Detailed introduction to tucatinib/tucatinib instruction manual

Tucatinib is an oral small molecule tyrosine kinase inhibitor, mainly used to treat HER2-positive advanced or metastatic solid tumors, especially in the treatment of breast cancer and colorectal cancer. Its mechanism of action stems from the highly selective inhibition of the HER2 receptor. This precise targeting reduces the interference with EGFR-related pathways, thus ensuring the efficacy while reducing the occurrence of related side effects.

1. Basic information and drug classification

Common name (English):Tucatinib

Trade name:Tukysa (overseas original research name)

Drug category:HER2 tyrosine kinase inhibitor (Tyrosine Kinase Inhibitor, TKI)

Dosage form and specifications: tablets, usually 150mg/tablet

Tucatinib inhibits the growth signaling of cancer cells by blockingHER2 receptor kinase activity, and has shown good targeted therapeutic effects especially in patients with HER2 gene overexpression or amplification.

2. Approved indications (refer to the US FDA and European EMA approval status)

(1)HER2-positive metastatic breast cancer (MBC): Tucatinib is indicated in combination with trastuzumab and capecitabine for the treatment of adult patients with HER2-positive, unresectable or metastatic breast cancer, including those with brain metastases. Such patients should have received at least one anti-HER2 regimen in the metastatic setting.

(2) HER2-positive, RAS wild-type metastatic colorectal cancer (mCRC): Tucatinib combined with trastuzumab is suitable for the treatment of patients with RAS wild-type, HER2-positive unresectable or metastatic colorectal cancer whose disease has progressed after fluoropyrimidine, oxaliplatin, and irinotecan-based chemotherapy.

3. Recommended usage and dosage

(1)Breast cancer indications: The recommended dose is 300 mg orally twice daily in combination with trastuzumab and capecitabine.

(2)Colorectal cancer indication: Still 300 mg twice daily, combined with trastuzumab.

(3) Medication precautions: It is recommended that patients take it at the same time every day, with or without meals. The tablets should be swallowed whole and avoid chewing, crushing or taking separately. If the patient misses a dose or vomits, he or she should not take additional doses but should take them as usual at the next dose time.

4. Pharmacokinetic characteristics

Tucatinib is a highly selective HER2 inhibitor, which is mainly metabolized by the liver in the body. The drug has good blood-brain barrier penetration ability, which is particularly important for patients with brain metastases. Its half-life allows stable maintenance of a twice-daily dosing regimen, making it suitable for long-term management.

5. Common side effects and monitoring

Although the side effects of tucatinib are reduced compared with other broad-spectrum tyrosine kinase inhibitors, you still need to pay attention to the following during treatment:

Gastrointestinal reactions: Such as diarrhea, nausea, vomiting

Abnormal liver function: Regular monitoring of aminotransferase (ALT/AST) and bilirubin levels is required

Fatigue: One of the more common adverse reactions

Skin reaction: Rarely common but need to pay attention to the occurrence of rash

If serious adverse events occur, dose reduction or treatment suspension should be considered based on the grade of toxicity.

6. Medication contraindications and precautions

(1)Contraindications: It is contraindicated for those allergic to the components of tucatinib.

（2）Pregnant and lactating women: Pregnant women are not recommended to use it and need to use contraception during the medication; risks should be weighed before use during lactation, and it is recommended to suspend breastfeeding.

(3)Drug interactions: Tucatinib is a CYP3A metabolic substrate. It is necessary to avoid combining it with strong CYP3A inducers or inhibitors to prevent abnormal blood concentration.

7. Storage and Compatibility

Tucatinib should be stored in a dry environment below 25°C, avoiding high temperature and humidity. Tablets should be kept intact and should not be used broken.

Reference materials:https://www.tukysa.com/