Exploratory analysis of biomarkers associated with clinical outcomes from the study of lenvatinib in differentiated cancer of the thyroid

Background: Lenvatinib significantly prolonged progression-free survival (PFS) versus placebo in the phase III Study of (E7080) LEnvatinib in differentiated Cancer of the Thyroid (SELECT) of patients with radioiodine-refractory differentiated thyroid cancer. This exploratory analysis investigated potential predictive biomarkers of lenvatinib efficacy and target engagement. Patients and methods: Circulating cytokine/angiogenic factors (CAFs) in blood samples collected at baseline and throughout treatment were analysed from patients randomised to receive lenvatinib or placebo from August 5, 2011 to October 4, 2012. For CAF biomarker analyses, patients were dichotomised by baseline levels. Tumour tissues were analysed for BRAF and NRASIKRASIHRAS mutations. Results: Tumours and CAFs were analysed from 183/392 (47%) and 387/392 (99%) patients, respectively. Lenvatinib PFS benefit was maintained in all assessments. For lenvatinibtreated patients, interaction-term analyses revealed that low baseline Ang2 level was predictive of tumour shrinkage (P-interaction = 0.016) and PFS (P-interaction = 0.018). Vascular endothelial growth factor and fibroblast growth factor 23 (FGF23) were significantly upregulated with lenvatinib, and FGF23 upregulation on cycle 1/day 15 was associated with longer PFS. In mutation analyses, no significant differences in clinical outcomes were observed. BRAF(WT) may be a negative prognostic factor for PFS in placebo-treated patients with papillary thyroid cancer (P = 0.019). Conclusion: The lenvatinib PFS benefit was maintained regardless of baseline CAF or BRAF/RAS status. Baseline Ang2 was predictive of PFS in a subgroup of lenvatinib-treated patients, indicating that Ang2 may be predictive of lenvatinib sensitivity. BRAF(WT) may be a poor prognostic factor in patients with radioiodine-refractory papillary thyroid cancer. Improved PFS associated with upregulated FGF23 suggests that lenvatinib-induced FGF receptor inhibition contributes to lenvatinib efficacy.