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Patient Handout: Vemurafenib and Cobimetinib

What are Vemurafenib and Cobimetinib?

Vemurafenib (brand name Zelboraf) and cobimetinib (brand name Cotellic) are two medications used together to treat certain types of cancer, particularly melanoma. These drugs are targeted therapies that work by blocking specific proteins involved in the growth and spread of cancer cells.

  • Vemurafenib is a BRAF inhibitor that works by blocking a mutated BRAF protein, which is found in some cancer cells, including melanoma. This protein normally helps cancer cells grow and divide. By inhibiting this protein, vemurafenib can slow or stop the growth of cancer cells.
  • Cobimetinib is a MEK inhibitor that blocks the MEK protein, which is involved in the same signaling pathway as BRAF. This pathway helps cancer cells grow and survive. By inhibiting MEK, cobimetinib prevents cancer cells from dividing and spreading.

Together, vemurafenib and cobimetinib target different points in the BRAF/MEK pathway, making their combination therapy more effective in treating cancer.

How Do Vemurafenib and Cobimetinib Work Together?

In some cancers, including melanoma, a mutation in the BRAF gene leads to overactive cell growth. Vemurafenib targets the mutated BRAF protein, while cobimetinib inhibits MEK, which works in the same pathway. By blocking both BRAF and MEK, the combination therapy helps prevent cancer cells from growing and spreading.

How Are Vemurafenib and Cobimetinib Taken?

Both vemurafenib and cobimetinib are taken by mouth in the form of tablets.

  • Vemurafenib (Zelboraf): Usually taken twice a day, with or without food.
  • Cobimetinib (Cotellic): Usually taken once a day, for 21 days, followed by 7 days off (a 28-day cycle).

Important Administration Information:

  • Take both medications exactly as prescribed by your doctor.
  • You should take vemurafenib and cobimetinib at the same time each day to help you remember.
  • If you miss a dose, take it as soon as you remember unless it’s almost time for your next dose. Do not take two doses at once.
  • If you vomit after taking a dose, do not take another dose. Just take your next dose at the regular time.

Possible Side Effects

Vemurafenib and cobimetinib can cause side effects, some of which may be serious. It is important to inform your doctor if you notice any unusual symptoms.

Common Side Effects:

  • Rash: You may develop a skin rash, which can be mild to severe. Report any new or worsening rashes to your doctor.
  • Diarrhea: Loose stools are common, so it is important to stay hydrated. If diarrhea becomes severe, contact your doctor.
  • Fatigue: Feeling tired or weak is common during treatment.
  • Nausea and Vomiting: Some people experience nausea or vomiting. Anti-nausea medications can help manage these symptoms.
  • Joint and Muscle Pain: Pain or stiffness in your muscles or joints may occur.
  • Fever: Mild fever is common but should be monitored.

Serious Side Effects:

  • Liver Problems: Both drugs can affect your liver. Symptoms of liver problems include yellowing of the skin or eyes, dark urine, or abdominal pain. Contact your doctor if you notice these symptoms.
  • Eye Problems: Cobimetinib can cause eye problems, such as blurred vision or vision loss. Notify your doctor if you experience any changes in vision.
  • Heart Problems: Cobimetinib may cause heart-related side effects. Symptoms such as chest pain, shortness of breath, or swelling in the legs should be reported immediately.
  • Severe Rash or Skin Issues: Some patients experience severe skin reactions, such as blistering or peeling of the skin. Contact your doctor if you notice any signs of severe skin problems.
  • Severe Bleeding: You may be at an increased risk of bleeding. Report unusual bruising, bleeding, or nosebleeds to your doctor.

Precautions Before Taking Vemurafenib and Cobimetinib

Before starting treatment with vemurafenib and cobimetinib, inform your healthcare provider if you:

  • Have liver problems, as both drugs are metabolized in the liver.
  • Have heart issues, as cobimetinib may affect heart function.
  • Have eye problems, because cobimetinib can cause vision changes.
  • Are pregnant or planning to become pregnant: Both drugs can harm an unborn baby. You should use effective birth control during treatment and for at least 2 weeks after the last dose of vemurafenib and 2 weeks after the last dose of cobimetinib.
  • Are breastfeeding: These medications may pass into breast milk, so breastfeeding is not recommended while on this treatment.

What to Avoid While Taking Vemurafenib and Cobimetinib

  • Pregnancy: Both vemurafenib and cobimetinib can harm an unborn baby. Use effective contraception during treatment and for a time after stopping the medications.
  • Sun Exposure: Vemurafenib can increase your sensitivity to the sun. Avoid sun exposure and use sunscreen, sunglasses, and protective clothing when outdoors.
  • Live Vaccines: Avoid receiving live vaccines during treatment, as these medications can weaken your immune system.
  • Grapefruit: Avoid grapefruit and grapefruit juice, as they can interact with these medications and affect how they work in your body.

Regular Monitoring

Your healthcare provider will monitor your health regularly throughout treatment with blood tests and other exams, including:

  • Blood tests: To check for liver problems and to monitor overall health.
  • Eye exams: To monitor for any eye-related side effects caused by cobimetinib.
  • Skin exams: To monitor for any new skin changes or the development of additional skin cancers.

When to Contact Your Doctor

Call your healthcare provider immediately if you experience any of the following:

  • Yellowing of your skin or eyes, dark urine, or stomach pain (possible liver issues)
  • Vision changes, such as blurred vision or vision loss (possible eye problems)
  • Chest pain, shortness of breath, or swelling in your legs (possible heart issues)
  • Severe rash, blistering, or skin peeling
  • Unusual bruising, bleeding, or nosebleeds (possible bleeding issues)
  • Severe diarrhea, blood in your stool, or dehydration
  • Persistent fever or chills

Disclaimer:

This handout is for educational purposes only and should not be considered medical advice. Always follow the instructions provided by your healthcare provider regarding treatment and care. For personalized advice, consult your healthcare provider or pharmacist.