General Inclusion Criteria:

Subject must meet all of the following applicable inclusion criteria to participate in this
study:

   1. Written informed consent and HIPAA authorization for release of personal health
   information prior to registration. NOTE: HIPAA authorization may be included in the
   informed consent or obtained separately.

   2. Age ≥ 18 years at the time of consent.

   3. First language must be English.

   4. ECOG Performance Status of ≤ 2 within 14 days prior to registration.

   5. Histological or cytological confirmation of Stage IV (per AJCC 8th edition) non-small
   cell lung cancer (NSCLC).

   6. At least one intracranial metastasis on MRI imaging.

   7. Confirmation of positive ALK rearrangement per local standard of care testing.

   8. All subjects must have brain metastases and be either asymptomatic or minimally
   symptomatic per investigator discretion without plan for surgical intervention within
   28 days of study start. Patients with neurological symptoms that are controlled with
   dose of corticosteroids or anti-epileptic medications are eligible. Patients with
   asymptomatic leptomeningeal disease may be eligible for trial providing they meet all
   other eligibility criteria.

   9. Subjects must be planning on therapy with alectinib. Alectinib may have been started
   up to 6 weeks prior to radiation.

10. Prior non-ALK directed therapy for metastatic disease is permitted. Patients who have
   received prior neoadjuvant, adjuvant chemotherapy, radiotherapy, immunotherapy (PD-1
   or PD-L1 monoclonal antibodies) or chemoradiotherapy with curative intent for
   non-metastatic disease must have experienced a treatment-free interval of at least 3
   months from registration since the last chemotherapy, radiotherapy, immunotherapy, or
   chemoradiotherapy cycle.

11. Documentation of consultation with a radiation oncologist confirming agreement to
   delay radiation therapy.

12. Demonstrate adequate organ function as defined in the protocol. All screening labs to
   be obtained within 14 days prior to registration.

13. Females of childbearing potential must have a negative serum pregnancy test within 14
   days prior to registration. See protocol for definition of childbearing potential.

14. Females of childbearing potential and males must be willing to abstain from
   heterosexual intercourse or to use an effective method(s) of contraception as outlined
   in the protocol.

15. HIV-infected patients on effective anti-retroviral therapy with undetectable viral
   load within 6 months of registration are eligible for this trial.

16. Patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral
   load must be undetectable on suppressive therapy, if indicated. Patients with a
   history of hepatitis C virus (HCV) infection must have been treated and cured. For
   patients with HCV infection who are currently on treatment, the HCV viral load must be
   undetectable to be eligible for this trial.

17. As determined by the enrolling physician or protocol designee, ability of the subject
   to understand and comply with study procedures for the entire length of the study.

Exclusion Criteria:

Subjects meeting any of the criteria below may not participate in the study:

   1. Active infection requiring systemic therapy.

   2. Malabsorption syndrome or other condition that would interfere with enteral absorption

   3. Pregnant or breastfeeding (NOTE: breast milk cannot be stored for future use while the
   mother is being treated on study).

   4. Patients with a prior or concurrent malignancy whose natural history or treatment has
   the potential to interfere with the safety or efficacy assessment of the
   investigational regimen, per treating physician discretion, are not eligible for this
   trial.

   5. Treatment with any investigational drug within 28 days prior to registration.

   6. History of other malignancy within 5 years prior to screening, except for
   appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, or
   Stage I uterine cancer.

   7. Acute viral, autoimmune, alcoholic, or other types of acute hepatitis.