Osimertinib

Approved Uses

Osimertinib is primarily used to treat non-small cell lung cancer (NSCLC) that tests positive for specific mutations in the epidermal growth factor receptor (EGFR) gene. These mutations include exon 19 deletions or exon 21 L858R mutations. It is used in the following situations:

• After Surgery: It may be used as an additional (adjuvant) treatment after the primary tumor has been surgically removed to help lower the risk of the cancer coming back.
• First-Line Treatment: It is used as the first treatment for patients whose NSCLC has spread to other parts of the body (metastatic).
• Advanced or Recurrent Cancer: It is used for metastatic NSCLC that has a specific mutation called T790M, particularly if the cancer has worsened during or after treatment with other EGFR inhibitor medications.
• Stage III Lung Cancer: It is used for adults with locally advanced, unresectable Stage III NSCLC whose disease has not worsened after receiving platinum-based chemotherapy combined with radiation therapy.

Genetic Testing

Before starting treatment, a healthcare provider will perform a specific laboratory test on the tumor tissue or blood to confirm that the cancer has the necessary EGFR mutations. This ensures the medication is appropriate for the specific type of cancer being treated.

Targeting Cancer Growth

Osimertinib is a type of medication known as a kinase inhibitor. It is designed to treat non-small cell lung cancer that has specific genetic mutations in a protein called epidermal growth factor receptor (EGFR).

In certain types of lung cancer, the EGFR protein is mutated, acting like a switch that is stuck in the "on" position. This sends constant signals to the cancer cells to divide and spread throughout the body. Osimertinib works by interfering with this process in the following ways:

• Binding to mutated proteins: The medication attaches to the mutated EGFR proteins on the surface of the cancer cells.
• Blocking signals: Once attached, it blocks the chemical signals that tell the cancer cells to grow and survive.
• Slowing progression: By cutting off these growth signals, the drug helps to slow down or stop the spread of the cancer and may help shrink tumors.

This medication is specifically effective against certain mutations, such as exon 19 deletions and exon 21 L858R mutations. It is also designed to target the T790M mutation, which is a specific change that can develop in cancer cells and make them resistant to other similar treatments.

Common Side Effects

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

• Diarrhea
• Skin rash, dry skin, or itching
• Nail changes, such as redness, tenderness, or breaking
• Nausea or decreased appetite
• Mouth sores
• Feeling tired or weak
• Muscle, bone, or joint pain
• Cough
• Headache or back pain

Serious Side Effects

Some side effects can be severe and require immediate medical attention. Contact a healthcare provider right away if you experience:

• Lung problems: New or worsening shortness of breath, cough, or fever.
• Heart problems: Fast or pounding heartbeat, dizziness, or sudden swelling in the legs or feet.
• Eye problems: Blurred vision, eye pain, watery eyes, or sensitivity to light.
• Severe skin reactions: Widespread rash, blistering, or peeling skin.
• Blood cell changes: Signs of infection (such as fever and chills) or unusual bruising and bleeding.

Lung Problems

Osimertinib may cause inflammation of the lungs, known as interstitial lung disease (ILD) or pneumonitis. This condition can be severe or life-threatening. Symptoms to watch for include:

• New or worsening shortness of breath
• Cough
• Fever

Heart Conditions

This medication can affect the heart's electrical activity, leading to a condition called QTc interval prolongation. It may also weaken the heart muscle (cardiomyopathy). Monitoring may include:

• Periodic electrocardiograms (ECG) to check heart rhythm
• Echocardiograms or MUGA scans to check how well the heart pumps blood
• Blood tests to monitor electrolyte levels, such as potassium and magnesium

Skin and Eye Reactions

Severe skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, have been reported. Additionally, inflammation of the cornea (keratitis) may occur. Seek medical attention for symptoms like:

• Severe rash, blistering, or peeling skin
• Eye pain, redness, blurred vision, or light sensitivity

Blood Disorders

In rare cases, osimertinib may cause aplastic anemia, a condition where the body stops producing enough new blood cells. Symptoms may include persistent fever, unusual bruising, or bleeding.

