Cancer Stem-cell Therapeutics Limited (CAST Ltd) is a medical biotech startup based in Hong Kong, focusing on the research and development of innovative cancer therapeutics by targeting the cancer stem cells (CSCs) and combating relapse. The startup employs its patented technology “Flavonoid dimers” to target an essential ROS-scavenger enzyme (PRDX1) in CSCs. PRDX1 overexpression causes multidrug resistance, tumor progression and metastasis. “Flavonoid dimers” can inhibit PRDX1 and chemosensitize CSCs towards conventional chemo drugs, thereby eradicating CSCs, preventing cancer relapse and prolonging disease-free survival of cancer patients.