This leaflet provides information about two different brands of ofatumumab.

Arzerra is used to treat chronic lymphocytic leukemia (CLL), sometimes in combination with other cancer medicines.

Kesimpta is used to treat relapsing forms of multiple sclerosis in adults (including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease).

Ofatumumab may also be used for purposes not listed in this medication guide.

Ofatumumab may cause a serious brain infection that can lead to disability or death. Call your doctor right away if you have problems with speech, thought, vision, or muscle movement.

If you've ever had hepatitis B, using ofatumumab can cause this virus to become active or get worse. Tell your doctor if you don't feel well and you have right-sided upper stomach pain, vomiting, loss of appetite, or yellowing of your skin or eyes.

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using ofatumumab.

Arzerra is given as an infusion into a vein. A healthcare provider will give you this injection. You may be given other medications to help prevent a reaction to the infusion. You may need to start using these medications up to 2 hours before the start of your ofatumumab infusion.

Arzerra is usually given in a 28-day treatment cycle. You may need to use the medicine only during the first 1 or 2 weeks of each cycle. Your dosing schedule may change with further doses. Your doctor will determine how long to treat you with ofatumumab.

Arzerra must be given slowly, and one infusion can take up to several hours to complete.

Kesimpta is injected under the skin, usually once per month. The first 3 doses are given weekly. A healthcare provider may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Prepare an injection only when you are ready to give it. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Avoid injecting Kesimpta into scars, moles, or stretch marks, or into skin that is red, bruised, scaly, hard, or tender.

You will need frequent medical tests while using ofatumumab, and your next dose may be delayed based on the results.

If you've ever had hepatitis B, using ofatumumab can cause this virus to become active or get worse. You may need frequent liver function tests while using this medicine and for several months after you stop.

Store Kesimpta prefilled syringes in their original carton in a refrigerator. Protect from light and freezing. Do not shake the syringe.

Each Kesimpta prefilled syringe is for one use only. Throw it away after one use, even if there is still medicine left inside.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

You should not use Kesimpta if you have active hepatitis B.

Tell your doctor if you have ever had:

• an active or chronic infection;

• a condition for which you have used an immunosuppressant medication; or

• hepatitis B.

You may need to take antiviral medicine if you are found to have any risk factors for hepatitis B. Follow your doctor's dosing instructions very carefully.

You should be current on all vaccines before you start using ofatumumab. Tell your doctor if you have received any vaccines within the past 4 weeks.

Tell your doctor if you are pregnant or planning to become pregnant.

Kesimpta may harm an unborn baby. Use effective birth control to prevent pregnancy while using Kesimpta, and for at least 6 months after your last dose.

If you use ofatumumab while you are pregnant, make sure any doctor caring for your new baby knows that you used the medicine during pregnancy. Being exposed to ofatumumab in the womb could affect your baby's vaccination schedule during the first 6 months of life.

It may not be safe to breastfeed while using ofatumumab. Ask your doctor about any risk.

Call your doctor for instructions if:

• you miss an appointment for your Arzerra injection; or

• you miss one of the first 3 weekly doses of Kesimpta.

If you miss a monthly dose of Kesimpta, use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

You should not receive a vaccine while using ofatumumab. Some vaccines may not work as well and may not fully protect you from disease. Other vaccines may not be safe for you while you are using ofatumumab. Vaccines include shots to prevent influenza, measles, mumps, rubella (MMR), rotavirus, typhoid, yellow fever, varicella (chickenpox), and herpes zoster (shingles).

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 or up to 24 hours later. Tell your caregiver right away if you feel dizzy, tired, nauseated, light-headed, feverish, chilled, sweaty, itchy, or have a skin rash, headache, muscle pain, back pain, stomach pain, irregular heartbeats, chest tightness, trouble breathing, or swelling and irritation in your throat.

Ofatumumab may cause a serious brain infection that can lead to disability or death. Call your doctor right away if you have problems with speech, thought, vision, or muscle movement. These symptoms may start gradually and get worse quickly.

Ofatumumab may cause serious side effects. Call your doctor at once if you have:

• pain, redness, swelling, or itching where the medicine was injected;

• right-sided upper stomach pain, vomiting, loss of appetite, yellowing of your skin or eyes, and not feeling well;

• a lung infection--fever, chills, cough with mucus, chest pain, feeling short of breath;

• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath; or

• signs of tumor cell breakdown--tiredness, weakness, muscle cramps, nausea, vomiting, diarrhea, fast or slow heart rate, tingling in your hands and feet or around your mouth.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects of ofatumumab may include:

• side effects during an infusion;

• irritation where an injection was given;

• fever, low blood cell counts;

• cold symptoms such as stuffy nose, sneezing, sore throat;

• cough, chest tightness, trouble breathing, lung infection;

• diarrhea, nausea;

• rash; or

• headache, tiredness.

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.

Tell your doctor about all your other medicines, especially:

• drugs that weaken the immune system such as cancer medicine, steroids, and medicines to prevent organ transplant rejection.

This list is not complete. Other drugs may affect ofatumumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.