Yonsa

Prostate Cancer Treatment

Yonsa is indicated for the treatment of metastatic castration-resistant prostate cancer (mCRPC). This is a form of advanced prostate cancer that has spread beyond the prostate gland to other parts of the body, such as the bones or lymph nodes.

The term "castration-resistant" means that the cancer continues to grow or spread even when the levels of testosterone in the body are kept very low through surgical or medical treatments.

Combination Therapy

Yonsa is used as part of a combination therapy. It must be taken along with methylprednisolone, which is a corticosteroid. The steroid is used to help prevent certain side effects that can occur when the body's hormone production is altered by the medication.

Typical Use Cases

Healthcare providers prescribe Yonsa for patients in the following situations:

• The patient has been diagnosed with prostate cancer that is no longer responding to standard hormone therapies.
• The cancer has metastasized, meaning it has moved to other areas of the body.
• The patient is able to follow a regimen that includes both Yonsa and the required steroid medication.

Mechanism of Action

Yonsa is a type of hormone therapy known as a CYP17 inhibitor. It works by interfering with an enzyme called CYP17, which the body uses to produce androgens (male hormones), such as testosterone. Many prostate cancer cells rely on these hormones to grow and survive.

While other treatments may only stop hormone production in the testes, Yonsa blocks the production of androgens in three specific areas:

• The testes
• The adrenal glands (glands located on top of the kidneys)
• The prostate tumor itself

By significantly lowering androgen levels in these areas, the medication helps slow or stop the growth of the cancer.

Formulation and Absorption

Yonsa uses a micronized formulation, meaning the active ingredient is broken down into very small particles. This technology is designed to help the body absorb the medication more effectively. Because of this improved absorption, Yonsa can be taken at a lower dose than some other forms of abiraterone to achieve the same therapeutic effect.

This medication is used in combination with a corticosteroid, such as methylprednisolone. Because Yonsa blocks the production of several types of hormones, the steroid is needed to help the body maintain a healthy balance and prevent side effects like high blood pressure or low potassium levels.

Common Side Effects

The most common side effects reported by patients taking Yonsa include:

• Joint swelling or discomfort
• Muscle pain or aches
• Hot flashes
• Diarrhea
• Cough
• Headache
• Urinary tract infection
• Upper respiratory tract infection
• High blood pressure
• Increased frequency of urination at night

Serious Side Effects

Some side effects can be severe and may require medical intervention. Contact your healthcare provider immediately if you experience:

• Liver problems: Symptoms may include yellowing of the eyes or skin (jaundice), dark-colored urine, or severe nausea and vomiting.
• Heart and blood pressure issues: This may manifest as chest pain, irregular or rapid heartbeats, shortness of breath, or significant swelling in the feet and ankles due to fluid retention.
• Low potassium (hypokalemia): Signs include muscle weakness, leg cramps, or a fluttering sensation in the chest.
• Adrenal gland problems: Because Yonsa is taken with the steroid methylprednisolone, stopping the steroid suddenly or experiencing severe physical stress can lead to adrenal insufficiency. Symptoms include extreme tiredness, dizziness, confusion, or weight loss.

Mineralocorticoid Excess

Yonsa can cause high blood pressure (hypertension), low potassium levels (hypokalemia), and fluid retention. These issues result from increased mineralocorticoid levels caused by the medication. Healthcare providers typically monitor blood pressure and potassium levels at least once a month during treatment. Caution is used in patients with a history of heart failure or recent heart attack.

Hepatotoxicity

Serious liver toxicity, including liver failure, has been reported with this medication. Liver function tests, including ALT, AST, and bilirubin levels, are usually performed before starting treatment, every two weeks for the first three months, and monthly thereafter. Dose reductions or treatment interruption may be necessary if liver enzymes become significantly elevated.

