Cobimetinib is used in adults to treat a certain type of metastatic melanoma (skin cancer) that has spread to other parts of the body and cannot be removed with surgery. Cobimetinib is usually given together with another medicine called vemurafenib.

Cobimetinib is used only if your tumor has a specific genetic marker, for which your doctor will test.

Cobimetinib is also used alone to treat adults with blood cancers called histiocytic neoplasms.

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

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Your doctor will perform tests to make sure cobimetinib is the right treatment for you.

Cobimetinib is given in a 28-day treatment cycle. You may need to use the medicine only during the first 21 days of each cycle. Your doctor will determine how long to treat you with cobimetinib.

Do not change your doses or medication schedule without your doctor's advice.

You may take cobimetinib with or without food.

If you vomit shortly after taking cobimetinib, do not take another dose. Take your next dose as scheduled.

Check your skin on a regular basis while you are using cobimetinib. Tell your doctor if you notice any new skin change such as redness, sores that will not heal, a new wart, or a mole that has changed in size or color.

You will need frequent medical tests.

Store at room temperature away from moisture and heat.

Usual Adult Dose for Melanoma -- Metastatic:

60 mg orally once a day for first 21 days of each 28-day cycle until disease progression or unacceptable toxicity

Comments:
-The presence of BRAF V600E or V600K mutation in tumor specimens should be confirmed with an FDA-approved test prior to therapy initiation; information on FDA-approved tests available at http://www.fda.gov/CompanionDiagnostics.

Use: In combination with vemurafenib, indicated for treatment of patients with unresectable or metastatic melanoma with a BRAF V600E or V600K mutation.

Usual Adult Dose for Histiocytic Neoplasm:

60 mg orally once a day for first 21 days of each 28-day cycle until disease progression or unacceptable toxicity

Use: Treatment of adult patients with histiocytic neoplasms

You should not use cobimetinib if you are allergic to it.

Tell your doctor if you have ever had:

• heart disease, heart rhythm disorder;

• a history of eye problems (especially a problem with your retina);

• liver or kidney disease;

• skin problems not related to melanoma;

• a muscle disorder;

• a bleeding or blood clotting disorder such as hemophilia; or

• a condition for which you take a blood thinner such as warfarin (Coumadin, Jantoven).

May harm an unborn baby. Do not use if you are pregnant. Use effective birth control while using cobimetinib and for at least 2 weeks after your last dose. Tell your doctor if you become pregnant.

Do not breastfeed while using cobimetinib, and for at least 2 weeks after your last dose.

Cobimetinib may affect fertility in men or women. Pregnancy could be harder to achieve while either parent is using this medicine.

Use the medicine as soon as you remember, and then go back to your regular schedule. Do not use two doses at one time.

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

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Do not eat grapefruit or drink grapefruit juice while taking this medication.

Cobimetinib could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

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

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

• vision changes, partial vision loss, seeing halos around lights;

• unexplained muscle pain, tenderness, or weakness (especially if you also have fever and dark colored urine);

• easy bruising or bleeding (nosebleeds, bleeding gums);

• signs of bleeding inside the body--weakness, dizziness, headache, red or pink urine, bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;

• signs of a heart problem--cough, wheezing, shortness of breath (even with mild exertion), chest pain, fast heartbeats, swelling in your feet or ankles;

• low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;

• liver problems--nausea, upper stomach pain, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

• severe skin reaction--skin pain, itching, redness, bumps or pimples, thickened or wrinkled skin, skin rash that spreads and causes blistering and peeling.

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

Common side effects of cobimetinib may include:

• nausea, vomiting, diarrhea, upset stomach, heartburn;

• bumps similar to acne on face, scalp, chest, or upper back;

• dry skin, itching, rash;

• tiredness;

• swelling of arms, legs, or feet;

• pain and burning when you urinate;

• lung problems;

• fever;

• increased sensitivity to sunlight; or

• abnormal blood tests.

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.

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Other drugs may affect cobimetinib, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response during and after therapy. Your doctor will check your skin for any changes before, every 2 months during your treatment, and for up to 6 months after treatment.

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.