Gamma secretase inhibition by BMS-906024 enhances efficacy of paclitaxel in lung adenocarcinoma

Notch signaling is aberrantly activated in approximately one third of non-small cell lung cancers (NSCLC). We characterized the interaction between BMS-906024, a clinically relevant Notch gamma secretase inhibitor (GSI), and front-line chemotherapy in preclinical models of NSCLC. Chemosensitivity assays were performed on 14 human NSCLC cell lines. There was significantly greater synergy between BMS-906024 and paclitaxel than BMS-906024 and cisplatin (mean CI value = 0.54 and 0.85, respectively, P = 0.01). On an extended panel of 31 NSCLC cell lines, 25 of which were adenocarcinoma, the synergy between BMS-906024 and paclitaxel was significantly greater in KRAS- and BRAF-wildtype than KRAS- or BRAF-mutant cells (mean CI = 0.43 vs. 0.90, respectively; P = 0.003). Paclitaxel-induced Notch1 activation was associated with synergy between BMS-906024 and paclitaxel in the KRAS- or BRAF-mutant group. Knockdown of mutant KRAS increased the synergy between BMS-906024 and paclitaxel in heterozygous KRAS-mutant cell lines. Among KRAS- or BRAF-mutant NSCLC, there was a significant correlation between synergy and mutant or null TP53 status, as well as between synergy and a low H2O2 pathway signature. Exogenous overexpression of activated Notch1 or Notch3 had no effect on the enhanced sensitivity of NSCLC to paclitaxel by BMS-906024. In vivo studies with cell line- and patient-derived lung adenocarcinoma xenografts confirmed enhanced antitumor activity for BMS-906024 plus paclitaxel versus either drug alone via decreased cell proliferation and increased apoptosis. These results show that BMS-906024 sensitizes NSCLC to paclitaxel, and that wildtype KRAS and BRAF status may predict better patient response to the combination therapy.

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