(tucatinib)

Prescribing Information
Download Prescribing Information

2 DOSAGE AND ADMINISTRATION

2 DOSAGE AND ADMINISTRATION

2.1 Patient Selection

Select patients for treatment of unresectable or metastatic colorectal cancer with TUKYSA based on the presence of:

•
HER2 overexpression or gene amplification [see Clinical Studies (14.2)]. FDA-authorized tests for the detection of HER2 overexpression and gene amplification in patients with unresectable or metastatic colorectal cancer are not currently available, and
•
RAS wild-type [see Clinical Studies (14.2)]. Information on FDA-authorized tests for the detection of RAS mutations in patients with unresectable or metastatic colorectal cancer is available at http://www.fda.gov/CompanionDiagnostics.

2.2 Recommended Dosage

The recommended dosages for TUKYSA are listed in Table 1.

Table 1: Recommended Dosage
*
Refer to the Prescribing Information of combination agents for dosing and administration information.

Indication

Recommended TUKYSA Dosage

Duration of Therapy

Unresectable or Metastatic Breast Cancer

Maintenance Treatment of HER2‑Positive Breast Cancer

300 mg orally twice daily in combination with trastuzumab and pertuzumab.*

Until disease progression or unacceptable toxicity.

Unresectable or Metastatic Breast Cancer

HER2-Positive Breast Cancer

300 mg orally twice daily in combination with trastuzumab and capecitabine.*

When given in combination with TUKYSA, the recommended dosage of capecitabine is 1000 mg/m2 orally twice daily taken within 30 minutes after a meal. TUKYSA and capecitabine can be taken at the same time.

Until disease progression or unacceptable toxicity.

Unresectable or Metastatic Colorectal Cancer

300 mg orally twice daily in combination with trastuzumab.*

Until disease progression or unacceptable toxicity.

Administration Instructions

Advise patients to swallow TUKYSA tablets whole and not to chew, crush, or split prior to swallowing. Advise patients not to ingest a tablet if it is broken, cracked, or not otherwise intact.

Advise patients to take TUKYSA approximately 12 hours apart and at the same time each day with or without a meal [see Clinical Pharmacology (12.3)].

If the patient vomits or misses a dose of TUKYSA, instruct the patient to take the next dose at its usual scheduled time.

2.3 Dosage Modifications for Adverse Reactions

The recommended TUKYSA dose reductions and dosage modifications for adverse reactions are provided in Tables 2 and 3. Refer to the Prescribing Information of combination agents for information about dosage modifications for these drugs.

Table 2: Recommended TUKYSA Dose Reductions for Adverse Reactions

Dose Reduction

Recommended TUKYSA Dosage

First

250 mg orally twice daily

Second

200 mg orally twice daily

Third

150 mg orally twice daily

Permanently discontinue TUKYSA in patients unable to tolerate 150 mg orally twice daily.

Table 3: Recommended TUKYSA Dosage Modifications for Adverse Reactions
Abbreviations: ALT = alanine aminotransferase; AST = aspartate aminotransferase; ULN = upper limit of normal.
*
Grades based on National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.03.

Adverse Reaction*

Severity

TUKYSA Dosage Modification

Hepatotoxicity [see Warnings and Precautions (5.1)]

ALT or AST >3 × ULN

AND

Bilirubin >2 × ULN

Permanently discontinue TUKYSA.

ALT or AST >3 × ULN

AND

Bilirubin > ULN to ≤2 × ULN

Repeat testing within 48-72 hours to determine if worsening.

Grade 2 bilirubin (>1.5 to 3 × ULN)

Hold TUKYSA until recovery to ≤ Grade 1, then resume TUKYSA at the same dose.

Grade 3 ALT or AST (>5 to 20 × ULN)

Hold TUKYSA and repeat testing within 48-72 hours to determine if worsening. Consider permanent discontinuation or hold until recovery to ≤ Grade 1, then resume TUKYSA at the next lower dose. Permanently discontinue TUKYSA for recurrent Grade 3 ALT or AST.

Grade 3 bilirubin (>3 to 10 × ULN)

Hold until recovery to ≤ Grade 1, then resume TUKYSA at the next lower dose.

Grade 4 ALT or AST (>20 × ULN)

OR

Grade 4 bilirubin (>10 × ULN)

Permanently discontinue TUKYSA.

Diarrhea [see Warnings and Precautions (5.2)]

Grade 3 without antidiarrheal treatment

Initiate or intensify appropriate medical therapy. Hold TUKYSA until recovery to ≤ Grade 1, then resume TUKYSA at the same dose.

Grade 3 with antidiarrheal treatment

Initiate or intensify appropriate medical therapy. Hold TUKYSA until recovery to ≤ Grade 1, then resume TUKYSA at the next lower dose.

Grade 4

Permanently discontinue TUKYSA.

Other adverse reactions [see Adverse Reactions (6.1)]

Grade 3

Hold TUKYSA until recovery to ≤ Grade 1, then resume TUKYSA at the next lower dose.

Grade 4

Permanently discontinue TUKYSA.

2.4 Dosage Modifications for Severe Hepatic Impairment

For patients with severe hepatic impairment (Child-Pugh C), reduce the recommended dosage to 200 mg orally twice daily [see Use in Specific Populations (8.7), Clinical Pharmacology (12.3)].

2.5 Dosage Modifications for Concomitant Use with Strong CYP2C8 Inhibitors

Avoid concomitant use of strong CYP2C8 inhibitors with TUKYSA. If concomitant use with a strong CYP2C8 inhibitor cannot be avoided, reduce the recommended dosage to 100 mg orally twice daily. After discontinuation of the strong CYP2C8 inhibitor for 3 elimination half-lives, resume the TUKYSA dose that was taken prior to initiating the inhibitor [see Drug Interactions (7.1), Clinical Pharmacology (12.3)].

