Tukysa® (tucatinib) tablets for HER2‑positive metastatic breast cancer

What Tukysa® Is and How It Works

Tukysa (tucatinib) is an oral, small‑molecule tyrosine kinase inhibitor that selectively blocks human epidermal growth factor receptor 2 (HER2). It helps slow tumor growth by inhibiting HER2 signaling inside cancer cells and has demonstrated activity in brain metastases. Tukysa is used for adults with unresectable or metastatic HER2‑positive breast cancer, including those with brain metastases, in combination with trastuzumab and capecitabine. It is also used with trastuzumab for previously treated HER2‑positive, RAS wild‑type metastatic colorectal cancer.

YouDrugstore is a licensed Canadian pharmacy headquartered in Manitoba, and licensed pharmacists review prescriptions before dispensing; we offer brand and generic medicines at Canadian prices and OTC health products, with online ordering and customer‑service chat during posted hours.

Patients often compare the Tukysa price when starting therapy and when planning refills. You can buy Tukysa online from our pharmacy and have it shipped to the US. Many people also ask about buying Tukysa without insurance and how to manage out‑of‑pocket costs. Tukysa tablets are swallowed whole and can be taken with or without food.

Tukysa is taken twice daily on a continuous schedule. In breast cancer, it is combined with trastuzumab and capecitabine in 21‑day cycles. In colorectal cancer, it is combined with trastuzumab on a repeating schedule. Your oncology team determines the full regimen, monitoring response and tolerability. Learn more about the condition on our Breast Cancer page.

Dosage and Usage

• Standard dose: 300 mg of tucatinib by mouth twice daily (two 150 mg tablets morning and evening), taken continuously.
• With breast cancer regimens: use with trastuzumab and capecitabine in 21‑day cycles as directed by the prescriber.
• With colorectal regimens: use with trastuzumab; capecitabine is not typically included.
• Swallow tablets whole. Do not crush, chew, or split.
• Take with or without food, at roughly the same times each day.
• If a dose is missed or if vomiting occurs after a dose, take the next scheduled dose at the usual time. Do not take extra doses.
• Report persistent diarrhea, mouth sores, or yellowing of skin or eyes to the care team promptly.
• Drug interactions: avoid strong CYP2C8 inhibitors (for example, gemfibrozil) and strong inducers (such as rifampin). Tucatinib can increase levels of sensitive CYP3A substrates; prescribers may adjust other medicines.

• Store Tukysa at 20–25 °C (68–77 °F) in the original bottle with the desiccant.
• Keep the container tightly closed and protect from moisture.
• Do not store in a bathroom. Avoid excessive heat, cold, or direct sunlight.
• For travel, keep tablets in your carry‑on bag in the original labeled bottle.
• If a flight or trip is delayed, you have enough tablets on hand for extra days.
• Use a pill organizer only if humidity is controlled; otherwise keep in the bottle.

Benefits and Savings

Tukysa improves outcomes in pretreated HER2‑positive metastatic breast cancer. In clinical studies, adding tucatinib to trastuzumab and capecitabine extended progression‑free survival and overall survival, including in patients with brain metastases. Many patients experienced slower disease progression and a reduction in central nervous system events.

For HER2‑positive metastatic colorectal cancer (RAS wild‑type), tucatinib plus trastuzumab offers another targeted option after standard chemotherapy. Oral dosing, a consistent twice‑daily schedule, and established dose‑modification guidance support ongoing treatment when tolerated.

Ordering through a Canadian pharmacy can lower the monthly Tukysa cost. Typical savings are 60–80% compared with common US prices, especially for multi‑month supplies. This can help manage Tukysa out of pocket cost and support continuity of care, even without insurance. Reorder reminders are available so you can plan refills before running low.

We source through licensed, vetted international partner pharmacies to supply authentic brand medications with a broad selection and competitive pricing.

For current offers, see our Tukysa coupon page.

Side Effects and Safety

• Diarrhea
• Nausea or vomiting
• Fatigue
• Abdominal pain
• Decreased appetite and weight loss
• Stomatitis or mouth sores
• Rash
• Headache
• Elevated liver enzymes (ALT/AST), or bilirubin
• Hand‑foot syndrome (often from combination capecitabine)

Serious risks include severe diarrhea and hepatotoxicity; liver tests are often monitored during therapy. Embryo‑fetal toxicity can occur; effective contraception is recommended during treatment and for a period after. When combined with trastuzumab, there is a risk of left ventricular dysfunction related to trastuzumab exposure. Dose interruptions or reductions may be required if adverse effects persist or lab values rise. Tucatinib can interact with CYP2C8 inhibitors/inducers and may raise levels of sensitive CYP3A substrates; clinicians may adjust co‑medications. Hypoglycemia can occur if diabetes medicines such as insulin or sulfonylureas are part of a patient’s regimen; prescribers often reduce those doses.

Onset Time

Gastrointestinal effects like diarrhea can begin in the first one to two weeks and often improve with antidiarrheals and dose adjustments. Tumor responses are usually assessed on imaging after six to eight weeks, with broader benefits becoming clearer by two to three months. In patients with brain metastases, intracranial responses may be observed on early follow‑up scans, though timelines vary.

Compare With Alternatives

Neratinib and lapatinib are older oral HER2 kinase inhibitors sometimes used in later‑line settings. Tucatinib is more selective for HER2 and has demonstrated activity in brain metastases when combined with trastuzumab and capecitabine.

Trastuzumab deruxtecan (an antibody‑drug conjugate) is a potent option after prior HER2‑directed therapies and may be used before or after tucatinib depending on clinical factors and guidelines.

Hormone receptor‑positive disease often includes endocrine therapy, either earlier in the pathway or alongside HER2 targeting. Some patients may receive agents like Anastrozole or Fulvestrant at different stages of care. For broader context on diagnosis and care, see our Cancer category.

Combination Therapy

• Breast cancer: tucatinib + trastuzumab + capecitabine (standard combination).
• Colorectal cancer (RAS wild‑type): tucatinib + trastuzumab after prior chemotherapy.
• Supportive care: antidiarrheals, antiemetics, and skin care for hand‑foot syndrome as needed.
• Glycemic therapy: prescribers may lower insulin or sulfonylurea doses to reduce hypoglycemia risk.

Patient Suitability and Cost‑Saving Tips

Tukysa is intended for adults with HER2‑positive metastatic or unresectable disease after prior anti‑HER2 therapy. It is not recommended in pregnancy or during breastfeeding. People with active, uncontrolled liver disease, significant drug‑interaction risks, or severe, ongoing diarrhea may need an alternative or a modified plan.

Kidney function usually does not require adjustment for mild to moderate impairment. For liver function, prescribers may adjust the starting dose in moderate impairment and avoid use in severe impairment. Regular monitoring of liver tests helps guide safe dosing.

Ways to lower the Tukysa tablets price include choosing a multi‑month supply when appropriate, which can reduce per‑month expense and shipping frequency. You can set reorder reminders in your account so you have time to upload new prescriptions if needed. If you are paying cash, comparing the Tukysa cash price across pack sizes can also help. Patient assistance programs from manufacturers or foundations may be available to eligible individuals through their clinics, separate from pharmacy pricing. This can be useful for those seeking Tukysa no insurance options.

Authoritative Sources

Manufacturer patient website for TUKYSA (tucatinib)

US Prescribing Information (Seagen): TUKYSA

Health Canada Drug Product Database

Order Tukysa® from YouDrugstore: add to cart, upload your prescription, and we ship with prompt, express shipping.

This content is for educational purposes only and does not replace advice from your oncology team or other licensed healthcare professionals.