1ST Biotherapeutics licenses Parkinson’s candidate 1ST-104 to SK Biopharmaceuticals in a deal worth up to $314.8 million, plus a $2.2 million equity investment.
Written By: Khushi Patel, PharmD
Reviewed By: Pharmacally Editorial Team
1ST Biotherapeutics has granted SK Biopharmaceuticals exclusive global rights to 1ST-104, an oral Parkinson’s disease candidate that combines Type 2 LRRK2 inhibition with c-Abl inhibition. The agreement includes up to $314.8 million in licensing milestones, alongside a separate $2.2 million strategic equity investment.
Dual-Target Approach to Parkinson’s Disease
1ST-104 is an oral small-molecule candidate that simultaneously inhibits leucine-rich repeat kinase 2 (LRRK2) and c-Abl, two targets implicated in Parkinson’s disease biology. The dual-inhibition strategy distinguishes the program from approaches focused on LRRK2 alone.
LRRK2 is directly linked to Parkinson’s disease pathogenesis and has become an important therapeutic target. However, some Type 1 LRRK2 inhibitors have encountered development challenges, including pulmonary findings reported in preclinical studies.
1STBIO developed 1ST-104 as a next-generation Type 2 LRRK2 inhibitor. The company reports that its Type 2 binding mode differentiates the candidate from conventional Type 1 inhibitors and has demonstrated target selectivity and blood-brain barrier (BBB) permeability in preclinical studies.
$314.8 Million Deal Includes Future Milestones
The $314.8 million headline value includes a $1.8 million upfront payment and a further $1.8 million short-term milestone tied to candidate selection. This leaves approximately $311 million in additional potential milestone payments, although the companies have not disclosed the detailed allocation across development, regulatory and commercial events. The separate $2.2 million strategic equity investment is not included in the licensing value.
Following commercialization, 1STBIO will also be eligible for tiered royalties based on global net sales.
Strategically, the transaction represents an example of SK Biopharmaceuticals’ Open Innovation Center and its East-West Bridge strategy, which connects promising Asian drug candidates with the company’s global clinical development and commercialization capabilities.
Preclinical Program Moves Toward Clinical Development
The announcement describes 1ST-104 as an early-stage Parkinson’s disease program and does not disclose human clinical efficacy, safety, dosing, or clinical trial data. The available evidence remains preclinical, with target selectivity and BBB permeability supporting continued development.
The program also benefits from 1STBIO’s participation in the LRRK2 Investigative Therapeutics Exchange (LITE), a research consortium supported by The Michael J. Fox Foundation for Parkinson’s Research. The company has participated in LITE since 2024 and continues to engage in scientific and technical collaboration through the consortium.
Partners Combine Discovery and Global Development
1STBIO CEO Jamie Jae Eun Kim said the agreement brings together the company’s discovery and lead-optimization capabilities with SK Biopharmaceuticals’ global development and commercial expertise. SK Biopharmaceuticals CEO Donghoon Lee similarly highlighted the combination of early-stage discovery with clinical development and commercialization capabilities.
The partnership will now advance 1ST-104 through subsequent development stages. The companies have not disclosed a clinical trial start date, planned Phase 1 design, regulatory filing schedule, or development timeline.
For Parkinson’s disease, the key development question will be whether 1ST-104’s Type 2 LRRK2 profile, CNS penetration, and dual LRRK2/c-Abl inhibition translate into an acceptable safety profile and meaningful clinical activity in patients.
Reference
1ST Biotherapeutics and SK Biopharmaceuticals Announce Exclusive Global License Agreement for Parkinson’s Disease Candidate ʻ1ST-104, 1ST Bio, 17 September 2026
About the Writer
Khushi Patel is a Pharm.D (Linkedin) professional with a strong foundation in clinical pharmacy, patient-centered care, regulatory affairs, and pharmacovigilance, with published work on Brugada syndrome.
Her interests include regulatory affairs, pharmacovigilance, guideline integration, multimodal therapy, pharmacogenomics, and antibiogram utilization, with a focus on evidence-based clinical decision-making and medication safety.
As a Pharmacally healthcare writer, she translates clinical and scientific evidence into clear, accurate, and clinically relevant healthcare content, while continuously developing her expertise in evolving pharmacy practice.
