First FDA Approved Drug for HLH Save

The first drug specifically for primary hemophagocytic lymphohistiocytosis (HLH) was approved today, the FDA announced.

Emapalumab (Gamifant), manufactured by Novimmune SA, may be used in all patients (including newborns and older children) "who have refractory, recurrent, or progressive disease or intolerance with conventional HLH therapy," the FDA said.

HLH is a very rare condition in which immune cells go into overdrive, releasing pro-inflammatory molecules that damage many of the body's organs. It can be inherited (primary HLH), with various genes implicated, but can also be secondary to other conditions. In the primary form, symptoms typically develop shortly after birth. Allogeneic hematopoietic stem cell transplant is the most effective treatment and can result in cure. Other treatments include chemotherapy and immunotherapy, according to the National Institutes of Health.

Emapalumab's efficacy was demonstrated in a 27-patient pediatric trial, with 70% able to proceed to stem cell transplant, the FDA said.

The agency cautioned that patients receiving the drug should not receive live-pathogen vaccines and should be tested for latent tuberculosis before starting treatment. Infections are a concern with the drug and clinicians should actively monitor patients for them.