How do I define mucus plug presence in my patients with moderate-to-severe asthma?
“Mucus plugs are not sputum, and they can be present in the absence of cough. So, having a productive cough does not mean you have mucus plugs, and it doesn't rule out mucus plugs. There are really no diagnostic tools in terms of patient-reported outcome measures that will tell you who has plugs and who doesn't have plugs. You actually have to look for them on imaging, and you need CT imaging to find plugging. The classical way that they measure mucus plugs is that they do a CT and then they look at the CT and count the number of sub-segmental airways that are occluded completely. You get a count of one for each occluded airway — the maximum count is 20 — and it requires a pretty onerous process where two radiologists are reading the CT and figuring out what the plugs are the counts.”
Mucus plugs are highly common in cases of type 2 asthma, and are a consequence of airway mucin MUC5AC cross-linked with Charcot-Leyden crystals (CLCs) and eosinophils producing inflammatory peroxidases that result in “very thick concretion that’s tethered to the airway.”
“They don't respond to inhaled steroids, oral steroids, nor bronchodilators. So, all our current conventional treatments do not get rid of plugs,” Lugogo said.” They make people have lower lung function. You get more air trapping. So, they do have clinical consequences for our patients, and in the context of asthma, about half the patients have mucus plugs.”
Lugogo’s advice for clinicians based on her team’s latest VESTIGE findings is to more formally adopt strategies to identify mucus plugs in patients not improving from their type 2 asthma. Initiating dupilumab has shown these patients can achieve benefit within 4 weeks.
“There's a little more improvement by 26 weeks, but it's a pretty rapid depletion improvement in plugs,” Lugogo said. “And so, you can talk to your patients about this topic, show them the plugs, and let them know with some confidence that if they have plugs, there is likely to be a clinical impact on mucus plug scores, and consequently we would expect improvements in obstruction, symptoms, and so forth.”
Lugogo additionally discussed ongoing research into artificial intelligence (AI) and machine learning to assist in automating mucus plug counting, given the time-laden standard currently at practice. The ultimate goal, she hypothesized, would be to receive automated mucus plug scores post-scan.
“There’s more to come on this topic,” Lugogo said. “I think it's going to continue to grow in terms of interest and in our ability to increase the clinical applicability of mucus plugs.”
Lugogo’s disclosures include AbbVie, Amgen, Apogee Therapeutics, AstraZeneca, Foresee Pharmaceuticals, Genentech, GSK, Incyte, Niox, Regeneron, Sanofi and Teva Pharmaceuticals
References
Perez De Llano L, Dunican E, Lugogo NL, et al. Dupilumab Reduces Mucus Burden Irrespective of Baseline Respiratory Characteristics in Patients with Uncontrolled Moderate-to-Severe Asthma: Results from the VESTIGE Study. Poster presented at: CHEST Annual Meeting 2025. Chicago, IL. October 19 – 22, 2025.
Castro M, Papi A, Porsbjerg C, et al. Effect of dupilumab on exhaled nitric oxide, mucus plugs, and functional respiratory imaging in patients with type 2 asthma (VESTIGE): a randomised, double-blind, placebo-controlled, phase 4 trial. Lancet Respir Med. 2025;13(3):208-220. doi:10.1016/S2213-2600(24)00362-X