Cobimetinib is a targeted cancer medicine. It blocks a cell signal (the MEK pathway) that helps cancer cells grow. It is often used with vemurafenib.
Brand Name(s)
- US: Cotellic
- Canada: Cotellic
Warning(s)
- Tell all of your health care providers that you take cobimetinib.
- Serious drug interactions can happen. Some HIV, infection, and seizure medicines must not be used with this drug. Avoid grapefruit and grapefruit juice.
- This drug is sometimes used with vemurafenib. Side effects can increase when used together.
- You may sunburn more easily. Use SPF 30+ sunscreen and protective clothing. Avoid tanning beds.
- This drug may raise your chance of getting certain other cancers. You will need a skin exam before you start and every 2 months during treatment. Do monthly skin self-checks.
- Heart problems can happen, including high blood pressure and heart failure. You may need heart tests and blood pressure checks.
- Muscle damage (rhabdomyolysis) can happen. Call your care team right away if you have muscle pain, tenderness, or weakness.
- Serious eye problems, including retinal detachment, can happen. Get help right away for halos or bright colors around lights, flashing lights, new floaters, a curtain-like shadow, or sudden vision loss. Regular eye exams are recommended.
- Bleeding, infections, liver problems, kidney problems, and electrolyte changes can occur. You may need regular blood tests.
- May cause dizziness and increase fall risk.
- Fertility may be affected in some people.
- Pregnancy: This drug may harm an unborn baby. Use birth control while on treatment and for some time after your last dose; ask your doctor how long. If you become pregnant, call your doctor right away.
- Breastfeeding: Do not breastfeed while taking this drug and for 2 weeks after the last dose.
- Seek urgent care for signs of a severe reaction: trouble breathing, swelling of the face or throat, severe rash or peeling skin.
Kind of Cancers It Is Used For (not a complete list)
- Melanoma (a type of skin cancer), often when the tumor has a BRAF V600 change and used with vemurafenib.
- Histiocytic neoplasms (a rare group of growths).
Mechanism of Action
Cobimetinib is a MEK inhibitor. It blocks MEK1 and MEK2 proteins in the MAPK/ERK pathway. This slows down signals that tell cancer cells to grow and divide.
In melanoma, it is often combined with vemurafenib (a BRAF inhibitor) to block the pathway at two points. This can make the treatment work better against tumors driven by the BRAF mutation.
Common Side Effects
- Diarrhea, nausea, vomiting, or upset stomach
- Heartburn or stomach pain
- Dry mouth
- Mouth irritation or mouth sores
- Skin irritation or rash; acne; dry, thick, or sensitive skin
- Sun sensitivity
- Headache or feeling tired or weak
- Dizziness
- Changes in vision or eye discomfort
Call your care team right away if you have signs of bleeding; infection (fever, chills, sore throat); yellowing of the skin or eyes; dark urine; trouble urinating; severe muscle pain; severe headache; fainting; one-sided weakness; or any sudden or severe vision change.
Learn more about cobimetinib on MedlinePlus
Last reviewed: 2025-12-17
