P12. Long term treatment with erlotinib in advanced non-small cell lung cancer patients

Background: Erlotinib is nowadays an established treatment for metastatic non-small cell lung cancer (NSCLC) patients with tumours harbouring epidermal growth factor receptor (EGFR) activating mutations. After a year of initial treatment most patients progress, but some very long responses have been observed. We here present the results of patients treated with erlotinib that did not progress in the 12 months from beginning of treatment.

Materials and methods: In this prospective observational trial NSCLC patients stage IIIB/IV treated between 2008 in 2011 that received erlotinib for more than a year were included. Demographic data, smoking status, side effects of treatment were observed and progression free and overall survival calculated. We analysed results with descriptive statistics and the Cox regression model.

Results: We observed 128 (31.7%) long-term survivors among 403 patients that were treated with erlotinib in the 4-year period. Mean age was 63 (37-81) years, 57% were female, and most common was ECOG PS 1 (58.6%), 55 patients (42%) received erlotinib in the first, 42 (32.8%) in the second and others in the third line or as maintenance therapy. EGFR mutation status is known for 39 patients, others were treated before testing was available or testing was not possible, 26 (66.7%) patients had known EGFR activating mutations and in 13 (33.3%) patients no EGFR mutations were detected. Most tumours were adenocarcinomas and about half patients were ex-smokers, 93% of patients experienced rash and 35% had diarrhoea, other side effects were rare. Most common was partial remission (58.5%) followed by stable disease (28.5%), 8% of patients had complete remission. Median progression free survival was 15.4 months and median overall survival was 24.6 months.

Conclusions: Our analysis confirmed the long-term benefit of treatment with erlotinib. As expected, most tumours were adenocarcinomas, but a surprisingly high proportion of long-surviving patients had tumours not harbouring EGFR activating mutations.

Keywords: Non-small cell lung cancer (NSCLC); erlotinib; epidermal growth factor receptor (EGFR) mutation