ABSTRACT Background Sorafenib is a multikinase inhibitor with antitumor and anti-angiogenic activity. This study was designed to evaluate the efficacy and tolerability of sorafenib monotherapy for patients with advanced lung adenocarcinoma previously treated with EGFR tyrosine-kinase inhibitors. Methods A phase II, single arm clinical trial (NCT00922584) was conducted in 6 centers in China. Patients with stage IIIB or IV adenocarcinoma, ECOG score of 0-2, no more than 1 previous chemotherapy regimen with 1 prior EGFR-TKI treatment failure, or, with K-ras mutation were enrolled. Patients received oral sorafenib 400mg bid continuously until disease progression or intolerable toxicity. Results Between Dec 2008 and Jun 2010, 65 patients were enrolled and 64 could be analyzed. The median time of sorafenib administrated was 3.7 months (range, 0.23 - 14months). The median follow-up time was 5.5 months (range, 0.3 – 30.6months). The primary endpoint disease control rate (DCR) was 32.8%, including 2 (3.2%) partial responses and 19 (29.7%) patients with stable disease (lasting more than 3 months), which did not meet the predefined statistical hypothesis of 38.4%. However, the secondary endpoint including median PFS and OS were improved compared with history data (pemetrexed1, EGFR TKIs2-3), 3.7 months (95%CI:3.5 ∼ 3.9) and 7.4months (95%CI:5.7 ∼ 9.2) respectively. Logistic and COX regression analysis showed no correlation between DCR or survival results with age, gender, smoking status, PS, and other clinical factors. The most common toxicity was hand foot skin reaction (HFSR) (71.9%), and the incidence at 4weeks, 8weeks,12weeks was 64.1%,45.3% and 37.5% respectively, showing a decline of HFSR incidence along with the time of therapy . 21.9% of patients occurred ≥grade 2 other dermatologic reactions other than HFSR, followed by diarrhea (26.2%), hypertension (15.4%) . Dose interruptions due to toxicity happened in 19 patients (29.2%). Conclusion Sorafenib monotherapy has encouraging efficacy improving PFS and OS with tolerable toxicity as second or third line treatment in patients with advanced lung adenocarcinoma, who have failed prior chemotherapy and EGFR-TKI treatment. Further randomized studies are needed to confirm the clinical benefit of sorafenib in such patients. Disclosure All authors have declared no conflicts of interest.