Samsung Bioepis Files Keytruda Biosimilar With FDA, Presents 555-Patient Lung Cancer Data

Samsung Bioepis has asked the FDA to approve SB27, a biosimilar of Merck's Keytruda (pembrolizumab), and it put its Phase 3 evidence on display a week later.

The company announced the Biologics License Application on Friday, Oct. 30. It covers 18 indications, including melanoma, non-small cell lung cancer and head and neck cancer. On Nov. 6 the company presented the full Phase 3 dataset as a poster at the Society for Immunotherapy of Cancer annual meeting in Phoenix, which runs Nov. 4 to 8.

The trial numbers

The Phase 3 study was double-blind and randomized. It enrolled 555 patients with metastatic non-squamous non-small cell lung cancer across 14 countries. Of those, 283 received SB27 and 272 received reference Keytruda, each at 200 mg every three weeks alongside chemotherapy.

The primary endpoint was objective response rate at Week 24, meaning the share of patients whose tumors measurably shrank. SB27 posted 34.6%. Keytruda posted 37.9%. The 90% confidence interval for the ratio between the two arms ran from 0.737 to 1.071.

Samsung Bioepis says the trials confirmed equivalence to the original drug. It also says rates of treatment-emergent adverse events and serious ones were similar across the two products. The FDA has made no finding on SB27.

A separate Phase 1 study enrolled 163 patients with resected stage 2 to 3A lung cancer. It compared SB27 against both EU-sourced and U.S.-sourced Keytruda, and the company presented it at the European Society for Medical Oncology congress in Madrid. Exposure ratios fell inside the prespecified 0.80 to 1.25 range in every comparison. In cycle 1, SB27 versus U.S. Keytruda came in at 0.93 (90% CI 0.86 to 1.01). No patients developed neutralizing antibodies.

The Tech Times described the Phoenix poster as the first full Phase 3 data disclosure for any pembrolizumab biosimilar.

Samsung Bioepis ran the two trials at the same time, starting in 2024, and says it plans to finish both this year.

The money at stake

Keytruda generated $31.7 billion in 2025, up 7%, making it the world's best-selling prescription drug. Merck's Q3 2026 earnings release put sales at $25.0 billion for the first nine months of this year, according to analysis from Sathguru. The U.S. accounts for about 60% of sales.

The drug also makes up 49% of Merck's total revenue, per Sathguru's math on Merck's reported $65.0 billion in 2025 sales. Sathguru compared that to Humira, which was 37% of AbbVie's revenue in 2022, the year before U.S. biosimilars launched.

The underlying patent expires in mid-to-late 2028 in both the U.S. and the EU, according to Sathguru. The Tech Times puts the core U.S. composition-of-matter patent on the intravenous formulation at December 2028.

If the FDA runs a standard 12-month review, the Tech Times estimates a decision could come as early as the fourth quarter of 2027. That would be about a year before that patent expires. The sources do not show that the FDA has formally accepted SB27 for review.

A smaller prize than the headline

Sathguru's analysts argue that Keytruda's $31.7 billion is not the market biosimilars can actually reach. They point to three factors: patients shifting to the subcutaneous version, Keytruda Qlex; Medicare price setting under the Inflation Reduction Act; and price competition among entrants.

Sathguru also notes Keytruda's growth has slowed from 20 to 30% a year in 2019 to 2022 down to 7% in 2025.

The company's own framing is about access. "We will strive to once again demonstrate our research and development capabilities during the U.S. marketing authorization review process for SB27, and to expand treatment options and improve accessibility for patients through biosimilars in the immunotherapy field," said Shin Dong-hoon, head of Clinical Medicine at Samsung Bioepis.

Competition is how a $31.7 billion-a-year drug eventually gets cheaper. Merck's patent protection exists for good reason, but it has an end date.

The field is filling up

Samsung Bioepis is not alone. Formycon and Zydus Lifesciences announced on Oct. 13 that the FDA accepted their pembrolizumab biosimilar, FYB206, for review. Sathguru reports a decision is expected in the third quarter of 2027. That makes FYB206 the first pembrolizumab biosimilar application the FDA has accepted, according to Sathguru.

In South Korea, Samsung Bioepis filed with the Ministry of Food and Drug Safety in August, covering 16 indications. Sathguru says Celltrion also filed in Korea in August. Amgen has indicated a U.S. filing by the end of 2026.

The next concrete markers are the FDA's handling of the SB27 application, the expected FYB206 decision in the third quarter of 2027, and whether Amgen files before year-end as it has indicated.

Merck has not been quoted in the filings or announcements on how it plans to defend Keytruda's position.