Siamab Therapeutics

Siamab Therapeutics, Inc. was a biopharmaceutical firm that operated in the oncology space, focusing on the development of therapeutics for difficult-to-treat solid tumors. Founded in 2006 by Dr. Ajit Varki, a distinguished professor at the University of California, San Diego (UCSD), the company was built upon his foundational research in glycobiology. The company's scientific focus originated from Dr. Varki's discoveries related to the unique sugars, specifically tumor-associated carbohydrate antigens (TACAs), found on the surface of cancer cells. In 2015, the company relocated to Massachusetts, adopting a capital-efficient, semi-virtual operational model. Jeff Behrens, an entrepreneur with a diverse background in healthcare IT and biotechnology, including roles at Biogen Idec and Edimer Pharmaceuticals, served as the President and CEO.

The core of Siamab's business was its proprietary technology platform designed for the rapid discovery and development of therapeutic antibodies that target TACAs. These antigens are compelling targets because they are highly specific to cancer cells and are associated with chemoresistance and the suppression of immune function in solid tumors. The company's business model revolved around advancing its proprietary antibody candidates through preclinical development and forging strategic collaborations with larger pharmaceutical companies. This strategy was validated through a significant collaboration with Boehringer Ingelheim to discover antibody therapeutics against TACAs. The company operated on a lean model, successfully raising over $12 million from angel investors and leveraging an additional $7 million from grants and corporate partnerships, a notable achievement without traditional venture capital funding.

Siamab's lead program, ST1, was an antibody-drug conjugate (ADC) targeting Sialyl-Tn (STn), a specific TACA expressed in a variety of solid tumors, including ovarian, pancreatic, colon, and prostate cancers. The presence of STn is linked to metastatic disease, poor prognosis, and reduced survival. The ST1 therapeutic was engineered to bind with high specificity and affinity to STn, enabling the targeted delivery of a cytotoxic agent to cancer cells. Preclinical studies demonstrated ST1's efficacy in inhibiting tumor growth in multiple cancer models, with complete regression observed in some cases, alongside a favorable safety profile in non-human primate studies. A significant finding was ST1's ability to also target and deplete myeloid-derived suppressor cells (MDSCs), which inhibit the body's immune response against tumors, suggesting a dual-action mechanism. In August 2019, Siamab was acquired by an undisclosed large biopharmaceutical company in a deal valued at up to $202 million, marking a successful exit for its angel investors and validating its focused approach to oncology research.

Keywords: glycan-targeted therapeutics, tumor-associated carbohydrate antigens, TACA, antibody-drug conjugate, ADC, Sialyl-Tn, STn, solid tumor oncology, cancer immunology, preclinical development, monoclonal antibodies, biopharmaceutical, cancer immunotherapy, chemoresistance, ST1 program, Ajit Varki, Jeff Behrens, Boehringer Ingelheim collaboration, acquired biotech, angel-funded startup, glycan-specific targeting, myeloid-derived suppressor cells, ovarian cancer treatment, pancreatic cancer therapy