Luspatercept-aamt injection is used to treat anemia (a lower than normal number of red blood cells) in adults who are receiving blood transfusions to treat thalassemia (an inherited condition that causes a low number of red blood cells). Luspatercept-aamt injection is also used to treat anemia in adults with certain types of myelodysplastic syndrome (a group of conditions in which the bone marrow produces blood cells that are misshapen and does not produce enough healthy blood cells) and who are receiving blood transfusions, but have not responded to or cannot receive treatment with an erythropoiesis-stimulating agent (ESA). Luspatercept-aamt is in a class of medications called erythroid maturation agents. It works by increasing the number and quality of red blood cells.

Luspatercept-aamt injection comes as a powder to be mixed with liquid and injected subcutaneously (just under the skin). It is usually injected once every 3 weeks by a doctor or nurse in a medical office or clinic.

Your doctor may need to adjust your dose of luspatercept-aamt injection or delay or stop your treatment depending on how well your body responds to the medication and if you experience certain side effects. Be sure to tell your doctor how you are feeling during your treatment with luspatercept-aamt injection.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Before receiving luspatercept-aamt,

• tell your doctor and pharmacist if you are allergic to luspatercept-aamt, any other medications, or any of the ingredients in luspatercep-aamt injection. Ask your pharmacist or for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: hormone replacement therapy (HRT) or oral contraceptives (birth control pills). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you smoke or if you have or have ever had blood clots in your legs, lungs, or eyes; high blood pressure; extramedullary hematopoietic masses (formation of blood cells outside of the bone marrow that create clumps of developing blood cells in other areas of your body); an enlarged liver or spleen; or if you have had your spleen removed.
• tell your doctor if you are pregnant or plan to become pregnant. You may need to have a pregnancy test before starting treatment. You should not become pregnant while you are taking luspatercept-aamt. You should use effective birth control to prevent pregnancy during your treatment with luspatercept-aamt and for at least 3 months after your final dose. Talk to your doctor about birth control methods that will work for you. If you become pregnant while using luspatercept-aamt injection, call your doctor immediately. Luspatercept-aamt may harm the fetus.
• tell your doctor if you are breastfeeding. Do not breastfeed while you are using luspatercept-aamt injection and for 3 months after your final dose.
• you should know that this medication may decrease fertility in women. Talk to your doctor about the risks of using luspatercept-aamt injection.

If you miss an appointment to receive an injection of luspatercept-aamt, you should call your healthcare provider right away to reschedule your appointment.

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.

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

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

• muscle or joint pain
• bone pain
• headache
• flu-like syndrome
• cough
• diarrhea
• nausea
• stomach pain
• tiredness
• pain, redness, or itching at injection site

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

• leg pain or feeling of warmth in the lower leg
• swelling of the hands, feet, ankles, or lower legs
• sudden chest pain
• shortness of breath
• trouble breathing
• rash
• hives
• weakness or numbness of an arm or leg
• difficulty walking
• sudden, severe headache
• confusion
• dizziness or faintness
• sudden changes in vision, such as loss of vision or blurred vision
• trouble speaking
• sudden, severe back pain; numbness, weakness or trouble moving feet, legs, hands or arms; or loss of bowel and bladder control

Luspatercept-aamt 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).

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

Keep all appointments with your doctor and the laboratory. Your doctor will order blood tests to check your body's response to luspatercept-aamt before each injection. Your blood pressure should be checked regularly.

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.