Boundless Bio, Inc., a clinical-stage oncology company, develops cancer therapeutics to address the unmet need of patients with oncogene amplified tumors by targeting extrachromosomal DNA. Its lead product candidate is BBI-355, an oral inhibitor of checkpoint kinase 1 that is in Phase 1/2 clinical trial in patients with oncogene amplified cancers. The company is also developing BBI-825, an oral inhibitor of ribonucleotide reductase, which is in Phase 1/2 clinical trial in cancer patients with resistance gene amplifications; and ecDTx 3 program targeting a kinesin involved with the cellular mechanism for segregation of ecDNA. Boundless Bio, Inc. was formerly known as Pretzel Therapeutics, Inc. and changed its name to Boundless Bio, Inc. in July 2019. The company was incorporated in 2018 and is headquartered in San Diego, California.