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Keros is weighing up a sale as part of a poison pill defence. Credit: Catherine Falls Commercial via Getty Images. Keros Therapeutics’ board of directors has authorised a ‘poison pill defence’— in response to increasing investor interest in “influencing the company’s control”. The move comes after certain investors – including one individual holding 11.2% of Keros’s outstanding common stock as of 6 April 2025 – expressed a desire to shape the company’s strategic decisions. US-based Keros stated that the limited-duration stockholder rights plan is designed to protect the integrity of its ongoing strategic review process, which could include the potential sale of the company. As a result of the announcement, Keros’s shares jumped by 13%, reaching $11.67 per share at market open. The company confirmed it has initiated a process to evaluate strategic alternatives and plans to provide updates on the process within 60 days of the 10 April announcement. This update follows a series of challenges faced by Keros related to its cibotercept clinical programme for pulmonary arterial hypertension (PAH). In December 2024, Keros halted higher-dose cohorts from the Phase II TROPOS study (NCT05975905) after a safety review revealed concerning adverse events, including fluid buildup around the heart – a development that saw the company’s shares plunge by more than 77%. Keros suspended the two higher-dose groups and eventually ended the study in January 2025, citing “the ongoing safety review due to new observations of pericardial effusion adverse events”. The candidate was positioned as a rival to MSD’s PAH drug Winrevair (sotatercept). The US Food and Drug Administration (FDA) approved Winrevair in March 2024 and it is projected to reach blockbuster status, generating up to $6.4bn in global sales by 2030, as per GlobalData, the parent company of Pharmaceutical Technology. Keros’s lead candidate is a TGF-beta inhibitor dubbed elritercept. The candidate is being investigated in the ongoing Phase III RENEW study (NCT06499285), targeting transfusion-dependent anaemia in very low, low or intermediate-risk myelodysplastic syndrome (MDS) patients. In December 2024, Takeda inked a deal worth up to $1.3bn with Keros to further develop, manufacture and commercialise elritercept worldwide outside of mainland China, Hong Kong and Macau. According to GlobalData’s Pharma Intelligence Center, elritercept is projected to generate up to $425m in 2030, if approved. Keros is also advancing its pipeline with KER-065, a candidate for Duchenne muscular dystrophy (DMD), which has shown positive early-stage results. The company announced in March 2025 that KER-065 was well tolerated in Phase I trials, with evidence of activin inhibition across “tissues of interest”. Following this announcement, Keros said  it plans to engage with regulatory authorities in Q3 2025, with a Phase II trial for DMD expected to begin in Q1 2026, pending regulatory feedback.

SEOUL, South Korea, April 9, 2025 /PRNewswire/ -- Darnatein, a wholly-owned subsidiary of OSR Holdings, Inc. (NASDAQ: OSRH), today announces that it has successfully secured an additional international patent for its protein-based osteoarthritis treatment technology, marking a significant step in its expansion into the global market. Activin/BMP7 Chimera Protein Technology Registered in China Darnatein has officially registered a patent with the China National Intellectual Property Administration (CNIPA) for the core technology behind its break-through disease-modifying osteoarthritis drug (DMOAD) lead drug candidate, DRT-101. Following the national registration of the patent in South Korea in November last year, this marks the company's first successful international patent registration as part of its efforts to secure global intellectual property rights through the PCT (Patent Cooperation Treaty) route in key regions such as the EU, the United States, and China. The technology basis is an AI-enhanced innovative protein structure generator designed to provide therapeutics that overcome the current limitations of standard of care treatment in osteoarthritis—a condition for which only symptom management options currently exist. This technology represents a wholly new approach to protein design and is expected to address the underlying causes of disease. This treatment approach may significantly improve treatment outcomes not only for osteoarthritis but also for a wide range of other musculoskeletal disorders. In particular, the DRT-101 chimeric protein, which recombines the natural BMP7 and Activin proteins into a wholly novel structure, has already been shown to enhance both therapeutic efficacy and safety in vivo, in studies conducted between 2020 and 2024 at the University of California, San Diego, School of Medicine. Senyon Choe, Darnatein Chief Executive Officer, stated, "The protein design technology now also patented in China has been developed over years from a core platform strategy to the current technology with the potential to revolutionize the global OA treatment market. Securing intellectual property rights in China, one of the largest markets in the world, is a crucial stepping-stone for our global expansion." Constance Höfer, Chief Scientific Officer of OSR Holdings, stated, "Darnatein's groundbreaking