Koselugo

Neurofibromatosis Type 1 (NF1)

Koselugo is used to treat patients with neurofibromatosis type 1 (NF1), a genetic disorder that causes tumors to grow on nerves throughout the body. It specifically targets a type of tumor known as a plexiform neurofibroma.

Plexiform Neurofibromas

Plexiform neurofibromas are tumors that grow along the nerve sheaths. These tumors can be present at birth or develop during childhood and may cause various health issues as they grow. Koselugo is prescribed when these tumors meet specific criteria:

• Symptomatic: The tumors are causing physical symptoms such as pain, disfigurement, or functional impairment (such as difficulty moving or breathing).
• Inoperable: The tumors cannot be completely removed by surgery because of their size, location, or the risk of causing significant damage to surrounding nerves and tissues.

Approved Age Groups

This medication is approved for use in both pediatric and adult populations:

• Children 2 years of age and older.
• Adults with NF1 who have symptomatic, inoperable plexiform neurofibromas.

The goal of treatment is typically to shrink the tumors or prevent them from growing further, which may help manage the symptoms associated with the condition.

Targeting Cell Growth

Koselugo is a type of medication called a kinase inhibitor. It works by blocking the activity of specific proteins known as MEK1 and MEK2. These proteins are part of a complex signaling chain in the body that controls how cells grow and divide.

In individuals with neurofibromatosis type 1 (NF1), a genetic change causes this signaling chain to stay active more than it should. This constant signaling leads to the development of plexiform neurofibromas, which are tumors that grow along the nerves and can cause pain, weakness, or other physical complications.

By interfering with the MEK proteins, Koselugo helps to:

• Block the signals that promote tumor cell growth.
• Prevent the tumors from getting larger.
• Shrink the size of the tumors in some cases.

This targeted approach focuses on the specific biological pathway responsible for the tumor growth associated with NF1, rather than affecting all rapidly dividing cells in the body.

Common Side Effects

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

• Digestive symptoms such as nausea, vomiting, diarrhea, stomach pain, or constipation.
• Skin reactions including rashes, acne, dry skin, itching, or inflammation around the nails.
• Fatigue or general weakness.
• Muscle, bone, or joint pain.
• Mouth sores or swelling of the gums.
• Headache or fever.
• Swelling in the hands, legs, or feet.

Serious Side Effects

Some side effects require immediate medical attention. Contact a healthcare provider right away if you notice:

• Vision changes: Blurred vision, loss of vision, or seeing light flashes or dark spots.
• Heart issues: New or worsening shortness of breath, swelling in the lower legs, or a pounding heartbeat.
• Muscle damage: Severe muscle pain, tenderness, or dark-colored urine.
• Severe skin reactions: Widespread rash, blistering, or peeling skin.
• Bleeding risks: Increased bruising or bleeding that is difficult to stop.

Heart Problems

Koselugo can cause a decrease in the heart's ability to pump blood, known as cardiomyopathy. Healthcare providers typically perform heart function tests, such as echocardiograms or MUGA scans, before starting treatment and at regular intervals during therapy to monitor heart health.

Eye and Vision Issues

Serious eye problems can occur, including blurred vision or loss of sight. A condition called retinal pigment epithelial detachment (RPED) has been reported in patients taking this medication. Regular eye examinations are usually required, and any new vision changes should be reported immediately.

Muscle and Skin Toxicity

This medication may cause muscle breakdown (rhabdomyolysis) and increased levels of creatine phosphokinase (CPK) in the blood. Severe skin rashes, including acne-like sores or redness, can also develop. Healthcare providers may monitor blood tests and skin condition throughout treatment to manage these risks.

Bleeding Risks

There is an increased risk of bleeding while taking this medication. This can include serious internal bleeding or more common issues like nosebleeds and bruising.

Vitamin E Intake

Koselugo capsules contain high amounts of Vitamin E. Taking additional Vitamin E supplements while on this medication can lead to an overdose of the vitamin, which may further increase the risk of bleeding.

Pregnancy and Reproduction

Koselugo can cause harm to an unborn baby. Effective birth control is recommended for both females and males with female partners of reproductive potential during treatment and for a period after the last dose. Breastfeeding is generally not recommended during treatment and for one week after the final dose.

Pregnancy

Koselugo may cause harm to a fetus when administered to a pregnant person. Before starting treatment, a pregnancy test is typically performed for individuals of reproductive potential to ensure they are not pregnant.

Effective birth control should be used during treatment and for a period after the final dose:

• Females: Use effective contraception during treatment and for at least 1 week after the last dose.
• Males: Use effective contraception during treatment and for at least 1 week after the last dose if you have a female partner of reproductive potential.

If pregnancy occurs during treatment, it is important to notify a healthcare provider immediately to discuss the potential risks to the fetus.

Breastfeeding

It is not known whether Koselugo passes into human breast milk. Due to the risk of serious side effects in a nursing infant, breastfeeding is not recommended during treatment and for 1 week following the final dose.

Fertility

Based on findings from animal studies, Koselugo may affect female fertility. The long-term impact on human fertility is not fully known. Individuals concerned about their ability to have children should discuss this with their healthcare provider before starting treatment.

Dosage Forms

Koselugo is supplied as a capsule for oral administration. The capsules are intended to be swallowed whole with water and should not be chewed, crushed, or opened before use.

• Oral Capsule: This is the only available form for this medication.

FDA Approval History

The U.S. Food and Drug Administration (FDA) first approved Koselugo in April 2020. This initial approval was for pediatric patients 2 years of age and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN). In May 2024, the FDA expanded the approval to include adult patients with the same condition.

Approved Indications

Koselugo is indicated for the treatment of adult and pediatric patients (2 years of age and older) with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. These are tumors that grow along the nerves and are considered inoperable when they cannot be completely removed without risking significant survival or causing major functional issues.

Regulatory Designations

During its development, Koselugo received several special regulatory designations from the FDA, including:

• Orphan Drug Designation: Granted to support the development of drugs for rare diseases.
• Breakthrough Therapy Designation: Intended to expedite the development and review of drugs for serious conditions where preliminary clinical evidence indicates substantial improvement over available therapies.
• Priority Review: Assigned to applications for drugs that would provide significant improvements in the safety or effectiveness of the treatment, diagnosis, or prevention of serious conditions.

Safety Monitoring

The FDA monitors the safety of Koselugo through ongoing surveillance and adverse event reporting systems. Healthcare providers and patients are encouraged to report side effects to the FDA MedWatch program. There is currently no Boxed Warning or Risk Evaluation and Mitigation Strategy (REMS) program required for this medication.

Insurance and Pharmacy Factors

The out-of-pocket cost for Koselugo is largely determined by your insurance plan's specific benefits. Most insurance providers require a prior authorization process before they will cover the medication. Additionally, because Koselugo is a specialty drug, it is often only available through specific specialty pharmacies rather than standard retail locations.

Generic Status

Koselugo is a brand-name medication containing the active ingredient selumetinib. There is currently no generic version available. Brand-name medications generally cost more than their generic counterparts.

Financial Assistance Programs

There may be options available to help manage the cost of treatment:

• Manufacturer Support: The company that makes Koselugo may offer patient assistance programs or copay savings cards for those who meet certain eligibility requirements.
• Non-profit Organizations: Some foundations provide financial aid to patients with rare diseases to help cover medication costs or insurance premiums.

Patients should consult with their healthcare provider or insurance company to understand the specific costs associated with their treatment plan.