The IPO Buzz: ARCH Venture’s Boundless Bio Files Plans for $100 Million IPO

ARCH Venture Partners is the big name behind Boundless Bio Inc. (BOLD Proposed), a Phase 1 cancer biotech that filed plans for a $100 million IPO on Wednesday (March 6, 2024) after the closing bell. The S-1 filing did not disclose terms for the IPO. This is a NASDAQ listing.

Boundless Bio was founded in 2018 by ARCH Venture Partners and Paul Mischel, M.D., a Stanford  professor who is internationally recognized for his expertise in extrachromosomal DNA (ecDNA), the prospectus says. Dr. Mischel, the vice chair of research and a professor of pathology at the Stanford University School of Medicine, is the chairman of Boundless Bio’s Scientific Advisory Board.

Goldman Sachs, Leerink Partners, Piper Sandler and Guggenheim Securities are the joint book-runners.

Extrachromosomal DNA – known as ecDNA – is “a root cause of oncogene amplification observed in more than 14 percent of cancer patients,” the prospectus says. An example of an oncogene is the HER2 oncogene found in some breast cancer and ovarian cancer cells, according to the City of Hope website.

Boundless Bio, based in San Diego, says in the prospectus: “ecDNA are large circular units of nuclear DNA that are a primary mechanism of gene amplification and, like oncogene amplifications, are detected only in cancer cells, not in healthy cells.”

In the prospectus, Boundless Bio says that “we are, to our knowledge, the first company formed to develop new cancer medicines directed at ecDNA and the only company to date to bring an ecDTx into the clinic to treat cancer patients.” The California clinical biotech says that “we consider ourselves to be the world’s leading ecDNA company.” 

The Phase 1 biotech is developing small molecule drugs called ecDTx that are “designed to preferentially kill ecDNA-bearing cancer cells, but not healthy cells without ecDNA,” Boundless Bio says in the prospectus.

Boundless Bio’s lead ecDTx candidate, known as BBI-355, is “a novel, oral, selective inhibitor of checkpoint kinase 1 (CHK1), which manages ecDNA replication and transcription in cancer cells,” the prospectus says.

This lead ecDTX drug candidate, BBI-355, is being studied in a first-in-human Phase 1/2 clinical trial called POTENTIATE with clinical trial results expected in the second half of 2024, according to Boundless Bio’s prospectus. The company has two other ecDNA drug candidate programs, the S-1 filing says.

Boundless Bio is typical of most Phase 1 biotechs in that it has a history of net losses and no revenue from product sales, according to the prospectus.

For the year ended Dec. 31, 2023, Boundless Bio reported a net loss of $49.43 million on no product revenue, the prospectus says.

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