5F02

**5F02** is a synthetic small molecule that acts as a novel allosteric inhibitor of Poly(ADP-ribose) polymerase 1 (**PARP1**)[1][6][12][13][14][15]. Unlike clinical PARP1 inhibitors like olaparib, which compete with NAD+, 5F02 inhibits PARP1 by preventing its enzymatic activation through histone H4—targeting an allosteric regulatory site, not the NAD+-binding pocket[1][6]. This alternative mechanism provides a potential means to overcome resistance encountered with traditional PARP1 inhibitors. 5F02 displays potent anticancer activity in vitro and in animal models, and shows synergy with olaparib especially in BRCA-deficient cancer cell lines[1][6][15]. Structural-activity relationship studies have optimized its scaffold for improved potency and selectivity[1][6][13][15].