Siamab Therapeutics to Present New Data on its ST1 Antibody Therapeutic Program Targeting

“We are pleased to present new patient tumor data and ovarian carcinoma xenograft data for our ST1 antibody drug conjugate targeting STn at the AACR 2018 annual meeting,” said Jeff Behrens, president and chief executive officer of Siamab. “These research findings are exciting as they continue to show that STn provides a uniquely glycan-specific target for the treatment of solid tumors. Importantly, the findings demonstrate that our antibody therapeutic targeting STn offers the potential to go beyond tumor targeting to also directly target and deplete immune-suppressive MDSCs, enabling immune system re-engagement and increasing the potential for better patient outcomes.”

The poster presentation will highlight new data showing the presence of STn on the surface of MDSCs in a growing body of patient tumor samples, as well as data in patients and xenograft models linking STn expression on MDSCs to tumor cell STn expression. In addition, the poster will highlight data that demonstrates depletion of STn+ MDSCs after treatment with an anti-STn ADC in an ovarian carcinoma xenograft model.

Details for the poster presentation are as follows:

Abstract Title and Number: Myeloid derived suppressor cells (MDSCs) express Sialyl Tn (STn) and are a therapeutic target for anti-STn antibody drug conjugates (#6892)
Date: Wednesday, April 18, 2018
Time: 8:00 a.m.-12:00 p.m. CT
Session Title: Therapeutic Antibodies, including Engineered Antibodies 4
Location: McCormick Place, Poster Section 28
Poster Board Number: 20

Siamab’s proprietary technology platform enables the development of highly specific mAb therapeutics, including ADCs, targeting cancer cell surface glycans called tumor-associated carbohydrate antigens (TACAs). TACAs are an emerging set of tumor specific antigens implicated in immune suppression, chemoresistance and a cancer stem cell (CSC) phenotype. STn, the sialylated version of the carbohydrate Tn antigen, is broadly expressed in human cancers including ovarian, gastric, colon, prostate, pancreatic and lung. The presence of STn in tumors is associated with metastatic disease, poor prognosis, and reduced overall survival. Tumor STn expression is well-established and can be leveraged for targeted cancer therapy; however, its expression on immuno-suppressive tumor infiltrating lymphocytes, such as MDSCs, is a new finding. Siamab has identified and utilized the presence of STn on MDSCs to target and deplete MDSCs in vivo, providing a potential novel therapeutic approach for the treatment of solid tumors.

A copy of the poster will be made available on the company’s website after the presentation.

About Siamab Therapeutics, Inc.

Siamab Therapeutics, Inc. is a biopharmaceutical company developing novel cancer therapeutics targeting cancer-specific carbohydrate antigens seen in multiple solid tumors. Siamab’s proprietary platform enables the rapid discovery and development of therapeutic antibodies that bind with unprecedented specificity and affinity to the novel class of carbohydrate antigens present on cancer cells called tumor-associated carbohydrate antigens (TACAs). TACAs are an exciting cancer target class due to their cancer specificity, association with a chemoresistant phenotype, and ability to suppress immune function in solid tumors. The company’s lead program, ST1, targets Sialyl-Tn (STn), a tumor specific antigen expressed in multiple solid tumors including ovarian, gastric, colon, prostate, pancreatic and lung cancers. ST1 is in late-stage preclinical studies for the treatment of solid tumors. Visit www.siamab.com to learn more about the company.

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