technology represents a wholly new, AI-enhanced approach to therapeutic protein design. The successful patent registration in China underscores the novelty and relevance of this technology to the development of better treatment options for OA patients worldwide." Global Technological Competitiveness and Licensing Potential The osteoarthritis treatment market continues to grow, due to globally aging populations. In 2023, the market size reached approximately USD 8.9 billion and is projected to grow at an average annual rate of about 7%, reaching approximately USD 16.1 billion by 2032. China is experiencing rapid population aging and a surge in osteoarthritis cases, making it a highly promising market. Industry experts have remarked, "Darnatein's Activin/BMP7 chimera technology offers a superior profile to be developed into a potential DMOAD, or disease-modifying OA drug, compared to existing standard of care for osteoarthritis treatments," adding, "Big Pharma is looking for novel treatments that can slow, stop, or even reverse the cartilage degeneration and joint damage that occurs with OA. On this backdrop, Darnatein's chimeric protein approach represents a paradigm shift away from only symptom relief (e.g. painkillers and anti-inflammatories) to treatment options targeting the underlying pathobiology of OA" Darnatein is currently completing preclinical studies with DRT-101, its degenerative OA treatment candidate, with the goal to initiate Phase 1 clinical trials later this year. About Darnatein Founded in 2012, Darnatein is a biotherapeutics company based in South Korea developing a pipeline of innovative treatments for osteoarthritis and bone fusion, including DRT-101 as a ground breaking disease-modifying OA drug (DMOAD) candidate. Darnatein was established by Dr. Senyon Choe, one of the co-founders of the structural protein laboratory of the prestigious Salk Institute for Biological Studies in La Jolla, CA, and a faculty member of UC San Diego since 1993. Darnatein operates as a wholly owned subsidiary of OSR Holdings, Inc. following its acquisition in 2023. About OSR Holdings, Inc. OSR Holdings, Inc. is a global healthcare company dedicated to advancing biomedical innovation. Through its subsidiaries, OSR is engaged in oncology immunotherapies, degenerative disease biologics, and medical device distribution. OSR's vision is to acquire and operate a portfolio of innovative healthcare companies, improving patient care through cutting-edge research and development. For more information, visit . Contact [email protected] SOURCE OSR Holdings Inc. WANT YOUR COMPANY'S NEWS FEATURED ON PRNEWSWIRE.COM? 440k+ Newsrooms & Influencers 9k+ Digital Media Outlets 270k+ Journalists Opted In GET STARTED

iStock, Jolygon Merck continues to build the case for the pulmonary arterial hypertension drug that won FDA approval in 2024. In high-risk patients with pulmonary arterial hypertension, Merck ’s fusion protein therapeutic Winrevair reduced the likelihood of major morbidity and mortality by 76% in the Phase III ZENITH trial. Analysts at Guggenheim Partners called this outcome “striking” and “very impressive” in a note to investors Monday, pointing to improvements in key secondary outcomes in overall survival and transplant-free survival. The Guggenheim analysts also pointed out that Winrevair had “relatively consistent improvements” in mortality and morbidity across patient subgroups, including age, sex and disease subtype and severity. In November 2024, Merck announced that, following the recommendations of an independent data monitoring board, it was stopping ZENITH ahead of schedule due to “ overwhelming efficacy .” On Monday, the pharma revealed that in the Winrevair arm, 17.4% of patients experienced at least one major morbidity or mortality event, as opposed to 34.7% of placebo comparators. The data were presented at the 2025 American College of Cardiology’s Annual Scientific Session and Expo and simultaneously published in The New England Journal of Medicine . Winrevair is a recombinant activin receptor type IIA-Fc fusion protein that targets and binds to activin A and other ligands that belong to the TGF-β superfamily. This mechanism of action allows Winrevair to restore balanceto vascular proliferation, a key pathway that is altered in pulmonary arterial hypertension (PAH). In particular, PAH patients see high excessive cell proliferation in key arteries, leading to thickened blood vessel walls and, in turn, impaired blood flow. Winrevair was approved by the FDA to treat PAH in March 2024, making it the first-ever drug for the disease that targets activin signaling. Merck continues to build its evidence base for Winrevair. In March 2023, the pharma unveiled full data from the Phase III STELLAR trial, touting a 40.8-meter improvement in 6-minute walk distance in patients with PAH following treatment with the drug. Winrevair also cut the risk of death or clinical worsening by 84% versus placebo. Merck is also running the Phase III HYPERION study to assess the benefit of Winrevair when used with background therapy. In January 2025, the company ended the trial ahead of schedule , in line with the recommendations of an external committee, because of strong efficacy findings in an interim analysis. Results from HYPERION will be presented later this year, according to Merck’s Monday announcement.