Key Points

• Ibrance (palbociclib) is a kinase inhibitor that is taken by mouth to treat adults with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) advanced or metastatic breast cancer.
• Common side effects of Ibrance include low blood cell counts, nausea, vomiting, diarrhea, rash, hair loss, and fatigue. Most side effects go away after pausing or stopping treatment.
• More serious side effects of Ibrance that are less common or rare include interstitial lung disease and pneumonitis.

What is Ibrance?

Ibrance (palbociclib) is a kinase inhibitor that may be used to treat certain types of advanced or metastatic breast cancer. Specifically, it is FDA-approved to treat breast cancer that is hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative. It comes as a capsule that is taken in combination with an aromatase inhibitor or fulvestrant.

The way Ibrance works to treat cancer is by blocking signaling pathways that are involved in cell division. However, it affects normal healthy cells as well. This can lead to unwanted side effects.

10 side effects of Ibrance and how to manage them

In two phase 3 clinical trials (PALOMA-2 and PALOMA-3), Ibrance was studied while taken together with letrozole (an aromatase inhibitor) or fulvestrant. Side effects reported in both studies were similar. Here, we’ll review 10 side effects* of Ibrance that you should watch out for. We’ll offer tips on how to recognize and manage these side effects.

1. Low blood cell counts

It is common to experience low blood cell counts while taking Ibrance. This includes low white blood cells (neutropenia), low red blood cells (anemia), and low platelets. Researchers believe Ibrance can lower your blood cell count by stopping new cells from growing in your bone marrow. This causes less new cells to be able to replace old blood cells that die.

Having low blood cell counts can lead to infections and a higher risk of bleeding.Your doctor will monitor your blood cells through regular blood tests.

Low white blood cells

In studies, up to 83% of patients taking Ibrance had low white blood cells, including neutropenia. This happens around 2 weeks after starting treatment. If your white blood cells drop too low, your doctor might need to lower your dose or pause your treatment. They may ask you to wait to begin your treatment cycle to give your body a chance to make new white blood cells. Having low white blood cells puts you at a higher risk for infection. Tell your doctor right away if you develop a fever or other signs of illness.

Low red blood cells

Up to 30% of patients taking Ibrance experienced anemia (low red blood cells). This makes it harder for your body to get enough oxygen. If you have low red blood cells, you may feel dizzy, weak, or short of breath. Contact your care team if you notice any of these symptoms.

Low platelets

Having too little platelets can raise your risk for bleeding. In studies of Ibrance, thrombocytopenia (low platelets) was reported in up to 23% of patients. Watch out for signs of low platelets, such as blood in your urine or stool, easy bruising, and cuts or nosebleeds that take a long time to stop bleeding.

2. Nausea and vomiting

About 1 out of 3 patients who take Ibrance experience nausea, and up to 19% have vomiting during treatment. This can have a large impact on your quality of life. For most people, these side effects are mild and can be managed at home.

Tips for managing nausea and vomiting

• Stay hydrated by drinking plenty of fluids to prevent dehydration, which can make nausea worse
• Eat smaller meals more frequently throughout the day
• Choose bland foods that are easy to digest, like crackers and rice
• Try ginger chews or tea
• Talk to your doctor about anti-nausea medications

If nausea is affecting your normal daily activities or you have severe vomiting, contact your doctor to help you manage these side effects.

3. Diarrhea

Another stomach-related side effect you might experience while taking Ibrance is diarrhea. Not everyone will experience diarrhea, but in studies around 25% of patients taking Ibrance reported it. Below are some tips for managing diarrhea at home. If it becomes severe, call your doctor.

Tips for managing diarrhea

• Drink plenty of water or electrolyte drinks to replace lost fluids
• Stick to bland foods, like potatoes, rice, bananas, and applesauce
• Limit dairy products and caffeine, which can sometimes worsen diarrhea
• Try over-the-counter anti-diarrheal medications, or ask your doctor about a prescription-strength option

4. Mouth sores

Ibrance can weaken the tissue in your mouth, which may lead to mouth sores. Many types of sores in or around the mouth were reported during studies of Ibrance. Collectively, around 1 in 3 people will get mouth sores while taking Ibrance. These can include cheilitis, pain in the mouth, throat pain, swollen tongue, and ulcers in the mouth.

Tips for managing mouth sores

• Avoid acidic or spicy foods
• Cut food into small pieces for easier chewing and swallowing
• Suck on ice chips to help numb the pain
• Rinse your mouth with saltwater multiple times per day
• Try numbing lozenges or sprays, or over-the-counter pain relievers like acetaminophen (Tylenol)

Talk to your doctor if your mouth sores become severe or if they are interfering with eating or drinking. They can recommend ways to manage the pain, or may need to change your dose of Ibrance.

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5. Hair loss

Hair loss is a common concern with many cancer medications. During clinical trials, 18% to 33% of women reported hair loss or thinning from Ibrance. Hair thinning is more common from taking Ibrance than complete hair loss.

