Boundless Bio Announces First Patient Dosed in First-in-Human Phase 1/2 Clinical Trial of BBI-825 in Cancer Patients with Resistance Gene Amplifications

Boundless Bio (Nasdaq: BOLD), a clinical-stage oncology company interrogating extrachromosomal DNA (ecDNA) biology to deliver transformative therapies to patients with previously intractable oncogene amplified cancers, today announced that the first patient has been dosed with BBI-825 in a first-in-human, Phase 1/2 clinical trial for patients with locally advanced or metastatic cancer with resistance gene amplifications (NCT06299761). ecDNA are a key driver of high copy number amplification in cancer, and Boundless has validated multiple drug targets that are essential for ecDNA function in cancer cells. BBI-825, the Company's second ecDNA-directed therapy (ecDTx) to enter clinical trials, is a novel, selective, oral small molecule inhibitor of ribonucleotide reductase (RNR), a rate-limiting enzyme responsible for the de novo synthesis of deoxyribonucleotides, the building blocks of DNA. Boundless has identified an essential role for RNR in ecDNA assembly and repair and in the survival of certain oncogene amplified cancer cells.

“We are excited to announce dosing of the first patient in our first-in-human study of BBI-825, our second program to enter the clinic,” said Klaus Wagner, M.D., Ph.D., Chief Medical Officer at Boundless Bio. “BBI-825 represents a new approach in the potential treatment of oncogene amplifications, particularly in resistance associated with targeted therapy treatment of MAPK pathway-activated cancers.”

"Rapid resistance is a major limitation for targeted therapies, particularly in colorectal cancer, as patients with colorectal cancer often progress within about 6 months of initiating targeted treatment,” said Rona Yaeger, M.D., Gastrointestinal Oncologist and Early Drug Development Specialist at Memorial Sloan Kettering Cancer Center. “We have observed firsthand that tumors in patients treated with KRAS^G12C or BRAF^V600E targeted therapies develop resistance via MAPK pathway and receptor tyrosine kinase gene amplifications, and those with pre-existing amplifications have an overall worse outcome. There remains an incredible need for therapies that can prevent amplification-driven resistance or treat patients that have already acquired such resistance.”