Assess Efficacy & Safety of Selumetinib in Combination With Docetaxel in Patients Receiving 2nd Line Treatment for v-Ki-ras2 Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) Positive NSCLC

Inclusion Criteria:

1. Provision of signed, written and dated informed consent prior to any study specific procedures
2. Male or female, aged 18 years or older
3. Histological or cytological confirmation of locally advanced or metastatic NSCLC (IIIB-IV)
4. KRAS mutation positive tumour sample as determined by the designated testing laboratory
5. Failure of 1st line anti-cancer therapy due to radiological documentation of disease progression in advanced disease or subsequent relapse of disease following 1st line therapy

Exclusion Criteria:

1. Mixed small cell and non-small cell lung cancer histology.
2. Received >1 prior anti-cancer drug regimen for advanced or metastatic NSCLC. Patients who develop disease progression while on switch maintenance therapy (maintenance using an agent not in the first-line regimen) will not be eligible.
3. Receiving or have received systemic anti-cancer therapy within 30 days prior to starting study treatment
4. Other concomitant anti-cancer therapy agents excepts steroids
5. Prior treatment with a Mitogen-Activated protein Kinase (MEK) inhibitor or any docetaxel-containing regimen (prior treatment with paclitaxel is acceptable).
6. Last radiation therapy within 4 weeks prior starting study treatment, or limited field of radiation for palliation within 7 days of the first dose of study treatment