OSW-1

OSW-1 is a natural saponin isolated from the bulbs of Ornithogalum saundersiae. Relatively, its anticancer activities are about 10-100 times more potent than many anticancer drugs in clinical use. It exhibits exceptionally potent cytotoxic activities against NCI-60 human cancer cell lines with sub-nM IC50 values (more details available on request). However, it does not show any hemolytic toxicity even at 100 µg/mL concentration. OSW-1 meets all the requirements for an ADC payload such as sub-nM IC50 potency against a broad spectrum of cancers, a handler for conjugation, and etc. Furthermore it has the following unique competitive advantages over other commercially available payloads: 1) It is also highly potent against dormant (stem-like) cancer cells with sub-nM IC50 values; 2) It has excellent therapeutic selectivity; 3) It has a novel mechanism of action. Research has shown that OSW-1 disables/abolishes GRP78 pathway that is very important for cancer cell survival especially under stress conditions; 4) It can be conjugated to different types of linkers, and we know where and how to conjugate OSW-1 to antibodies via a linker. Potential mode of action/Key words: Abolishes GRP78 pathway, Anticancer