(tucatinib)
Risk Summary
TUKYSA is used in combination with other agents. Refer to the Prescribing Information of combination agents for pregnancy information.
Based on findings in animals and its mechanism of action, TUKYSA can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1)]. There are no available human data on TUKYSA use in pregnant women to inform a drug-associated risk. In animal reproduction studies, administration of tucatinib to pregnant rats and rabbits during organogenesis resulted in embryo-fetal mortality, reduced fetal weight and fetal abnormalities at maternal exposures ≥1.3 times the human exposure (AUC) at the recommended dose (see Data). Advise pregnant women and females of reproductive potential of the potential risk to the fetus.
The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.
Animal Data
In pilot embryo-fetal development studies, pregnant rats and rabbits received oral doses of tucatinib up to 150 mg/kg/day during the period of organogenesis.
In rats, oral administration of tucatinib resulted in maternal toxicity (body weight loss, reduced body weight gain, low food consumption) at doses ≥90 mg/kg/day. Fetal effects included reduced number of live fetuses, decreased fetal weight, and fetal abnormalities (increase in skeletal variations, incomplete ossification) at ≥90 mg/kg/day (approximately 3.5 times the human exposure at the recommended dose based on AUC).
In rabbits, oral administration of tucatinib resulted in increased resorptions, decreased percentages of live fetuses, and skeletal, visceral, and external malformations in fetuses at doses ≥90 mg/kg/day (1.3 times the human exposure at the recommended dose based on AUC). Fetal abnormalities included domed head, brain dilation, incomplete ossification of frontal and parietal bones, and a hole in the parietal bone.
Risk Summary
TUKYSA is used in combination with other agents. Refer to the Prescribing Information of combination agents for lactation information. When TUKYSA is used in combination, advise patients not to breastfeed during treatment and for the longest post-treatment duration recommended in the Prescribing Information of any of the individual products.
There are no data on the presence of tucatinib or its metabolites in human or animal milk or its effects on the breastfed child or on milk production. Because of the potential for serious adverse reactions in a breastfed child, advise women not to breastfeed during treatment with TUKYSA and for 1 week after the last dose.
TUKYSA can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)]. TUKYSA is used in combination with other agents. Refer to the Prescribing Information of combination agents for contraception and infertility information. When TUKYSA is used in combination, advise patients to use effective contraception during treatment and for the longest post-treatment duration recommended in the Prescribing Information of any of the individual products.
Pregnancy Testing
Verify the pregnancy status of females of reproductive potential prior to initiating treatment with TUKYSA.
Contraception
Females
Advise females of reproductive potential to use effective contraception during treatment with TUKYSA and for 1 week after the last dose.
Males
Advise male patients with female partners of reproductive potential to use effective contraception during treatment with TUKYSA and for 1 week after the last dose.
Infertility
Based on findings from animal studies, TUKYSA may impair male and female fertility [see Nonclinical Toxicology (13.1)].
The safety and effectiveness of TUKYSA in pediatric patients have not been established.
In HER2CLIMB-05, 51 patients who received TUKYSA were ≥65 years of age of whom 12 patients were ≥75 years of age. The incidence of ≥ Grade 3 adverse reactions was 57% in patients ≥65 years of age compared to 40% in patients <65 years of age. There were no overall differences in the effectiveness of TUKYSA in patients ≥65 years of age compared to younger patients. There were too few patients ≥75 years of age to assess differences in effectiveness or safety.
In HER2CLIMB, 82 patients who received TUKYSA were ≥65 years of age, of whom 8 patients were ≥75 years of age. The incidence of serious adverse reactions in those receiving TUKYSA was 34% in patients ≥65 years of age compared to 24% in patients <65 years of age. The most frequent serious adverse reactions in patients ≥65 years of age who received TUKYSA were diarrhea (9%), vomiting (6%), and nausea (5%). There were no observed overall differences in the effectiveness of TUKYSA in patients ≥65 years of age compared to younger patients. There were too few patients ≥75 years of age to assess differences in effectiveness or safety.
In MOUNTAINEER, 12 patients were ≥65 years of age. There were too few patients ≥65 years of age to assess differences in effectiveness or safety.
The use of TUKYSA in combination with capecitabine and trastuzumab is not recommended in patients with severe renal impairment (creatinine clearance [CLcr]: <30 mL/min estimated by Cockcroft-Gault Equation), because capecitabine is contraindicated in patients with severe renal impairment. Refer to the Prescribing Information of capecitabine for additional information in severe renal impairment.
No dose adjustment is recommended for patients with mild or moderate renal impairment (CLcr: 30 to 89 mL/min).
Tucatinib exposure is increased in patients with severe hepatic impairment (Child-Pugh C). Reduce the dose of TUKYSA for patients with severe (Child‑Pugh C) hepatic impairment [see Dosage and Administration (2.4), Clinical Pharmacology (12.3)].
No dose adjustment for TUKYSA is required for patients with mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment.
| This Medication Guide has been approved by the U.S. Food and Drug Administration. Revised: 10/2026 | ||
MEDICATION GUIDE TUKYSA® (too-KYE-sah) (tucatinib) tablets | ||
Important: If your healthcare provider prescribes TUKYSA in combination with capecitabine or pertuzumab, also read the Patient Information that comes with capecitabine or pertuzumab. | ||
What is the most important information I should know about TUKYSA? TUKYSA can cause serious side effects, including:
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See “What are the possible side effects of TUKYSA?” for more information about side effects. | ||
What is TUKYSA? TUKYSA is a prescription medicine used in adults:
Your healthcare provider will perform a test to make sure TUKYSA is right for you. It is not known if TUKYSA is safe and effective in children. | ||
Before taking TUKYSA, tell your healthcare provider about all of your medical conditions, including if you:
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. TUKYSA may affect the way your other medicines work, and other medicines may affect the way TUKYSA works. Know the medicines you take. Keep a list of all the medicines you take and show it to your healthcare provider and pharmacist every time you get a new medicine. | ||
How should I take TUKYSA?
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What are the possible side effects of TUKYSA? TUKYSA can cause serious side effects, including: The most common side effects of TUKYSA in combination with trastuzumab and pertuzumab in adults with HER2-positive breast cancer include: | ||
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The most common side effects of TUKYSA in combination with trastuzumab and capecitabine in adults with HER2-positive breast cancer include: | ||
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The most common side effects of TUKYSA in combination with trastuzumab in adults with RAS wild-type HER2-positive colorectal cancer include: | ||
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Your healthcare provider may change your dose of TUKYSA, temporarily stop, or permanently stop treatment with TUKYSA if you have certain side effects. TUKYSA may cause fertility problems in males and females, which may affect the ability to have children. Talk to your healthcare provider if you have concerns about fertility. These are not all of the possible side effects of TUKYSA. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. | ||
How should I store TUKYSA?
Keep TUKYSA and all medicines out of the reach of children. | ||
General information about the safe and effective use of TUKYSA. Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use TUKYSA for a condition for which it was not prescribed. Do not give TUKYSA to other people, even if they have the same symptoms that you have. It may harm them. You can ask your pharmacist or healthcare provider for information about TUKYSA that is written for health professionals. | ||
What are the ingredients in TUKYSA? Active ingredient: tucatinib Inactive ingredients: Tablet core: copovidone, crospovidone, sodium chloride, potassium chloride, sodium bicarbonate, colloidal silicon dioxide, magnesium stearate, and microcrystalline cellulose. Tablet coating: yellow film coat: polyvinyl alcohol, titanium dioxide, macrogol/polyethylene glycol, talc, and yellow iron oxide non-irradiated. | ||
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