Open-label Study of ELA026 in Participants With Secondary Hemophagocytic Lymphohistiocytosis (sHLH)

This study consists of two parts: Phase 1b (Part 1) and Phase 2/3 (Part 2). Part 1 is designed to evaluate the safety, efficacy, pharmacodynamics, and pharmacokinetics of ELA026 in pediatric and adult participants with treatment-naïve (TN) and relapsed/refractory sHLH. The main objectives of Part 1 are to determine the safety of ELA026 administered intravenously (IV) and subcutaneously (SC) to participants with sHLH and to identify the recommended Phase 3 dose and schedule for ELA026. Participants will be enrolled into a dose-escalating cohort (Cohort 1) followed by two fixed dose cohorts (Cohorts 2-3) treated over 12-weeks. Part 2 (SURPASS) is designed as an open-label, single-arm, multicenter, historical control registrational study to evaluate ELA026 in newly diagnosed TN adult and pediatric sHLH participants. All participants are diagnosed with HLH-2004 criteria unless indicated. Cohort A (primary cohort) will enroll newly diagnosed TN participants ≥18 years old with mHLH. Cohort B (exploratory cohort) will enroll participants including ≥18 years old participants with TN sHLH not triggered by malignancy; ≥18 years old participants with newly diagnosed TN mHLH diagnosed by biomarker criteria but not meeting HLH-2004 diagnostic criteria; and 6 to 17 year old participants with newly diagnosed TN sHLH (due to any trigger). For 6 to 12 year old participants, there is a safety lead-in cohort with refractory sHLH. Part 1 is closed to recruitment and Part 2 is recruiting for eligible participants.