Inclusion Criteria:

1. Male or female patients who are 18 years of age or older.

2. Willing and able to provide written informed consent.

3. Patients with a diagnosis of treatment-refractory MAC lung disease consisting of all
of the following (a) Microbiological, (b) Clinical, and (c) Radiographic criteria:

1. Microbiological criteria:

- One Pre-Study MAC-positive respiratory specimen. Documentation of a MAC
positive specimen collected per standard of care within 6 months of
screening.

- One Screening MAC-positive expectorated or induced sputum sample.

2. Clinical criteria: At least 2 of the following patient-reported clinical
symptoms:

- Cough with sputum production

- Cough without sputum

- Chest congestion

- Hemoptysis

- Dyspnea

- Fatigue

- Night sweats or unusual sweating

3. Radiographic criteria: Chest CT scan within 8 weeks prior to randomization with
abnormalities consistent with MAC lung disease.

4. Patients who are willing to comply with all the study activities and procedures
throughout the duration of the study and comply with all planned study visits and
study procedures from Screening through the LFU Visit.

5. All patients must agree to use an effective method of birth control.

6. Patients expected to survive with continued antimycobacterial therapy and appropriate
supportive care from Screening through the LFU Visit, in the judgment of the
Investigator.

Exclusion Criteria:

1. Patients with a presence of any suspected or confirmed disease or condition at
Screening or the time of randomization that, in the opinion of the Investigator, may
confound the assessment of symptom-based clinical response.

2. Patients with active pulmonary malignancy or any malignancy that required or would
require chemotherapy or radiation therapy within 1 year prior to randomization through
the LFU Visit.

3. Patients with creatinine clearance (CrCl) of ≤50 mL/min, as estimated by the Cockcroft
Gault formula, at Screening or at the time of randomization.

4. Patients with hemoglobin <10.0 g/dL or <6.2 mmol/L at Screening; donation of blood or
plasma within 28 days prior to randomization; or symptomatic loss of blood or
hemorrhage within 28 days prior to randomization.

5. Patients with severe hemoptysis within 28 days prior to randomization, defined as >100
mL over any 24-hour period or severe or extremely severe hemoptysis.

6. Patients with severe hepatic impairment, as evidenced by alanine aminotransferase
(ALT) or aspartate aminotransferase (AST) >3 × upper limit of normal (ULN) or total
bilirubin >2 × ULN, or clinical signs of cirrhosis or end-stage hepatic disease.

7. Patients who are pregnant or breastfeeding.

8. Patients with a mean QT interval corrected using Fridericia's formula (QTcF) >480 msec
based on triplicate 12-lead ECGs at Screening.

9. Patients with an immunodeficiency or an immunocompromised condition and risk for an
opportunistic pulmonary infection.

10. Patients with an anticipated start of new non-study antimycobacterial therapy to be
administered at any time between Screening and Month 6.

11. Patients who have received any investigational medication during the 30 days or 5 half
lives, whichever is longer, prior to randomization.

12. Patients with any prior exposure to epetraborole.

13. Patients with any condition that, in the opinion of the Investigator, interferes with
the ability to safely complete the study or adhere to study requirements, including
the patient's inability or unwillingness to comply with all study assessments and
visits.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Eligibility last updated 4/26/23. Questions regarding updates should be directed to the study team contact.