Bone metastasis reduces responsiveness to EGFR-TKIs in patients with EGFR-mutated advanced lung adenocarcinoma.

Abstract

e21085 Background: The response of epidermal growth factor receptor (EGFR) - tyrosine kinase inhibitors (TKIs) to bone metastasis site in patients with EGFR mutated lung adenocarcinoma remains to be determined. Methods: This is a retrospective analysis of the efficacy of EGFR-TKIs for lung adenocarcinoma patients with EGFR mutations, comparing patients with bone metastases (BM) and those with no bone metastases (NBM). BM patients need extra imaging to assess the efficacy of bone metastasis sites . Overall response rate (ORR), disease control rate (DCR), median progression-free survival (PFS) and progression patterns were evaluated. Results: Of the 502 patients, 175 were enrolled (BM 96, NBM 79) from January 2012 to December 2017. 125 patients had disease progression on January 31, 2018. The clinical characteristics of the two groups were not significantly difference. The median PFS was 11.0 months in NBM group and 7.0 months in BM group ( P= 0.013) . The median PFS in patients with multiple BM (≥ 4) was significantly lower than that in patients with oligometastases (1-3) and NBM (7.0 months vs 10.0 months vs 11.0 months, P = 0.003). Multivariate analysis confirmed that bone metastasis was an independently negative predictor of PFS for EGFR-TKIs ( P = 0.017). The ORR and DCR of NBM group were higher than those of BM group (70.9% vs 56.3%, P = 0.046 and 96.2% vs 85.4%, P= 0.017). Bone was one of the frequently progressive sites of EGFR-TKIs therapy, accounting for 52 of 125 (41.6%). The incidence of bone progression in NBM patients was significantly lower than that in BM patients(11.8% vs 62.2%, P < 0.001). Conclusions: Bone metastasis, especially multiple bone metastasis, reduces the response to EGFR-TKIs for lung adenocarcinoma with EGFR mutations. Bone metastasis monitoring should be a routine clinical practice for BM patients.