• Advanced unresectable or metastatic HER2-positive breast cancer in patients who previously received 1 anti-HER2-based regimens in the metastatic setting (in combination with trastuzumab and capecitabine).

Contraindicated in:

• Severe renal impairment (CCr <30 mL/min)
• OB: Pregnancy (may cause fetal harm)
• Lactation: Lactation.

Use Cautiously in:

• Severe hepatic impairment (↓ dose)
• Rep: Women of reproductive potential and men with female partners of reproductive potential
• Pedi: Safety and effectiveness not established in children.

CNS: headache.

Derm: palmar-plantar erythrodysesthesia, rash.

EENT: epistaxis.

F and E: hypokalemia, hypomagnesemia, hyponatremia, hypophosphatemia.

GI: diarrhea, hepatotoxicity, abdominal pain, hyperbilirubinemia, nausea, stomatitis, vomiting.

GU: ↑serum creatinine, ↓ fertility.

Hemat: anemia.

Metab: ↓appetite, ↓weight.

MS: arthralgia.

Neuro: peripheral neuropathy.

Misc: fatigue.

Drug-Drug:

• Strong CYP2C8 inhibitors, including gemfibrozil, may ↑ levels and risk of toxicity; avoid concurrent use.
• Strong CYP3A4 inducers or moderate CYP2C8 inducers, including rifampin, may ↓ levels and effectiveness; avoid concurrent use.
• May ↑ levels and risk of toxicity of CYP3A4 substrates; avoid concurrent with CYP3A4 substrates with narrow therapeutic range; if concurrent use unavoidable, ↓ dose of CYP3A4 substrate.
• May ↑ levels and risk of toxicity of P-glycoprotein substrates; consider ↓ dose of P-glycoprotein substrates with narrow therapeutic ranges.

• Tablets: 50 mg; 150 mg;

• PO (Adults): 300 mg twice daily; continue until disease progression or unacceptable toxicity. Concurrent use of strong CYP2C8 inhibitors — 100 mg twice daily; continue until disease progression or unacceptable toxicity.

Tukysa

• Acts as tyrosine kinase inhibitor of HER2, thereby inhibiting the growth of HER2-expressing tumors.

• Improved survival and progression-free survival in metastatic breast cancer.

Therapeutic Classification: antineoplastics

Pharmacologic Classification: kinase inhibitors

Absorption: High-fat foods increase extent of and delay absorption.

Distribution: Extensively distributed to extravascular tissues.

Metabolism/Excretion: Primarily metabolized by liver via CYP2C8 isoenzyme, and to a lesser extent by CYP3A4. Primarily excreted in feces (86%; 16% as unchanged drug), with 4% being excreted in urine.

Half-life: 8.5 hr.

(plasma concentrations)

• Instruct patient to take as directed about 12 hr apart. If patient vomits or a dose is missed, omit and take next dose at usual time. Advise patient to read Patient Information before starting therapy and with each Rx refill incase of changes.
• Inform patient of potential for severe diarrhea and to notify health care professional if a change in bowel movements or severe diarrhea occurs. May lead to loss of too much body fluids (dehydration), low blood pressure, kidney problems and death.
• Advise patient to notify health care professional if signs and symptoms of liver problems (itching, yellowing of skin or eyes, dark or brown urine, pain in upper right side of abdomen, feel very tired, decreased appetite, bleeding or bruising more easily than normal) occur.
• Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
• Rep: May cause fetal harm. Advise females of reproductive potential and males with female partners of reproductive potential to use effective contraception during and for at least 1 wk after last dose. Advise patient to avoid breastfeeding for at least 1 wk after last dose. Advise patient to notify health care professional immediately if pregnancy is suspected. May impair female and male fertility.
• Emphasize the importance of lab tests every 3 wk to monitor for liver problems.

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