Maintenance ZD1839 (IRESSA®) Following Completion of Front Line, Platinum-Based, Double Chemotherapy in Subjects With Advanced or Metastatic Non-Small Cell Lung Cancer (IMAC/Herbst)

Inclusion Criteria: Must sign Informed Consent Females and males aged 18 years and over. Confirmed stage IIIB (T4-pleural effusion) and IV NSCLC. Either complete response, partial response, or stable disease following at least 4 cycles (3 in the setting of intolerable toxicity) but no more than 6 cycles of definitive front line, platinum-based, doublet chemotherapy. No prior EGFR therapy No newly diagnosed intracerebral metastases while receiving or after completing chemotherapy At least 3 weeks (21 days) but no more than 4 weeks (28 days) since last dose of chemotherapy Must be completely healed from previous major oncologic surgery Life expectancy of ≥ 8 weeks. Exclusion Criteria: Known severe hypersensitivity to ZD1839 or any of the excipients of these products. Any evidence of clinically active interstitial lung disease (subjects with chronic, stable, radiographic changes who are asymptomatic need not be excluded). Other co-existing malignancies or malignancies diagnosed within the last 5 years with the exception of basal cell carcinoma or cervical cancer in situ. Any unresolved chronic toxicity greater than common toxicity criteria (CTC) grade 2 from previous anticancer therapy excluding peripheral neuropathy or alopecia. Evidence of any significant clinical disorder or laboratory finding that makes it undesirable for the subject to participate in the study. Pregnancy or breast feeding (women of child bearing potential). Women of childbearing potential must practice acceptable methods of birth control to prevent pregnancy. Treatment with a non-approved or investigational drug within 30 days before Day 1 of study treatment. Signs of neurological symptoms consistent with new onset spinal cord compression or CNS metastases. Treatment with any systemic anticancer therapies other than the prescribed protocol chemotherapy regimen (refer to Inclusion criterion -). Exception: Palliative radiotherapy for symptom relief of lesions present at diagnosis will be allowed; however, this radiotherapy must occur prior to completion of pre-study doublet chemotherapy. Males must also be willing to practice acceptable methods of birth control while taking the drug to prevent pregnancy of a partner.