Ambrx Soars on Synthetic ADC Linker Science

Dec 03, 2023

BIOTECH: Stock Up Nearly 700% Over Last 6 Months

Ambrx Biopharma Inc. (NASDAQ: AMAM) is a case study in the power of perseverance and good science.

“It’s an overnight success that was 20 years in the making,” said CEO Dan O’Connor.

That overnight success is a nearly 700% increase in its stock price and a string of recent capital raises following favorable clinical studies of Ambrx’s leading candidates – a treatment for breast cancer and a treatment for prostrate cancer with technologies utilizing research developed by Scripps Research CEO Peter Schultz.

That research envisioned using synthetic amino acids in therapeutics and led to the spinout of Ambrx from Scripps in 2003.

“Since then, the Ambrx scientists have been making it a reality and further refining this technology,” O’Connor said, adding the company’s drug candidates are “using the expanded genetic code, which Ambrx is a pioneer in doing.”

Specifically, Ambrx is pioneering next generation antibody drug conjugates (ADCs) and other engineered therapies to modulate the immune system. The company is advancing a portfolio of clinical and preclinical programs designed to optimize efficacy and safety in multiple cancer indications, including ARX517, its proprietary ADC targeting the prostate-specific membrane antigen (PSMA) and ARX788, its proprietary ADC targeting HER2 in breast cancer.

Ambrx’s ADC drugs target the cancers and deliver a chemotherapy treatment that is “highly potent,” O’Connor said. And while there are other companies that have tried to use ADCs in the past and failed, O’Connor believes Ambrx’s approach using synthetic amino acids to conjugate antibodies to drugs will succeed.

“We believe the answer lies with the stability of the conjugation,” he said, explaining that synthetic amino acid conjugation offers ADCs “more stable points of conjugation than nature would provide.” Traditional conjugation of ADCs can potentially lead to instability when they get into the blood and can “fall apart,” he added. The stability of synthetic ADCs has the potential to ensure targeted delivery of toxic payloads to cancer cells while minimizing off-target effects.

The promise of Ambrx’s synthetic amino acid ADC conjugation technology has caught the attention of investors, causing the company’s stock price to soar and leading to recent successful capital raises – remarkable for a company that was delisted from the New York Stock Exchange in December for sub-dollar trading.

O’Connor said that like a lot of companies that went public in 2021, Ambrx faced “headwinds” in the capital markets and its stock performed in a “downward trend.”

However, shortly after O’Connor joined the company in November of last year, Ambrx finished preparing an update on its breast cancer program, he said, and that data was selected for a “spotlight poster presentation” at a breast cancer conference.

In the months since, fueled by more positive clinical data shared publicly, Ambrx has successfully raised over $150 million in stock offerings. On June 28, Ambrx announced the closing of a previously announced market-priced registered direct offering of approximately $75 million of its American Depositary Shares (ADS) of the company at a price of $13.93 per ADS. The stock offering was the company’s first after leaving the NYSE and joining the NASDAQ market in mid-March.

In early March, shortly before moving from the NYSE to NASDAQ, Ambrx completed net sales of approximately $78 million of ADSs through the company’s at-the-market program.

The combination of positive data and the successful stock offerings has led to shares of AMAM climbing around 680%, from a Jan. 3 price of $2.07 to $16.16 as of July 3.

O’Connor credits Ambrx’s recent success in the market to its novel approach to using an ADC with a chemotherapy payload to address targets, especially in prostate cancer where other companies’ solutions have been unsuccessful.

“Now here we are able to move forward in development,” he said. “I think that has resonated; it’s something the market has appreciated and hence the opportunity to raise capital to fund the company’s work.”

Ambrx Biopharma Inc.

Founded: 2003CEO: Dan O’ConnorHeadquarters: San DiegoBusiness: Biopharmaceutical companyStock: AMAM (NASDAQ)Revenue: $7.4 million (FY2022)Employees: 75Website: www.ambrx.comNotable: Ambrx drug candidates utilize technologies developed by Scripps Research CEO Peter Schultz.