3H-Pyridazino[3,4,5-de]quinazolin-3-one, 8-[(1,3-dihydro-2H-isoindol-2-yl)methyl]-1,2-dihydro-
2X-121 is under investigation in clinical trial NCT03562832 (Investigation of Anti-tumour Effect and Tolerability of the PARP Inhibitor 2X-121 in Patients With Metastatic Breast Cancer Selected by the 2X-121 DRP).