Clinical trialNCT05827614TerminatedPhase 1Interventional

Study of the CHK1 Inhibitor BBI-355, an ecDNA-directed Therapy (ecDTx), and the RNR Inhibitor BBI-825, in Subjects With Tumors With Oncogene Amplifications

SponsorBoundless Bio, Inc.Enrollment85Anogenital CancerCervical Squamous Cell CarcinomaCutaneous Squamous Cell Carcinoma (CSCC)ER+ Breast CancerHead and Neck (HNSCC)High Grade Endometrial Carcinoma+6 more conditions

View the registry record on ClinicalTrials.gov

Summary

The lay summary the sponsor registered on ClinicalTrials.gov.

BBI-355 is an oral, potent, selective checkpoint kinase 1 (or CHK1) small molecule inhibitor in development as an ecDNA (extrachromosomal DNA) directed therapy (ecDTx). BBI-825 is an oral, potent, selective ribonucleotide reductase (or RNR) small molecule inhibitor. This is a first-in-human, open-label, 2-part, Phase 1/2 study to determine the safety profile and identify the maximum tolerated dose and recommended Phase 2 dose of BBI-355 administered as a single agent or in combination with BBI-825 or other select therapies.

clinicaltrials.gov ↗

Investigators

The overall officials registered on this study. Names that resolve to a findmyKOL profile link to it; the rest are shown as registered.

Robert Doebele, MD, PhD
Boundless Bio, Inc.
Study Director
clinicaltrials.gov ↗

A profile link is shown only when the registered name resolves to a person record with a confident, namesake-checked match; ambiguous names stay unlinked.

Sites

16 registered facilities, with the per-site recruitment status where the registry publishes one. ClinicalTrials.gov does not publish per-site enrollment counts.

United States

Ucla Medical Center
Los Angeles, California, United States
Sarcoma Oncology
Santa Monica, California, United States
Healthone
Denver, Colorado, United States
Florida Cancer Specialists
Lake Mary, Florida, United States
the University of Kansas
Fairway, Kansas, United States
Beth Israel Deaconess Medical Center
Boston, Massachusetts, United States
Dana Farber Cancer Institute
Boston, Massachusetts, United States
Start Midwest
Grand Rapids, Michigan, United States
Memorial Sloan Kettering Cancer Center
New York, New York, United States
Scri Oncology Partners
Nashville, Tennessee, United States
Md Anderson Cancer Center
Houston, Texas, United States
Next Oncology - Dallas
Irving, Texas, United States
Next Oncology
San Antonio, Texas, United States
Next Oncology
Fairfax, Virginia, United States
University of Washington, Fred Hutchinson Cancer Center
Seattle, Washington, United States
University of Wisconsin
Madison, Wisconsin, United States

Site investigator names are published by ClinicalTrials.gov only while a study recruits, so completed studies list sites without them.

Drugs studied

The drug and biological interventions registered on this study, normalized to their RxNorm ingredient where possible.

BBI-355BBI-825Erlotinib →Futibatinib →

Linked drugs open the directory filtered to KOLs working with them.clinicaltrials.gov ↗

Registration & key dates

Registry attributes as recorded on the ClinicalTrials.gov study record.

Start: 24 Mar 2023
Primary completion: 17 Mar 2026
Completion: 17 Mar 2026
Last update posted: 19 Aug 2026
Registered enrollment: 85
Registry id: NCT05827614

clinicaltrials.gov ↗

Source: ClinicalTrials.gov, via the CTTI AACT database, data as of 24 Aug 2026. Registry facts are shown as registered by the study sponsor; findmyKOL does not interpret them.