Pregnancy and Breastfeeding

Osimertinib can cause harm to a developing fetus. Effective birth control is typically recommended for patients and their partners during treatment and for a period after the final dose. Breastfeeding is generally not advised while taking this medication and for a short time after the last dose.

Pregnancy

Osimertinib may cause fetal harm when administered to a pregnant woman. Animal studies have shown that the medication can lead to pregnancy loss or developmental issues. Individuals who are pregnant or planning to become pregnant should discuss the potential risks and benefits with their healthcare provider before starting treatment.

Contraception Requirements

Because of the risk to a developing fetus, healthcare providers typically recommend strict contraception measures:

• For females: Use effective birth control during treatment and for at least 6 weeks after the final dose of osimertinib.
• For males: Men with female partners who could become pregnant should use effective birth control during treatment and for at least 4 months after the final dose.

Breastfeeding

It is not known whether osimertinib passes into human breast milk. Due to the potential for serious side effects in a nursing infant, breastfeeding is not recommended during treatment. Patients are typically advised to wait at least 2 weeks after their last dose of osimertinib before resuming breastfeeding.

Available Forms

Osimertinib is available in the following dosage form:

• Oral Tablet: This medication is taken by mouth.

The tablets are typically swallowed whole. For individuals who have difficulty swallowing tablets, the medication may be prepared as a liquid mixture by dispersing the tablet in water, following specific medical instructions provided by a healthcare professional.

FDA Approval and Indications

Osimertinib was first approved by the U.S. Food and Drug Administration (FDA) in 2015. It is indicated for the treatment of adult patients with non-small cell lung cancer (NSCLC) that tests positive for specific epidermal growth factor receptor (EGFR) mutations.

Current approved uses include:

• Adjuvant Therapy: Treatment after complete tumor removal in patients with early-stage NSCLC whose tumors have EGFR exon 19 deletions or exon 21 L858R mutations.
• Stage III NSCLC: Treatment for patients with locally advanced, unresectable Stage III NSCLC whose disease has not progressed following platinum-based chemotherapy and radiation, and whose tumors have specific EGFR mutations.
• First-line Metastatic Treatment: Initial treatment for patients with metastatic NSCLC that has EGFR exon 19 deletions or exon 21 L858R mutations.
• T790M Mutation-Positive NSCLC: Treatment for patients with metastatic NSCLC who have the EGFR T790M mutation and whose disease has worsened during or after treatment with other EGFR tyrosine kinase inhibitor (TKI) medicines.

Biomarker Testing

The FDA requires the use of an FDA-approved test to confirm the presence of specific EGFR mutations before starting treatment with osimertinib. This ensures the medication is appropriate for the patient's specific type of cancer.

Regulatory Requirements

There are currently no Boxed Warnings or Risk Evaluation and Mitigation Strategies (REMS) associated with osimertinib. However, it remains under standard FDA monitoring for safety and efficacy.

Osimertinib is a prescription medication, and its price can vary significantly based on several factors related to insurance and pharmacy services.

Insurance and Out-of-Pocket Costs

For most patients, the cost of osimertinib is determined by their health insurance provider. Factors that influence the final price include:

• The specific coverage levels of the insurance plan.
• Applicable copayments or coinsurance amounts.
• Whether the medication is covered under the plan's pharmacy or medical benefits.

Patients should contact their insurance company directly to confirm coverage details and any requirements for prior authorization.

Obtaining the Medication

As a specialized treatment for non-small cell lung cancer, osimertinib is typically obtained through specific pharmacy channels. Healthcare providers and pharmacists can provide guidance on the prescription process and help patients understand the costs associated with their specific treatment regimen. Patients may also inquire with their healthcare team about potential financial assistance programs that may be available to help manage out-of-pocket expenses.