Emapalumab-lzsg injection is used to treat adults and children (newborn and older) with primary hemophagocytic lymphohistiocytosis (HLH; an inherited condition in which the immune system does not work normally and causes swelling and damage to the liver, brain, and bone marrow) whose disease has not improved, has gotten worse, or has come back after previous treatment or who are unable to take other medications. Emapalumab-lzsg injection is in a class of medications called monoclonal antibodies. It works by blocking the action of a certain protein in the immune system that causes inflammation.

Emapalumab-lzsg comes as a liquid to be injected into a vein over 1 hour by a doctor or nurse in a hospital or medical facility. It is usually given 2 times per week, every 3 or 4 days, for as long as your doctor recommends that you receive treatment.

Your doctor may start you on a low dose of emapalumab-lzsg injection and gradually increase your dose, not more than once every 3 days.

Emapalumab-lzsg injection may cause a severe reaction during or shortly after the infusion of the medication. A doctor or nurse will monitor you carefully while you are receiving the medication. If you experience any of the following symptoms, tell your doctor immediately: skin redness, itching, fever, rash, excessive sweating, chills, nausea, vomiting, lightheadedness, dizziness, chest pain, or shortness of breath.

Your doctor or pharmacist will give you the manufacturer’s patient information sheet (Medication Guide) when you begin treatment with emapalumab-lzsg injection and each time you receive the medication. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit the Food and Drug Administration (FDA) website (http://www.fda.gov/Drugs/DrugSafety/ucm085729.htm) or the manufacturer’s website to obtain the Medication Guide.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Before receiving emapalumab-lzsg injection,

• tell your doctor and pharmacist if you are allergic to emapalumab-lzsg, any other medications, or any of the ingredients in emapalumab-lzsg injection. Ask your pharmacist or check the Medication Guide for a list of the ingredients.
• tell your doctor if you have or have ever had any medical condition.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving emapalumab-lzsg injection, call your doctor.
• you should know that emapalumab-lzsg injection may decrease your ability to fight infection from bacteria, viruses, and fungi and increase the risk that you will get a serious or life-threatening infection. Tell your doctor if you often get any type of infection or if you have or think you may have any type of infection now. This includes minor infections (such as open cuts or sores), infections that come and go (such as herpes or cold sores), and chronic infections that do not go away. If you experience any of the following symptoms during or shortly after your treatment with emapalumab-lzsg injection, call your doctor immediately: fever, sweats, or chills; muscle aches; cough; bloody mucus; shortness of breath; sore throat or difficulty swallowing; warm, red, or painful skin or sores on your body; diarrhea; stomach pain; frequent, urgent, or painful urination; or other signs of infection.
• you should know that receiving emapalumab-lzsg injection increases the risk that you will develop tuberculosis (TB; a serious lung infection), especially if you are already infected with TB but do not have any symptoms of the disease. Tell your doctor if you have or have ever had TB, if you have lived in a country where TB is common, or if you have been around someone who has TB. Your doctor will check you for TB before starting treatment with emapalumab-lzsg injection and may treat you for TB if you have a history of TB or have active TB. If you have any of the following symptoms of TB or if you develop any of these symptoms during your treatment, call your doctor immediately: cough, coughing up blood or mucus, weakness or tiredness, weight loss, loss of appetite, chills, fever, or night sweats.
• do not have any vaccinations without talking to your doctor during your treatment with emapalumab-lzsg injection and for at least 4 weeks after your final dose.

Unless your doctor tells you otherwise, continue your normal diet.

Emapalumab-lzsg injection may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• constipation
• nose bleeds

Some side effects can be serious. If you experience any of these symptoms or those listed in the HOW section and SPECIAL PRECAUTIONS section, stop taking emapalumab-lzsg injection and call your doctor immediately or get emergency medical treatment:

• fast, slow, or irregular heartbeat
• fast breathing
• muscle cramps
• numbness and tingling
• bloody or black, tarry stools
• vomiting blood or brown material that resembles coffee grounds
• decreased urination
• swelling in the hands, feet, ankles, or lower legs

Emapalumab-lzsg injection may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Keep all appointments with your doctor and the laboratory. Your doctor will check your blood pressure regularly and will order certain lab tests before and during your treatment with emapalumab-lzsg injection to check your body’s response to the medication.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

• Gamifant^®