Siamab's first program - ST1 - targets a tumor associated carbohydrate antigen ("TACA1") present in a number of solid tumors including ovarian, prostate, pancreatic, gastric, and colon. Expression of TACA1 in tumors is correlated with metastatic disease, poor prognosis, decreased survival, and lack of response to chemotherapy. De novo expression of TACA1 can suppress innate immune function, change the malignant phenotype, and lead to more aggressive cell behaviors.
Siamab has generated and characterized a panel of highly specific antibodies targeting TACA1. The targeted epitopes are glycan-specific, which offers the potential to bind to multiple glycosylated proteins on cancer cell. These antibodies have been shown to bind with high affinity as well as demonstrate protein internalization in cancer cell lines, and are able to significantly inhibit the growth of tumors in vivo. The ST1 program is in late preclinical development for the treatment of solid tumors.