Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 12/13/2021
Gamifant Side Effects Center

What Is Gamifant?

Gamifant (emapalumab-lzsg) is an interferon gamma (IFN?) 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.

What Are Side Effects of Gamifant?

Common side effects of Gamifant include:

Dosage for Gamifant

The recommended starting dosage of Gamifant is 1 mg/kg as an intravenous infusion over 1 hour twice per week. Dexamethasone is administered concomitantly with Gamifant.

What Drugs, Substances, or Supplements Interact with Gamifant?

Gamifant may interact with CYP450 substrates. Tell your doctor all medications and supplements you use.

Gamifant During Pregnancy or Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using Gamifant; it is unknown how it would affect a fetus. It is unknown if Gamifant passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Gamifant (emapalumab-lzsg) Injection, for Intravenous Use Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Gamifant Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your caregiver if you feel feverish, chilled, sweaty, itchy, light-headed, nauseated, or if you have chest pain, shortness of breath, or skin rash or redness.

You may get infections more easily, even serious or fatal infections. Call your doctor right away if you have signs of infection such as:

  • fever, chills, night sweats;
  • loss of appetite, weight loss;
  • feeling very tired;
  • warmth, redness, or painful sores on your skin;
  • cough, trouble breathing;
  • mouth and throat ulcers;
  • cough with bloody mucus; or
  • any other new or worsening signs of infection.

Common side effects may include:

  • fever; or
  • increased blood pressure.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Gamifant (Emapalumab-lzsg Injection)


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Gamifant Professional Information


The following adverse reactions are described elsewhere in the labeling:

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety data described in this section reflect exposure to GAMIFANT in which 34 patients with untreated primary HLH and previously treated patients with primary HLH (NCT01818492) received GAMIFANT at a starting dose of 1 mg/kg every 3 days with dose increases up to 10 mg/kg [see DOSAGE AND ADMINISTRATION and Clinical Studies]. The median duration of treatment with GAMIFANT was 59 days (range: 4 to 245 days) and the median cumulative dose was 25 mg/kg (range: 4 to 254 mg/kg).

The median age of study population was 1 year (range: 0.1 to 13 years), 53% were female, and 65% were Caucasian.

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 two (6%) of patients and included septic shock and gastrointestinal hemorrhage.

Disseminated histoplasmosis led to drug discontinuation in one patient. The most commonly reported adverse reactions (≥ 20%) were infections, hypertension, infusion-related reactions, and pyrexia. Adverse reactions reported in ≥ 10% of patients during treatment with GAMIFANT are presented in Table 2.

Table 2: Adverse Reactions Reported in ≥ 10% of Patients with Primary HLH

Adverse Reactions GAMIFANT
(%) (N = 34)
Infectionsa 56
Hypertensionb 41
Infusion-related reactionsc 27
Pyrexia 24
Hypokalemia 15
Constipation 15
Rash 12
Abdominal pain 12
Cytomegalovirus infection 12
Diarrhea 12
Lymphocytosis 12
Cough 12
Irritability 12
Tachycardia 12
Tachypnea 12
aIncludes viral, bacterial, fungal, and infections in which no pathogen was identified
bIncludes secondary hypertension
cIncludes events of drug eruption, pyrexia, rash, erythema, and hyperhidrosis

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, gastro-intestinal hemorrhage, epistaxis, and peripheral edema.


As with all therapeutic proteins, there is potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies in the studies described below with the incidence of antibodies in other studies or to other emapalumab products may be misleading.

The immunogenicity of emapalumab-lzsg has been evaluated using an electrochemiluminescence-based immunoassay (ECLIA). A total of 64 subjects were evaluated for anti-therapeutic antibodies (ATAs) to emapalumab-lzsg after treatment with GAMIFANT. ATAs were detected in 3/64 subjects (5%) who received GAMIFANT.

Treatment-emergent ATAs were detected in 1/33 (3%) of patients in the primary HLH clinical trial. The ATAs in this patient were found to have neutralizing ability. One patient receiving GAMIFANT through compassionate use developed transient non-neutralizing treatment-emergent ATAs. In both of these patients, ATAs occurred within the first 9 weeks following the initiation of GAMIFANT treatment. In addition, one healthy subject tested positive for ATAs following a single dose of GAMIFANT. No evidence of an altered safety or efficacy profile was identified in the primary HLH patients who developed antibodies to emapalumab-lzsg.

Read the entire FDA prescribing information for Gamifant (Emapalumab-lzsg Injection)

© Gamifant Patient Information is supplied by Cerner Multum, Inc. and Gamifant Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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