FDA approves Sobi's Gamifant for rare, fatal childhood disease

The FDA has approved Sobi's Gamifant, a treatment for primary hemophagocytic lymphohistiocytosis (HLH).

The extremely rare condition usually manifests within the first year of life, progresses quickly and is usually fatal, with a median survival of less than two months.

HLH is caused by hyper-inflammation whereby massive over-expression of interferon gamma (IFNy) is thought to cause the immune system to attack the body’s tissues and organs.

Gamifant (emapalumab-lzsg), the first significant improvement in primary HLH induction therapy in 24 years – is approved to treat adults, children and babies who have refractory, recurrent or progressive disease or intolerance to conventional HLH therapy.

The medicine works by controlling the inflammation and preparing the patient for a hematopoietic stem cell transplant – the only cure for HLH. Hematopoietic stem cells are those that give rise to other blood cells.

Gamifant is the only treatment for HLH approved by the FDA following a phase 2/3 clinical study (NCT01818492) of 34 primary HLH patients. The primary endpoint was achieved, with 63% of patients demonstrating an overall response at the end of treatment.

Also, 70% of participants went on to have a hematopoietic stem cell transplant. Of the 27 refractory patients treated in the study, 82% had a genetically confirmed primary HLH diagnosis. The most common adverse reactions reported during the study were infections (56%), hypertension (41%), infusion-related reactions (27%), and fever (24%).

Dr Michael Jordan, who is based at the Cincinnati Children’s Hospital Medical Center HLH Center of Excellence, and primary investigator in the clinical trial, said: “HLH is a disorder of immune regulation in which many cytokines are deranged, but interferon gamma appears to play a critical role. 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 hematopoietic stem cell transplant.”

Gamifant was developed and submitted for approval to the FDA by Novimmune. Sobi, full name Swedish Orphan Biovitrum, acquired the exclusive global rights to Gamifant in August 2018. The drug should be available for treatment in the US in the first quarter of 2019.

The approval comes weeks after Sobi bought the rights to AstraZeneca’s respiratory syncytial virus drug, Synagis (palivizumab), for an upfront $1.5 billion in cash and shares, plus certain conditional payments.