1ST Biotherapeutics and SK Biopharmaceuticals Announce Exclusive Global License Agreement for Parkinson's Disease Candidate ‘1ST-104’

• Deal valued at up to $314.8 million, including milestones, with a separate $2.2 million strategic equity investment
• Collaboration leverages 1STBIO’s Type 2 LRRK2/c-Abl dual inhibitor to advance next-generation Parkinson's treatment

YONGIN, South Korea, September 17, 2026 — 1ST Biotherapeutics, Inc. (“1STBIO”) and SK Biopharmaceuticals Co., Ltd. (“SKBP”) today announced that they have entered into an exclusive global licensing agreement and strategic equity investment (SI) partnership to advance 1ST-104, a novel drug candidate for the treatment of Parkinson's disease.

Under the terms of the agreement, 1STBIO will receive an upfront payment of $1.8 million. The total licensing agreement is valued at up to $314.8 million, including a short-term milestone of $1.8 million upon candidate selection and additional milestones. Upon commercialization, 1STBIO is also eligible to receive tiered royalties based on global net sales. Separately, SKBP has made a $2.2 million strategic equity investment in 1STBIO to foster a long-term partnership.

The licensed program, 1ST-104, is being developed as an oral small-molecule treatment for Parkinson's disease, using a dual-inhibition strategy that simultaneously inhibits LRRK2 and c-Abl. LRRK2 is considered a therapeutic target directly linked to the pathogenesis of Parkinson's disease. However, some Type 1 LRRK2 inhibitors have faced development challenges, particularly due to pulmonary findings reported in preclinical studies.

To address these limitations, 1STBIO developed 1ST-104 as a next-generation Type 2 LRRK2 inhibitor. By leveraging a Type 2 binding mode, 1ST-104 offers a differentiated approach compared to conventional Type 1 inhibitors and has demonstrated target selectivity along with blood-brain barrier (BBB) permeability in preclinical studies. Furthermore, since 2024, 1STBIO has been a member of LITE (LRRK2 Investigative Therapeutics Exchange), the research consortium supported by The Michael J. Fox Foundation for Parkinson's Research (MJFF)—the world’s leading non-profit funder of Parkinson’s disease research. Through LITE, the company continues to engage in global scientific and technical collaboration.

"This agreement serves as a strong validation of 1ST Biotherapeutics' proprietary discovery capabilities in next-generation target identification and lead optimization," said Jamie Jae Eun Kim, CEO of 1ST Biotherapeutics. "It marks a major milestone by uniting our early-stage R&D strength with SK Biopharmaceuticals' proven global development and commercial expertise. Through close collaboration with SK Biopharmaceuticals, we will leverage the strengths of both companies to advance the subsequent development of 1ST-104."

Donghoon Lee, CEO of SK Biopharmaceuticals, said, "This collaboration is significant in that it combines 1ST Biotherapeutics' early-stage discovery capabilities with SK Biopharmaceuticals' clinical development and commercialization expertise." He added, "We will work to translate this candidate into successful clinical development, opening up new possibilities for the treatment of Parkinson's disease."

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About 1ST Biotherapeutics, Inc.

Founded in 2016, 1ST Biotherapeutics is a science-driven biopharmaceutical company developing therapies for neurodegenerative diseases, immuno-oncology, and rare diseases. The Company’s immuno-oncology candidate FB849 is currently being evaluated in a Phase 1/2 clinical trial following the dosing of the first patient in the U.S. in 2023, with clinical development also underway in Korea. For its combination clinical trials, MSD has agreed to provide KEYTRUDA® (pembrolizumab) at no cost. FB-101, a c-Abl inhibitor being developed for Parkinson’s disease, has completed a Phase 1 single ascending dose (SAD) study in the U.S.

For more information, visit https://www.1stbio.com.

About SK Biopharmaceuticals Co., Ltd.

SK Biopharmaceuticals Co., Ltd., together with its U.S. subsidiary SK Life Science, Inc., is a global biopharmaceutical company focused on the discovery, development, and commercialization of treatments for central nervous system disorders. The company independently developed and commercialized XCOPRI® (cenobamate tablets) for the treatment of partial-onset seizures in adults, and continues to build a global pipeline spanning CNS disorders and oncology. For more information, visit https://www.skbp.com/eng.do.

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