USP1-IN-11 (compound 38-P2) is a selective, reversible, and non-competitive inhibitor of USP1 (Ubiquitin-specific protease 1). It promotes the activation of the DDR (DNA damage repair) pathway, inducing cell cycle arrest and apoptosis, thereby inhibiting cell viability. USP1-IN-11 increases the sensitivity of cells resistant to Olaparib and shows synergistic effects with Andrographolide in cancer cells with normal BRCA function. In the MDA-MB-436 xenograft model, USP1-IN-11 exhibits a significant dose-dependent antitumor effect.