The Efficacy and Safety of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Combined With Thymosin in Advanced Non-Small Cell Lung Cancer Patients Harboring Active Epidermal Growth Factor Receptor Mutations

Objective To explore the efficacy and safety of EGFR-TKI combined with thymosin therapy in advanced non-small cell lung cancer (NSCLC) patients harboring active EGFR mutations. Methods Patients confirmed as advanced NSCLC with active EGFR mutations were recruited from August 2008 to July 2018 retrospectively. Patients treated with EGFR-TKI were classified as the EGFR-TKI group. And those received EGFR-TKI and thymosin therapy were designated as the EGFR-TKI plus thymosin group. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), tumor response and adverse effects. Results The median PFS was significantly longer in EGFR-TKI plus thymosin group than that in EGFR-TKI group (14.4 months vs. 9.2 months; HR=0.433, 95% CI 0.322 - 0.582, P<0.0001). The median OS was also prolonged in EGFR-TKI plus thymosin group than that in EGFR-TKI group (29.5 months vs. 19.8 months; HR=0.430, 95% CI 0.319 - 0.580, P<0.0001). The objective response rate in EGFR-TKI plus thymosin group and EGFR-TKI group were 60.0% versus 60.8% (P=0.918). The disease control rate was 96.9% in EGFR-TKI plus thymosin group and 97.7% in EGFR-TKI group (P=1.000). There were no significant differences in adverse effects between the two groups. The number of CD3(+)T cells in peripheral blood decreased significantly after treatment including both CD3(+)CD4(+)T and CD3(+)CD8(+)T subsets in EGFR-TKI group, but not in EGFR-TKI plus thymosin group. Conclusions Combination of EGFR-TKI and thymosin can significantly prolong the PFS and OS compared with EGFR-TKI monotherapy without more adverse events, which offers a new strategy in clinic.