BK60106 is a selective inhibitor of the transmembrane protein CD99, which causes cell death in Ewing Sarcoma cells by directly binding to the extracellular structural domain of CD99.

In ER⁺/HER2⁻ breast cancer cell lines (e.g., MCF-7 and T47D), BK60106 (0.1–10 μM, 24–72 h) effectively inhibited cell proliferation and induced G1 phase arrest. BK60106 also downregulated phosphorylation of the CDK4/6 downstream target pRb and suppressed E2F target gene expression, indicating its role as a CDK4/6 pathway inhibitor[1].

In MCF-7 xenograft mouse models, BK60106 (100 mg/kg, oral gavage, once daily for 21 days) significantly suppressed tumor growth with over 70% inhibition and showed no marked body weight loss or toxicity, demonstrating favorable antitumor efficacy and safety[1].