Evaluation of the Safety and Efficacy of ELA026 in Participants With Secondary Hemophagocytic Lymphohistiocytosis

Open to people ages 6 years and up

1. All countries: ≥12 years at the time of HLH diagnosis (Cohort 1-4).

   US only: ≥12 years at the time of HLH diagnosis (Cohort 1-4) and 6 to <12 years at the time of HLH diagnosis (Cohorts 2-4)

2. Treatment naïve OR;
3. Relapsed refractory HLH. Participant is hospitalized with HLH confirmed criteria based on fulfilling 5 out of 8 HLH-2004 diagnostic criteria

1. Known or previous treatment for primary HLH
2. Any other significant concurrent, uncontrolled medical condition that in the opinion of the Investigator contraindicates participation in this study
3. Hemopoietic Stem Cell Transplant (HSCT) within 100 days of the first dose of ELA026.

4. All countries except US: Treatment with CAR T-Cell therapy within 3 months of the first dose of ELA026.

   US Only: Treatment with CAR T-Cell therapy allowed within 3 months of first dose.

5. Ongoing administration of any investigational treatment (excluding dexamethasone) within 14 days prior to Screening or 5 drug half-lives, whichever is shorter
6. Live or attenuated vaccine received within 6 weeks or bacille Calmette-Guerin (BCG) vaccine within 12 weeks prior to Screening