FDA OKs Gamifant, First Drug for Rare Immune Disease HLH

Megan Brooks

November 20, 2018

The US Food and Drug Administration (FDA) has approved emapalumab (Gamifant, Novimmune) for the treatment of adult and pediatric (newborn and older) patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent, or progressive disease or intolerance to conventional HLH therapy.

Emapalumab, an interferon gamma-blocking antibody, is the first treatment approved specifically for HLH.

"This approval fills an unmet medical need for these patients," Richard Pazdur, MD, director, FDA Oncology Center of Excellence, and acting director, Office of Hematology and Oncology Products, FDA Center for Drug Evaluation and Research, said in a news release.

Primary HLH is an ultra-rare, rapidly progressing, often fatal syndrome of hyperinflammation thought to be driven by hyperproduction of interferon gamma, ultimately leading to organ failure. The immediate goal of treatment is to rapidly control hyperinflammation and prepare for hematopoietic stem-cell transplant (HSCT). The current conventional treatment prior to transplant includes steroids and chemotherapy and are not specifically approved to treat primary HLH.

The FDA approved emapalumab based on results of a clinical trial of 27 pediatric patients (median age, 1 year) with suspected or confirmed primary HLH with refractory, recurrent, or progressive disease during conventional HLH therapy or who were intolerant of conventional HLH therapy.

According to the FDA, 63% of patients experienced a response and 70% were able to proceed to HSCT. Emapalumab is indicated to be administered through intravenous infusion over 1 hour twice per week until HSCT.

"HLH is a disorder of immune regulation in which many cytokines are deranged, but interferon gamma appears to play a critical role," Michael Jordan, MD, of the Division of Bone Marrow Transplantation and Immune Deficiency at Cincinnati Children's Hospital Medical Center, HLH Center of Excellence, said in a company news release.

"While we have long understood the pivotal role of this cytokine in HLH, until emapalumab's approval we did not have a medicine that could specifically hit this target. Emapalumab represents an entirely new approach to treating primary HLH and helping these very sick patients reach HSCT," said Jordan, who was principal investigator of the emapalumab clinical trial.

Commonly reported adverse reactions include infections, hypertension, infusion-related reactions, low potassium, and fever.

The FDA cautions that patients receiving emapalumab should not receive any live vaccines and should be tested for latent tuberculosis. They should also be closely monitored and treated promptly for infections while receiving the drug. Full prescribing information is available online.

Emapalumab had breakthrough and orphan drug designation and priority review status. The drug is currently under review by the European Medicines Agency.

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