SEED's 'Molecular Glue' Drug Enters Human Trials, Targeting 'Undruggable' Cancer Proteins

KING OF PRUSSIA, PA – January 09, 2026 – In a significant step forward for a new class of cancer therapies, SEED Therapeutics announced today that the first patient has been dosed in a Phase 1 clinical trial for ST-01156. The novel drug, an orally administered 'molecular glue degrader,' is designed to destroy a key cancer-driving protein previously considered beyond the reach of conventional medicine, offering a potential new weapon against a range of advanced solid tumors.

The first-in-human study marks a critical milestone for the biotechnology firm and for the burgeoning field of targeted protein degradation (TPD). It will initially enroll patients with any advanced solid tumor malignancy, while focusing on cancers with strong preclinical evidence of dependency on the drug's target, including the rare pediatric cancer Ewing sarcoma, certain KRAS-mutant cancers, and hepatocellular carcinoma.

Unsticking Cancer with a New Class of Drugs

At the heart of ST-01156's innovative approach is a strategy that turns the cell's own quality control machinery against itself. For decades, drug developers have focused on creating small molecule inhibitors that block the function of a harmful protein. However, many proteins that drive cancer lack the distinct binding pockets necessary for such inhibitors to work, earning them the moniker 'undruggable.'

Molecular glue degraders bypass this limitation entirely. Instead of merely blocking a target, they act as a molecular matchmaker. ST-01156 is designed to bind simultaneously to its target, a protein called RBM39, and to a component of the cell's natural protein disposal system, known as an E3 ubiquitin ligase. By 'gluing' these two together, the drug effectively tags RBM39 as cellular trash, marking it for destruction by the proteasome, the cell's recycling center.

RBM39 is a crucial regulator of RNA splicing, a fundamental process that determines which proteins a cell produces. In many cancers, RBM39 is overactive and helps tumor cells survive and proliferate. By eliminating the RBM39 protein altogether, ST-01156 aims to trigger a cascade of events that leads to cancer cell death. This catalytic mechanism, where one drug molecule can trigger the destruction of many target protein molecules, promises a more potent and durable anti-tumor effect.

Furthermore, ST-01156 has been engineered as a small, orally available molecule with the ability to cross the blood-brain barrier. This brain-penetrant property is a significant advantage, potentially allowing it to treat cancers that have spread to the central nervous system, a common and devastating complication.

A Beacon of Hope for Rare and Stubborn Cancers

The initiation of this trial carries particular weight for patients with Ewing sarcoma, a rare and aggressive cancer of the bone or soft tissue that primarily affects children and young adults. The treatment landscape for this disease has been tragically stagnant, with the press release noting that no new therapeutic agent has been approved in the last 30 years. The prognosis for patients with recurrent or metastatic disease remains grim, highlighting a desperate unmet need.

In recognition of this, the U.S. Food and Drug Administration (FDA) has granted ST-01156 both Orphan Drug Designation and Rare Pediatric Disease Designation for the treatment of Ewing sarcoma. These designations are intended to incentivize the development of therapies for underserved populations and can provide a pathway for accelerated regulatory review. Preclinical studies have provided a strong basis for this hope, with ST-01156 demonstrating complete tumor regression in animal models of the disease.

“Dosing the first patient with ST-01156 marks an important milestone for SEED and for patients with cancers that urgently need new therapeutic options,” said Dr. Lan Huang, PhD, Co-Founder, Chair, and Chief Executive Officer of SEED Therapeutics. “We believe RBM39 degradation represents a powerful and differentiated therapeutic strategy, and we look forward to advancing this program through clinical development.”

Forged by Scientific Titans and Strategic Alliances

While the science is cutting-edge, the credibility of SEED Therapeutics is anchored by a formidable foundation of scientific leadership and powerful industry partnerships. The company was co-founded by a team of scientific luminaries, most notably Nobel Laureate Professor Avram Hershko, whose 2004 Nobel Prize in Chemistry was awarded for the discovery of the very ubiquitin-proteasome system that molecular glues harness.

This unparalleled scientific pedigree, which also includes pioneers in E3 ligase biology and structure like Prof. Ning Zheng and Prof. Michele Pagano, is bolstered by strategic collaborations with pharmaceutical giants Eli Lilly and Co. and Eisai Co., Ltd. These partnerships serve as a powerful validation of SEED's proprietary RITE3™ platform for rationally designing molecular glues and provide the substantial resources and development expertise needed to navigate the long road to drug approval. This combination of Nobel-level science and big pharma backing positions SEED as a serious contender in the highly competitive TPD space.

The Path Through the Clinic

The Phase 1a study is an open-label, dose-escalation trial designed to rigorously test the drug in humans for the first time. Its primary goal is to evaluate the safety and tolerability of ST-01156 and to determine the optimal dose for future studies. The drug will be administered orally, once daily for five days out of every seven.

Secondary objectives will provide the first hints of the drug's effectiveness, characterizing its pharmacokinetics (how the drug moves through the body) and looking for preliminary evidence of anticancer activity. The trial's design also integrates sophisticated biomarker analyses from the outset to understand how the drug is engaging its target in patients' cells.

“This trial is thoughtfully designed to build on the powerful preclinical signals of safety and efficacy while integrating PK, PD, and biomarker learning from the outset, with the goal of learning from each patient to optimize therapeutic development,” stated George Demetri, MD, a Professor at Harvard Medical School and Dana-Farber Cancer Institute who chairs SEED's Scientific Advisory Board. “The initiation of clinical dosing brings us one step closer to translating the novel mechanism of ST-01156 action into meaningful benefit for patients.”

The study is being conducted at some of the world's most prestigious cancer centers, including Dana-Farber Cancer Institute, Memorial Sloan Kettering Cancer Center, and MD Anderson Cancer Center, ensuring the highest standards of clinical research. The progress of ST-01156 through this trial will be a closely watched test of one of the most promising new frontiers in drug discovery.