MAC2v3 study update – March 2024

Posted on March 11, 2024   |   
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This blog post was authored by Emily Henkle, PhD, MPH, and reviewed by the Bronchiectasis and NTM Content Review and Evaluation Committee.

Hello NTM community!

The MAC2v3 clinical trial led by Dr. Kevin Winthrop and team at Oregon Health & Science University is mid-way through its 6th year. This study is important to the NTM lung disease community as it is designed to test whether two drugs (azithromycin and ethambutol) are as helpful in treating MAC (a common type of NTM) as the “big three” (azithromycin, ethambutol, and rifampin) in producing a negative sputum culture. The researchers are also studying whether two drugs are easier to tolerate than three.

We are working hard to reach our new target enrollment of 466 participants, reduced from 500. As of February, we are pleased to share that the study has enrolled over 400 participants. We are hoping to finish enrollment this fall. This means there are still openings for new participants.

We continue to meet with our study advisory committee, patient advisory panel, and data monitoring committee regularly. These committees provide guidance and ensure that all aspects of the study remain safe. The MAC2v3 study does not have any analyses planned until all the data is in, so we need to follow all patients for 12 months before we can look at the results.

Patients can still be referred virtually for this study without the need to travel to OHSU or local sites. There is no additional requirement other than reaching out to study coordinators. Those interested candidates as well as those accepted can remain with their preferred (treating) physician while getting the benefit of guidance from NTM experts.

Please note, patients must be enrolled prior to starting treatment. If you would like more information regarding participation, or to refer a patient, email and they will be happy to help. We have an amazing network of 30+ physicians at 22 sites in North America that are actively enrolling patients, from Hawaii to New York to Texas to Toronto, Canada.

For more information: visit or [#NCT03672630]

Thanks for reading! Emily Henkle, PhD, MPH
MAC2v3 Co-investigator
OHSU-PSU School of Public Health Portland, OR