Belzutifan - Dosage, Benefits, and Side Effects

What Is Belzutifan?

Belzutifan, sometimes referred to as MK-6482, is used to treat Von Hippel-Lindau's (VHL) illness. VHL is a rare hereditary condition. It leads to the development of tumors and cysts in several organs, including the brain, spine, kidneys, and pancreas. Belzutifan offers a tailored therapy approach for VHL illness by blocking a particular protein implicated in the formation of malignant tumors.

Is Belzutifan FDA-approved?

On August 13th, 2021, the United States Food and Drug Administration (FDA) approved Belzutifan for the management of clear cell renal cell carcinoma associated with von Hippel-Lindau (VHL) disease.

Drug Group:

Belzutifan is a medicine from a group called hypoxia-inducible factor (HIF) inhibitors. It is used to treat kidney cancer, certain brain and spinal cord tumors, and some pancreatic tumors in adults with Von Hippel-Lindau (VHL) disease. VHL is an inherited condition that causes tumors and cysts to grow in different organs.

What Is the Mechanism of Action?

Belzutifan works by blocking hypoxia-inducible factors, which help tumors form abnormal blood vessels and grow. By stopping this process, the medicine helps slow tumor growth and control the disease linked to VHL.

Belzutifan Dosage

• The usual dose of Belzutifan is 120 mg, taken once daily by mouth.

• It can be taken with or without food.

• Take it at the same time every day. Swallow the tablet whole.

• Do not chew, crush, or break it.

• If you miss a dose, take it later the same day.

• Take the next dose the following day as usual.

• Do not take extra tablets.

• If you vomit after taking Belzutifan, do not take another dose.

• Wait and take the next dose the next day.

How Does Belzutifan Work?

Belzutifan is also called MK-6482. It blocks a protein called HIF-2 alpha. This protein helps tumors grow in low-oxygen conditions. By blocking it, Belzutifan slows tumor growth. It is especially useful in clear cell renal cell carcinoma.

How Should Belzutifan Be Taken?

• Take 120 mg once daily by mouth.

• Take it at the same time every day.

• It can be taken with or without food.

• Swallow the tablet whole.

• Do not chew or crush it.

Benefits of Belzutifan in VHL Disease

• It can shrink tumor size.

• It can slow tumor growth.

• Symptoms may improve over time.

• In some cases, surgery may be avoided.

• It is easy to take because it is a pill.

What Should Patients Tell the Doctor?

• Tell the doctor about all medical problems.

• This includes high blood pressure or kidney issues.

• Tell them about all medicines and supplements you take.

• This helps the doctor use Belzutifan safely.

Possible Side Effects of Belzutifan

• Feeling tired.

• Low red blood cells (anemia).

• High blood pressure.

• Nausea or vomiting.

• Loss of appetite.

• Joint pain.

• Headache.

• Trouble breathing.

• Cough.

For Doctors:

Description:

Belzutifan, an inhibitor of hypoxia-inducible factor-2α (HIF-2α), has the chemical name 3­[(1S,2S,3R)-2,3-Difluoro-2,3-dihydro-1-hydroxy-7-(methylsulfonyl)-1H-inden-4-yl]oxy]-5­fluorobenzonitrile. It is a white to light brown powder with a molecular formula of C17H12F3NO4S and a molecular weight of 383.34 Daltons. The compound exhibits solubility in acetonitrile, dimethoxyethane, and acetone; is sparingly soluble in ethyl acetate; is very slightly soluble in Isopropanol and toluene; and remains insoluble in water. Belzutifan is available as blue, film-coated tablets for oral use, each containing 40 mg of Belzutifan. The tablets contain various inactive ingredients, including croscarmellose sodium, hypromellose acetate succinate, magnesium stearate, mannitol, microcrystalline cellulose, and silicon dioxide.

Therapeutic Uses of Belzutifan:

• Belzutifan, also known as MK-6482, is a hypoxia-inducible factor prolyl hydroxylase inhibitor.

• Used in the treatment of clear cell renal cell carcinoma (ccRCC), a type of kidney cancer.

• It acts by stabilizing hypoxia-inducible factor-2 alpha (HIF-2α), thereby reducing tumor growth. It can be prescribed for patients who are not candidates for surgery or systemic therapies.

• It may offer an alternative for those with advanced or metastatic ccRCC.

Dosage Forms and Strengths:

40 mg blue oval-shaped tablets with a film coating, plain on one side and embossed with "177" on the other.

Dosage and Administration:

The recommended dosage for Belzutifan is 120 mg once daily until disease progression or unacceptable toxicity. Take it at the same time daily, with or without food. Swallow the tablets whole; do not chew, crush, or split. If a dose is missed, take it as soon as possible on the same day; resume the regular schedule the next day.

Do not take extra tablets to compensate for a missed dose. If vomiting occurs, do not retake the dose and take the next dose the following day. Dosage reductions for adverse reactions are made in steps: first to 80 mg, then to 40 mg. A third reduction results in permanent discontinuation.

Indications:

Belzutifan is a drug that is used to treat some kinds of cancer, particularly renal cell carcinoma (RCC), which is a kind of cancer that is related to Von Hippel-Lindau (VHL) disease. Treating people with this particular type of renal cell carcinoma linked to VHL illness is the primary use of Belzutifan. It functions by blocking a certain enzyme that is necessary for the development of blood vessels, which aids in the reduction or slowing of tumor growth.

