MAC2v3 study update – December 2022

Posted on January 06, 2023   |   
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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 beginning its 5th 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.

As of today, the study has enrolled over 300 participants, but are wishing to increase that amount to reach a target of 500. Therefore, there are plenty of openings for new participants. Now that most people with NTM lung disease are feeling more confident following the pandemic and returning to doctor’s appointments in person, we are hoping to quickly recruit more patients with MAC interested in participating.

We are pleased to share that our funder, the Patient-Centered Outcomes Research Institute or PCORI has extended the project for two more years. However, the MAC2v3 study does not have any analysis planned until all the data is in, so we need to finish enrollment before we can look at the results.

We have gained some great insight on how symptoms of MAC change in the first 6 months as we have continued to enroll new participants in the study. This information was presented at the American Thoracic Society (ATS) annual meeting in May 2021 and May 2022. We observed significant improvements in overall self-reported Respiratory Symptoms and Health Perception scores. Patients reported a wide range of symptoms at study start. As expected, the most common self-reported treatment side effects were GI-related, occurring in about half of study participants. In addition, we continue to meet with our study advisory committee and data monitoring committee regularly. These committees provide guidance and ensure that all aspects of the study remain safe.

As we began this study in the midst of the COVID pandemic, we adjusted how those interested in the study could be referred. Patients can 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, or to refer a patient, email and they will be happy to help. We have an amazing network of 30+ physicians at 22 sites 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