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Gamifant (emapalumab-lzsg) is an interferon gamma (IFNγ)-neutralizing antibody indicated for the treatment of adult and pediatric (newborn and older) patients with:
Gamifant may increase the risk of fatal and serious infections with pathogens including mycobacteria, herpes zoster virus... and histoplasma capsulatum. Do not administer Gamifant in patients with these infections until appropriate treatment has been initiated.
Gamifant (emapalumab-lzsg) is an interferon gamma (IFNγ)-neutralizing antibody indicated for the treatment of adult and pediatric (newborn and older) patients with:
Gamifant may increase the risk of fatal and serious infections with pathogens including mycobacteria, herpes zoster virus, and histoplasma capsulatum. Do not administer Gamifant in patients with these infections until appropriate treatment has been initiated.
In patients with primary HLH receiving Gamifant in clinical trials, serious infections such as sepsis, pneumonia, bacteremia, disseminated histoplasmosis, necrotizing fasciitis, viral infections, and perforated appendicitis were observed in 32% of patients.
In patients with HLH/MAS in Still’s disease receiving Gamifant in clinical trials, serious infections such as pneumonia, cytomegalovirus infection, cytomegalovirus infection reactivation, and sepsis were observed in 13% of patients.
Evaluate patients for tuberculosis risk factors and test for latent infection prior to initiating Gamifant. Administer tuberculosis prophylaxis to patients at risk for tuberculosis or known to have a positive purified protein derivative (PPD) test result.
Consider prophylaxis for herpes zoster, Pneumocystis jirovecii, and fungal infection while receiving Gamifant. Employ surveillance testing during treatment with Gamifant.
Closely monitor patients receiving Gamifant for signs or symptoms of infection, promptly initiate a complete diagnostic workup appropriate for an immunocompromised patient, and initiate appropriate antimicrobial therapy.
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 in patients with primary HLH, 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.
Infusion-related reactions in patients with HLH/MAS in Still’s disease, including pyrexia, headache, paresthesia, bone pain, pruritic rash, and peripheral coldness, were reported with Gamifant treatment in 13% of patients. Infusion-related reactions were reported as mild in 8% of patients and as moderate in 5% of patients.
Monitor patients for infusion-related reactions, which can be severe. Interrupt the infusion for infusion reactions and institute appropriate medical management before continuing infusion at a slower rate.
Serious adverse reactions were reported in 53% of patients. The most common serious adverse reactions (≥3%) included infections, gastrointestinal hemorrhage, and multiple organ dysfunction. Fatal adverse reactions occurred in 2 (6%) of patients and included septic shock and gastrointestinal hemorrhage.
The most common adverse reactions were (≥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%).
Serious adverse reactions were reported in 12 patients (31%), with the most common serious adverse reaction being pneumonia (5%). Fatal adverse reactions occurred in two patients (5%) and included multiple organ dysfunction and circulatory shock.
The most common adverse reactions (≥10%) for Gamifant included viral infection (44%), rash (21%), anemia (18%), leukopenia (15%), thrombosis (15%), bacterial infections (13%), headache (13%), hyperglycemia (13%), infusion-related reactions (13%), abdominal pain (10%), hypertension (10%), pyrexia (10%), and thrombocytopenia (10%).
1. Gamifant (emapalumab-lzsg) prescribing information. Stockholm, Sweden: Sobi, Inc. 2025. 2. FDA approves Gamifant® (emapalumab-lzsg) as first-ever treatment for adults and children with macrophage activation syndrome in Still's disease [news release]. Sobi, Inc. June 28, 2025. Accessed June 28, 2025. https://www.sobi.com/en/press-releases/fda-approves-gamifantr-emapalumab-lzsg-first-ever-treatment-adults-and-children-macrophage-activation-syndrome-stills-disease-2342991 3. De Benedetti F, Prencipe G, Bracaglia C, Marasco E, Grom AA. Targeting interferon-γ in hyperinflammation: opportunities and challenges. Nat Rev Rheumatol. 2021;17(11):678-691. doi:10.1038/s41584-021-00694-z 4. Data on file. Stockholm, Sweden: Sobi, Inc. 2025. 5. Young HA, Hodge DL. Interferon-γ. In: Henry HL, Norman AW, eds. Encyclopedia of Hormones. Academic Press; 2003:391-397. doi:10.1016/B0-12-341103-3/00151-0 6. Morimoto A, Nakazawa Y, Ishii E. Hemophagocytic lymphohistiocytosis: pathogenesis, diagnosis, and management. Pediatr Int. 2016;58(9):817-825. doi:10.1111/ped.13064
Gamifant is the first FDA-approved treatment for patients with HLH/MAS in known or suspected Still's disease, including systemic Juvenile Idiopathic Arthritis (sJIA), with an inadequate response or intolerance to glucocorticoids, or with recurrent MAS.
Read the press release forGamifant's approval in MAS is the latest advancement in the treatment of HLH. Gamifant received its first FDA approval in 2018 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.1,2
Gamifant is an interferon gamma (IFNγ)-blocking antibody that targets a key mediator of hyperinflammation, which drives the life-threatening symptoms of primary HLH and MAS in Still's disease.1-4
As Sobi remains dedicated to providing access to innovative treatments, we are pleased to announce that this new indication for patients with MAS in Still's disease is now the first FDA-approved treatment option for MAS in Still's disease, meeting an unmet need for patients.1,2
IFNγ is a central and upstream mediator of the hyperinflammatory feedback loop in MAS with Still's disease. IFNγ is a key “macrophage-activating factor,” increasing cytokine and chemokine production and phagocytosis in a continuous feedback loop.3
Gamifant is a monoclonal antibody that binds with affinity to free and receptor-bound IFNγ, neutralizing its activity.1,4
Gamifant binds to free and receptor-bound forms of IFNγ1,4
This neutralizes IFNγ activity and blocks intracellular signaling1,4
Hyperactivation of macrophages by excess IFNγ is prevented1,6
Hyperinflammation is subdued1,4
Interested in more information about treatment with Gamifant and MAS in Still's disease? Reach out and get your questions answered by a Gamifant Representative today.
Contact Sobi nowThere are 2 pathways to access Gamifant. Keep in mind that your institution and the patient's insurance will dictate how Gamifant should be ordered.
Download the ordering guidePhone: 800-850-4306, option 2
Fax: 800-823-4506
Patient pays out of
pocket to SP
Phone: 877-625-2566
Fax: 888-752-7626
connect.mckesson.com
Patient pays out
of pocket to hospital
Patient pays out of pocket to infusion center/physician practice
Gamifant Cares offers access and reimbursement support to help patients access Gamifant. Gamifant Cares provides information regarding patient healthcare coverage options and financial assistance information that may be available to help patients with financial needs.