Contraindications:

In pregnant women, it may be harmful to the growing fetus. Belzutifan appears to impair fertility. Hence, it is imperative that both female patients and male patients who have female partners who can conceive utilize effective contraception during treatment and for one week following the last dosage.

What Are the Adverse Reactions of Belzutifan?

• Hypertension.

• Dyspnea (difficulty breathing).

• Cough.

• Rash.

• Decreased appetite.

• Headache.

• Vomiting.

Pharmacological Aspects of Belzutifan

Mechanism of Action:

Belzutifan works by blocking a protein called HIF-2α, which helps cells respond to low oxygen levels. Under normal conditions, the VHL protein degrades HIF-2α, but when VHL is dysfunctional, HIF-2α accumulates and activates genes that promote tumor growth and new blood vessel formation. Belzutifan binds to HIF-2α and prevents it from interacting with HIF-1β, thereby reducing cancer-related gene activity. This action slows tumor growth, as shown in animal studies of kidney cancer.

Pharmacodynamics:

Plasma erythropoietin (EPO) levels exhibited dose - and exposure-dependent reductions, reaching up to 120 mg once daily. The most significant EPO suppression, approximately 60 percent from baseline, occurred after 2 weeks of consecutive Belzutifan dosing, with levels returning to baseline after 12 weeks. Higher Belzutifan exposure correlated with an increased incidence of Grade 3 anemia in patients with baseline hemoglobin levels <12 mg/dL. Belzutifan at the recommended dosage does not cause substantial QT interval prolongation (>20 milliseconds) in cardiac electrophysiology.

Pharmacokinetics:

In individuals with VHL disease-associated RCC, the average steady-state Cmax is 1.3 μg/mL (42 percent), and AUC0-24h is 16.7 µg•hr/mL (52 percent), achieved after about 3 days. Both Cmax and AUC (concentration maximum and area under the curve) show proportional increases within a dose range of 20 mg to 120 mg.

Absorption peaks at a median Tmax ( time to peak drug concentration) of one to two hours, with a high-fat meal causing a two-hour delay in peak Belzutifan concentration but no significant impact on Cmax or AUC.

The steady-state volume of distribution is 130 Liters (35%), with 45% plasma protein binding. Belzutifan undergoes primary metabolism by genes, with a lesser contribution from CYP3A4. Clearance is 7.3 L/hr (51%) on average, and the elimination half-life is 14 hours.

Drug Interactions:

• Calcium and vitamin D.

• Chlorpheniramine and Dextromethorphan.

• Diltiazem.

• Nirmatrelvir and Ritonavir.

• Clopidogrel.

• Acetaminophen.

• Alprazolam.

Use in Specific Populations:

Pregnancy:

• Belzutifan can harm an unborn baby. This is based on animal studies.

• There is very limited information about its use in pregnant women.

• In animal studies, Belzutifan caused the death of the fetus and bone defects.

• These effects happened at doses lower than those used in humans.

• Women who are pregnant or may become pregnant should be told about these risks.

• The exact risk of birth defects or miscarriage in patients using Belzutifan is not known.

• In the general population, birth defects occur in about 2 to 4 percent of pregnancies, and miscarriage occurs in about 15 to 20 percent of pregnancies.

Lactation:

It is recommended that women avoid breastfeeding while undergoing Belzutifan treatment and for 1 week after the final dose, due to limited data on the presence and effects of Belzutifan or its metabolites in human milk. This precaution prevents potentially serious adverse reactions in the breastfed child.

Pediatrics:

The safety and effectiveness of Belzutifan have not been established in pediatric patients.

Geriatrics:

3.3 percent of patients receiving Belzutifan were aged 65 and older, and clinical trials did not include sufficient numbers of patients aged 65 and older to determine differences in response compared with younger patients.

Renal Impairment:

No dosage modification is recommended for Belzutifan in mild to moderate renal impairment. However, Belzutifan has not been studied in patients with severe renal impairment.

Hepatic Impairment:

Similarly, no dosage modification is recommended in mild hepatic impairment, but there is no study data for moderate or severe hepatic impairment.

Clinical Studies:

• Belzutifan is an FDA-approved drug (approved in 2021) that blocks hypoxia-inducible factor-2 alpha. It is used to treat renal cell carcinoma in patients with Von Hippel-Lindau (VHL) disease.

• Belzutifan was studied to assess its efficacy and safety for treating central nervous system (CNS) hemangioblastomas. Seven patients with VHL disease and a total of 25 hemangioblastomas received Belzutifan at a dose of 120 mg once daily. The median treatment duration was 13 months.

• The study showed a 71 percent objective response rate. The median time to response was five months. No complete responses were seen. However, 71.4 percent of patients had a partial response, and 28.5 percent had stable disease.

• Reported side effects included low hemoglobin levels, fatigue, and dizziness. No cases of severe anemia were observed.

• Overall, Belzutifan appears to be effective and safe for treating CNS hemangioblastomas in patients with VHL disease. However, larger studies and longer follow-up are needed to confirm its long-term benefits.

Conclusion:

Belzutifan is a targeted cancer medicine that works by blocking a protein that helps tumors grow. Stopping this pathway slows cancer growth and limits tumor survival. It offers a more focused treatment option with fewer effects on normal cells. Talk to our cancer specialist before taking this drug.