Ibrance

Approved Uses

Ibrance is used to treat a specific type of breast cancer known as hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer. It is indicated for patients whose cancer is advanced or metastatic, meaning it has spread to other parts of the body.

This medication is not used alone; it is prescribed in combination with other hormone therapies. The specific combination depends on the patient's medical history and previous treatments:

• With an aromatase inhibitor: Ibrance is used as the first hormone-based therapy in postmenopausal women or in men.
• With fulvestrant: Ibrance is used in adults whose cancer has progressed or spread after they have already received hormone therapy.

Healthcare providers determine if Ibrance is appropriate based on the specific receptors found on the cancer cells and the stage of the disease.

Mechanism of Action

Ibrance belongs to a class of drugs known as kinase inhibitors. It is a targeted therapy that specifically interferes with the process cancer cells use to multiply.

Targeting CDK4 and CDK6 Proteins

Inside the body, certain proteins called cyclin-dependent kinases (specifically CDK4 and CDK6) regulate the cell cycle, which is the process cells go through to grow and divide. In some types of breast cancer, these proteins become overactive, signaling the cancer cells to divide rapidly and uncontrollably.

Ibrance works by:

• Blocking Protein Activity: The medication attaches to CDK4 and CDK6 proteins to stop them from sending growth signals.
• Interrupting the Cell Cycle: By inhibiting these proteins, Ibrance prevents cancer cells from moving from one stage of growth to the next.
• Slowing Progression: When the cell cycle is interrupted, the cancer cells cannot reproduce as quickly, which can help shrink tumors or prevent them from growing larger.

This medication is used for cancers that are hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-). It is typically used in combination with hormone therapy to provide a dual approach to stopping cancer cell growth.

Common Side Effects

Many people taking Ibrance experience mild to moderate side effects. These may include:

• Fatigue and weakness
• Nausea and vomiting
• Diarrhea
• Mouth sores or inflammation
• Thinning hair or hair loss
• Decreased appetite
• Skin rash
• Increased risk of minor infections, such as the common cold

Serious Side Effects

Some side effects can be severe and require immediate medical attention. These include:

• Low blood cell counts: This is a common serious side effect. It includes low white blood cells (neutropenia), which increases infection risk; low red blood cells (anemia), which causes tiredness; and low platelets (thrombocytopenia), which can lead to easy bruising or bleeding.
• Lung problems: Ibrance can cause severe or life-threatening inflammation of the lungs, known as interstitial lung disease or pneumonitis. Symptoms include new or worsening cough, chest pain, or shortness of breath.
• Severe infections: Because the drug lowers white blood cell counts, the body may have difficulty fighting off serious infections.
• Blood clots: There is a risk of developing blood clots, including those that travel to the lungs (pulmonary embolism).

Healthcare providers will perform regular blood tests to monitor blood cell counts while a patient is taking this medication.

Low Blood Cell Counts

The most common serious side effect of Ibrance is neutropenia, a condition characterized by low levels of white blood cells. This can weaken the immune system and increase the risk of developing serious infections. Healthcare providers typically monitor complete blood counts before starting treatment and at the beginning of each cycle.

Lung Inflammation

Ibrance can cause severe or life-threatening inflammation of the lungs, known as interstitial lung disease (ILD) or pneumonitis. It is important to monitor for new or worsening respiratory symptoms, such as:

• Shortness of breath
• Cough
• Chest pain

Infection Risk

Because this medication can lower the body's ability to fight germs, infections may occur more easily. Signs of infection that require medical attention include fever and chills.

Blood Clots

There is a risk of developing blood clots, including pulmonary embolism (a clot in the lung). Symptoms may include sudden shortness of breath, rapid breathing, or sharp chest pain that worsens when breathing deeply.

Pregnancy and Reproduction

Ibrance can cause harm to an unborn baby. Effective birth control is recommended for females during treatment and for a period after the last dose. Males with female partners of reproductive potential should also use effective contraception. The medication may also impair male fertility.

Food and Drug Interactions

Grapefruit and grapefruit juice can interact with Ibrance and may lead to higher levels of the medication in the body, increasing the risk of side effects.

Pregnancy Considerations

Ibrance can cause harm to a developing fetus. Healthcare providers typically perform a pregnancy test before starting treatment to ensure the patient is not pregnant. If pregnancy occurs during treatment, it is important to inform a healthcare professional immediately.

Contraception

Because of the risk of fetal harm, specific contraception timelines are recommended for patients and their partners:

• Females: Those who can become pregnant should use effective birth control during treatment and for 3 weeks after the last dose.
• Males: Men with female partners of reproductive potential should use effective birth control during treatment and for 14 weeks after the last dose.

Breastfeeding

It is not known if this medication passes into breast milk. To avoid potential risks to a nursing child, breastfeeding is not recommended during treatment and for at least 3 weeks after the final dose.

Fertility

Based on findings in animal studies, Ibrance may impair male fertility. Patients may wish to discuss reproductive health and potential options with their clinical team before beginning therapy.

Available Forms

Ibrance is supplied in the following oral forms:

• Capsules
• Tablets

Both the capsules and tablets are intended to be swallowed whole. They should not be crushed, chewed, or opened. While the capsules must be taken with food, the tablets can be taken with or without a meal.

FDA Approval and Indications

Ibrance (palbociclib) is approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer. It is used in the following treatment regimens:

• In combination with an aromatase inhibitor as the initial endocrine-based therapy.
• In combination with fulvestrant for patients whose disease has progressed following endocrine therapy.

Regulatory Safety Information

The FDA monitors the safety of approved medications through various reporting systems. In 2020, the FDA identified a potential signal of serious risk regarding interstitial lung disease (ILD) and pneumonitis associated with the use of CDK4/6 inhibitors, including Ibrance. The agency determined that the product labeling should include information about these risks.

There are currently no Boxed Warnings or Risk Evaluation and Mitigation Strategies (REMS) programs required for Ibrance. Patients are typically monitored through regular blood tests and clinical evaluations to manage potential side effects such as low white blood cell counts.

Factors Influencing Cost

The price you pay for Ibrance can vary based on several factors:

• Insurance Coverage: Your specific health insurance plan, including your deductible and copayment or coinsurance requirements, will determine your out-of-pocket costs.
• Pharmacy Choice: Ibrance is a specialty medication and may only be available through specific specialty pharmacies, which can influence the price.
• Dosage: While different strengths often have similar pricing, the total cost may depend on the specific treatment cycle prescribed by your healthcare provider.

Generic Availability

Currently, Ibrance is only available as a brand-name drug. There is no generic version of palbociclib available at this time, which typically means the cost remains higher than it would be for a generic alternative.

Financial Assistance Programs

Because Ibrance is a specialty medication, there are options that may help reduce the cost for eligible patients:

• Manufacturer Support: The drug manufacturer may offer copay cards or savings programs for people with commercial insurance to help lower out-of-pocket expenses.
• Patient Assistance Programs: For those without insurance or who are underinsured, non-profit organizations or the manufacturer may provide the medication at a lower cost or for free based on financial need.
• Medicare Coverage: Most Medicare Part D plans cover Ibrance, though it is often placed on a high-cost specialty tier, which may result in significant coinsurance costs during certain phases of coverage.

It is recommended to contact your insurance provider or speak with a specialty pharmacist to get an accurate estimate of your specific costs.