Keytruda SC Quarterly Sales Top $800 Million... South Korean Firms See 'Mixed Fortunes'

SC sales top KRW 1.11 trillion
Up 79% from the previous quarter
Expectations rise for Alteogen to reach its next milestone
A challenge for biosimilar developers

Merck (MSD) of the United States posted quarterly sales of more than $800 million for its immuno-oncology drug Keytruda in subcutaneous (SC) form just one year after its launch. With the patent expiration of Keytruda, the world's top-selling drug, approaching, the shift from intravenous (IV) to SC administration is gathering pace. The prospects for South Korean companies are diverging: Alteogen supplies the technology for Keytruda's switch to SC, while Samsung Bioepis and Celltrion are developing Keytruda biosimilars.

Merck said on Oct. 29 local time that its sales for the third quarter of 2026 totaled $18.085 billion (KRW 24.176 trillion), up 5% from the same period a year earlier. Sales of its key product Keytruda, combining IV and SC formulations, rose 6% to $8.601 billion (KRW 11.4978 trillion), accounting for nearly half of the company's total sales. Winrevair, a treatment for pulmonary arterial hypertension, generated $694 million (KRW 927.7 billion), while Gardasil, a cervical cancer vaccine, brought in $1.995 billion (KRW 2.6653 trillion); sales of the two products grew 93% and 14%, respectively. On the strength of its solid results, Merck raised the lower end of its annual sales forecast from $66.3 billion to $66.8 billion.

Growth in SC sales stood out in particular. They rose 79% from the previous quarter to $830 million (KRW 1.1095 trillion), more than six times their level in the first quarter. By contrast, IV sales fell 5% from a year earlier to $7.771 billion (KRW 10.3883 trillion). As a result, SC's share of total Keytruda sales climbed from 1.6% in the first quarter to 9.7% in the third quarter.

Merck's push to shift patients to SC is driven by the approaching patent cliff. Keytruda's patent on its active ingredient expires in the United States in 2028 and in Europe in 2031. After those dates, lower-cost biosimilars being developed by pharmaceutical companies at home and abroad are expected to flood the market. Merck's strategy is to minimize the drop in sales by moving existing patients to the SC formulation, which cuts administration time from around 30 minutes to 1-2 minutes. The company has officially set a target of switching 30-40% of Keytruda use to SC within two years of its launch.

Among South Korean companies, Alteogen is expected to benefit most directly. In June 2020, Alteogen signed a licensing agreement with Merck for its ALT-B4 technology for conversion to subcutaneous injection, and in February 2024, the agreement was amended to grant Merck exclusive rights for Keytruda SC. Under the deal, Alteogen will receive milestone payments in stages of up to $1 billion (KRW 1.3368 trillion), depending on sales, followed by royalties of 2% of net sales. In August 2026, the company disclosed that it would receive about KRW 34.4 billion as its first sales milestone payment. That amount is equivalent to 16% of its consolidated revenue last year. With third-quarter sales surpassing the cumulative total for the first half of the year, the next milestone could be reached sooner as well.

By contrast, the calculations for biosimilar developers have become more complex, as a faster shift to SC could shrink the IV market they are targeting. In South Korea, Samsung Bioepis and Celltrion have reached the threshold for commercialization. After confirming equivalence to the original drug in Phase 1 and Phase 3 clinical trials in June 2026, Samsung Bioepis became the first South Korean company to apply to the Ministry of Food and Drug Safety (MFDS) in August for marketing authorization for SB27. Celltrion applied for marketing authorization for CT-P51 in the same month.

The biggest remaining variable is patent litigation. In May 2026, Merck had two of Halozyme's patents invalidated by the U.S. Patent Trial and Appeal Board, in response to a patent infringement lawsuit brought by Halozyme in the United States. In Europe, however, after a ruling in Halozyme's favor in Germany, a Dutch court also ruled in its favor this month, blocking the launch of Keytruda SC in eight countries, including France and Italy. As these decisions were not reflected in the latest results, sales growth and supply conditions may vary by country going forward.

This content was produced with the assistance of AI translation services.