Boundless Bio

Boundless Bio is a clinical-stage precision oncology company focused on extrachromosomal DNA (ecDNA), large circular units of nuclear DNA found in cancer cells that drive oncogene amplification. The company states that ecDNA are rarely present in healthy cells but occur in the cancer cells of more than 17% of patients with solid tumors, and it positions ecDNA as both a root cause of oncogene amplification and a therapeutic vulnerability. Its stated aim is to build a new therapeutic category it calls ecDNA-directed therapies (ecDTx).

The company frames the clinical problem as follows: greater than 25% of all cancers carry oncogene amplifications and more than 5 million newly diagnosed cancers worldwide each year harbor them, yet existing targeted therapies and immunotherapies developed largely for oncogene mutations or fusions have been largely ineffective in amplification-driven disease. Rather than targeting the protein products of activated oncogenes, Boundless Bio says it targets the underlying process by which overexpressed oncogenes arise and persist.

Reported pipeline assets include BBI-355, an oral CHK1 inhibitor in a Phase 1/2 trial in oncogene-amplified cancers; BBI-825, an oral RNR inhibitor that began a Phase 1/2 study in patients with resistance gene amplifications; and BBI-940, described as an oral kinesin degrader that entered a Phase 1 first-in-human trial in ER+/HER2- breast cancer and TNBC-LAR subtypes. The company is described as operating proprietary platforms: Spyglass, comprising ecDNA-positive/negative in vitro and in vivo preclinical models and imaging/analytics used to identify druggable ecDNA-associated targets, and ECHO, an algorithm to detect ecDNA from routine next-generation sequencing data for patient selection.

Founding story

Boundless Bio was formed in 2018 in San Diego. Chairman and co-founder Jonathan Lim, a serial biotech entrepreneur who has served as CEO or chairman of five biotech companies, recruited CEO Zachary Hornby, with whom he had worked for 13 years across four companies. The company had six scientific founders, three of them based at UC San Diego and one at The Scripps Research Institute; Paul Mischel, M.D., affiliated with UC San Diego and the Ludwig Institute for Cancer Research, is described as a scientific co-founder and chairs the scientific advisory board, and Ben Cravatt, Ph.D., of Scripps Research is described as a director and co-founder. The founding premise was that ecDNA, observed for 50-60 years but only recently resolvable with modern genomic and imaging technologies, could be understood and exploited therapeutically. Early collaborations with UC San Diego helped translate the underlying ecDNA science into drug discovery.

Business model

Boundless Bio develops proprietary small-molecule and degrader therapeutics in-house and advances them through its own clinical trials, financed to date by venture rounds and a public equity offering. It pairs drug candidates with internally developed discovery and patient-selection tools (Spyglass models and the ECHO NGS-based ecDNA detection algorithm), placing it at the intersection of oncology drug development and molecular diagnostics.

Traction

Two candidates, BBI-355 and BBI-825, were in Phase 1 testing at the time of the March 2024 IPO, with results expected later in 2024 and in early 2025 respectively; proof-of-concept data for BBI-355 was guided for the second half of 2024. A third candidate, BBI-940, is reported to have advanced into a Phase 1 first-in-human trial. Cumulative disclosed financing includes roughly $254 million in private capital plus $100 million of IPO proceeds.

Latest developments

Boundless Bio completed its Nasdaq IPO in March 2024, raising $100 million at $16 per share under the ticker BOLD, with proceeds directed toward clinical development of BBI-355 and BBI-825. A subsequent profile reports BBI-940, an oral kinesin degrader, entering Phase 1 first-in-human testing in ER+/HER2- breast cancer and TNBC-LAR.