Horizon Therapeutics plc Announces Phase 2 Trial Evaluating Dazodalibep for the Treatment of Sjögren’s Syndrome Meets Primary Endpoint in the Second Study Population; Only Phase 2 Trial to Meet Primary Endpoint in Both Patient Populations

Horizon Therapeutics plc (Nasdaq: HZNP) today announced that the primary endpoint was met for the second population in its Phase 2 clinical trial evaluating dazodalibep for the treatment of Sjögren’s syndrome. The Phase 2 trial evaluated two patient populations and positive results in the first patient population were announced in September 2022. Dazodalibep is the only medicine in development to achieve the primary endpoint in both patient populations in a Phase 2 trial.

Today, the Company announced that the second population achieved the primary endpoint. This patient population includes those with moderate-to-severe symptomatology including dryness, pain and fatigue despite lacking additional organ involvement and is defined as patients with a European Alliance of Associations for Rheumatology (EULAR) Sjögren’s Syndrome Patient Reported Index (ESSPRI) score of ≥ 5, indicative of significant symptomatic burden, and a score of <5 on the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI), which measures organ involvement. At Day 169, dazodalibep-treated patients achieved a 1.8-point reduction in their ESSPRI scores compared to placebo-treated patients who achieved a 0.53-point reduction, resulting in a least squares mean difference of 1.27 (p=0.0002). The ESSPRI is a composite endpoint that measures dryness, pain and fatigue severity. The previously announced positive results were in patients with moderate-to-severe systemic disease: systemic clinical manifestations in one or more organ systems in addition to the traditional Sjogren’s manifestations, and an ESSDAI of ≥ 5.

“There are currently no disease-modifying FDA approved treatments for Sjögren’s and the population in this trial represents a large subset of patients who have a clear unmet clinical need,” said Frederick B. Vivino, M.D., M.S., former director of the Penn Sjögren's Center and chief, division of rheumatology at Penn Presbyterian Medical Center, University of Pennsylvania Perelman School of Medicine. “Participants in this study had been excluded from other recent trials, despite their substantial disease burden. The positive results from the Phase 2 trial are very promising in addressing many debilitating symptoms of people living with Sjogren’s.”