Abstract: Background and purpose: Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is of advantage in treating non-small cell lung cancer (NSCLC) patients with EGFR mutations. However, their clinical effects vary individually. This study aimed to evaluate whether the EGFR ligand, plasma transforming growth factor α (TGF-α), could act as a predictor for the EGFR-TKI treatment efficiency in NSCLC patients with EGFR mutations and the association between TGF-α and prognosis in these patients. Methods: Seventy-five NSCLC patients with EGFR gene positive mutation were included in the current study from May 2012 to Jul. 2014 in Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine. Plasma TGF-α was measured using enzyme-linked immunosorbent assay (ELISA) in all of the patients before EGFR-TKI treatment. The radiographic evaluation was performed 2 months after the therapy. The association between TGF-α and clinical outcome and its prediction efficiency were determined, followed by the further analysis of the association between TGF-α and overall survival (OS) as well as progression-free survival (PFS). Results: After EGFR-TKI treatment, there were 20 patients with partial response (PR), 25 with stable disease (SD) and 30 with progression disease (PD) in all 75 NSCLC patients harboring EGFR positive mutation. The disease control (DC) rate reached 60%. Patients in PD group presented statistically significant higher plasma TGF-α than patients in the DC group (P<0.01). Multivariate COX model indicated that smoking status, lymph node metastasis and plasma TGF-α levels were independent risk factors for prognosis in these patients. The ROC analysis revealed that baseline plasma TGF-α showed good prediction efficiency [area under the curve (AUC)=0.926] and the cut-off point of TGF-α was 16.75 pg/mL. Higher level of TGF-α (≥16.75 pg/mL) was associated with smoking history, clinical stage, lymph node metastasis and clinical outcome of the patients (P<0.05). In comparison to patients with low TGF-α, the patients with high TGF-α concentration presented significantly reduced median OS and PFS (log-rank P<0.05). Conclusion: Higher plasma TGF-α (≥16.75 pg/mL) had a predictive role in EGFR-TKI resistance and poor prognosis.

Key words: Transforming growth factor α, Epidermal growth factor receptor-tyrosine kinase inhibitor, Nonsmall cell lung cancer, Prognosis