A Window of Opportunity Study for Investigating Drug Tolerant Persister (DTP) to Preoperative Brigatinib in Resectable Non-small Cell Lung Cancer (NSCLC) Harboring ALK Fusions.

Inclusion Criteria:

1. Male or female patients 20 years or older.
2. Voluntary written consent must be given before performance of any study related procedure not part of standard medical care, with the understanding that consent may be withdrawn by the patient at any time without prejudice to future medical care.
3. Female patients who:

   * Are postmenopausal for at least 1 year before the screening visit, OR
   * Are surgically sterile, OR
   * If they are of childbearing potential, agree to practice 2 effective methods of contraception, at the same time, from the time of signing the informed consent through 4 months after the last dose of study drug, or agree to completely abstain from heterosexual intercourse

   Male patients, even if surgically sterilized (i.e., status post-vasectomy), who:
   * Agree to practice effective barrier contraception during the entire study treatment period and through 4 months after the last dose of study drug, or
   * Agree to completely abstain from heterosexual intercourse
4. Treatment-naïve stage I to IIIa non-small cell lung cancer according to the AJCC 8th edition and amenable to surgical resection.
5. Documented ALK rearrangement (VENTANA ALK (D5F3) CDx Assay or appropriate diagnostic method)
6. Brain magnetic resonance imaging (MRI) (or CT if contraindication to MRI) within the last 60 days showing no evidence of metastatic disease
7. Eastern Cooperative Oncology Group (ECOG) performance status and/or other performance status 0 or 1
8. Documentation that the patient is a candidate for surgical resection of their lung cancer by certified surgeon.
9. Measurable disease defined by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria
10. Clinical laboratory values as specified below within 4 weeks before the first dose of study drug:

    * ALT/aspartate aminotransferase (AST) ≤2.5 × upper limit of normal (ULN); ≤5 × ULN is acceptable if liver metastases are present.
    * Total serum bilirubin ≤1.5 × ULN (\<3.0 × ULN for patients with Gilbert syndrome).
    * Estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2, using the modification of diet in renal disease (MDRD) equationd) Serum lipase ≤1.5 × ULN.
    * Absolute neutrophil count ≥1.5 × 10\^9/L.
    * Platelet count ≥75 × 10\^9/L.
    * Hemoglobin ≥8 g/dL.
11. Ability to swallow oral medications

Exclusion Criteria:

1. Clinical stage IIIb or IIIc or distant metastases (including malignant pleural effusion) identified in CT, PET-CT, brain imaging or biopsy.
2. Female patients who are both lactating and breastfeeding or have a positive serum pregnancy test during the screening period or a positive urine pregnancy test on Day 1 before first dose of study drug.
3. Any serious medical or psychiatric illness that could, in the investigator's opinion, potentially interfere with the completion of treatment according to this protocol
4. Treatment with any investigational products within 4 weeks before the first dose of study drug
5. Had major surgery within 30 days of the first dose of brigatinib. Minor surgical procedures such as catheter placement or minimally invasive biopsies are allowed.
6. Have been diagnosed with another primary malignancy other than NSCLC, except for adequately treated nonmelanoma skin cancer or cervical cancer in situ; definitively treated nonmetastatic prostate cancer; or patients with another primary malignancy who are definitively relapse-free with at least 3 years elapsed since the diagnosis of the other primary malignancy.
7. Have symptomatic brain metastasis (parenchymal or leptomeningeal). Patients with asymptomatic brain metastasis or who have stable symptoms that did not require an increased dose of corticosteroids to control symptoms in the past 7 days before the first dose of brigatinib may be enrolled.
8. Have current spinal cord compression (symptomatic or asymptomatic and detected by radiographic imaging). Patients with leptomeningeal disease and without cord compression are allowed.
9. Have significant, uncontrolled, or active cardiovascular disease, specifically including, but not restricted to:

   * Myocardial infarction within 6 months before the first dose of brigatinib.
   * Unstable angina within 6 months before first dose of brigatinib.
   * Congestive heart failure within 6 months before first dose of brigatinib.
   * History of clinically significant atrial arrhythmia (including clinically significant bradyarrhythmia), as determined by the treating physician.
   * Any history of clinically significant ventricular arrhythmia.
   * Had a cerebrovascular accident or transient ischemic attack within 6 months before first dose of brigatinib.
10. Have uncontrolled hypertension. Patients with hypertension should be under treatment on study entry to control blood pressure.
11. Have a history or the presence at baseline of pulmonary interstitial disease, drug-related pneumonitis, or radiation pneumonitis.
12. Have an ongoing or active infection, including, but not limited to, the requirement for intravenous antibiotics.
13. Have a known history of HIV infection. Testing is not required in the absence of history.
14. Have malabsorption syndrome or other GI illness that could affect oral absorption of brigatinib.
15. Have a known or suspected hypersensitivity to brigatinib or its excipients.
16. Are pregnant, planning a pregnancy, or breastfeeding.
17. Have any condition or illness that, in the opinion of the investigator, would compromise patient safety or interfere with the evaluation of brigatinib.
18. Received systemic treatment with strong cytochrome P-450 (CYP)3A inhibitors, strong CYP3A inducers, or moderate CYP3A inducers within 14 days before enrollment.