Revolo Biotherapeutics reported positive topline Phase IIa data in eosinophilic esophagitis (EoE), but the biotech has not yet revealed the outcome of an all-important symptom scale.

Revolo announced that its 36-patient Phase IIa trial of IRL-201104 (NCT05084963) led to a numeric reduction in the primary endpoint of eosinophil counts, which are thought to be a disease hallmark. In EoE, eosinophils build up in the oesophagus, driving an allergic, inflammatory reaction that causes difficulty swallowing.

To earn eventual approval in EoE, however, Revolo will need to show regulators that its drug both reduces eosinophil counts and also improves patient symptoms. Sanofi and Regeneron’s Dupixent (dupilumab)—the only FDA-approved drug for EoE—earned registration by meeting its co-primary endpoints of reducing eosinophil counts and improving symptoms along the Dysphagia Symptom Questionnaire (DSQ) in a Phase III study (NCT03633617).

Revolo’s Phase IIa trial includes DSQ as a secondary endpoint, though the company did not report any data on this measure as part of its topline results. However, the biotech pointed to additional data showing IRL-201104 treated patients had an increase in regulatory B cells and regulatory T cells, suggesting a strong anti-inflammatory effect.

Still, recent drug development history has shown that the two endpoints of eosinophil reduction and symptom improvement do not always come hand in hand. California-based Allakos abandoned its Phase III programme in EoE (NCT04322708) after lirentelimab met one primary endpoint of reducing eosinophil counts but failed its co-primary endpoint of symptom reduction along DSQ.

IRL-201104 is a synthetic peptide that reduces neutrophil recruitment into the lung, thereby decreasing inflammation. In the Phase IIa study, there were no reported serious adverse events or study drug discontinuations.

Revolo is based in London, UK, and New Orleans, US, and the company’s pipeline also includes drug candidates for allergies and autoimmune diseases.