Lapatinib

Decreases in left ventricular ejection fraction (LVEF) have been reported (usually within the first 3 months of treatment); baseline and periodic LVEF evaluations are recommended. Interrupt treatment with decreased LVEF ≥ grade 2 or LVEF • Dermatologic toxicity: Severe cutaneous reactions have been reported with use. Discontinue therapy if life-threatening dermatologic reactions (eg, progressive skin rash with blisters or mucosal lesions) such as erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis occur.

Diarrhea is common (onset is generally within 6 days and duration is 4 to 5 days); may be severe and/or fatal. Diarrhea is best managed with early intervention; instruct patients to immediately report any bowel pattern changes. After first unformed stool, administer antidiarrheal agents; severe diarrhea may require hydration, electrolytes, antibiotics (if duration >24 hours, fever, or grade 3/4 neutropenia), and/or treatment interruption, dose reduction, or discontinuation.

Hepatotoxicity (ALT or AST >3 times ULN and total bilirubin >2 times ULN) has been reported with lapatinib; may be severe and/or fatal. Onset may occur within days to several months after treatment initiation. Monitor transaminases, bilirubin, and alkaline phosphatase (at baseline and every 4 to 6 weeks during treatment, and as clinically indicated); discontinue with severe changes in liver function during treatment; do not reinitiate.

Interstitial lung disease (ILD) and pneumonitis have been reported (with lapatinib monotherapy and combination chemotherapy); monitor for pulmonary symptoms which may indicate ILD or pneumonitis; discontinue treatment for grade 3 (or higher) pulmonary symptoms indicative of ILD or pneumonitis (eg, dyspnea, dry cough).

QTC prolongation has been observed; use caution in patients with a history of QTC prolongation or with medications known to prolong the QT interval; baseline and periodic 12-lead ECG should be considered; correct electrolyte (potassium, calcium, and magnesium) abnormalities prior to and during treatment. Concurrent use with other drugs which may prolong QTC interval may increase the risk of potentially fatal arrhythmias. Disease related concerns:

Use with caution in patients with hepatic impairment; dose reductions should be considered in patients with preexisting severe (Child-Pugh class C) hepatic impairment. Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

Patients who carry the HLA alleles DQA1*02:01 and DRB1*07:01 may experience a greater incidence of severe liver injury than patients who are noncarriers. These alleles are present in ~15% to 25% of Caucasian, Asian, African, and Hispanic patient populations and 1% in Japanese populations.