Keytruda biosimilars: the first filings start a staggered race
- Samsung Bioepis filed its pembrolizumab biosimilar (SB27) with the FDA on 30 October 2026, just over two weeks after the FDA accepted Formycon's FYB206; a decision on FYB206 is expected in Q3 2027.
- Keytruda generated $31.7 billion in 2025, 49% of Merck's sales, making it the single largest biosimilar opportunity of the next five years.
- Markets open in stages: parts of Latin America, MENA and Southeast Asia now, the US from December 2028, the EU from January 2031 and Japan in 2032–33.
- More than 15 developers across the US, Europe, South Korea, China and India: three have filed and three more expect to file by 2028.
- Timing of market opening, the shift to subcutaneous Keytruda Qlex, Medicare price setting and price competition will shape the size of the opportunity and the value of deals.
On 30 October 2026, Samsung Bioepis announced that it had filed its proposed pembrolizumab biosimilar, SB27, with the US Food and Drug Administration. The application covers 18 of Keytruda's indications and is supported by a Phase 1 pharmacokinetic study in 163 patients and a Phase 3 study in 555 patients with first-line non-squamous non-small cell lung cancer. It follows, by just over two weeks, the FDA's acceptance of the first pembrolizumab biosimilar application: Formycon's FYB206, partnered with Zydus for the US and Canada, announced 13 October 2026, with a decision expected in the third quarter of 2027 — see Sathguru's analysis of the patent landscape behind these filings. Samsung Bioepis and Celltrion filed in Korea in August, and Amgen has indicated a US filing by the end of 2026.
With two US applications now filed roughly two years before Merck expects US biosimilar competition to begin, we see pembrolizumab biosimilars moving from development into regulatory review. In this post, we set out the context: scale of the franchise, the order in which markets will open, and the shape of the pipeline. This is the first in a series of posts on the Keytruda (pembrolizumab) biosimilar opportunity; and we intend to build on this with a deep dive into various factors that will shape the single largest biosimilar opportunity over the next 5 years.
Keytruda's scale and the pembrolizumab biosimilar opportunity
Keytruda, including the subcutaneous Keytruda Qlex, generated $31.7 billion in 2025, up 7%, and $25.0 billion in the first nine months of 2026 (Merck Q3 2026 earnings release). It is the largest-selling medicine globally. The US accounts for about 60% of sales.
We find the concentration as notable as the size. Keytruda made up 49% of Merck's total sales in 2025 ($31.7 billion revenue from Keytruda as a share of Merck's corporate revenue of $65.0 billion; Merck FY2025 results), and the same share in January–September 2026. For comparison, Humira accounted for 37% of AbbVie's revenue in 2022 ($21.2 billion of $58.1 billion; AbbVie FY2022 results), the year before US biosimilars launched. Growth within the franchise itself is mellowing, from 20–30% a year in 2019–2022 to 7% in 2025, as adoption in major indications matures.
Hover or tap a bar for the US and international split.
Headline sales, however, are not the market we expect biosimilars to address. Several layers will shape that opportunity, including the move of patients to subcutaneous Keytruda, Medicare price setting under the Inflation Reduction Act, and price competition among entrants. In a later post, we will deep dive into these multi-variate scenarios that will impact size of opportunity for Keytruda (pembrolizumab) biosimilars.
Keytruda biosimilar market entry: a five-year global timeline
Loss of exclusivity for pembrolizumab will be spread over five years, as patent terms, extensions and regulatory exclusivity differ by market.
- Already open: parts of Latin America, MENA and Southeast Asia, where patent protection is limited; biosimilars launched in Argentina and Paraguay in 2025.
- 2028: Korea, India and China, as the compound patent expires.
- From December 2028: the US, at the end of the extended compound patent; two further patents expiring in May and November 2029 may be litigated or settled.
- 20 January 2031: the EU, when the supplementary protection certificate and its six-month paediatric extension lapse. Regulatory data exclusivity already ended in July 2026.
- 2032–33: Japan, after patent term extension.
Why the US and EU open two years apart
The underlying patent expires in mid-to-late 2028 in both the US and the EU, yet the two markets will open about two years apart. The difference lies in how each system extends patent life.
