Inclusion Criteria:

1. Histologically or cytologically confirmed locally advanced (not amenable for multimodality treatment) or metastatic Non-small Cell Lung Cancer (NSCLC)
2. Documented Anaplastic Lymphoma Kinase (ALK) rearrangement via testing of tissue or blood
3. No prior systemic anticancer treatment for NSCLC (adjuvant/neoadjuvant chemotherapy allowed if 12 months prior to randomization; prior ALK tyrosine kinase inhibitor [TKI] such as alectinib is not allowed in any setting)
4. Measurable disease (1 or more target lesions per Response Evaluation Criteria in Solid Tumors [RECIST] 1.1)
5. Pretreatment tumor tissue

Exclusion Criteria:

1. Patient's cancer has a known oncogenic driver alteration other than ALK.
2. Known allergy/hypersensitivity to excipients of neladalkib or alectinib.
3. Ongoing or recent radiotherapy as per protocol-specified timeframes prior to randomization
4. Major surgery within 4 weeks prior to randomization
5. Uncontrolled clinically relevant infection requiring systemic therapy
6. Known active tuberculosis, or active Hepatitis B or C
7. QT corrected for heart rate by Fridericia's formula (QTcF) > 470 msec on repeated assessments
8. Clinically significant cardiovascular disease
9. Brain metastases associated with progressive neurological symptoms or requiring increasing doses of corticosteroids to control CNS disease
10. Active malignancy requiring therapy within 2 years prior to randomization