San Diego’s Ambrx Files for IPO to Advance Antibody-Drug Conjugates

Ambrx logo

[Corrected 5/6/14, 11 am. See below.] San Diego-based Ambrx, a biotech company with a new approach to developing protein therapeutics for treating, cancers, diabetes, and other diseases and disorders, plans to raise as much as $86 million in an IPO, according to a regulatory filing that was made public Friday. The company submitted its IPO plans confidentially on March 28th.

Using recombinant DNA-based protein biosynthesis, Ambrx can insert non-native amino acids at precisely selected sites in native proteins as they are being made within the cells. The technology enables Ambrx to impart new functionality to biotherapeutic compounds, and Ambrx has focused in particular on antibody-drug conjugates (ADCs).

Ambrx has an internal ADC drug program that includes a number of anti-cancer compounds, as well as long-acting proteins for growth hormone deficiency, weight management, and other disorders.

The company’s lead ADC product is a preclinical biotherapeutic targeting cancer cells that express human epidermal growth factor 2 (HER2). The antibody protein is conjugated with a cytotoxic drug payload, and is intended for the treatment of breast cancer and other solid tumors that express and over-express HER2. Ambrx says it expects to begin clinical trials next year with the drug, known as ARX788.

Ambrx was founded in 2003, and has raised more than $106 million in venture capital. The company says it has raised more than $200 million in non-dilutive funding by collaborating with pharmaceutical companies on particular drug development programs. The partners include Bristol-Myers Squibb, Merck, Eli Lilly, Zhejiang Medicine, and others in deals that also could eventually lead to additional milestone payments as well as royalties on the sale of collaboration products.

[Corrected to show $80 million in accumulated deficits, instead of debt.] The company has about $61.6 million in available cash, slightly more than $80 million in accumulated deficits, and 74 employees. Ambrx plans to list on the NASDAQ market under the symbol AMBX.

The biggest shareholders (followed by the size of their pre-IPO stakes) are: Tavistock BIO (19.3 percent), Maverick Capital (17.4 percent), Apposite Healthcare Fund (9.5 percent), Versant Ventures (7.5 percent), 5AM Ventures (6.9 percent), Roche (6.2 percent), and Merck (5.2 percent).

Author: Bruce V. Bigelow

In Memoriam: Our dear friend Bruce V. Bigelow passed away on June 29, 2018. He was the editor of Xconomy San Diego from 2008 to 2018. Read more about his life and work here. Bruce Bigelow joined Xconomy from the business desk of the San Diego Union-Tribune. He was a member of the team of reporters who were awarded the 2006 Pulitzer Prize in National Reporting for uncovering bribes paid to San Diego Republican Rep. Randy “Duke” Cunningham in exchange for special legislation earmarks. He also shared a 2006 award for enterprise reporting from the Society of Business Editors and Writers for “In Harm’s Way,” an article about the extraordinary casualty rate among employees working in Iraq for San Diego’s Titan Corp. He has written extensively about the 2002 corporate accounting scandal at software goliath Peregrine Systems. He also was a Gerald Loeb Award finalist and National Headline Award winner for “The Toymaker,” a 14-part chronicle of a San Diego start-up company. He takes special satisfaction, though, that the series was included in the library for nonfiction narrative journalism at the Nieman Foundation for Journalism at Harvard University. Bigelow graduated from U.C. Berkeley in 1977 with a degree in English Literature and from the Columbia University Graduate School of Journalism in 1979. Before joining the Union-Tribune in 1990, he worked for the Associated Press in Los Angeles and The Kansas City Times.