Boundless Bio, Inc. is a clinical-stage oncology company, which is engaged in cancer therapeutics that address the unmet need in patients with oncogene amplified tumors by targeting extrachromosomal DNA (ecDNA). Using its proprietary Spyglass platform, it identifies targets essential for ecDNA functionality in oncogene amplified cancer cells, then designs and develops small molecule drugs called ecDNA-directed therapeutic candidates (ecDTx) to inhibit those targets. The Company’s lead therapeutic candidate ecDTx, BBI-355, is an oral, selective inhibitor of checkpoint kinase 1 (CHK1), which manages ecDNA replication and transcription in cancer cells. BBI-355 demonstrated CHK1 inhibition and tumor regressions in oncogene amplified preclinical cancer models, including those enabled by ecDNA, and is being studied in a first-in-human, Phase I/II clinical trial in patients with oncogene amplified cancers. Its next program is directed at a previously undrugged kinesin target.