Tubulin-IN-51 is an orally active tubulin inhibitor with an IC50 of 31 nM. It promotes tubulin polymerization in vitro and does not competitively bind with Paclitaxel. Tubulin-IN-51 inhibits the binding of Vinblastine to tubulin and suppresses tumor growth in various nude mouse xenograft models, including those using A549 human non-small cell lung cancer (NSCLC) cells and U87-MG human glioblastoma.

Tubulin-IN-51 (Compound 8) enhances tubulin polymerization, similar to the action of paclitaxel, and prevents [^3H]vinblastine from binding to tubulin. At low concentrations (10-35 nM), Tubulin-IN-51 induces apoptosis by reducing the proportion of cells in the G1 phase, while at higher concentrations (35-200 nM), it arrests cells in the G2/M phase, mirroring the effects observed with paclitaxel. This compound inhibits the proliferation of KB, KB 8.5, and KBV1 cells with IC50 values of 23 nM, 67 nM, and 953 nM, respectively.

Tubulin-IN-51 (Compound 8) administered intravenously at 15-20 mg/kg on days 0, 7, 14, and 21 post-scheduling is effective in inhibiting tumor growth in A549 NSCLC xenograft mouse models. Additionally, oral administration of Tubulin-IN-51 at 2.5-50 mg/kg on days 0 and 7 post-scheduling suppresses tumor growth in U87-MG human glioblastoma xenograft mouse models.