TUKYSA: Uses, Dosage & Side Effects
A highly selective HER2-targeted tyrosine kinase inhibitor for metastatic HER2-positive breast cancer, including patients with brain metastases
TUKYSA (tucatinib) is a highly selective oral tyrosine kinase inhibitor that targets the HER2 (human epidermal growth factor receptor 2) protein. It is used in combination with trastuzumab and capecitabine for the treatment of adults with HER2-positive metastatic breast cancer, including those whose cancer has spread to the brain. TUKYSA works by blocking HER2 signaling pathways that drive cancer cell growth, and its selectivity for HER2 over EGFR contributes to a more favorable side-effect profile. The landmark HER2CLIMB trial demonstrated significant improvements in progression-free survival and overall survival, including in patients with brain metastases—a population with historically limited treatment options.
Quick Facts: TUKYSA
Key Takeaways
- TUKYSA (tucatinib) is a highly selective HER2 tyrosine kinase inhibitor taken orally in combination with trastuzumab and capecitabine for HER2-positive metastatic breast cancer that has progressed after prior HER2-directed therapies.
- It is one of the few HER2-targeted therapies with proven efficacy in patients with brain metastases, as demonstrated in the HER2CLIMB trial with significant improvements in progression-free survival and overall survival in this difficult-to-treat population.
- Diarrhea and hepatotoxicity (liver damage) are the most important side effects to monitor; liver function tests must be performed before and during treatment, and diarrhea should be treated promptly at the first sign of symptoms.
- TUKYSA interacts with many medications through CYP enzyme inhibition and P-glycoprotein inhibition; patients must inform their doctor about all concurrent medications, including herbal supplements such as St. John’s wort.
- TUKYSA must not be taken during pregnancy due to risk of fetal harm; effective contraception is required for both women and men of reproductive potential during treatment and for at least 1 week after the last dose.
What Is TUKYSA and What Is It Used For?
TUKYSA contains the active substance tucatinib, which belongs to a class of cancer medications known as protein kinase inhibitors. Specifically, tucatinib is a small-molecule tyrosine kinase inhibitor that targets HER2 (human epidermal growth factor receptor 2, also known as ErbB2). HER2 is a protein found on the surface of some cancer cells, and when it is overexpressed or amplified—a condition known as HER2-positive cancer—it sends powerful growth signals that drive rapid and uncontrolled cell proliferation. Approximately 15–20% of all breast cancers are HER2-positive, and these cancers tend to be more aggressive and more likely to recur than HER2-negative breast cancers.
What sets tucatinib apart from other HER2-targeted tyrosine kinase inhibitors is its remarkably high selectivity for HER2 over EGFR (epidermal growth factor receptor, also called HER1). While earlier-generation dual HER2/EGFR inhibitors such as lapatinib and neratinib block both receptors, tucatinib was specifically designed to inhibit HER2 with minimal EGFR inhibition. This selectivity is clinically significant because many of the most troublesome side effects of HER2-targeted therapies—such as severe diarrhea, skin rashes, and oral mucositis—are driven by EGFR inhibition in normal epithelial tissues rather than by HER2 inhibition. By sparing EGFR, tucatinib aims to provide effective HER2 blockade with a more manageable toxicity profile.
TUKYSA is specifically approved for use in adults with HER2-positive breast cancer that has met the following criteria: the cancer has spread beyond the breast to distant sites (metastatic) or is locally advanced and cannot be removed by surgery (unresectable), and the patient has previously received one or more anti-HER2-based treatment regimens in the metastatic setting. TUKYSA is not used alone—it is always prescribed as part of a triple combination regimen together with trastuzumab (a monoclonal antibody targeting HER2) and capecitabine (an oral chemotherapy agent). This combination approach attacks HER2-positive cancer through multiple complementary mechanisms: tucatinib blocks intracellular HER2 signaling, trastuzumab blocks the extracellular domain of HER2 and recruits immune cells, and capecitabine provides direct cytotoxic activity against dividing cancer cells.
One of the most clinically important features of TUKYSA is its demonstrated efficacy in patients with brain metastases. Brain metastases occur in up to 50% of patients with HER2-positive metastatic breast cancer and represent a major unmet medical need, as many systemic treatments cannot effectively cross the blood–brain barrier. Tucatinib is a small molecule that can penetrate the central nervous system, and the pivotal HER2CLIMB clinical trial specifically included and evaluated patients with active or previously treated brain metastases. The results showed that the addition of tucatinib to trastuzumab and capecitabine significantly improved both progression-free survival and overall survival in patients with brain metastases, establishing TUKYSA as one of the preferred treatment options for this challenging clinical scenario.
