ST-01156, a drug that degrades RBM39, for advanced solid cancers

A Phase 1/1B Study of ST-01156, a Small Molecule RBM39 Degrader, in Patients With Advanced Solid Malignancies

This trial will test whether ST-01156 is safe and shows early anti-cancer activity in adults (and some teens with Ewing sarcoma) who have advanced or metastatic solid tumors like liver, biliary tract, or Ewing sarcoma.

Quick facts

• Phase: PHASE1
• Study type: Interventional
• Enrollment: 171 (estimated)
• Ages: 16 Years and up
• Sex: All
• Sponsor: SEED Therapeutics, Inc. (industry)
• Locations: 6 sites (Duarte, California and 5 other locations)
• Trial ID: NCT07197554 on ClinicalTrials.gov

What this trial studies

This Phase 1/1b, open-label, multicenter dose-escalation study gives participants ST-01156, a small-molecule degrader of RBM39, to determine safety, tolerability, pharmacokinetics, and early anticancer activity. Part 1 uses a dose-escalation design to identify the maximum tolerated dose and/or recommended Phase 2 dose. Participants must have measurable or evaluable advanced unresectable or metastatic solid tumors and meet organ function and performance-status requirements. The protocol includes screening, regular safety and imaging assessments, and pharmacokinetic sampling at planned timepoints.

Who should consider this trial

Good fit: Ideal candidates are adults (≥18 years) or adolescents ≥16 with Ewing sarcoma, unresectable or metastatic solid tumors, measurable disease, ECOG ≤2, and adequate organ function who have completed required washout from prior therapies.

Not a fit: Patients with active untreated brain metastases, recent radiotherapy or recent systemic anticancer therapy, poor organ function, or tumors without a biological rationale for RBM39 targeting are less likely to benefit.

Why it matters

Potential benefit: If successful, ST-01156 could become a new treatment option for patients whose tumors depend on RBM39, offering tumor control where other therapies have failed.

How similar studies have performed: RBM39-directed degradation is an emerging and relatively novel approach: related molecular-glue degraders have shown early signals in cancer but RBM39-specific clinical efficacy remains largely unproven.

Eligibility criteria

Inclusion Criteria:

* Age ≥ 18 years on the day of signing the consent form, except for adolescents with Ewing Sarcoma or other malignancies for which there is a biological rationale to support participation, in which case the participant is ≥ 16 years old.
* Has a metastatic or locally advanced and unresectable solid tumor.
* Has at least 1 measurable lesion or evaluable disease per RECIST v1.1.
* Has an ECOG performance status ≤ 2 at screening.
* Has adequate organ function as defined in the protocol.

Exclusion Criteria:

* Has received prior radiotherapy within 2 weeks of treatment.
* Has known active CNS metastases and/or carcinomatous meningitis. Participants with previously treated brain metastases may participate, provided they are radiologically stable
* Has received treatment with any local or systemic anticancer therapy or investigational anticancer agent within 14 days or 5 half-lives, whichever is shorter.
* Had major surgery within 28 days before study therapy administration
* Has toxicities from previous anticancer therapies that have not resolved to baseline levels, with the exception of alopecia and peripheral neuropathy.
* Has previously received a RBM39 inhibitor/degrader.

Where this trial is running

Duarte, California and 5 other locations

• The City of Hope National Medical Center — Duarte, California, United States (RECRUITING)
• Hoag Memorial Hospital — Newport Beach, California, United States (RECRUITING)
• Mass General Brigham Cancer Institute — Boston, Massachusetts, United States (NOT_YET_RECRUITING)
• Dana Farber Cancer Institute — Boston, Massachusetts, United States (RECRUITING)
• Memorial Sloan Kettering Cancer Center — New York, New York, United States (RECRUITING)
• The University of Texas MD Anderson Cancer Center — Houston, Texas, United States (RECRUITING)

Study contacts

• Study coordinator: Dr. Eric Rowinsky Chief Medical Officer

Conditions: Advanced Solid Tumors, Ewing Sarcoma, Hepatocellular Carcinoma, Biliary Tract Cancer, cancer, solid tumors, RBM39, RBM39 degrader