Methods: Triptolide's inhibition of cell viability was detected by sulforhodamine B (SRB) assay. Cell cycle was measured by flow cytometry and cell apoptosis was assessed by flow cytometry and western blot. Expression of β-catenin was analyzed by western blot and immunofluorescence (IF). The anti-tumor effects of triptolide were determined using a subcutaneous in-vivo model. Cell proliferation and apoptosis were evaluated by immunohistochemistry (IHC) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, respectively. The expression level of p-p70S6K and p-GSK-3α/β was evaluated by western blot and IHC.
Results: Triptolide inhibited cell proliferation, induced S-phase cell cycle arrest and apoptosis in taxol-resistant A549 (A549/TaxR) cells. Moreover, intraperitoneal injection of triptolide resulted in a significant delay of tumor growth without obvious systemic toxicity in mice. Additionally, triptolide reversed epithelial-mesenchymal transition (EMT) through repression of the p70S6K/GSK3/β-catenin signaling pathway.
Conclusions: Our study provides evidence that triptolide can reverse EMT in taxol-resistant lung adenocarcinoma cells and impairs tumor growth by inhibiting the p70S6K/GSK3/β-catenin pathway, indicating that triptolide has potential to be used as a new therapeutic agent for taxol-resistant lung adenocarcinoma.
EXPERIMENTAL DESIGN: Tumor tissue EGFRm status was determined at screening using the central cobas tissue test or a local tissue test. Baseline circulating tumor (ct)DNA EGFRm status was retrospectively determined with the central cobas plasma test.
RESULTS: Of 994 patients screened, 556 were randomized (289 and 267 with central and local EGFR test results, respectively) and 438 failed screening. Of those randomized from local EGFR test results, 217 patients had available central test results; 211/217 (97%) were retrospectively confirmed EGFRm positive by central cobas tissue test. Using reference central cobas tissue test results, positive percent agreements with cobas plasma test results for Ex19del and L858R detection were 79% [95% confidence interval (CI), 74-84] and 68% (95% CI, 61-75), respectively. Progression-free survival (PFS) superiority with osimertinib over comparator EGFR-TKI remained consistent irrespective of randomization route (central/local EGFRm-positive tissue test). In both treatment arms, PFS was prolonged in plasma ctDNA EGFRm-negative (23.5 and 15.0 months) versus -positive patients (15.2 and 9.7 months).
CONCLUSIONS: Our results support utility of cobas tissue and plasma testing to aid selection of patients with EGFRm advanced NSCLC for first-line osimertinib treatment. Lack of EGFRm detection in plasma was associated with prolonged PFS versus patients plasma EGFRm positive, potentially due to patients having lower tumor burden.