The approval of TUKYSA was based primarily on the results of the HER2CLIMB trial (NCT02614794), a randomized, double-blind, placebo-controlled phase 2 study published in the New England Journal of Medicine in 2020. This trial enrolled 612 patients with HER2-positive metastatic breast cancer who had previously received trastuzumab, pertuzumab, and ado-trastuzumab emtansine (T-DM1). Patients were randomized 2:1 to receive tucatinib or placebo in combination with trastuzumab and capecitabine. The primary endpoint of progression-free survival was significantly improved in the tucatinib group (7.8 months versus 5.6 months; hazard ratio 0.54), and overall survival was also significantly improved (21.9 months versus 17.4 months; hazard ratio 0.66). Among patients with brain metastases, progression-free survival at one year was 24.9% with tucatinib versus 0% with placebo.
TUKYSA was specifically engineered to inhibit HER2 with approximately 1,000-fold greater selectivity over EGFR. This means it effectively blocks the cancer-driving HER2 signals while largely sparing EGFR in normal tissues such as the skin and gut lining. This targeted design is why TUKYSA generally causes fewer and less severe skin-related and gastrointestinal side effects compared with older dual HER2/EGFR inhibitors.
What Should You Know Before Taking TUKYSA?
Contraindications
TUKYSA has one absolute contraindication: hypersensitivity (allergy) to tucatinib or to any of the other ingredients in the tablet formulation. If you have previously experienced an allergic reaction to this medication, you must not take it again. The inactive ingredients in TUKYSA include copovidone, crospovidone, sodium chloride, potassium chloride, sodium hydrogen carbonate, colloidal anhydrous silica, magnesium stearate, and microcrystalline cellulose, with a film coating containing polyvinyl alcohol, titanium dioxide, macrogol, talc, and yellow iron oxide.
It is important to note that because TUKYSA is always used in combination with trastuzumab and capecitabine, the contraindications for those two medications also apply. Your doctor will review the complete list of contraindications for all three drugs before starting treatment. In particular, capecitabine has additional contraindications including complete deficiency of dihydropyrimidine dehydrogenase (DPD), severe hepatic impairment, severe renal impairment, and concurrent treatment with sorivudine or its analogues.
Warnings and Precautions
TUKYSA can cause serious liver problems. Your doctor will perform liver function tests before starting treatment and at regular intervals during treatment. Signs of liver damage include yellowing of the skin or eyes (jaundice), dark urine, itching, pain or discomfort in the upper right part of the abdomen, unusual tiredness, and loss of appetite. Contact your doctor immediately if you experience any of these symptoms.
Diarrhea is very common with TUKYSA and can be severe. Tell your doctor at the first sign of diarrhea (loose stools) so that treatment can be started promptly. If diarrhea persists alongside nausea and/or vomiting, seek medical attention immediately, as dehydration can become life-threatening. Your doctor may prescribe anti-diarrheal medications and may need to reduce your dose or temporarily stop treatment.
Before starting TUKYSA, tell your doctor about all medical conditions you have, particularly any liver disease or history of liver problems. Your doctor will assess your liver function using blood tests (measuring ALT, AST, and bilirubin levels) before the first dose and will continue to monitor these values regularly throughout treatment. If your liver enzymes become significantly elevated, your doctor may need to reduce the dose, temporarily pause treatment, or discontinue TUKYSA permanently depending on the severity.
TUKYSA should not be used in children and adolescents under 18 years of age. The safety and efficacy of tucatinib have not been studied in this age group.
Pregnancy and Breastfeeding
TUKYSA can cause harm to an unborn baby when taken by a pregnant woman. Before starting treatment, your doctor will require a pregnancy test. If you are pregnant, think you may be pregnant, or are planning to have a baby, talk to your doctor before taking this medication. Your doctor will weigh the potential benefit to you against the risk to the unborn child.
If you are a woman of childbearing potential, you must use reliable contraception to prevent pregnancy while taking TUKYSA and for at least 1 week after the last dose. If you are a man with a female partner of childbearing potential, you must also use reliable contraception during treatment and for at least 1 week after the last dose. If you become pregnant during treatment, tell your doctor immediately so that the benefits and risks of continuing treatment can be assessed.
