Indications for TYKERB:
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. Limitation of use: patients should have disease progression on trastuzumab before initiating Tykerb in combination with capecitabine. 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 1hr before or 1hr after a meal (capecitabine should be taken with food or within 30mins 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. 12hrs 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). Interrupt if diarrhea is NCI CTC grade 3, or grade 1 or 2 with complicating features develop; may restart at lower dose (reduced from 1250mg/day to 1000mg/day or from 1500mg/day to 1250mg/day) when resolves ≤ grade 1; permanently discontinue if diarrhea is grade 4. Other toxicities: 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).
Risk of severe hepatotoxicity; discontinue if occurs; do not retreat. Monitor LFTs before, every 4–6 weeks during therapy and as indicated. 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 or certain others, cumulative high dose anthracyclines); correct electrolyte disturbances before starting. Monitor for interstitial lung disease or pneumonitis; discontinue if pulmonary symptoms ≥grade 3 (NCI CTCAE). Discontinue if severe skin reaction (eg, Stevens-Johnson syndrome, toxic epidural necrolysis) is suspected. Severe hepatic impairment: consider dose reduction. Diarrhea: promptly treat with anti-diarrheal agents; if severe, may require fluids, electrolytes, antibiotics and therapy interruption/discontinuation. Monitor ECG. Embryo-fetal toxicity. Advise females of reproductive potential and males (w. female partners) to use effective contraception during and for 1 week after the last dose. Pregnancy: exclude status prior to initiation. Nursing mothers: not recommended (during and for 1 week after the last dose).
Tyrosine kinase inhibitor.
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 substrates of P-glycoprotein, CYP2C8, and CYP3A4; adjust doses.
Diarrhea (may be severe), hand/foot syndrome, nausea, rash (may be severe), vomiting, fatigue; hepatotoxicity, decreased LVEF, QT prolongation, interstitial lung disease, pneumonitis.
Testing considerations: HER2 protein overexpression