KING OF PRUSSIA, PA — SEED Therapeutics has advanced its lead cancer drug candidate, ST-01156, into a first-in-human clinical trial, a step that will test whether the company’s molecular glue degrader technology can translate promising laboratory results into treatments for patients with advanced solid tumors.
The clinical-stage biotechnology company presented details of the ongoing Phase 1 study at the 2026 American Society of Clinical Oncology Annual Meeting, outlining a development strategy aimed at several cancers linked to the RNA-binding protein RBM39.
The trial represents a key transition for SEED from preclinical research into human testing, where the company’s platform and lead asset will face their first significant clinical validation.
ST-01156 is designed to degrade RBM39, a protein involved in RNA splicing processes that influence tumor growth, survival and DNA damage response pathways. The approach seeks to eliminate the target protein rather than inhibit its activity, a strategy researchers believe could address cancer-driving mechanisms that have proven difficult to target with conventional drugs.
According to the company, the open-label Phase 1 study is enrolling patients with advanced solid malignancies and is expected to include approximately 30 to 50 participants.
The primary goals are to evaluate safety, tolerability and dose selection. Researchers will also measure drug exposure, target engagement and preliminary signs of anti-tumor activity.
SEED is incorporating real-time measurements of RBM39 degradation in peripheral blood mononuclear cells as part of its dose-selection strategy, alongside pharmacokinetic and safety data. The company believes the approach could help identify an optimal dose more efficiently before moving into later-stage studies.
The development plan includes expansion cohorts focused on tumor types where RBM39 biology appears particularly relevant, including Ewing sarcoma, advanced hepatocellular carcinoma, KRAS-mutant cancers, biliary tract cancer, endometrial cancer and tumors with DNA damage repair abnormalities.
The rationale for those indications stems largely from preclinical findings. SEED reported tumor regression in laboratory models of Ewing sarcoma and neuroblastoma, as well as complete regression in certain animal models of Ewing sarcoma, neuroblastoma and KRAS-mutant colorectal cancer.
“ST-01156 is designed to address a biologically important and difficult-to-drug target through selective RBM39 degradation,” James Tonra, the company’s president and chief scientific officer, stated in connection with the presentation.
The drug is administered orally once daily for five days in a seven-day cycle, though the protocol allows investigators to shift to continuous daily dosing if emerging data support that approach.
The study, registered as NCT07197554, remains in the dose-escalation stage. Data from the initial patient cohorts are expected to guide both the recommended Phase 2 dose and the design of subsequent expansion studies.
For SEED, the outcome of the trial may determine whether its molecular glue degrader platform can establish a competitive position in a rapidly growing field of targeted protein degradation therapies, where biotechnology companies are seeking new ways to address cancer targets long considered beyond the reach of traditional drug development.
Support the local news that supports Chester County. MyChesCo delivers reliable, fact-based reporting and essential community resources—free for everyone. If you value that, click here to become a patron today.