This randomized, multicenter, Phase III, open-label study will evaluate the efficacy and safety of alectinib versus crizotinib and to evaluate the pharmacokinetics of alectinib in asian participants with treatment-naive ALK-positive advanced NSCLC. Participants will be randomized 2:1 into one of the two treatment groups to receive either alectinib (600 milligrams [mg] twice daily [BID]) or crizotinib (250 mg BID) orally, respectively.

Inclusion Criteria:

• Histologically or cytologically confirmed diagnosis of advanced or recurrent (Stage IIIB not amenable for multimodality treatment) or metastatic (Stage IV) NSCLC that is ALK-positive as assessed by the Ventana immunohistochemistry (IHC) test. Sufficient tumor tissue available to perform ALK IHC is required. Ventana IHC testing will be performed at the designated central laboratory
• Life expectancy of at least 12 weeks
• Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-2
• No history of receiving systemic treatment for advanced, recurrent (Stage IIIB not amenable for multimodality treatment) or metastatic (Stage IV) NSCLC
• Adequate hematologic function: Platelet count greater than equal to (>=) 100×10^9 per liter (/L); absolute neutrophil count (ANC) >=1500 cells per microliter (cells/mcL); hemoglobin>=9.0 grams per deciliter (g/dL)
• Adequate renal function: an estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease (MDRD) formula of >=45 milliliters per minute per 1.73 square meter
• Participants must have recovered from effects of any major surgery or significant traumatic injury at least 28 days before receiving the first dose of study treatment
• Measurable disease (by Response Evaluation Criteria in Solid Tumors version 1.1 [RECIST v1.1]) before administration of study treatment
• Previous brain or leptomeningeal metastases are allowed if the participant is asymptomatic (e.g., diagnosed incidentally at study baseline). Asymptomatic central nervous system (CNS) lesions may be treated at the discretion of the investigator as per local clinical practice. If participant has neurological symptoms or signs because of CNS metastasis, the participant must complete whole-brain radiation or gamma knife irradiation treatment. In all cases, radiation treatment must be completed >=14 days before enrollment and disease must be clinically stable
• For all females of childbearing potential, a negative serum pregnancy test result must be obtained within 3 days prior to starting study treatment
• For women who are not postmenopausal (>=12 months of non-therapy-induced amenorrhea) or surgically sterile (absence of ovaries and/or uterus), agreement to remain abstinent or use single or combined contraceptive methods that result in a failure rate of <1% per year during the treatment period and for at least 3 months after the last dose of study drug. Abstinence is acceptable only if it is in line with the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not acceptable methods of contraception. Examples of contraceptive methods with a failure rate of <1% per year include tubal ligation, male sterilization, hormonal implants, established, proper use of combined oral or injected hormonal contraceptives, and certain intrauterine devices. Alternatively, two methods (e.g., two barrier methods such as a condom and a cervical cap) may be combined to achieve a failure rate of <1% per year. Barrier methods must always be supplemented with the use of a spermicide
• For men, agreement to remain abstinent or use a condom plus an additional contraceptive method that together result in a failure rate of <1% per year during the treatment period and for at least 3 months after the last dose of study drug. Abstinence is acceptable only if it is in line with the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not acceptable methods of contraception

Exclusion Criteria:

• A malignancy within the previous 3 years (other than curatively treated basal cell carcinoma of the skin, early gastrointestinal (GI) cancer by endoscopic resection, in situ carcinoma of the cervix, or any cured cancer that is considered to have no impact in progression-free survival (PFS) or overall survival (OS) for the current NSCLC)
• Any GI disorder that may affect absorption of oral medications, such as malabsorption syndrome or status post-major bowel resection
• Liver disease characterized by:
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than (>) 3× the upper limit of normal (ULN; >=5×ULN for participants with concurrent liver metastases) confirmed on two consecutive measurements; or
• Impaired excretory function (e.g., hyperbilirubinemia), synthetic function, or other conditions of decompensated liver disease such as coagulopathy, hepatic encephalopathy, hypoalbuminemia, ascites, and bleeding from esophageal varices; or
• Acute viral or active autoimmune, alcoholic, or other types of hepatitis
• National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0 Grade 3 or higher toxicities because of any previous therapy (e.g., radiotherapy) (excluding alopecia), which have not shown improvement and are strictly considered to interfere with current study medication
• History of organ transplant
• Co-administration of anti-cancer therapies other than those administered in this study
• Baseline QTc >470 ms or symptomatic bradycardia
• Administration of strong/potent cytochrome P4503A inhibitors or inducers within 14 days prior to the receiving the first dose of study treatment and during treatment with alectinib or crizotinib
• Administration of agents with potential QT interval prolonging effects within 14 days prior to receiving the first dose of study drug
• History of hypersensitivity to any of the additives in the alectinib or crizotinib drug formulation
• Pregnant or lactating
• Known human immunodeficiency virus (HIV-positivity or acquired immunodeficiency syndrome (AIDS)-related illness
• Any clinically significant concomitant disease or condition that could interfere with, or for which the treatment might interfere with, the conduct of the study or the absorption of oral medications or that would, in the opinion of the Principal Investigator, pose an unacceptable risk to the participant in this study
• Any psychological, familial, sociological, or geographical condition that potentially hampers compliance with the study protocol requirements or follow-up procedures; those conditions should be discussed with the participant before study entry

For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data\_sharing