Carol Satler, MD Vice President of Medical Affairs in North America for Sobi, discusses the ultra rare disease primary haemophagocytic lymphohistiocytosis (HLH) and a new FDA approved treatment Emapalumab. HLH is an often-fatal syndrome of hyperinflammation in which massive hyperproduction of interferon gamma (IFNy) is thought to drive immune system hyperactivation, ultimately leading to organ failures.

It is estimated that fewer than 100 cases of primary HLH are diagnosed each year in the US, but this is believed to represent under diagnosis. Diagnosis is challenging due to the variability in signs and symptoms, which may include fevers, swelling of the liver and spleen, severe low red and white blood cell counts, bleeding disorders, infections, neurological symptoms, organ dysfunction and organ failure. Primary HLH can rapidly become fatal if left untreated, with median survival of less than two months. The immediate goal of treatment is to quickly control the hyperinflammation and to prepare for haematopoietic stem-cell transplant. The current conventional treatment prior to transplant includes steroids and chemotherapy and are not specifically approved to treat primary HLH.

Emapalumab is a monoclonal antibody (mAb) that binds to and neutralises interferon gamma (IFNy). In the US, emapalumab is indicated for paediatric (new born and older) and adult primary haemophagocytic lymphohistiocytosis (HLH) patients with refractory, recurrent or progressive disease, or intolerance to standard-of-care HLH therapy. Emapalumab is the first and only medicine approved in the US for primary HLH, an ultra-rare syndrome of hyperinflammation that usually occurs within the first year of life and can rapidly become fatal unless diagnosed and treated. The FDA approval is based on data from the pivotal phase 2/3 study (NCT01818492).