Medication Guide

MEDICATION GUIDE

   

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:

•
Liver Problems. TUKYSA can cause severe liver problems that can lead to death, especially if you restart TUKYSA after previously stopping treatment due to liver problems. Your healthcare provider will do blood tests to check your liver function before starting treatment with TUKYSA, every 2 weeks for the first 2 months, and then every 3 weeks during treatment with TUKYSA, or as needed. Tell your healthcare provider right away if you get any signs and symptoms of liver problems including:
o
itching
o
yellowing of your skin or eyes
o
dark or brown urine (tea-colored)
o
pain in the upper right side of your stomach-area (abdomen)
o
feeling very tired
o
decreased appetite
o
bleeding or bruising more easily than normal
•
Diarrhea. TUKYSA can cause severe diarrhea that can lead to loss of too much body fluids (dehydration), low blood pressure, kidney problems, and death. Tell your healthcare provider right away if you have a change in your bowel movements or severe diarrhea. Your healthcare provider may prescribe medicines to treat your diarrhea during treatment with TUKYSA.

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:

•
in combination with the medicines trastuzumab and pertuzumab for maintenance treatment of a type of breast cancer called human epidermal growth factor receptor-2 (HER2)-positive breast cancer that has spread:
o
to nearby tissue or lymph nodes and cannot be removed by surgery (unresectable locally advanced) or
o
to other parts of the body (metastatic).
•
in combination with trastuzumab and capecitabine to treat HER2-positive breast cancer that has spread to other parts of the body (metastatic), or cannot be removed by surgery, who have received 1 or more anti-HER2 metastatic breast cancer treatments.
•
in combination with the medicine trastuzumab to treat a type of colorectal cancer called RAS wild-type HER2-positive colorectal cancer that has spread to other parts of the body (metastatic), or cannot be removed by surgery, who have received treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy and it did not work or is no longer working.

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:

•
have liver problems.
•
are pregnant or plan to become pregnant. TUKYSA can harm your unborn baby.
Females who are able to become pregnant:
o
Your healthcare provider will do a pregnancy test before you start treatment with TUKYSA.
o
Use effective birth control (contraception) during treatment with TUKYSA and for 1 week after the last dose of TUKYSA. Talk with your healthcare provider about forms of birth control that you can use during this time.
o
Your healthcare provider will tell you how long you should use birth control (contraception) after your treatment with trastuzumab, pertuzumab, or capecitabine.
o
Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with TUKYSA.
 
Males with female partner who are able to become pregnant:
o
Use effective birth control during treatment with TUKYSA and for 1 week after the last dose of TUKYSA.
•
are breastfeeding or plan to breastfeed. It is not known if TUKYSA passes into your breast milk. Do not breastfeed during treatment with TUKYSA and for 1 week after the last dose of TUKYSA. Your healthcare provider will tell you how long you should not breastfeed after your treatment with trastuzumab and pertuzumab.

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?

•
Take TUKYSA exactly as your healthcare provider tells you.
•
Follow your healthcare provider’s instruction for taking TUKYSA with the medicines trastuzumab, trastuzumab and capecitabine, or trastuzumab and pertuzumab.
•
Take TUKYSA 2 times a day, with or without a meal.
•
Take TUKYSA about 12 hours apart and at the same times every day.
•
Swallow TUKYSA tablets whole. Do not chew, crush, or split TUKYSA tablets before swallowing. Do not take TUKYSA tablets if they are broken, cracked, or damaged.
•
If you vomit or miss a dose of TUKYSA, take your next dose at your regular time.

What are the possible side effects of TUKYSA?

TUKYSA can cause serious side effects, including:

•
See “What is the most important information I should know about TUKYSA?”

The most common side effects of TUKYSA in combination with trastuzumab and pertuzumab in adults with HER2-positive breast cancer include:

•
diarrhea
•
muscle and joint pain
•
liver problems
•
nausea
•
tiredness
•
rash
•
vomiting

The most common side effects of TUKYSA in combination with trastuzumab and capecitabine in adults with HER2-positive breast cancer include:

•
diarrhea
•
rash, redness, pain, swelling or blisters on the palms of your hands or soles of your feet
•
nausea
•
liver problems
•
vomiting
•
mouth sores (stomatitis)
•
decreased appetite
•
low red blood cell counts (anemia)
•
rash

The most common side effects of TUKYSA in combination with trastuzumab in adults with RAS wild-type HER2-positive colorectal cancer include:

•
diarrhea
•
tiredness
•
rash
•
nausea
•
stomach-area (abdomen) pain
•
infusion related reactions
•
fever

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?

•
Store TUKYSA at room temperature between 68°F to 77°F (20ºC to 25ºC).
•
Keep TUKYSA in its original container. The TUKYSA bottle contains a desiccant packet to help keep your tablets dry (protect from moisture). Keep the desiccant in the bottle.
•
Tightly close the bottle of TUKYSA after you take your dose.
•
TUKYSA must be used within 3 months after opening the bottle. Throw away (discard) any unused tablets 3 months after opening the bottle.

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.

This product’s labeling may have been updated. For the most recent prescribing information, please visit https://www.pfizer.com.

Manufactured for: Seagen Inc., Bothell, WA 98021
TUKYSA is a registered trademark owned by Seagen Inc.
©2026 Seagen Inc.
For more information, call 1-800-438-1985.
LAB-1594-1.0

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