Neratinib - An Overview

Overview

Neratinib is a drug that is used to treat HER2 (human epidermal growth factor 2)-positive breast cancer. Also, it is recommended for people who have been previously treated with Trastuzumab and other lines of treatment. Neratinib is effective in combination with Capecitabine to treat advanced or metastatic hormone receptor-positive breast cancer that has developed after at least two therapies in the past. Neratinib is a kinase inhibitor. Neratinib blocks cancerous changes by inhibiting an overactive protein that promotes cancer cell movement and, consequently, reduces the burden of the disease.

In 2017, Neratinib was approved by the FDA (U.S. Food and Drug Administration) for early-stage HER2-positive breast cancer as an extended adjuvant treatment following Trastuzumab adjuvant therapy. In 2020, it received another FDA approval for its use in advanced or metastatic HER2-positive breast cancer. For advanced HER2-positive cases, Neratinib is approved for use in combination with Capecitabine.

For Patients

Why Is Neratinib Medication Prescribed?

Neratinib is used to treat adults with hormone receptor-positive cancer of the breast (breast cancer that grows on hormones such as estrogen) following Trastuzumab and other drugs. When at least two different drugs have been used to treat advanced hormone receptor-positive breast cancer that has progressed to other regions of the body, Neratinib is taken in conjunction with Capecitabine.

Neratinib belongs to a group of drugs known as kinase inhibitors. It works by preventing an aberrant protein that instructs cancer cells to proliferate from carrying out its function. Neratinib’s mechanism of action helps reduce or halt the growth of cancerous cells.

What Are the Clinical Indications Of Neratinib?

Use of Neratinib is approved and effective for the extended adjuvant therapy of adult patients diagnosed with early focal HER2-positive breast cancer.

What Is the Dosage of Neratinib?

Neratinib is an orally administered cancer medicine available as tablets. The generally prescribed dose of Neratinib is 240 milligrams (mg) once daily for 1 year.

What Are the Things to Inform the Doctor Before Taking the Drug?

You must inform your doctor if you are on other medications before starting this drug.

You should also inform them about the following conditions:

• Pregnancy.

• Heart disease.

• Migraines.

• Kidney diseases.

• Stroke.

• Cancer.

• Diabetes.

How Should Neratinib be Used?

Neratinib is available as an oral tablet. The tablets should be swallowed whole, without splitting, chewing, or crushing. Neratinib is typically taken once a day with food for a year when used alone to treat breast cancer. Neratinib is basically taken every morning with food on days one through 21 of a 21-day cycle unless your condition worsens or you experience severe side effects when used in conjunction with Capecitabine for the treatment of advanced breast cancer or breast carcinoma that has spread to other regions of the body. Neratinib should be taken daily at around the same time. You must follow all the instructions on your prescription label and ask your pharmacist or doctor to clarify any parts you do not understand.

What Special Precautions Should I Follow?

• If you have an allergy to Neratinib, any other drugs, or any of the substances in Neratinib tablets, let your doctor and pharmacist know before you start taking the drug. For an ingredient list, consult the Medication Guide or ask your pharmacist.

• While taking Neratinib, let your doctor and pharmacist know about any other prescription and over-the-counter drugs, vitamins, nutritional supplements, and herbal products you are currently taking or intend to use. Your doctor might need to adjust the dosages of your prescription drugs or keep a close eye out for any negative effects.

• Antacids should be taken at least 3 hours before or after Neratinib.

• If you have liver disease or have ever had it, let your doctor know.

• If you are currently pregnant, intend to get pregnant, or intend to have a child, let your doctor know. While taking Neratinib, you should avoid getting pregnant. If you are a woman, you must perform a pregnancy test before beginning therapy and use birth control to avoid getting pregnant while taking Neratinib and for at least one month following the last dosage. Birth control should be used by both of you and your partner while taking Neratinib and for three months following your last dosage if you are a man. Discuss birth control options with your physician while undergoing therapy.

• If you are nursing or intend to breastfeed, let your physician know. While using Neratinib and for up to one month following your last dosage, you should not breastfeed.

• You should be aware that Neratinib can cause severe diarrhea.

What Are Neratinib Side Effects?

Some common side effects of Neratinib include:

• Nausea and vomiting.

• Stomach pain.

• Rash or skin reactions.

• Mouth sores.

• Muscle spasms.

• Diarrhea and stomach discomfort.

• Heartburn.

• Swollen mouth ulcers.

