Randomized Comparative Study of Erlotinib and Pemetrexed in the Maintenance Treatment of Advanced Lung Cancer Patients.

Inclusion Criteria:

* Age ≥18 years
* Signed written informed consent
* Histologically or cytological diagnosed stage IIIB/IV non-squamous histology NSCLC
* Received platinum based doublet chemotherapy for 4 cycles as first line therapy before this study
* Patients upon enrolment has at least stable disease following the platinum doublet; with documented (confirmed or unconfirmed) radiographic evidence of a tumor response of complete response (CR), partial response (PR), or stable disease (SD) according to RECIST version 1.1 criteria
* Estimated Life expectancy ≥ 3 months
* Eastern cooperative oncology group performance status (ECOG PS) 0-2
* Adequate organ function

Exclusion Criteria:

* Age ˂18 years
* Predominantly squamous cell and/or mixed small cell, non-small cell histology
* Current treatment on another therapeutic clinical study or within the last 30 days of entering the study
* Spinal cord compression unless treated with the patient attaining good pain control and stable or recovered neurologic function, carcinomatous meningitis, or leptomeningeal disease
* Any of the following within the 3 months prior to starting study treatment: myocardial infarction, severe/unstable angina, coronary/peripheral artery bypass graft, congestive heart failure, or cerebrovascular accident including transient ischemic attack
* Ongoing cardiac dysrhythmias of national cancer institute-common terminology criteria for adverse events (NCI CTCAE) Grade \>2, uncontrolled atrial fibrillation of any grade, or corrected QT interval (QTc) \>470 msec
* Pregnancy or breastfeeding
* Prior malignancy (other than current NSCLC): patients will not be eligible if they have evidence of active malignancy (other than non-melanoma skin cancer or localized cervical cancer, or localized and presumed cured prostate cancer) within the last 3 years
* Other severe acute or chronic medical or psychiatric conditions, or laboratory abnormalities that would impose, in the judgment of the investigator and/or sponsor, excessive risk associated with study participation or study drug administration, and which would, therefore, make the patient inappropriate to enter this study
* Uncontrolled third-space fluid collections
* Progressive brain metastases
* Hypersensitivity to the study drugs
* Inability to take corticosteroid drugs, folic acid, or vitamin B12
* Patients with epidermal growth factor receptor (EGFR) positive, anaplastic lymphoma kinase (ALK) positive (documented using fluorescence in situ hybridization (FISH) and/or immunohistochemistry (IHC)), or unknown EGFR and ALK test results