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Boundless Bio Raises $105M in Series B Financing

NEW YORK – Boundless Bio said on Wednesday it has raised $105 million in a Series B funding round led by Nextech Invest and RA Capital Management.

New investors that participated in the funding round included Fidelity Management & Research, Redmile Group, Wellington Management, Surveyor Capital, PFM Health Sciences, and Logos Capital, along with existing investors ARCH Venture Partners, City Hill Ventures, Vertex Ventures HC, GT Healthcare Capital Partners, Boxer Capital of Tavistock Group, and Alexandria Venture Investments. Jakob Loven, a partner at Nextech Invest, will join the Boundless Bio board of directors.

With the new funding, the La Jolla, California-based firm, which launched in 2019, plans to advance its extrachromosomal DNA (ecDNA)-directed therapeutic programs and companion diagnostic into the clinic. The company is using its Spyglass ecDNA discovery platform to develop drug candidates that target ecDNA-driven, gene-amplified tumors.

Using the Spyglass platform, Boundless has discovered and validated three ecDNA-essential targets and has initiated drug discovery against each target, Boundless Bio CEO Zachary Hornby said in a statement. It has also begun developing a companion diagnostic to identify patients with ecDNA-driven tumors, called ECHO, or ecDNA Harboring Oncogenes.

EcDNA are units of DNA that are outside of tumor cell chromosomes. They contain functional genes and are transcriptionally active. Based on Boundless Bio's research, ecDNA drive gene amplification and copy number heterogeneity in cancer cells and are present in many solid tumors but generally not in healthy cells. ecDNA have also been tied to tumor resistance to treatments including chemotherapy, targeted therapy, immunotherapy, and radiation.

"This financing round and stellar investor syndicate reflects the investment community's appreciation for the high unmet clinical need of patients with oncogene-amplified cancers and the promise of our innovative approach to targeting ecDNA to improve and prolong the lives of these patients," Hornby said.