South Korea-based SK Biopharmaceuticals Co., Ltd. (KRX: 326030) has licensed exclusive global rights to 1ST-104, a preclinical oral small-molecule dual inhibitor of leucine-rich repeat kinase 2 (LRRK2) and c-Abl for Parkinson's disease, from fellow South Korea-based 1ST Biotherapeutics, Inc. (1STBIO). The deal is worth up to USD 314.8 million in total including milestones, with a USD 1.8 million upfront payment and a separate USD 2.2 million strategic equity investment by SK Biopharmaceuticals (SKBP) in 1STBIO.
1ST-104 is described by 1STBIO as a Type 2 LRRK2 inhibitor, meaning it binds LRRK2 in its inactive conformation rather than the active-state binding mode used by Type 1 inhibitors. The company said this approach has demonstrated target selectivity and blood-brain barrier permeability in preclinical studies, and positions 1ST-104 as differentiated from earlier LRRK2 programs that encountered pulmonary findings in preclinical work. The simultaneous inhibition of c-Abl is part of 1STBIO's dual-inhibition strategy. No investigational new drug filing date has been disclosed.
Under the agreement, 1STBIO is eligible to receive a short-term milestone of USD 1.8 million upon candidate selection, plus additional development, regulatory, and commercial milestones comprising the headline total. Tiered royalties on global net sales are also included. SKBP takes on clinical development and commercialization responsibility globally, supported by its US commercial infrastructure through subsidiary SK Life Science, which markets cenobamate (Xcopri) for partial-onset seizures in adults.
The deal is described by both companies as the first transaction executed through SKBP's Open Innovation Center, a newly established in-licensing mechanism. It follows two other significant SKBP in-licensing announcements in 2026: a collaboration with Insilico Medicine valued at up to USD 2.5 billion for AI-enabled CNS drug discovery, and a license agreement with Biohaven Ltd for the Kv7 ion channel platform and opakalim for epilepsy, valued at up to USD 795 million.
Biogen and Denali Therapeutics' BIIB122 (DNL151), a Type 1 LRRK2 inhibitor, failed to meet primary and secondary endpoints in the Phase IIb LUMA study in unselected early-stage Parkinson's patients in May 2026. The LUMA failure raises questions about LRRK2 inhibition in unselected Parkinson's populations — a patient-selection question that will be relevant to 1ST-104's clinical design.