Boundless Bio (BOLD) Leerink Global Healthcare Conference 2025 summary

Scientific and clinical strategy

• Focuses on targeting oncogene amplification-driven tumors, which represent about 25% of cancer patients and are often resistant to standard therapies.

• Leverages the unique biology of extrachromosomal DNA (ecDNA) in cancer cells to identify novel drug targets and vulnerabilities.

• Developed ECHO, a bioinformatic diagnostic tool that detects ecDNA using standard sequencing data, enabling patient segmentation in clinical trials.

• ECHO is currently used retrospectively in the phase 1/2 Potentiate study to classify patients by ecDNA status and inform statistical analysis.

• Preliminary proof-of-concept data, including ECHO findings, are expected by the end of the year.

Lead programs and trial design

• Lead asset BBI-355 is being tested as a single agent in gynecologic cancers with high replication stress and in combination with targeted therapies for EGFR, FGFR, and CDK4/6 amplifications.

• CHK1 was identified as a synthetic lethal target in ecDNA-driven tumors due to its role in managing replication stress.

• The trial includes both single-agent and combination arms, with data from multiple cohorts anticipated by year-end.

• Diagnostic data will retrospectively segment patients by ecDNA status to correlate with therapeutic response.

Competitive landscape and differentiation

• CHK1 inhibitors have shown promise in early studies, with Acrivon advancing a related compound using a different biomarker approach focused on replication stress.

• The lead compound is oral and CHK1-selective, differing from competitors' IV and CHK1/2 inhibitors.

• ECHO diagnostic uses standard sequencing data, offering practical integration into current clinical workflows compared to competitors' central lab-based diagnostics.