• Appetite loss.

• Loss of weight.

• Bleeding from the nose.

• Issues with the nails or alterations in muscular spasms.

Serious side effects are possible. Call your doctor right away if you experience any of the symptoms listed here.

• Yellow skin and eyes.

• Soreness or discomfort in the appropriate upper stomach region or black urine.

• Fatigue.

• Indications of infection include nausea, vomiting, rash, fever, trouble urinating, and discomfort during urination.

Symptoms of Overdose of Neratinib

In case of overdose, immediate medical assistance must be obtained, or a poison control center must be contacted. Diarrhea, nausea, vomiting, and stomach pain may be some of the symptoms that could be observed in a case of Neratinib overdose.

The other symptoms of an overdose of Neritinib are as follows:

• Muscle spasm.

• Dry skin.

• Bladder pain.

• Urinary tract infection.

• Sore mouth.

• Rash.

• Fever.

• Weight loss.

• Loss of appetite.

• Tiredness.

• Nosebleed.

• Dark-colored urine.

• Yellowing of the eyes and skin.

Missed Dose:

If a dose is missed, do not compensate for it. Instruct the patient to carry on the next scheduled daily dose of Neratinib.

Storage:

Store Neratinib at room temperature, between 20 and 25 degrees Celsius. Temporary temperatures of 15 to 18 degrees Celsius are acceptable.

For Doctors:

Indication:

Neratinib is a drug that belongs to the family of kinase inhibitors and is employed in extended adjuvant therapy in adult patients presenting with early-stage HER2-positive breast cancer after adjuvant therapy with Trastuzumab. Neratinib breast cancer therapies offer appreciable therapeutic outcomes in indicated cases.

What Is the Dosage of Neratinib?

1. To Treat Breast Cancer in Its Early Stages:

Adults can be given 240 mg (6 tablets of 60 milligrams each) once daily for a minimum of 1 year. If necessary and tolerated, the patient’s dosage can be modified accordingly. Antidiarrheal drugs like Loperamide must be given alongside as a premedication to deal with diarrhea. Premedication should start from day one of Neratinib therapy and continue until day 56.

2. For the Management of Metastatic or Advanced Breast Cancer:

For metastatic breast cancers, Neratinib is often given in combination with another anticancer drug called Capecitabine. In such scenarios, the daily Neratinib dose should be kept at 240 mg, while the Capecitabine dose has to be maintained at 750 milligrams per square meter. The Capecitabine should be given from day 1 to 14 for each of the 21-day cycles with Neratinib. From day 15 to 21, Neratinib alone should be given. Once the 21-day cycle is completed, the next 21-day cycle begins. With that, Capecitabine has to be restarted for the first 14 days, and the cycle continues until the treatment course is completed.

Dosing Considerations:

• The recommended dosage form for Neratinib is 240 mg (six tablets) taken daily with a meal for one year. However, if the patient's hepatic functions are severely impaired (Child-Pugh class C), the starting dose should be kept as low as 80 milligrams.

• Neratinib tablets at varying doses should be taken around the same time each day to reinforce compliance.

• The tablets must be swallowed whole, and no chewing, breaking, or other alteration is allowed.

• If a dose is missed, it should not be attempted to bridge it; instead, continue the scheduled daily dosage.

What Are the Pharmacological Aspects of Neratinib?

Mechanism of Action:

Neratinib is an irreversible kinase inhibitor because it binds irreversibly to proteins, modulating cellular signaling pathways associated with cellular growth and division. The major cellular components inhibited by Neratinib are the HER2 receptors (human epidermal growth factor receptor 2) and the EGFR receptor (epidermal growth factor receptor). They belong to the family of receptor tyrosine kinases.

• Targeting HER2: HER2 is a member of the ErbB family of receptors, which is believed to be amplified in certain types of breast cancer, particularly in HER2-positive breast cancer. This amplification in the cell activates a signaling cascade that promotes cell growth, survival, and, ultimately, tumor development. Neratinib is preferentially localized to the intracellular domain of the HER2 tyrosine kinase and exerts a blocking effect on the enzymatic activity of HER2. It inhibits receptor activation and cellular signaling that would cascade to increased cell growth and survival.

• Targeting EGFR: In addition to HER2, Neratinib has been shown to inhibit EGFR, a common target in many cancers. At the same time, Neratinib inhibits EGFR, thereby disrupting other signals critical to cancer cell growth.

