ONX 0801– Thymidylate Synthase Inhibitor

ONX 0801 is a novel targeted compound that expands upon an already proven class of drugs by combining two established approaches to improving outcomes for cancer patients. These approaches include receptor-mediated targeting of tumor cells and inhibition of thymidylate (TS), a key enzyme involved in cell growth and division.

ONX 0801 is believed to target cells through the alpha-folate receptor, which is primarily located on the cell's surface of some kinds of tumor cells. Once ONX 0801 enters the cell via this receptor, the compound inhibits, or switches off, TS, a key enzyme in cell growth and division. ONX 0801 is believed to be distinct from currently marketed TS inhibitors, such as pemetrexed, 5 fluorouracil (5-FU), and raltitrexed, due to its selective uptake by the alpha-folate receptor.¹ Because the alpha-folate receptor is minimally expressed on most healthy tissue, ONX 0801 may spare healthy cells during treatment, possibly leading to fewer side effects and lowering toxicity.

The alpha-folate receptor is overexpressed in a number of tumor types with significant unmet needs, including ovarian cancer and lung cancer.

ONX 0801 is currently in Phase 1 clinical development.


  1. http://cancerres.aacrjournals.org/cgi/content/abstract/65/24/11721?ck=nck “BGC 945, a Novel Tumor-Selective Thymidylate Synthase Inhibitor Targeted to A-Folate Receptor–Overexpressing Tumors,” Jackman et al. Cancer Research 2005.