The primary objective of this open-label, single arm Phase II trial is to explore the efficacy of BIBW 2992 defined by the objective response rate (CR, PR) as determined by RECIST criteria in patients with advanced NSCLC Stage IIIB or IV whose tumors harbor activating mutations within exon 18 to exon 21 of the EGFR receptor. Patients progressing or relapsing after one prior cytotoxic chemotherapy regimen as well as chemotherapy naïve patients (only in stage 2) will be allowed to enter into the trial.

Inclusion criteria:

1. Patients with pathologically confirmed diagnosis of NSCLC Stage IIIB (with pleural effusion) adenocarcinoma or Stage IV adenocarcinoma.
2. Presence of activating mutation(s) in exon 18 to exon 21 of the EGFR-receptor confirmed by direct DNA sequencing of NSCLC tumor tissue.
3. Progressive disease following a first line cytotoxic chemotherapy regimen or have recurrent disease after prior neoadjuvant or adjuvant chemotherapy. Patients who have not received first-line cytotoxic chemotherapy can be enrolled in stage 2 of the trial, if the criteria for entering stage 2 are met.
4. Patients with at least one tumor lesion that can accurately be measured by computed tomography (CT) or magnetic resonance imaging (MRI) in at least one dimension with longest diameter to be recorded as 20 mm using conventional techniques or 10 mm with spiral CT scan.
5. Male or female patient aged 18 years.
6. Life expectancy of at least three (3) months.
7. Written informed consents that is consistent with ICH-GCP guidelines.
8. Eastern Cooperative Oncology Group (ECOG) performance score 0, 1 or 2.

Exclusion criteria:

1. More than one (1) prior cytotoxic chemotherapy treatment regimen for relapsed or metastatic NSCLC.
2. Chemo-, hormone- (other than Megace®) or immunotherapy within the past 4 weeks or within less than four half-lives of the previous drug prior to treatment with the trial drug and/or persistence of toxicities of prior anticancer therapies which are deemed to be clinically relevant.
3. Previous treatment with erlotinib (Tarceva®), gefitinib (Iressa®) or any other EGFR inhibiting small molecule or antibody.
4. Brain metastases, which are symptomatic; patients with treated, asymptomatic brain metastases are eligible with stable brain disease for at least four (4) weeks without the requirement for steroids or anti-epileptic therapy.
5. Significant or recent acute gastrointestinal disorders with diarrhea as a major symptom e.g., Crohns disease, malabsorption, or CTCAE Grade >2 diarrhea of any etiology at baseline.
6. Patients who have any other life-threatening illness or organ system dysfunction, which in the opinion of the investigator, would either compromise patient safety or interfere with the evaluation of the safety of the test drug.
7. Other malignancies diagnosed within the past five (5) years (other than non-melanomatous skin cancer and in situ cervical cancer).
8. Radiotherapy within the past 2 weeks prior to treatment with the trial drug.
9. Patients with any serious active infection (i.e., requiring an IV antibiotic, antifungal, or antiviral agents).
10. Patients with known HIV, active hepatitis B or active hepatitis C.
11. Known or suspected active drug or alcohol abuse.
12. Women of child-bearing potential or men who are able to father a child unwilling to use a medically acceptable method of contraception during the trial.
13. Pregnancy or breast feeding.
14. Patient unable to comply with the protocol.
15. History of clinically significant or uncontrolled cardiac disease, including congestive heart failure, angina, myocardial infarction, arrhythmia, including New York Heart Association (NYHA) functional classification of 3.
16. Cardiac left ventricular function with resting ejection fraction of less than 50% measured by multigated blood pool imaging of the heart (MUGA scan) or echocardiogram.
17. QTc interval greater than 0.47 second.
18. Prior treatment with anthracyclines with a cumulative dose of doxorubicin (or equivalent) greater than 400 mg/m2.
19. Absolute neutrophil count (ANC) less than 1500/mm3.
20. Platelet count less than 100 000 /mm3.
21. Bilirubin greater than 1.5 mg / dl (greater than 26 micromol / L, SI unit equivalent).
22. Aspartate amino transferase (AST) or alanine amino transferase (ALT) greater than three times the upper limit of normal (if related to liver metastases greater than five times the upper limit of normal).
23. Serum creatinine greater than 1.5 times of the upper normal limit or calculated/measured creatinine clearance equal or less than 45 ml / min.
24. Patients with known pre-existing interstitial lung disease