Abstract:

Objective To evaluate the efficacy of osimertinib as the second'line treatment for patients with epidermal growth factor receptor (EGFR)'mutant advanced non'small cell lung cancer (NSCLC), and to explore the relationship of location of metastasis before treatment and progression after drug resistance with the efficacy. Methods  From January 1, 2017 to January 1, 2019, 67 patients with advanced NSCLC who were treated with 1-2 generation EGFR'tyrosine kinase inhibitor (TKI) and 50 patients who developed drug resistance after first'line chemotherapy were included. EGFR exon T790M was mutant in all 117 patients. Osimertinib 80 mg was orally administrated once a day until the disease progressed or intolerable adverse reactions were observed. Curative effects of the whole group and different subgroups were analyzed. Results  As of October 31, 2020, 28 of 117 patients still took osimertinib, with the longest duration of 43.2 months. Eighty'nine cases progressed after treatment, and 45 cases of them died. The median progression'free survival (PFS) of the whole group was 15.2 (95% CI: 12.352'18.114) months and the median overall survival (OS) was not reached. Subgroup analysis showed that gender, the first'line treatment, and the location of the metastatic lesions before treatment had impacts on PFS (P<0.05). The first'line treatment, EGFR mutation type and primary extrafocal metastasis type before treatment were related to OS (P<0.05). The presence of intrapulmonary metastasis, pleural metastasis, pleural effusion tumor exfoliated cells, liver metastasis, lymph node metastasis and bone metastasis shortened median PFS (P<0.05), and the presence of intrapulmonary metastasis, lymph node metastasis, liver metastasis and bone metastasis shortened median OS (P<0.05). There were also differences in median PFS and death rate among patients with different location of progressive lesions, but there was no significant difference (P>0.05). The death rate of patients with bone metastasis was the highest (75.0%), while the median PFS of patients bearing adrenal metastasis was the shortest (7.1 months). Conclusion  Osimertinib showed good efficacy as the second'line treatment for advanced NSCLC bearing EGFR positive mutation. The PFS of first'line treatment with EGFR'TKI sequenced by osimertinib is longer than that of first'line chemotherapy sequenced by osimertinib. The prognosis of patients with intra'and extra'pulmonary metastasis before treatment is poor, and the influence of the location of progression on the effect is limited.

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