Tucatinib

Tucatinib is a prescription medication used for the treatment of advanced or metastatic breast cancer.

• Tucatinib is available under the following different brand names: Tukysa

Common side effects of Tucatinib include:

• diarrhea, 
• nausea, 
• vomiting, 
• stomach pain, 
• loss of appetite, 
• anemia, 
• mouth sores, 
• rash, 
• headache, 
• tiredness, and 
• abnormal liver function tests

Serious side effects of Tucatinib include:

• hives, 
• difficulty breathing, 
• swelling of the face, lips, tongue, or throat, 
• severe or ongoing diarrhea, 
• pain, blisters, bleeding, or severe rash in the palms of the hands or the soles of the feet, 
• blisters or ulcers in the mouth, 
• red or swollen gums, 
• trouble swallowing, 
• seizure, 
• loss of appetite, 
• stomach pain (upper right side), 
• tiredness, 
• itching, 
• dark urine, 
• clay-colored stools, 
• yellowing of the skin or eyes (jaundice), 
• pale skin, 
• unusual tiredness, 
• lightheadedness, 
• shortness of breath, and 
• cold hands and feet

Rare side effects of Tucatinib include:

• none 

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult dosage

Tablet

• 50 mg
• 150 mg

Advanced or Metastatic Breast Cancer

Adult dosage

• 300 mg orally twice daily in combination with trastuzumab and capecitabine

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Tucatinib has no noted severe interactions with any other drugs.
• Tucatinib has no noted serious interactions with any other drugs.
• Tucatinib has no noted moderate interactions with any other drugs.
• Tucatinib has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• None

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Tucatinib?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Tucatinib?”

Cautions

• Severe hepatotoxicity has been reported; monitor ALT, AST, and bilirubin prior to initiation, every 3 weeks during treatment, and as clinically indicated
• May cause fetal harm
• Diarrhea
  • Severe diarrhea, including dehydration, acute kidney injury, and death, has been reported
  • Administer antidiarrheal treatment as clinically indicated
  • Perform diagnostic tests as clinically indicated to exclude other causes of diarrhea
• Drug interaction overview
  • Tucatinib is a substrate of CYP3A4, CYP2C8, P-glycoprotein (P-gp), and BCRP
  • Also, reversible inhibitor of CYP3A4 and CYP2C8; time-dependent inhibitor of CYP3A4; P-gp inhibitor
  • Strong CYP3A or moderate CYP2C8 inducers
  • Avoid coadministration
    • Concomitant use of tucatinib with a strong CYP3A or moderate CYP2C8 inducer decreased tucatinib plasma concentrations, which may reduce the efficacy of tucatinib
  • CYP2C8 inhibitors
    • Avoid coadministration with strong CYP2C8 inhibitors; reduce tucatinib dose if concomitant use cannot be avoided
    • Concomitant use of tucatinib with a strong CYP2C8 inhibitor may increase tucatinib plasma concentrations, which may increase the risk of tucatinib toxicity
    • Coadministration with moderate CYP2C8 inhibitors: Increase monitoring for tucatinib toxicity
  • CYP3A substrates
    • Avoid coadministration with sensitive CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities
  • P-gp substrates
    • Consider reducing the dose of P-gp substrates, where minimal concentration changes may lead to serious or life-threatening toxicities

Pregnancy and Lactation

• Based on animal data and its mechanism of action, fetal harm may occur when administered to pregnant females
• No data is available on use in pregnant females to inform a drug-associated risk
• Verify the pregnancy status of females of reproductive potential before treatment
• Contraception
  • Females of reproductive potential or males with female partners of reproductive potential: Use effective contraception during treatment and at least 1 week after the final dose
• Infertility
  • May impair male and female fertility
• Lactation
  • No data is available on the presence of tucatinib or its metabolites in human or animal milk or its effects on the breastfed child or on milk production
  • Advise females not to breastfeed during treatment and for at least 1 week after the final dose