It is not known whether tucatinib passes into breast milk. You should not breastfeed during treatment with TUKYSA and for at least 1 week after the last dose. Talk to your doctor about the best way to feed your baby during treatment. The trastuzumab and capecitabine components of the combination regimen have their own specific breastfeeding restrictions as well.
Driving and Using Machines
TUKYSA is not expected to affect your ability to drive or use machines. However, you are responsible for assessing whether you are fit to operate motor vehicles or perform tasks that require alertness. If you experience side effects that affect your concentration or coordination, do not drive or use heavy machinery until the symptoms resolve.
TUKYSA contains 55.3 mg sodium (the main component of table salt) per 300 mg dose, which corresponds to 2.75% of the maximum recommended daily sodium intake for adults. It also contains 60.6 mg potassium per 300 mg dose. This should be taken into consideration by patients with reduced kidney function or those on a potassium-restricted diet. Discuss with your doctor if you have any concerns about sodium or potassium intake.
How Does TUKYSA Interact with Other Drugs?
Tucatinib is metabolized in the liver primarily by the CYP2C8 enzyme and, to a lesser extent, by CYP3A4. Tucatinib itself is a strong inhibitor of CYP2C8, a moderate inhibitor of CYP3A4, and an inhibitor of the drug transporters P-glycoprotein (P-gp) and organic anion-transporting polypeptides OATP1B1 and OATP1B3. These pharmacokinetic properties mean that TUKYSA has the potential to interact with a wide range of medications. It is essential that you tell your doctor about all medicines you are taking, have recently taken, or plan to take, including prescription drugs, over-the-counter medications, vitamins, and herbal supplements.
Major Interactions
The following drug interactions are considered clinically significant and may require dose adjustments, additional monitoring, or avoidance of the combination:
| Drug / Class | Effect | Clinical Action |
|---|---|---|
| Rifampicin (strong CYP3A4 inducer) | Significantly decreases tucatinib blood levels, reducing efficacy | Avoid concurrent use; consider alternative antibiotics |
| St. John’s wort (strong CYP3A4 inducer) | May significantly reduce tucatinib levels | Do not use during TUKYSA treatment |
| Phenytoin, Carbamazepine (strong CYP3A4 inducers) | May significantly reduce tucatinib levels | Avoid concurrent use; discuss alternative anticonvulsants |
| Itraconazole, Ketoconazole, Voriconazole, Posaconazole (strong CYP3A4 inhibitors) | May increase tucatinib blood levels and toxicity | Avoid if possible; if used, monitor closely for side effects |
| Darunavir, Saquinavir, Tipranavir (HIV protease inhibitors) | May increase tucatinib levels | Close monitoring required; dose adjustment may be needed |
| Repaglinide (CYP2C8 substrate) | TUKYSA increases repaglinide levels, risk of hypoglycemia | Avoid concurrent use or reduce repaglinide dose; monitor blood glucose |
Moderate Interactions
The following interactions are of moderate clinical significance. Your doctor may need to adjust dosing or increase monitoring when these medications are used together with TUKYSA:
| Drug / Class | Effect | Clinical Action |
|---|---|---|
| Digoxin (P-gp substrate) | TUKYSA may increase digoxin levels | Monitor digoxin levels closely; dose adjustment may be needed |
| Sirolimus, Tacrolimus (immunosuppressants) | TUKYSA may increase levels of these drugs | Therapeutic drug monitoring recommended |
| Midazolam, Triazolam (CYP3A4 substrates) | TUKYSA may increase sedation and CNS depression | Use reduced doses; monitor for excessive sedation |
| Lovastatin, Lomitapid (CYP3A4 substrates) | TUKYSA may increase statin levels, risk of myopathy | Monitor for muscle pain; dose adjustment may be needed |
| Everolimus, Ibrutinib (anticancer CYP3A4 substrates) | TUKYSA may increase levels of these agents | Monitor closely; oncologist should adjust doses if needed |
| Buspiron (CYP3A4 substrate) | TUKYSA may increase buspiron levels | Monitor for increased sedation; dose reduction may be needed |
| Avanafil, Vardenafil (PDE5 inhibitors) | TUKYSA may increase levels of these drugs | Use reduced doses; monitor for side effects |
| Alfentanil (opioid analgesic) | TUKYSA may increase alfentanil levels and respiratory depression | Reduce alfentanil dose; monitor respiratory function |
| Naloxegol (peripherally acting opioid antagonist) | TUKYSA may increase naloxegol levels | Monitor for gastrointestinal side effects; dose adjustment may be needed |
| Darifenacin, Ebastin (various substrates) | TUKYSA may increase levels of these drugs | Monitor for increased side effects; consider dose adjustment |
Because tucatinib affects multiple drug-metabolizing enzymes and transporters, new drug interactions are being identified regularly. Always tell your doctor, pharmacist, or nurse about every medication you are taking—including herbal remedies, vitamins, and supplements—before starting or changing any treatment while on TUKYSA.
