Antitumor activity of a combination of dual PI3K/mTOR inhibitor SAR245409 and selective MEK1/2 inhibitor pimasertib in endometrial carcinomas

作者：Inaba Kanako; Oda Katsutoshi^*; Ikeda Yuji; Sone Kenbun; Miyasaka Aid; Kashiyama Tomoko; Fukuda Tomohiko; Uehara Yuriko; Arimoto Takahide; Kuramoto Hiroyuki; Wada Hiraike Osamu; Kawana Kei; Yano Tetsu; Osuga Yutaka; Fujii Tomoyuki

来源：Gynecologic Oncology, 2015, 138(2): 323-331.

DOI：10.1016/j.ygyno.2015.05.031

• Endometrial carcinoma
• MEK
• MAPK
• PI3K/mTOR
• Molecular target therapy

Objective. We aimed to clarify whether dual inhibition of PI3K/MAPK and MAPK pathways synergistically suppresses cell growth in endometrial cancer cells.
Methods. We exposed a panel of 12 endometrial cancer cell lines to a PI3K/mTOR inhibitor (voxtalisib, SAR245409) and/or a MEK inhibitor (pimasertib). The effect of each drug singly or in combination was evaluated by MU assay, flow cytometry, and immunoblotting. Combination indexes (CIs) were calculated using the Chou-Talalay method to evaluate the synergy.
Results. The IC50 values for SAR245409 and pimasertib varied from 0.5 mu M to,7 mu M and from 0.1 mu M to >20 mu M, respectively. A combination of both compounds (1 mu M 5AR245409 and 30 nM pimasertib) caused a synergistic antitumor effect in 6 out of 12 endometrial cell lines (Cl, 0.07-0.46). The synergistic effect was exclusively observed in 6 pimasertib-sensitive cell lines (IC50 of pimasertib, AM). We found that 30 nM pimasertib, a concentration much lower than the IC50 for each cell line, was sufficient to cause a synergistic effect with SAR245409. Flow cytometric analysis showed that this combination significantly increased the population of G1 cells. However, a combination of rapamycin (an mTOR inhibitor) and pimasertib did not induce a synergistic effect in endometrial cancer cells, except for HEC-1B cells.
Conclusions. The combination of a PI3K/mTOR inhibitor and a MEK inhibitor induced a synergistic antitumor effect in certain endometrial cancer cells. This study underscores the importance of using optimized doses of antitumor agents, singly or in combination, in treating endometrial cancer.

• 出版日期2015-8