Smaller markets open first
Some markets are already open, and the first products approved there were developed by regional companies rather than by the developers now filing in the US. We expect developers with a multi-region plan to use this sequence to build commercial experience before the larger markets open.
Precedents: ustekinumab and adalimumab
This EU-before-US pattern is not new to biologics. Stelara (ustekinumab) biosimilars launched in Europe from July 2024, about six months ahead of the settled US entry date, and even within the US, Amgen's Wezlana reached the market in January 2025, roughly 15 months after the underlying patents expired, once licensing and settlement terms were in place — a precedent we examined in more depth here. Humira (adalimumab) shows a larger version of the same pattern: Amgen's biosimilar was approved by the FDA as early as September 2016, but under its settlement with AbbVie it launched in Europe only in October 2018 and did not reach the US until January 2023 — a gap of more than four years that we flagged at the time in our 2018 year-end round-up.
The global pembrolizumab biosimilar pipeline and regulatory pathway
More than 15 companies are developing intravenous pembrolizumab biosimilars. Three have filed with a regulator (Formycon, Samsung Bioepis and Celltrion) and Amgen is expected to follow shortly.
- Filed with a regulator: Formycon's FYB206, partnered with Zydus for the US and Canada, has an accepted FDA application with a decision expected in Q3 2027. Samsung Bioepis (SB27) filed in Korea in August and in the US in October 2026, and Celltrion (CT-P51) filed in Korea in August 2026.
- Filing by 2028: Amgen (ABP 234) expects to file in the US in late 2026, Sandoz (GME751) has completed Phase 1 and plans to file in 2027, and Alvotech (AVT32), co-developed with Dr. Reddy's, is targeting an EU filing in 2028.
- In clinical trials: Qilu (QL2107), partnered with Cipla in the US and Orion in the EU, is in Phase 3; Henlius (HLX17) is in Phase 1/3; and Enzene/Alkem, Intas and Hetero are at Phase 3 or protocol stage in India.
- No subcutaneous biosimilar yet: no developer has disclosed a subcutaneous pembrolizumab biosimilar; every programme above is intravenous.
In our reading, the pipeline has been shaped by a change in regulatory expectations. In October 2025, the FDA issued draft guidance indicating that comparative efficacy studies are generally not needed where analytical and pharmacokinetic data are sufficient, and the EMA has moved in a similar direction. Several sponsors adjusted their programmes as a result: Formycon ended its Phase 3 study by agreement with the FDA, Sandoz reduced its Phase 3, Bio-Thera stopped its Phase 1/3, and Celltrion ended the EU portion of its trial. India and China have not moved in the same direction: India's revised similar biologics guidelines keep confirmatory safety and efficacy studies mandatory for monoclonal antibodies, and China's 2015 biosimilar guideline generally expects comparative clinical studies. Since trials in these countries cost less than studies run for the FDA and EMA, programmes aimed at them continue to run Phase 3 studies with efficacy endpoints.
The pipeline is global, with programmes in the US and Europe, South Korea, China and India, and regional products already on sale in several smaller markets. In our view, this mix of in-house programmes and cross-border partnerships, each with a different balance of risk, capital and value, will shape how the market is contested once it opens.
US and European developers
Formycon holds the first FDA-accepted application and has licensed regional rights to Zydus (US and Canada), MS Pharma (MENA) and Lotus (Asia-Pacific). Amgen has completed two Phase 3 studies and plans a US filing in late 2026. Sandoz expects to be ready to file in 2027 after reducing its Phase 3, and Alvotech is co-developing its candidate with Dr. Reddy's, with an EU filing targeted for 2028.
South Korea
Samsung Bioepis and Celltrion both filed in Korea in August 2026. Samsung Bioepis's Phase 1 and Phase 3 studies met their endpoints in June 2026, and its US application covers 18 indications. Celltrion ran a global Phase 3 and ended the EU portion in July 2026.
China
Qilu is in Phase 3 against Keytruda in metastatic non-squamous lung cancer, with Cipla holding US rights and Orion EU rights. Henlius is running an international Phase 1/3 under investigational approvals from both China's NMPA and the FDA. Bio-Thera has completed Phase 1 and partnered with Avalon for Saudi Arabia and the wider MENA region.