What Is the Correct Dosage of TUKYSA?
TUKYSA should always be taken exactly as prescribed by your doctor or pharmacist. Do not change your dose or stop taking TUKYSA without consulting your healthcare team. The treatment is intended to be taken continuously for as long as it continues to provide clinical benefit and the side effects remain manageable.
Adults
Standard Adult Dose
300 mg (two 150 mg tablets) taken orally twice daily, approximately 12 hours apart, at the same times each day. Can be taken with food or between meals.
TUKYSA is used in combination with:
- Trastuzumab: Administered intravenously according to the prescribed schedule
- Capecitabine: 1,000 mg/m² taken orally twice daily on days 1–14 of each 21-day cycle
Dose Reductions for Side Effects
If you experience certain side effects, your doctor may lower your TUKYSA dose. The 50 mg tablets are available to facilitate dose reductions. Possible reduced dose levels include:
- First reduction: 250 mg twice daily
- Second reduction: 200 mg twice daily
- Third reduction: 150 mg twice daily
If further dose reduction below 150 mg twice daily is required, your doctor will discontinue TUKYSA.
How to Take TUKYSA
TUKYSA tablets can be taken with food or on an empty stomach. Swallow the tablets whole, one after another. Do not chew, crush, or break the tablets, as this may alter how the active ingredient is released and absorbed. Take each dose approximately 12 hours apart, at the same times each day, to maintain consistent drug levels in your body.
If you vomit after taking a dose of TUKYSA, do not take an additional dose. Simply take the next scheduled dose at the usual time.
Children and Adolescents
TUKYSA is not approved for use in children or adolescents under 18 years of age. The safety and efficacy of tucatinib have not been established in pediatric patients. HER2-positive breast cancer is exceedingly rare in this age group.
Elderly Patients
No specific dose adjustment is required for elderly patients based on age alone. However, elderly patients may be more susceptible to certain side effects, particularly diarrhea and hepatotoxicity. Your doctor will monitor you closely and may adjust the dose based on how well you tolerate the treatment and your overall health status, including kidney and liver function.
Missed Dose
If you forget to take a dose of TUKYSA, do not take a double dose to make up for it. Simply take the next dose at the regular scheduled time. If you are unsure about what to do, contact your doctor or pharmacist for advice. Try to set an alarm or use a pill organizer to help remember your doses.
Overdose
If you take more TUKYSA than prescribed, contact your doctor or pharmacist immediately. If possible, show them the packaging so they can identify the product and the amount taken. There is no specific antidote for tucatinib overdose. Treatment would be supportive, focusing on managing symptoms and monitoring liver function, electrolytes, and hydration status.
TUKYSA is a long-term treatment that should be taken continuously. Do not stop taking TUKYSA without first discussing it with your doctor, even if you feel well. Stopping treatment prematurely may allow the cancer to progress. If you experience side effects that are difficult to manage, talk to your doctor about dose adjustments rather than stopping on your own.
What Are the Side Effects of TUKYSA?
Like all medicines, TUKYSA can cause side effects, although not everyone gets them. The side effects listed below reflect the safety profile observed in clinical trials when TUKYSA was used in combination with trastuzumab and capecitabine. It is important to note that some side effects may also be attributable to the companion medications (trastuzumab and capecitabine) rather than tucatinib alone.
Your doctor will monitor you for side effects throughout treatment. Many side effects can be managed with supportive care, dose reductions, or temporary treatment interruptions. Contact your healthcare team if you experience any new or worsening symptoms during treatment.