• Effects on Signaling Pathways: As for the mechanisms of Neratinib's action, several primary signaling pathways are targeted, including the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. These pathways are important in controlling cell cycle progression and other essential cell activities. By blocking these routes, Neratinib suppresses oncogenic processes, enabling tumor shrinkage.

• Clinical Implications: Neratinib therapy's targeted approach is used in patients with HER2-positive breast carcinomas who have previously received additional therapies, such as Trastuzumab. Because it is irreversible, the drug remains effective even after being eliminated from the blood circulation. It proves critical in cancer treatment; after a patient has a challenge with cancer, there is a risk of recurrence.

Pharmacokinetics

Pharmacokinetics studies a drug's absorption, distribution, metabolism, and excretion in the body. Pharmacokinetic profiling of Neratinib is essential in identifying optimal doses for its therapeutic applications and adverse effects.

• Absorption: Neratinib is taken orally, and its absorption is good when taken with food. Food increases drug uptake, leading to higher plasma concentrations. After ingestion, peak plasma concentrations of Neratinib usually occur at around two to eight hours after dose administration. This peak time delay is relevant in dosage, indicating when the drug reaches its active levels in the bloodstream. Patients should take Neratinib with a meal to modulate its absorption and enhance its effectiveness.

• Distribution: Once absorbed, Neratinib has a large volume of distribution, meaning it is extensively distributed throughout the body. This ability also means the drug can penetrate multiple target sites, especially by extending into tumors. In addition, Neratinib has a high protein binding affinity, with over 99% of the drug bound to plasma proteins such as albumin. Protein binding is vital in pharmacokinetics since it can affect the amount of free drug available for action, its pharmacological effects, and drug-to-drug interactions.

• Metabolism: Metabolism is mainly carried out in the liver; it is primarily metabolized by cytochrome P450 enzymes, particularly CYP3A4. This metabolic pathway, mediated by various CYP450 isoforms, is responsible for converting Neratinib into its active or inactive forms. There is genetic polymorphism in CYP3A4 activity, and this, along with other drugs and certain foods, may affect Neratinib metabolism. It is essential to appreciate this metabolic pathway, as several CYP3A4 inducers or inhibitors can alter the plasma levels of Neratinib, either increasing or decreasing its therapeutic effectiveness or enhancing its toxicity.

• Elimination: In this regard, Neratinib is mainly eliminated through the gastrointestinal tract, especially in the feces, and only a small amount is excreted in the urine. This route of elimination has been interpreted to mean that the drug has undergone extensive biotransformation. Also, it can be induced by the wear of CYP (a couple of years of protection) in redoxin-containing systems, which are typical of many hepatocytes. The terminal elimination half-life of Neratinib is approximately seven to seventeen hours, which describes the time taken for the concentration of the drug in the bloodstream to be reduced by 50 percent. The drug's effective concentration is maintained with once-daily administration, making oral spray satisfactory and highlighting its potential for the least adverse effects possible.

Pharmacodynamics:

• Dose-Response Relationship: Neratinib pharmacodynamic effect: with increasing Neratinib dose, HER2 and EGFR signaling inhibition increases. Higher doses of Neratinib lead to greater target inhibition; that is, stronger HER2 and EGFR blockade results in decreased cancer cell proliferation and increased cancer cell death. Higher doses, however, are associated with a higher risk of adverse effects like a higher incidence of diarrhea, nausea, and vomiting. The clinicians must decide whether the benefit of increased doses outweighs the risk of adverse side effects.

• Effect on Biomarkers: This is a critical component of Neratinib's pharmacodynamics. The drug has been associated with several biomarker changes.

• Downstream Signaling Pathway Inhibition: Decreased HER2 phosphorylation ultimately leads to reduced signaling through downstream pathways, such as MAPK (Mitogen-activated protein kinases) or PI3K/AKT. These pathways are essential for cells to progress through the cell cycle and survive; tumor cells' viability diminishes when these pathways are blocked.

• Biomarker Evaluation in Clinical Practice: Tracking these indicators has been effective in determining treatment outcomes and enabling the modification of treatment regimens. For example, evaluating HER2 phosphorylation and associated signaling activity may help physicians determine how well Neratinib targets the tumor and whether patients will respond.

Clinical Studies and Efficacy:

• The ExteNET trial (NCT00878709) was a multicenter, randomized, double-blind, placebo-controlled study of Neratinib following adjuvant Trastuzumab in women with HER2-positive breast cancer.

