in Q3 2026 and a Canadian dossier has also been filed. Under the BsUFA review clock, FDA aims to complete review within 12 months of acceptance, with a decision possible as early as Q3 2027.
No comparative Phase III: the regulatory pathway is itself the news
What makes FYB206 notable is not merely that it is 'another biosimilar' but how it was developed: under an agreement reached with FDA in February 2025, the program required no comparative Phase III efficacy trial. Formycon CEO Stefan Glombitza said the pathway materially shortened the program and cut development spending. For the industry, it is a landmark demonstration — FDA's biosimilar regulation is easing comparative efficacy studies while tightening CMC and process characterization, and FYB206 is the first filing-level embodiment of that policy shift.
Two 'firsts' in one month: OMLYCLO and FYB206
October produced an unusual cluster of biosimilar firsts. On October 5, Celltrion announced the US launch of OMLYCLO (omalizumab-igec) — the first and only FDA-approved interchangeable biosimilar to XOLAIR, covering all four XOLAIR indications (moderate-to-severe allergic asthma, CRSwNP, IgE-mediated food allergy and chronic spontaneous urticaria), meaning pharmacy-level substitution is possible subject to state pharmacy laws. On September 25, Teva's Degevma (denosumab-adet) was approved across all Xgeva indications, completing the denosumab pair alongside the March-approved Prolia biosimilar. With FYB206's acceptance, October has showcased the full biosimilar spectrum — approvals, launches, and the first filing against the biggest molecule of all.
Editorial view: the capacity and process dividend of a US$8.4B-per-quarter blockbuster
Merck reported combined KEYTRUDA and KEYTRUDA QLEX sales of US$8.4B in Q2 2026 (with the subcutaneous QLEX contributing US$463M). As key patents approach expiry, Keytruda is set to become the single largest biosimilar opportunity in history. For CDMOs, the value of this news sits upstream: commercial biosimilar manufacturing and tech-transfer orders are becoming the stable base load of large-molecule CDMO businesses, while interchangeability and the no-comparative-Phase-III pathway raise the bar on quality systems, batch consistency and process characterization. As earlier industry analysis noted, the first-to-launch player could capture over 30% share with the top three taking 60–70% — launch timing is the revenue watershed. Capacity holders with strong CMC, including biosimilar manufacturing footprints in China, stand to benefit directly from this 'process wins' transition.
FAQ
What is FYB206 and who develops it?
FYB206 is a proposed biosimilar to pembrolizumab (Keytruda). Formycon handles development, filing and supply while retaining global rights; Zydus holds exclusive US and Canada commercialization rights. FDA accepted the BLA on October 13, 2026, and under a 12-month review clock a decision could come as early as Q3 2027.
Why is no comparative Phase III required?
Per the companies, FDA agreed in February 2025 that a comparative Phase III efficacy trial was not required. That aligns with FDA's broader shift away from comparative efficacy studies toward CMC and analytical characterization, shortening timelines and cutting costs. Acceptance is not approval — the review could still end in a Complete Response Letter.
What does this mean for CDMOs?
Keytruda's US$8.4B Q2 2025 quarterly sales make it the largest biosimilar target ever; the imitation race will generate substantial commercial manufacturing, tech-transfer and analytical characterization orders. With no comparative Phase III and interchangeability requirements, competition shifts to process and quality systems — favoring CDMOs with compliant, scaled capacity and biosimilar delivery track records.