The BELIEF trial (NCT01562028) examined the efficacy of E+B for the 1st line treatment of European p with advanced NSCLC harboring exon 19 deletion or exon 21 L858R epidermal growth factor receptor (EGFR) mutations with or without pretreatment T790M. Median progression-free survival (mPFS) was 13.8 months (m) (95% CI 10.3-16.2) for the 109 p enrolled in the study. mPFS was 16m (95% CI 13.1-not estimable [NE]) and 10.4m (95% CI 9.2-15.6) for the 37 T790M(+) p and 72 T790M(-) p, respectively (P = 0.089). We have previously shown that low BRCA1 levels neutralize the negative effect of pretreatment T790M and are associated with longer PFS to erlotinib. Low astrocyte elevated gene 1 (AEG1) levels are associated with longer PFS to erlotinib. A secondary objective of the BELIEF trial was the assessment of the prognostic impact of BRCA1 and AEG1 mRNA expression in the baseline tumor tissue.

We assessed the baseline mRNA expression levels of BRCA1 and AEG1 and correlated them with PFS and response in the 109 EGFR-mutant NSCLC p of the BELIEF trial. BRCA1 and AEG1 mRNA levels were estimable by quantitative-real time PCR in 46 and 61 p respectively. Expression levels were divided into two groups according to their median.

No statistically significant associations were found among the expression of the two biomarkers and gender, smoking status, histology, PS or type of EGFR mutation. The association of BRCA1 and AEG1 mRNA with PFS did not differ according to T790M status (interaction P = 0.81 and 0.42, respectively). Among the T790M (+) p, those with low BRCA1 mRNA had a longer mPFS of 24.6m (95% CI: 4.9-NE) compared to 15.4 m (95% CI: 2.7-NE) for p with high BRCA1 mRNA; P = 0.63. For all and T790M (-) p, BRCA1 levels did not differentiate mPFS to E+B (low vs high BRCA1 mRNA, 11.0 m [95% CI: 6.0-NE] vs 9.5 m [95% CI: 7.2-NE]; P = 0.99 and 6.9 m [95% CI: 2.1-NE] vs 9.4 m [95% CI: 4.1-NE]; P = 0.71, respectively). Similarly, among the T790M (+) p, those with low AEG1 expression had a longer mPFS of 24.6m (95% CI: 4.9-NE) compared to 15.4 m (95% CI: 5.2-NE) for those with high AEG1 mRNA; P = 0.93. For all and T790M(-) p, AEG1 levels did not differentiate mPFS to E+B (low vs high AEG1 mRNA, 10.3 m [95% CI: 8.4-24.6] vs 15.4 m [95% CI: 6.0-33.9]; P = 0.90 and 10.3m [95% CI: 8.4-NE] vs 13.3m [95% CI: 4.7-33.9] P = 0.67). No statistically or clinically significant associations were found among BRCA1, AEG1 mRNA levels and response to E+B.

The BELIEF trial reconfirms our previous findings that pretreatment EGFR T790M is present in 34% of the patients. E+B is associated with a prolonged mPFS of 24.6m for EGFR-mutant p with both pretreatment EGFR T790M and low BRCA1 mRNA expression, as observed in our previous study with erlotinib alone. Similar results were observed for AEG1 levels though the interaction was not statistically significant for either biomarker.

Citation Format: Rafael Rosell, Niki Karachaliou, Ana Giménez-Capitán, Carles Codony-Servat, Oliver Gautschi, Enriqueta Felip, Alessandra Curioni-Fontecedro, Solange Peters, Santiago Ponce-Aix, Martin Früh, Miklos Pless, Sanjay Popat, Sinead Cuffe, Paolo Bidoli, Adolfo Favaretto, Roswitha Kammler, Urania Dafni, Zoi Tsourti, Miguel Angel Molina-Vila, Rolf A. Stahel. The role of BRCA1 and AEG1 mRNA expression in advanced non-small-cell lung cancer (NSCLC) patients (p) with EGFR activating and pretreatment T790M mutations receiving the combination of erlotinib plus bevacizumab (E+B) in the BELIEF trial. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 269.