• Written informed consent obtained from participant or participant's legal representative

• Be willing and able to adhere to the study visit schedule and other protocol requirements

• All genders ≥ 18 years of age at Visit 1

• Documentation of a CF diagnosis as evidenced by one or more clinical features consistent with the CF phenotype

• Documentation of persistently positive NTM culture results that are positive for the same species or sub-species (either M. avium complex, M. abscessus complex, or both M. avium and M. abscessus). Persistently positive cultures are those which meet ONE of the following criteria, after first ignoring any negative culture results that occur within 7 days of a positive culture:

∙ The two most recent NTM culture results from sputum or BAL taken at least 28 days apart are positive.

∙ OR

‣ At least one NTM culture result in the previous 4 months from sputum or BAL is positive. If there are four or more cultures in the last 12-months at least 3 out of the 4 most recent cultures must be positive for NTM. If there are three or fewer cultures in the past 12 months, then at least 2 of the 3 most recent cultures must be positive for NTM even if some of those cultures are more than 12 months ago.

• Current NTM species or subspecies has never been treated or previous treatment was associated with clearance of NTM and completed \> 2 years prior to Day 1

• FEV1 ≥ 25 % of predicted value at Screening

• Able to expectorate sputum

• Clinically stable with no significant changes in health status within 7 days prior to Day 1

⁃ Enrolled in the CFF Patient Registry (CFF PR)

⁃ Willing to discontinue chronic azithromycin use for the duration of the study

• Written informed consent obtained from participant or participant's legal representative

• Be willing and able to adhere to the study visit schedule and other protocol requirements

• All genders ≥ 18 years of age at Visit 1

• Documentation of a CF diagnosis as evidenced by one or more clinical features consistent with the CF phenotype

• History of current or prior treatment for NTM pulmonary disease with M. abscessus or M avium (or both M. avium and M. abscessus)

∙ Previously received treatment with guideline-based antibiotics for \>12 months without having treatment discontinued for reasons of culture clearance OR

‣ Currently receiving treatment with guideline-based antibiotics for \>12 months

• FEV1 ≥ 25 % of predicted value at Screening

• Able to expectorate sputum

• Not hospitalized within 7 days prior to Day 1

• Enrolled in the CFF Patient Registry (CFF PR)

⁃ Be willing and able to continue guideline-based antibiotic therapy for M. abscessus or M avium (or both M. avium and M. abscessus) concurrent with IV gallium, if currently on treatment