Annals of Rheumatic Diseases Publishes Results from Phase 2 Study of emapalumab in Patients with Secondary HLH/Macrophage Activation Syndrome

Results showed that MAS remission was seen in 13 of 14 patients with sHLH/MAS receiving emapalumab who had an inadequate response to high-dose glucocorticosteroids

WALTHAM, Mass., April 04, 2023 (GLOBE NEWSWIRE) -- Sobi North America, the North American affiliate of Swedish Orphan Biovitrum AB (Sobi®) (STO:SOBI), today announced that the Annals of Rheumatic Diseases has published results from an open-label, single-arm, multicenter phase 2 study evaluating the safety and efficacy of emapalumab, an anti-interferon-gamma monoclonal antibody, being investigated in patients with Systemic Juvenile Idiopathic Arthritis (sJIA) or Adult-onset Still's Disease (AOSD) who developed secondary hemophagocytic lymphohistiocytosis (sHLH)/Macrophage Activation Syndrome (MAS) following an inadequate response to high-dose glucocorticosteroids.

In the published study, 14 patients with sJIA or AOSD and sHLH/MAS who did not respond to high-dose glucocorticosteroids received emapalumab. MAS remission was seen in 13 of the 14 patients by week 8, at a median time of 25 days, based on clinical and laboratory criteria. All 14 patients completed the trial, entered long-term follow-up and were alive at the end of follow-up. Based on the results of this study, Sobi decided to continue to evaluate emapalumab in this patient population and initiated the EMERALD phase 3 study, which is ongoing.

"I believe that the results of this study represent an important milestone for the identification of a potential novel targeted treatment for patients with sJIA or AOSD with sHLH/MAS who have failed high-dose glucocorticoids," said Dr. Fabrizio De Benedetti, Head of the Division of Pediatric Rheumatology and Head of the Laboratory of ImmunoRheumatology at Bambino Gesù Children's Hospital in Rome, Italy. "We are eager to collect more data so that emapalumab becomes part of the therapeutic armamentarium for this rare disease and its high unmet medical need."

sHLH/MAS is a rare, life-threatening condition characterized by uncontrolled hyperinflammation which may develop on a background of rheumatologic diseases such as sJIA. It is classified as a secondary form of HLH and is caused by excessive activation and expansion of T cells and macrophages. A body of scientific evidence has been accumulated suggesting interferon gamma (IFNγ) is a major driver of hyperinflammation in diseases such as sHLH/MAS.

“The results published in the Annals of Rheumatic Diseases are encouraging for patients with sJIA or AOSD developing sHLH/MAS, who have had an inadequate response to high dose glucocorticoid treatment,” said Dr. Alexei Grom, Research Director, Division of Rheumatology and Professor of Pediatrics at Cincinnati Children's Hospital Medical Center, in Cincinnati, Ohio. “The ability of emapalumab to achieve MAS remission is meaningful as there is a high unmet need for these patients.”

“We are pleased that this newly published clinical data shows the potential benefit of emapalumab in patients with secondary HLH,” said Tony Hoos, Head of Research & Development and Medical Affairs, Chief Medical Officer at Sobi. “We remain committed to evaluating emapalumab as a potential new treatment option for patients affected by this severe condition. If our ongoing EMERALD phase 3 study in sHLH/MAS confirms the benefit, we are intending to file a supplemental Biologics License Application.”

Emapalumab is marketed in the United States as Gamifant® and is indicated for the treatment of adult and pediatric (newborn and older) patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent or progressive disease or intolerance with conventional HLH therapy.
Gamifant has not been reviewed or approved by the U.S. Food and Drug Administration for sHLH/MAS.

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About macrophage activation syndrome (MAS)
Macrophage activation syndrome (MAS) is a severe complication of rheumatic diseases, most frequently systemic juvenile idiopathic arthritis (sJIA) – a rare systemic disorder of auto-inflammatory nature with common clinical manifestations such as daily spiking fever, typical transient cutaneous rash, arthritis, lymphadenopathy, hepatosplenomegaly and serositis. MAS is characterized by fever, hepatosplenomegaly, liver dysfunction, cytopenias, coagulation abnormalities and hyperferritinaemia, possibly progressing to multiple organ failure and death. MAS is classified as a secondary form of haemophagocytic lymphohistiocytosis (HLH).

