SEED Therapeutics announced that the U.S. Food and Drug Administration has cleared its Investigational New Drug application for ST-01156, a first-in-class molecular glue degrader targeting RBM39. The clearance enables initiation of a first-in-human Phase 1 clinical trial in patients with advanced solid tumor and hematological malignancies, with first patient dosing expected in the first quarter of 2026.
The clinical trial will prioritize multiple cancers with convincing preclinical evidence of RBM39 dependency, utilizing biomarker-selected patient enrollment. ST-01156 has received Orphan Drug and Rare Pediatric Disease designations from the FDA for Ewing sarcoma, a rare pediatric malignancy with no new approved therapies in over 30 years.
Novel Mechanism of Action
ST-01156 works by inducing the degradation of RBM39, an important regulator of RNA splicing and transcription that is overexpressed and required for growth and survival in a broad range of cancers. The drug represents SEED's first clinical candidate developed through its proprietary RITE3™ platform, which rationally identifies the optimal E3 ligase for targeting disease-causing proteins and discovering drug-like "molecular glues."
"The FDA's clearance of our IND for ST-01156 validates the power of SEED's precision-engineered approach to protein degradation," said Dr. Lan Huang, Co-Founder, Chairman, and CEO of SEED. "ST-01156 represents a fundamentally new class of medicines with many opportunities for impacting human health."
Compelling Preclinical Data
In preclinical models, ST-01156 achieved complete tumor regression in xenografts of Ewing sarcoma, neuroblastoma, and KRAS mutant colon cancer. Patient-derived cancer models have identified multiple RBM39-dependent cancers to inform biomarker-guided enrollment strategies for the upcoming clinical trial.
"We are excited to bring this optimized RBM39 degrader into the clinic supported by compelling preclinical data, including complete tumor regression in multiple tumor models and precise target engagement," said Dr. James Tonra, President and Chief Scientific Officer of SEED.
Significant Market Opportunity
SEED's near-term strategy is designed to explore several RBM39-dependent cancers, including Ewing sarcoma, neuroblastoma, and KRAS-driven solid tumors. According to the company, this addressable patient population exceeds one million worldwide, representing a substantial market opportunity for this novel therapeutic approach.
Expert Leadership and Scientific Foundation
Clinical development of ST-01156 will be led by Dr. Eric Rowinsky, a globally recognized oncology expert with contributions to the approval of more than a dozen cancer therapies. The company was co-founded by four pioneers in targeted protein degradation, including Nobel Laureate Dr. Avram Hershko, who discovered the ubiquitin-proteasome system.
"The ability to precisely degrade disease-causing proteins using small molecules represents a transformational advance in drug discovery," said Dr. Hershko. "SEED's approach builds upon the fundamental principles of the ubiquitin-proteasome system, and I am proud to see this science translated into a novel therapy with the potential to benefit patients with hard-to-treat cancers."
Strategic Partnerships and Pipeline
SEED has established strategic partnerships with major pharmaceutical companies, including Eli Lilly as a cornerstone investor and research collaborator since the company's inception, and Eisai as a strategic investor and research collaborator. The company's pipeline includes nine programs spanning oncology, neurodegeneration, immunology, and virology.
ST-01156 is characterized as a brain-penetrant RBM39 degrader, potentially offering advantages for treating central nervous system malignancies and other RBM39-dependent cancers that require blood-brain barrier penetration.