• Two thousand eight hundred forty patients were randomized to receive either Neratinib (1,420) or a placebo (1,420) within two years of completing Trastuzumab treatment.

• Randomization was based on hormone receptor status, nodal status, and the sequence of Trastuzumab administration.

• Patients received 240 mg of Neratinib or placebo orally once daily for one year.

• The primary endpoint was invasive disease-free survival, tracked for two years and 28 days after randomization.

• Participants were predominantly white, with a median age of 52, and 99.7 percent had an ECOG performance status of zero to one.

• 57 percent had hormone receptor-positive disease, 24 percent were node-negative, and 30 percent had four or more positive nodes.

• 81 percent were enrolled within a year of completing Trastuzumab, with median times to randomization of 4.4 months for Neratinib and 4.6 months for placebo.

• The median treatment duration was 11.6 months for Neratinib and 11.8 months for placebo.

What Are the Contraindications of Neratinib?

There are no contraindications reported.

Warnings and Precautions:

• Diarrhea: Patients receiving Neratinib have been reported to have severe diarrhea and its complications, such as dehydration, hypotension, and renal failure. In the ExteNET trial, fatigue and severe diarrhea were among the most frequently reported adverse events. A considerable number of patients suffered from diarrhea, some presenting with grade 3 diarrhea. Subgroups' median time to onset of grade 3 diarrhea occurred in the first week of the drug and lasted for a few days. To prevent this side effect, patients are advised to begin using Loperamide prophylactically with the first dose of Neratinib and continue it throughout the first two cycles of treatment. All patients should be watched for diarrhea, and more antidiarrheals should be provided. If diarrhea is abundant and associated with dehydration, electrolytes and fluids should be provided. If there is a persistent episode of diarrhea, a stool culture may be obtained to assess for infectious causes of diarrhea.

• Hepatotoxicity: Neratinib is hepatotoxic, with associated elevations in liver enzymes. Tests related to liver function should be undertaken before Neratinib commences, and then every 3 months thereafter, approximately. Testing should also be done when the patients have abnormal diarrhea or other disease symptoms that may be attributed to some liver disorder, including increased fatigue, nausea, vomiting, or stomach pain.

• Embryo-Fetal Toxicity: It has been proven in animal studies that pregnant women receiving Neratinib medicine may potentially cause harm to a developing fetus. Animal studies have also noted that taking this drug when pregnant could lead to unwanted and dangerous effects. A description of the risks is necessary to explain to women, and women who have the potential for conception must take birth control measures not only during the treatment period but at least for one month after that.

Specific Considerations

• Pregnancy: According to animal studies and the mechanism of action of the drug, Neratinib may cause fetal harm if it is given to a pregnant woman. Such data is currently not available until the drug is assessed during pregnancy. In studies on pregnant rabbits, it has been demonstrated that Neratinib leads to abortion, embryo or fetal death, and fetal malformations at lower exposure levels than in patients receiving the recommended doses of the drug. Pregnant women need to know the likely risk to the embryo. For this population group, background risks of severe birth defects or miscarriage are also ill-defined. However, these events are known to occur in the U.S. (United States) population.

• Lactation: There is no information concerning the detection of Neratinib and its metabolites in nursing mothers’ milk or the consequences for nursed infants. Studies done on nursing infants have established that there is a risk of life-threatening reactions in nursing infants. Hence, lactating women are cautioned against breastfeeding while on Neratinib and for one month after the last dose.

• Females and Males of Reproductive Potential: Women able to conceive are advised to perform a pregnancy test before the commencement of treatment with Neratinib since the drug is known to be harmful to the fetus. During therapy and for at least one month after the last dose, effective contraception should be practiced, and effective contraception should be maintained. Efforts should be made to ensure that male patients with female partners at risk of becoming pregnant practice effective contraceptives during therapy and for three months after the last dose according to the basic oncology principles.

• Pediatric Use: The safety and effectiveness of Neratinib in children are still under investigation.

• Geriatric Use: The mean age in the Neratinib study was 52, and some individuals were older than 65. Older patients are more likely to have treatment discontinuation due to adverse reactions compared to younger patients. Side effects that are regarded as severe adverse reactions were higher among elderly patients, with several complications, such as vomiting, diarrhea, renal failure, and dehydration, being the most frequent.

• Hepatic Impairment: This adjustment is unnecessary in patients with mild to moderate liver impairment. However, in hepatically impaired patients, Neratinib clearance is expected to decrease; thus, lower doses will be required.