A Study of Emapalumab for Pediatric Aplastic Anemia

Inclusion Criteria:

• Patients undergoing workup for suspected newly diagnosed sAA:

• Patients with severe cytopenias and a hypocellular marrow concerning for sAA

• Patients that meet the definition for suspected sAA (Camitta Criteria) asfollows:

Marrow Cellularity: <25%, or 25-50% with <30% residual hematopoietic cells Peripheral cytopenias (at least 2 of 3) Absolute neutrophil count (ANC): <500 x 10^9/L Platelets: <20 x 10^9/L Absolute Reticulocyte Count: <60 x 10^9/L

• Patients that do not have evidence of leukemia or MDS

• Patients < 25 years of age at time of diagnosis

• Able to tolerate emapalumab and IST (with standard institutional organ functioncriteria)

Exclusion Criteria:

• Uncontrolled infection at presentation.

• Patients who have undergone previous treatment for sAA.

• Patients with known inherited bone marrow failure

• Patient who has completed a full workup for sAA including having results back fromtelomere testing, DEB and genetics (when applicable), as well as having anappropriate willing and available donor and would otherwise be admitted for HSCTwithin 2 weeks of enrolling on the trial

• Patients with leukemia or MDS

• Patient or parent or guardian unable to give informed consent or unable to complywith the treatment protocol including research tests.