Very Common
May affect more than 1 in 10 patients
- Diarrhea – the most frequently reported side effect; can be severe and may require anti-diarrheal medication, dose reduction, or treatment interruption
- Nausea – feeling sick to the stomach; anti-nausea medications may help
- Vomiting – often accompanies nausea; may lead to dehydration if persistent
- Stomatitis / oral mucositis – mouth sores, inflammation of the oral mucosa, and mouth ulcers
- Hepatotoxicity – liver damage detected by blood tests (elevated ALT, AST, bilirubin); may cause jaundice, dark urine, itching, or upper abdominal pain
- Skin rash – may include redness, itching, or skin eruptions
- Joint pain (arthralgia) – pain in the joints
- Weight loss – unintentional decrease in body weight
- Epistaxis (nosebleeds) – bleeding from the nose
Common
May affect 1 in 10 to 1 in 100 patients
- Palmar-plantar erythrodysesthesia (hand-foot syndrome) – redness, swelling, tingling, or peeling of the skin on the palms and soles (primarily related to capecitabine)
- Fatigue – feeling tired or lacking energy
- Decreased appetite – reduced desire to eat
- Abdominal pain – pain in the stomach or belly area
- Headache – pain in the head
- Anemia – low red blood cell count, which may cause tiredness and shortness of breath
Uncommon
May affect 1 in 100 to 1 in 1,000 patients
- Severe hepatotoxicity – serious liver injury requiring permanent discontinuation
- Severe dehydration – resulting from persistent diarrhea, nausea, and vomiting
- Interstitial lung disease – inflammation of the lung tissue (may be related to trastuzumab)
Contact your doctor or seek emergency medical care immediately if you experience: severe or persistent diarrhea (more than 4 loose stools per day or diarrhea with blood); yellowing of the skin or eyes; dark-colored urine; severe abdominal pain; high fever; signs of severe dehydration (very dry mouth, dizziness, confusion, inability to urinate); or difficulty breathing. These may be signs of serious complications that require urgent treatment.
It is important to report all suspected side effects to your healthcare provider. Ongoing monitoring of the benefit-risk balance of TUKYSA is conducted by regulatory authorities worldwide. By reporting side effects, you help contribute to the continued safety surveillance of this medication. In the European Union, side effects can be reported through the national pharmacovigilance system. In the United States, adverse events can be reported to the FDA MedWatch program.
How Should You Store TUKYSA?
Proper storage of TUKYSA is important to ensure the medication remains effective and safe throughout the treatment period. Follow these storage guidelines carefully:
- Temperature: No special storage conditions are required. Store at room temperature.
- Packaging: Keep the tablets in the original aluminum foil blister packs until ready for use. This protects the tablets from moisture and light.
- Children: Keep this medicine out of the sight and reach of children. TUKYSA is a potent anticancer medication and accidental ingestion by a child could be extremely dangerous.
- Expiration date: Do not use TUKYSA after the expiration date stated on the blister pack and the carton. The expiration date refers to the last day of the stated month.
- Disposal: Do not throw unused tablets into household waste or down the drain. Ask your pharmacist how to dispose of medicines that are no longer needed. These measures help protect the environment.
TUKYSA 50 mg tablets are round, yellow, film-coated tablets imprinted with “TUC” on one side and “50” on the other side. TUKYSA 150 mg tablets are oval, yellow, film-coated tablets imprinted with “TUC” on one side and “150” on the other side. If your tablets look different from this description, contact your pharmacist.
What Does TUKYSA Contain?
Understanding the full composition of your medication is important, particularly if you have known allergies or sensitivities to any pharmaceutical ingredients. TUKYSA is available in two strengths, both formulated as yellow film-coated tablets.
Active Substance
Each film-coated tablet contains either 50 mg or 150 mg of tucatinib as the active ingredient. Tucatinib (chemical name: N6-[4,4-bis(4-fluorophenyl)butyl]-N2-[2-methyl-4-[2-(1-methylpiperidin-4-yl)ethylamino]phenyl]-7-oxo-6,8-dihydro-5H-pyrido[2,3-d]pyrimidine-2,6-diamine) is a small-molecule tyrosine kinase inhibitor with a molecular weight of approximately 480.6 daltons.
Inactive Ingredients
The tablet core contains: copovidone, crospovidone, sodium chloride, potassium chloride, sodium hydrogen carbonate, colloidal anhydrous silica, magnesium stearate, and microcrystalline cellulose.
The film coating contains: polyvinyl alcohol, titanium dioxide (E171), macrogol, talc, and yellow iron oxide (E172).
Available Pack Sizes
TUKYSA is supplied in aluminum foil blisters in the following pack sizes:
- TUKYSA 50 mg: 88 film-coated tablets (11 blisters with 8 tablets per blister)
- TUKYSA 150 mg: 84 film-coated tablets (21 blisters with 4 tablets per blister)
Not all pack sizes may be marketed in all countries. The marketing authorization holder is Pfizer Europe MA EEIG, Boulevard de la Plaine 17, 1050 Brussels, Belgium. The tablets are manufactured by Seagen B.V. (Schiphol, Netherlands) or Corden Pharma GmbH (Plankstadt, Germany).