About emapalumab-lzsg
Emapalumab-lzsg is a fully human, anti-IFNγ monoclonal antibody that binds free and receptor-bound IFNγ, neutralizing its biological activity. In the US, emapalumab-lzsg is indicated for pediatric (newborn and older) and adult primary hemophagocytic lymphohistiocytosis (HLH) patients with refractory, recurrent or progressive disease, or intolerance to conventional HLH therapy. Emapalumab-lzsg is the first and only medicine approved in the US for primary HLH, a 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 in 2018 was based on data from the phase 2/3 studies (NCT01818492 and NCT02069899). Emapalumab is indicated for administration through intravenous infusion over one hour twice per week until hematopoietic stem cell transplantation (HSCT). The efficacy and safety of emapalumab are currently being evaluated in a phase 3 study in patients with MAS in Still’s disease or systemic lupus erythematosus (SLE) (EMERALD; NCT05001737).

U.S. Indication for Gamifant® (emapalumab-lzsg)
Gamifant® (emapalumab-lzsg) is an interferon gamma (IFNγ)–blocking antibody indicated for the treatment of adult and pediatric (newborn and older) patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent, or progressive disease or intolerance with conventional HLH therapy.

Important Safety Information
Before initiating Gamifant, patients should be evaluated for infection, including latent tuberculosis (TB). Prophylaxis for TB should be administered to patients who are at risk for TB or known to have a positive purified protein derivative (PPD) test result or positive IFNγ release assay. During Gamifant treatment, patients should be monitored for TB, adenovirus, Epstein-Barr virus (EBV), and cytomegalovirus (CMV) every 2 weeks and as clinically indicated. Patients should be administered prophylaxis for herpes zoster, Pneumocystis jirovecii, and fungal infections prior to Gamifant administration.

Increased Risk of Infection with Use of Live Vaccines
Do not administer live or live attenuated vaccines to patients receiving Gamifant and for at least 4 weeks after the last dose of Gamifant. The safety of immunization with live vaccines during or following Gamifant therapy has not been studied.

Infusion-Related Reactions
Infusion-related reactions, including drug eruption, pyrexia, rash, erythema, and hyperhidrosis, were reported with Gamifant treatment in 27% of patients. In one-third of these patients, the infusion-related reaction occurred during the first infusion.

Adverse Reactions
In the pivotal trial, the most commonly reported adverse reactions (≥10%) for Gamifant included infection (56%), hypertension (41%), infusion-related reactions (27%), pyrexia (24%), hypokalemia (15%), constipation (15%), rash (12%), abdominal pain (12%), CMV infection (12%), diarrhea (12%), lymphocytosis (12%), cough (12%), irritability (12%), tachycardia (12%), and tachypnea (12%). Additional selected adverse reactions (all grades) that were reported in less than 10% of patients treated with Gamifant included vomiting, acute kidney injury, asthenia, bradycardia, dyspnea, gastrointestinal hemorrhage, epistaxis, and peripheral edema.

Please see full US prescribing information for Gamifant.

Sobi North America
As the North American affiliate of international biopharmaceutical company Sobi, the Sobi North America team is committed to Sobi’s vision of providing access to innovative treatments that make a significant difference in the lives of individuals with rare diseases. Our product portfolio includes multiple approved treatments focused on immunology, hematology and specialty care. With U.S. headquarters in the Boston area, Canadian headquarters in the Toronto area, and field sales, medical and market access representatives spanning North America, our growing team has a proven track record of commercial excellence. More information is available at or at

Sobi is a specialized international biopharmaceutical company transforming the lives of people with rare and debilitating diseases. Providing reliable access to innovative medicines in the areas of hematology, immunology and specialty care, Sobi has approximately 1,600 employees across Europe, North America, the Middle East, Asia and Australia. In 2022, revenue amounted to SEK 18.8 billion. Sobi’s share (STO:SOBI) is listed on Nasdaq Stockholm. More about Sobi at, LinkedIn and YouTube.

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