Tucatinib (Tukysa) is a highly selective HER2 tyrosine kinase inhibitor that has demonstrated significant value in the treatment of advanced HER2-positive breast cancer and colorectal cancer.

How to Use Tucatinib (Tukysa)

Indications and Combination Regimens

Breast cancer: Indicated in combination with trastuzumab and capecitabine for the treatment of advanced unresectable or metastatic HER2-positive breast cancer (including patients with brain metastases), in patients who have received at least one anti-HER2 regimen in the metastatic setting.

Colorectal cancer: Indicated in combination with trastuzumab for the treatment of RAS wild-type, HER2-positive unresectable or metastatic colorectal cancer, in patients who have experienced disease progression following treatment with fluorouracil, oxaliplatin, and irinotecan-based chemotherapy.

Administration Guidelines

Dosage: The recommended dosage is 300 mg taken orally twice daily, with or without food.

Timing: Administer doses approximately 12 hours apart, and it is recommended to take the medication at fixed times each day.

Dosage form handling: Swallow the tablets whole; do not chew, crush, or split them. Avoid taking if a tablet is broken.

Missed dose management: If a dose is missed or vomiting occurs after administration, do not make up for the missed dose—take the next dose at the originally scheduled time.

Dosage Adjustment of Tucatinib (Tukysa)

Diarrhea

Grade 3 (without antidiarrheal treatment): Suspend medication until symptoms resolve to ≤ Grade 1, then resume at the original dosage.

Grade 3 (with antidiarrheal treatment): Suspend medication until symptoms resolve to ≤ Grade 1, then resume at a reduced dosage.

Grade 4: Discontinue medication permanently.

Hepatotoxicity

Grade 2 bilirubin elevation: Suspend medication until values return to normal, then resume at the original dosage.

Grade 3 transaminase or bilirubin elevation: Suspend medication until values return to normal, then resume at a reduced dosage.

Grade 4 transaminase or bilirubin elevation: Discontinue medication permanently.

Medication Use in Special Populations for Tucatinib (Tukysa)

Patients with Hepatic or Renal Impairment

Severe hepatic impairment (Child-Pugh Class C): The recommended dosage is adjusted to 200 mg taken orally twice daily.

Renal impairment: No dosage adjustment is required for mild to moderate renal impairment; however, note that capecitabine is contraindicated in severe renal impairment.

Pregnant and Lactating Women

Pregnancy: Tucatinib has embryo-fetal toxicity. Patients must be informed of the potential risks to the fetus and use effective contraceptive measures.

Lactation: Breastfeeding is prohibited during treatment and for 1 week after the last dose.