India
Indian companies take part as US licensees (Zydus, Cipla), as co-developers (Dr. Reddy's with Alvotech) and as developers (Alkem, Intas, Hetero), with the developers running or planning Phase 3 studies in India.
Regional products already on sale
Biocad's Pembroria was approved in Vietnam in November 2025, and Bioeticos and Sana Pharma launched in Paraguay in 2025, followed by approval in Jordan in February 2026. mAbxience is in Phase 3 in first-line lung cancer.
Merck's biosimilar defence strategy: Keytruda Qlex and lifecycle management
Merck has been preparing for this period for some time. Keytruda Qlex, approved in the US in September 2025, uses Alteogen's hyaluronidase enzyme to allow administration in one to two minutes. It generated $830 million in the third quarter of 2026, about 10% of Keytruda family sales, and Merck aims to have 30–40% of US patients on it by the end of 2027. It is protected by patents to 2043 in the US (Merck FY2025 10-K). Merck has said it expects biosimilar impact to be immaterial in 2026. We would flag that the strategy is not without risk: Halozyme has obtained injunctions against Keytruda SC in nine European countries in a patent dispute over the enzyme. We will look at the subcutaneous formulation and its implications for biosimilar developers in a future post in this series.
Strategic outlook
With $31.7 billion in sales in 2025 and markets opening in stages through 2033, Keytruda (pembrolizumab) is, in our view, the single largest biosimilar opportunity of the next five years. The first filings set the clock for US review, and much of the positioning is still ahead. We expect several more partnerships to be explored and forged, and developers, licensees and investors to take key corporate decisions on where, when and with whom to compete. As we discuss the Keytruda opportunity with clients and partners, we believe the following factors will be critical:
- Timing of market opening: the US opens from December 2028 and the EU from January 2031, with emerging markets earlier, and patent litigation or settlements could move these dates.
- Shift to subcutaneous dosing: Keytruda Qlex was about 10% of Keytruda family sales in Q3 2026, and Merck aims to move 30–40% of US patients to it by the end of 2027.
- Medicare price setting: price setting under the Inflation Reduction Act will affect the US price that biosimilars compete against.
- Price competition: the number of biosimilars launching at the same time will determine how quickly prices fall.
Together, these factors will determine the timing and value of licensing deals, commercial partnerships and market entry in this category.
Follow along as we deep dive into each of the following strategic considerations in future posts in this series:
- Timing of market opening: patents and exclusivity in the US and EU, and the emerging markets that open earlier.
- Subcutaneous and lifecycle management: the Keytruda Qlex launch, the Merck–Alteogen partnership, and the Halozyme dispute.
- Regulatory precedents and pathways: how pembrolizumab has changed the evidence regulators expect from biosimilar developers.
- Who is in the pipeline: global landscape of developers, critical partnerships, and outlook.
- How large the market could be: critical drivers that will shape the biosimilar opportunity in each region.
We look forward to engaging with you on what these developments mean for your organisation, and to exploring the implications for your strategic decisions.
Related reading from Sathguru
- Biosimilar Approvals Are Getting Faster, but Patents Remain a Binding Constraint (29 Oct 2026) — covers the Formycon/Zydus FYB206 filing discussed above, alongside recent patent litigation in golimumab and nivolumab biosimilars, and why approval and patent timelines should be modelled separately by geography.
- Biosimilars, Novel Drugs, API: Momentum in Cross-Border Deals (1 Oct 2026) — on recent licensing and M&A activity across biosimilars and novel drugs, including the Samsung Bioepis–Teva biosimilar partnership and the growing role of Indian companies as both licensees and acquirers.
- Ustekinumab Biosimilar: Spotlighting Patent Litigations, Partnerships, Competition (2 Dec 2024) — an earlier case study in how settlements, marketing partnerships and the EU-before-US pattern played out for another blockbuster biologic.
- USFDA Reduces Data Requirement for Interchangeability (24 Jun 2024) — background on the FDA's earlier move to lower the evidence bar for biosimilars, a precursor to the October 2025 guidance discussed above.
Pushpa leads Sathguru's health and life sciences practice, advising on pharmaceutical business development, licensing and partnerships, market intelligence and regulatory strategy across global markets.
