Primary oxygenation outcomes included change in fraction of inspired oxygen (FiO₂), oxygen saturation (O₂ sat), respiratory rate, and the ROX index, a validated calculation of SpO₂/FiO₂/respiratory rate used to predict intubation risk in acute hypoxic respiratory failure, where higher values indicate improved oxygenation and reduced work of breathing.
Oxygenation Outcomes and Durability
Compared to placebo, patients receiving pegtarazimod required less supplemental oxygen during hospitalization, as measured by decreased FiO₂, with that benefit sustained through the 60-day follow-up window. The treatment group also demonstrated increased blood oxygen saturation and improved ROX index scores relative to controls.
"Patients treated with pegtarazimod had a sooner improvement in oxygen saturation, a decrease in oxygen requirements, a slight improvement in lung function, and also an improvement in quality of life," Criner said.
No safety concerns were identified over the study period.
NLR as a Response Biomarker
When patients were stratified by neutrophil-to-lymphocyte ratio (NLR), those with a high NLR—defined as > 9, consistent with strongly neutrophil-driven disease—showed the greatest respiratory benefit. This subgroup demonstrated less supplemental oxygen need, larger decreases in respiratory rate, and greater increases in the ROX index compared to patients with NLR below 9, aligning with pegtarazimod's mechanism of action.
Criner noted that while the NLR findings are based on a small sample, they are consistent with data from larger studies examining NLR as a marker of neutrophil-driven inflammation. The accessibility of NLR as a standard clinical lab value, rather than a specialized assay, could make it a practical patient selection tool if findings hold in larger trials.
Next Steps: Phase 2b and Beyond
Criner outlined what a definitive trial would require. A phase 2b study would need expanded enrollment, longer follow-up (a minimum of 6 months), and predefined efficacy endpoints targeting both mechanistic and clinical outcomes.
If replicated at scale, pegtarazimod could represent the first targeted anti-inflammatory strategy specifically designed for the acute hospitalized COPD setting, addressing a therapeutic gap that has persisted for half a century.
At ATS 2026, Criner also presented on pooled phase 3 data showing mepolizumab reduced COPD exacerbations and hospitalizations in patients with blood eosinophil counts starting at 150 cells/µL. Watch the interview here: Mepolizumab Reduced COPD Exacerbations, With Gerard Criner, MD.2
Editor’s note: Relevant disclosures for Criner include Pulmonx Corporation, GENZYME CORPORATION, GlaxoSmithKline, Olympus Corporation of the Americas, F. Hoffmann-La Roche AG, and AstraZeneca Pharmaceuticals.
References
Criner G, David J, Sadikot R, et al. Pegtarazimod (RLS-0071) Decreases Supplemental Oxygen Need in a Phase 2 Proof-of-Concept Trial in Hospitalized Participants With Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AE-COPD). Poster presented at ATS 2026 in Orlando, Florida, on May 18, 2026. https://ats2026.d365.events/education/sessions/b1bea76b-7dbc-4de6-ad83-8c87fba81834