In combination with capecitabine, for the treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 and who have received prior therapy including an anthracycline, a taxane, and trastuzumab. In combination with letrozole for the treatment of postmenopausal women with hormone receptor positive metastatic breast cancer that overexpresses HER2 for whom hormonal therapy is indicated.
Take 1 hour before or 1 hour after a meal (capecitabine should be taken with food or within 30min after food). HER2 metastatic breast cancer: 1250mg (5 tabs) once daily on Days 1–21 continuously in combination with capecitabine 2000mg/m2/day (administered orally in 2 doses approx. 12 hours apart) on Days 1–14 in a repeating 21 day cycle; continue until disease progression or unacceptable toxicity occurs. After recovery from left ventricular ejection fraction (LVEF) decrease: 1000mg/day. Severe hepatic dysfunction (Child-Pugh Class C): 750mg/day (no clinical data for this dose adjustment). Concomitant potent CYP3A4 inducers: may titrate up to 4500mg/day (no clinical data for this dose adjustment). Hormone receptor positive, HER2 positive metastatic breast cancer: 1500mg (6 tabs) once daily continuously in combination with letrozole 2.5mg once daily. After recovery from LVEF decrease: 1250mg/day. Severe hepatic dysfunction: 1000mg/day (no clinical data for this dose adjustment). Concomitant potent CYP3A4 inducers: may titrate up to 5500mg/day (no clinical data for this dose adjustment). For both: Concomitant potent CYP3A4 inhibitors: 500mg/day (no clinical data for this dose adjustment). Discontinue if ≥grade 2 NCI CTC toxicity occurs; may restart at 1250mg/day if toxicity improves to grade 1; if recurs, may restart at 1000mg/day (with capecitabine); 1250mg/day (w. letrozole).
Tyrosine kinase inhibitor.
Confirm normal LVEF before starting. Discontinue if ≥grade 2 decrease in LVEF occurs, or if LVEF falls below institution's lower limit of normal; may restart after at least 2 weeks at reduced dose if asymptomatic and LVEF recovers. Conditions that impair left ventricular function, or risk factors for QT prolongation (eg, hypokalemia, hypomagnesemia, congenital long QT syndrome, concomitant antiarrhythmics, cumulative high dose anthracyclines); correct electrolyte disturbances before starting. Monitor for interstitial lung disease or pneumonitis; discontinue if pulmonary symptoms ≥grade 3 (NCI CTCAE). Monitor liver function tests before, every 4–6 weeks during therapy and as indicated; discontinue if hepatotoxicity occurs; do not retreat. Severe hepatic impairment: consider dose reduction. Pretreat for diarrhea with antimotility drugs. Monitor ECG. Pregnancy (Cat.D); avoid. Nursing mothers: not recommended.
Avoid potent CYP3A4 inhibitors (eg, ketoconazole), grapefruit; reduce dose if unavoidable. Avoid potent CYP3A4 inducers (eg, carbamazepine); slowly titrate dose up if unavoidable. May affect drugs that are affected by p-glycoprotein, CYP2C8.
Diarrhea (may be severe), nausea, vomiting, hand/foot syndrome, rash, fatigue; decreased LVEF, QT prolongation, interstitial lung disease, pneumonitis, hepatotoxicity (may be fatal).
Testing considerations: HER2 protein overexpression