Boundless Bio, Inc., a clinical-stage oncology company, develops interrogating extrachromosomal DNA (ecDNA) directed therapies for treating patients with oncogene amplified cancers. Its lead product candidate is BBI-940, an ecDNA-directed therapeutic candidate (ecDTx) that is in Phase 1/2 clinical trial in patients with estrogen receptor positive and human epidermal growth factor receptor 2 negative breast cancer, as well as patients with triple-negative breast cancer luminal androgen receptor subtype. The company was formerly known as Pretzel Therapeutics, Inc. and changed its name to Boundless Bio, Inc. in July 2019. Boundless Bio, Inc. was incorporated in 2018 and is headquartered in San Diego, California.