Tips for managing hair loss

• Style your hair differently, which may include a shorter hairstyle that is easier to manage
• Consider wearing hats or add hair pieces to make your hair fuller
• Brush your hair gently
• Avoid wearing tight hair accessories
• Use gentle shampoos

6. Rash

Another side effect to look out for while taking Ibrance is skin rash. In clinical trials, 17% to 18% of people taking Ibrance reported skin rash. While you’re taking Ibrance, skin rashes may come and go. They can be itchy and uncomfortable. It’s important to take proper care of them so they don’t become infected.

Tips for managing rash

• Use gentle cleansers that are free of fragrances when showering or bathing
• Apply a fragrance-free, hypoallergenic moisturizer to keep your skin hydrated and reduce itching
• Avoid rough or irritating fabrics and wear loose-fitting clothing
• Apply cool compresses to help with itching
• Ask your doctor about over-the-counter creams that can help with inflammation and itching, like hydrocortisone and diphenhydramine

If you notice your rash is not improving, very painful, oozing, or if you have a fever, call your doctor right away. They can check to make sure your rash is not infected.

7. Infections

Because Ibrance can affect your immune system, it can make it harder for your body to fight off infections. Patients taking Ibrance commonly experience infections, including the common cold, urinary tract infections, influenza, pneumonia, gastroenteritis, tooth infection, eye infection, and herpes. Make sure to call your doctor if you notice any signs of an infection, especially if you have a fever. Some other signs of infection may include chills, pain with urination, body aches, and cough.

Tips for preventing infections

• Wash your hands often
• Wear a mask in crowded places
• Avoid contact with people who might be sick
• Maintain a healthy diet

8. Fatigue

Fatigue, or feeling tired, is another common side effect of Ibrance. It can be hard to increase your energy, even with rest. Fatigue can be a symptom of more serious medical conditions, such as anemia. Your body may also be lacking nutrients from feeling less hungry (another side effect of Ibrance). Discuss your energy levels with your care team so they can rule out other things that might be going on.

Tips for managing fatigue

• Plan your schedule to allow yourself frequent rest breaks
• Take short naps throughout the day
• Practice good sleep hygiene to make sure you get enough sleep each night
• Maintain a balanced diet and avoid sugary drinks and processed foods

9. Low appetite

Ibrance can cause you to feel less hungry. This can be related to many factors, such as nausea, changes in taste, or feeling tired. While it can be difficult to eat, it is important for your body to continue to get all of the nutrients it needs.

Tips for managing low appetite

• Choose nutrient-dense foods, like nuts, seeds, and whole grains
• Keep snacks handy for when you are feeling hungry
• Drink fluids between meals instead of together with meals so they don’t fill you up too quickly
• Set a routine to get into the habit of eating at regular times
• Talk to your care team about ways to manage nausea, which can improve your appetite

10. Lung problems

Rarely, Ibrance can cause serious lung problems. These include pneumonitis (inflammation in the lungs) and interstitial lung disease. It is not fully clear how Ibrance causes these conditions, but researchers believe it could be due to changes in inflammatory cells in the lungs. Lung problems typically happen around 1 to 2 months after starting treatment.

Lung problems from Ibrance can be life-threatening, so it is important to notify your doctor right away if you notice any of the following symptoms:

• Chest pain
• Cough
• Shortness of breath
• Wheezing

What are the long-term effects of Ibrance?

Most side effects from Ibrance are expected to resolve after stopping treatment. These include nausea, diarrhea, and hair loss. However, more rare side effects like interstitial lung disease can have long-lasting effects from permanent damage to the lungs.

A 5-year, long-term study of patients taking Ibrance did not reveal delayed side effects or side effects that occurred as a result of cumulative exposure to the medication.

* This is not a complete list of side effects. See here for more information.

References

Finn, R. S., et. al. (2021). Long-Term Pooled Safety Analysis of Palbociclib in Combination with Endocrine Therapy for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Updated Analysis with up to 5 Years of Follow-Up. In: Oncologist. Available from: https://pubmed.ncbi.nlm.nih.gov/33486783/

Ibrance [package insert]. Revised 03/2024. Pfizer Laboratories Div Pfizer Inc - https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e0e6412f-50b4-4fd4-9364-62818d121a07

Hu, W., et. al. (2016). Mechanistic Investigation of Bone Marrow Suppression Associated with Palbociclib and its Differentiation from Cytotoxic Chemotherapies. In: Clinical Cancer Research. Available from: https://pubmed.ncbi.nlm.nih.gov/26631614/

National Cancer Institute. (2021). Mouth and Throat Problems: Cancer Treatment Side Effects. Available from: https://www.cancer.gov/about-cancer/treatment/side-effects/mouth-throat

Pfizer.com. About Ibrance. Accessed May 22, 2024 at https://www.ibrance.com/about-ibrance

Shohdy, K. S., et. al. (2017). Gastrointestinal adverse effects of cyclin-dependent kinase 4 and 6 inhibitors in breast cancer patients: a systematic review and meta-analysis. In: Therapeutic Advances in Drug Safety. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5638171/

Zhang, Y., et. al. (2022). Interstitial lung disease in patients treated with Cyclin-Dependent Kinase 4/6 inhibitors: A systematic review and meta-analysis of randomized controlled trials. In: The Breast. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8873944/

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