Frequently Asked Questions About TUKYSA
TUKYSA (tucatinib) is used in combination with trastuzumab and capecitabine to treat adults with HER2-positive breast cancer that has spread to other parts of the body (metastatic) or cannot be removed by surgery. It is particularly valuable for patients whose cancer has spread to the brain, as the HER2CLIMB trial demonstrated significant benefit in this population. TUKYSA is used after the patient has already received one or more HER2-directed treatment regimens.
TUKYSA is highly selective for HER2 with approximately 1,000-fold greater selectivity over EGFR (HER1). This differentiates it from older dual HER2/EGFR inhibitors like lapatinib and neratinib, which block both receptors. The high HER2 selectivity means TUKYSA generally causes fewer skin-related side effects and less severe diarrhea compared with dual inhibitors, because many epithelial toxicities are driven by EGFR inhibition rather than HER2 inhibition. Additionally, tucatinib is a small molecule that can cross the blood–brain barrier, making it effective against brain metastases.
Yes. One of the most important clinical features of TUKYSA is its demonstrated efficacy in patients with brain metastases from HER2-positive breast cancer. The HER2CLIMB trial specifically enrolled patients with active or previously treated brain metastases and showed that adding tucatinib to trastuzumab and capecitabine significantly improved progression-free survival (at one year: 24.9% vs. 0% with placebo) and overall survival in this subgroup. This makes the tucatinib combination one of the preferred treatment options for HER2-positive breast cancer with brain involvement.
Contact your doctor at the first sign of diarrhea. Early treatment with anti-diarrheal medications (such as loperamide) can help prevent the diarrhea from becoming severe. Drink plenty of fluids to prevent dehydration. If the diarrhea is severe (more than 4 loose stools per day), persistent, or accompanied by nausea and vomiting, seek medical attention promptly. Your doctor may need to temporarily pause TUKYSA treatment, reduce the dose, or prescribe additional supportive medications. Do not take an extra dose if you vomit after taking TUKYSA.
Yes, TUKYSA can be taken with food or on an empty stomach. There are no specific dietary restrictions with tucatinib. The tablets should be swallowed whole—do not crush, chew, or break them, as this may affect how the active ingredient is released. Take each dose approximately 12 hours apart at the same times every day to maintain consistent drug levels. However, be aware that capecitabine (one of the companion drugs) should be taken within 30 minutes after a meal, so you may wish to coordinate your dosing times accordingly.
TUKYSA is a long-term treatment taken continuously for as long as it continues to provide clinical benefit and the side effects remain tolerable. There is no predetermined treatment duration. Your doctor will regularly evaluate your response to treatment through imaging scans and blood tests. Treatment is typically continued until the cancer progresses, unacceptable toxicity occurs, or you and your doctor decide to stop for other reasons. Never stop taking TUKYSA without consulting your oncologist first.
References & Sources
- European Medicines Agency (EMA). TUKYSA (tucatinib) – Summary of Product Characteristics. EMA/CHMP, last updated 2025.
- U.S. Food and Drug Administration (FDA). TUKYSA (tucatinib) tablets – Prescribing Information. Seagen Inc., revised 2024.
- Murthy RK, Loi S, Okines A, et al. Tucatinib, Trastuzumab, and Capecitabine for HER2-Positive Metastatic Breast Cancer. N Engl J Med. 2020;382(7):597–609. doi:10.1056/NEJMoa1914609.
- Lin NU, Borges V, Anders C, et al. Intracranial Efficacy and Survival With Tucatinib Plus Trastuzumab and Capecitabine for Previously Treated HER2-Positive Breast Cancer With Brain Metastases in the HER2CLIMB Trial. J Clin Oncol. 2020;38(23):2610–2619. doi:10.1200/JCO.20.00775.
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 1.2025.
- European Society for Medical Oncology (ESMO). Metastatic Breast Cancer: ESMO Clinical Practice Guideline. Ann Oncol. 2024.
- Curigliano G, Mueller V, Borber V, et al. Tucatinib versus placebo added to trastuzumab and capecitabine for patients with pretreated HER2+ metastatic breast cancer with and without brain metastases (HER2CLIMB): final overall survival analysis. Ann Oncol. 2022;33(3):321–329.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List. Geneva: WHO, 2023.
- British National Formulary (BNF). Tucatinib – Drug Information. National Institute for Health and Care Excellence (NICE), 2025.
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