Boundless Bio Presents Preclinical Breast Cancer Data from Kinesin Degrader Program

Findings support ongoing Phase 1 clinical development of BBI-940, an oral, selective kinesin degrader.

Apr. 17, 2026 at 9:37pm

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A highly detailed, translucent X-ray image revealing the intricate internal structure of a breast cancer cell, with glowing lines highlighting the extrachromosomal DNA and the kinesin protein target, conceptually illustrating the molecular mechanisms underlying the development of a new targeted therapy.An X-ray view into the complex biology of breast cancer cells, exposing the critical role of extrachromosomal DNA and a novel kinesin target in driving tumor growth and therapeutic resistance.San Diego Today

Boundless Bio, a clinical-stage oncology company, presented preclinical data supporting its lead extrachromosomal DNA (ecDNA)-directed therapy, BBI-940, at the American Association for Cancer Research (AACR) Annual Meeting 2026. BBI-940 is a potentially first-in-class, oral, and selective kinesin degrader being evaluated in the ongoing Phase 1 KOMODO-1 trial in patients with advanced or metastatic estrogen receptor-positive, HER2-negative (ER+/HER2-) breast cancer and triple-negative breast cancer of the luminal androgen receptor subtype (TNBC-LAR).

Why it matters

Extrachromosomal DNA is a distinct enabler of chromosomal instability associated with oncogene amplification, therapeutic resistance, and poor outcomes for patients. Boundless Bio has discovered and validated a novel kinesin target that plays a critical role in ecDNA segregation during cell division, providing tumors with genomic plasticity. Selective degradation of this target delivered potent antitumor activity in validated breast cancer models, particularly those with ecDNA.

The details

Genetic and pharmacologic degradation of the kinesin target caused ecDNA mis-segregation, ecDNA depletion, and reduced viability of ecDNA+ cancer cells. Selective degradation of the kinesin target demonstrated sensitivity across multiple tumor types, including 32% sensitivity in breast cancer cell lines positive for ecDNA and FGFR1 gain. This molecularly defined subgroup was further validated in vivo with demonstrated monotherapy tumor regressions in an ecDNA+ TNBC-LAR model, and significant antitumor activity as monotherapy and combination in an ecDNA+/FGFR1+ ER+ breast cancer model.

  • The presentation took place on Tuesday, April 21, 2026, from 2:00 PM to 5:00 PM PT.
  • The ongoing, first-in-human Phase 1 KOMODO-1 clinical trial (NCT07408089) is evaluating BBI-940 in patients with advanced or metastatic ER+/HER2- breast cancer or TNBC-LAR.

The players

Boundless Bio

A clinical-stage oncology company dedicated to unlocking a new paradigm in cancer therapeutics that addresses the significant unmet need in patients with oncogene amplified tumors.

Chris Hassig, Ph.D.

Chief Scientific Officer of Boundless Bio.

BBI-940

Boundless Bio's lead extrachromosomal DNA (ecDNA)-directed therapy, a novel, oral, and selective kinesin degrader being evaluated in the ongoing Phase 1 KOMODO-1 clinical trial.

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What they’re saying

“Extrachromosomal DNA is well established as a distinct enabler of chromosomal instability associated with oncogene amplification, therapeutic resistance, and poor outcomes for patients.”

— Chris Hassig, Ph.D., Chief Scientific Officer of Boundless Bio

What’s next

The ongoing, first-in-human Phase 1 KOMODO-1 clinical trial (NCT07408089) is evaluating BBI-940 in patients with advanced or metastatic ER+/HER2- breast cancer or TNBC-LAR.

The takeaway

Boundless Bio's discovery and validation of a novel kinesin target essential for extrachromosomal DNA (ecDNA) segregation in cancer cells, but non-essential in healthy cells, has led to the development of BBI-940, a potentially first-in-class, oral, and selective kinesin degrader. The preclinical data support the ongoing clinical development of BBI-940 as a promising ecDNA-directed therapy for treating breast cancer patients, particularly those with ecDNA-positive tumors.