ALDH1A1 and ovarian serous carcinoma: Finally, we demonstrated that a combination of olaparib with an ALDH1A1 inhibitor, NCT-505, can synergistically reduce the viability of patient-derived organoids (PDOs) generated from primary high-grade serous ovarian carcinoma (HGSOC) tumor tissues, which possess mutant BRCA1/2 and positive ALDH1A1 expression.