Adrenocortical Insufficiency

Adrenal insufficiency may occur, especially if the accompanying corticosteroid (methylprednisolone) is stopped suddenly or if the patient experiences significant physical stress, such as surgery, trauma, or infection. Symptoms may include fatigue, dizziness, or nausea. Healthcare providers may increase the corticosteroid dose during these times.

Cardiovascular Events

There is an increased risk of heart-related issues, such as heart failure or irregular heartbeat (arrhythmia), particularly in patients with a history of cardiovascular disease. Safety has not been established in patients with significant heart conditions, such as unstable angina or severe heart failure.

Embryo-Fetal Toxicity

Yonsa is not indicated for use in women. It can cause significant harm to a developing fetus. Men with female partners of reproductive potential should use effective contraception during treatment and for three weeks after the final dose. Pregnant women or those who may become pregnant should not handle the tablets without protection, such as gloves, as the medication can be absorbed through the skin.

Product Interchangeability

Yonsa tablets are not interchangeable with other abiraterone acetate products, such as Zytiga, at the same dose. Yonsa uses an ultramicronized formulation that results in different absorption levels, and the prescribed dose must be followed exactly as directed for this specific brand.

Pregnancy Risks

Yonsa is not intended for use in women. It is contraindicated during pregnancy because it can cause fetal harm or lead to pregnancy loss. If this medication is used during pregnancy, or if a patient becomes pregnant while taking this drug, the fetus may be at risk.

Handling Precautions

Because of the risk of fetal harm, women who are pregnant or who may become pregnant should avoid handling Yonsa tablets without protection. If tablets are crushed or broken, they should not be handled by women in these groups. If contact is necessary, gloves should be worn.

Contraception Requirements

Men with female partners of reproductive potential should use effective birth control during treatment with Yonsa. This should continue for three weeks after the final dose to prevent accidental exposure to a developing fetus.

Breastfeeding

It is not known whether Yonsa passes into human breast milk or if it has any effects on a breastfed child. This medication is not approved for use in females.

Dosage Forms

Yonsa is supplied as a tablet for oral administration. It is used in combination with methylprednisolone.

• Oral tablet

FDA Approval and Indications

The U.S. Food and Drug Administration (FDA) approved Yonsa in May 2018. It is indicated for use in combination with methylprednisolone for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC). This condition refers to prostate cancer that has spread to other parts of the body and no longer responds to medical or surgical treatments that lower testosterone levels.

Regulatory Requirements and Safety

Yonsa is a micronized formulation of abiraterone acetate. Because of this specific formulation, the FDA-approved labeling notes that it is not interchangeable with other abiraterone acetate products on a milligram-to-milligram basis. The FDA requires that Yonsa be taken specifically with the corticosteroid methylprednisolone to help manage potential side effects related to hormone changes, such as high blood pressure or low potassium levels.

There are currently no Risk Evaluation and Mitigation Strategies (REMS) or boxed warnings required by the FDA for this medication. However, the regulatory labeling includes warnings regarding liver toxicity, cardiovascular events, and adrenal insufficiency. It is available only by prescription.

Factors Influencing Cost

The price you pay for Yonsa is determined by several factors, including:

• Insurance Coverage: Most commercial insurance plans and Medicare Part D provide coverage for Yonsa, but your specific out-of-pocket costs will depend on your plan's formulary and deductible.
• Pharmacy Selection: Prices may differ between retail pharmacies and specialty pharmacies, which are often required for oncology medications.
• Manufacturer Assistance: The drug manufacturer may offer copay cards or patient assistance programs for eligible individuals to help reduce the cost of the medication.

Formulation and Value

Yonsa is a micronized formulation of abiraterone acetate. While it contains the same active ingredient as other brands like Zytiga, the dosages are not the same and they are not interchangeable. This difference in formulation can impact how the drug is tiered by insurance companies.

Because Yonsa is typically used in combination with methylprednisolone, patients should also consider the cost of the secondary medication when budgeting for treatment.