The objectives of this single-arm, open-label trial are to assess the efficacy and safety of afatinib as second line treatment for patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harbouring a common EGFR mutation who have failed first-line platinum-based chemotherapy and to demonstrate that the efficacy and safety are comparable to the results seen in previous trials.

Inclusion criteria:

1. Pathologically confirmed diagnosis of Stage IIIB (with cytologically proven pleural effusion or pericardial effusion) or Stage IV adenocarcinoma of the lung. Patients with mixed histology are eligible if adenocarcinoma is the predominant histology.
2. Documented EGFR mutation (L858R and/or Deletion 19) with no other known EGFR mutation.
3. Measureable disease according to RECIST 1.1.
4. Radiologically confirmed progression or recurrence of disease during or following first line therapy with a platinum-based chemotherapy regimen.
5. Eastern Cooperative Oncology Group (ECOG) performance score of 0 or 1.
6. Adequate organ function.

Exclusion criteria:

1. More than one line of prior therapy for disease.
2. Previously received less than 3 cycles of platinum-based chemotherapy due to toxicity and/or intolerance of treatment.
3. Previous treatment with any EGFR targeting Tyrosine Kinase Inhibitor (TKI) or antibody.
4. Known pre-existing interstitial lung disease.