Lapatinib Disease Interactions

Cardiomyopathy was observed in clinical trials of certain EGFR inhibitors. Assess Left Ventricular Ejection Fraction (LVEF) by echocardiogram or multigated acquisition (MUGA) scan before initiation of these agents and then at 3 month intervals while on treatment. Caution is recommended when prescribing these agents to patients with conditions that could impair left ventricular function and it is recommended to withhold treatment with these agents if ejection fraction drops below the established lower limit of normal. For symptomatic congestive heart failure or persistent, asymptomatic LV dysfunction that does not resolve within 4 weeks, permanently discontinue these agents.

Cutaneous reactions, in some cases severe, have been reported with the use of EGFR inhibitors. Monitor patients who develop dermatologic or soft tissue toxicities while receiving these agents for the development of inflammatory or infectious sequelae. It is recommended to withhold treatment, and appropriate measures should be instituted as appropriate or discontinue the use of these agents for dermatologic or soft tissue toxicity associated with severe or life-threatening inflammatory or infectious complications. Advise patients to wear sunscreen and hats and limit sun exposure while receiving therapy with these agents as exposure to sunlight can exacerbate dermatologic toxicities.

The use of certain EGFR inhibitors has been associated with pulmonary toxicity. Serious cases of interstitial lung disease (ILD), including fatal cases and interstitial pneumonitis or pulmonary fibrosis have been reported. Caution is recommended when using these agents in patients with a history of interstitial pneumonitis or pulmonary fibrosis or those patients presenting with acute onset of new or progressive unexplained pulmonary symptoms such as dyspnea, cough, and fever pending diagnostic evaluation. If ILD is confirmed, permanently discontinue these agents and institute appropriate measures.

QT prolongation was observed in patients treated with certain EGFR inhibitors. These agents should be administered with caution in patients with congenital long QTc syndrome, congestive heart failure, electrolyte abnormalities, or those who are taking medications known to prolong the QTc interval. Serum electrolytes should be corrected prior to initiating therapy with these agents. Periodic monitoring of ECGs and electrolytes is recommended in these patients. Permanently discontinue the use of these agents in patients who develop QTc interval prolongation with signs/symptoms of life-threatening arrhythmia.

Pulmonary toxicity, sometimes fatal has been reported with agents that block HER2 activity. Pulmonary toxicity includes dyspnea, interstitial pneumonitis, pulmonary infiltrates, pleural effusions, non-cardiogenic pulmonary edema, pulmonary insufficiency and hypoxia, acute respiratory distress syndrome, and pulmonary fibrosis. Patients with symptomatic intrinsic lung disease or with extensive tumor involvement of the lungs, resulting in dyspnea at rest may be at increased risk of pulmonary toxicity and appear to have more severe toxicity. Patients should be monitored for pulmonary symptoms. Permanently discontinue treatment with these agents in patients diagnosed with interstitial lung disease or pneumonitis and institute appropriate care.

Lapatinib undergoes extensive metabolism in the liver. Hepatotoxicity has been associated with the use of lapatinib and it may be severe and fatal. The hepatotoxicity may occur days to several months after initiation of treatment. Therapy with lapatinib should be administered cautiously in patients with severe hepatic impairment and a dose reduction should be considered for patients with severe pre-existing hepatic impairment. Clinical monitoring of hepatic function (transaminases, bilirubin, and alkaline phosphatase) is recommended before initiation of treatment, every 4 to 6 weeks during treatment, and as clinically indicated. In patients who develop severe hepatotoxicity while on therapy, lapatinib should be discontinued and patients should not be retreated.

Decreases in left ventricular ejection fraction (LVEF) have been reported with agents that block HER2 activity. Patients who have received prior anthracyclines, those who received anthracycline after stopping therapy with agents that block HER2 activity, or patients who received prior radiotherapy to the chest area may be at higher risk of decreased LVEF. Therapy with these agents should be administered cautiously in patients with a previous history of heart conditions. Evaluate cardiac function before, during, and upon completion of treatment. Withhold or discontinue therapy with agents that block HER2 activity as appropriate, and for a confirmed clinically significant decrease in left ventricular function, or if the LVEF has not improved or has declined further. It is recommended to monitor overall cardiac function and LVEF by echocardiogram or MUGA scan as appropriate.

Thrombocytopenia has been reported with the use of agents that block HER2 activity. Monitor platelet counts prior to initiation of therapy and prior to each dose. If appropriate modify the dose according to clinical guidelines. Patients with decreased platelet count and patients on anti-coagulant treatment should be closely monitored during treatment with these agents.

Lapatinib pharmacokinetics have not been specifically studied in patients with renal impairment or in patients undergoing hemodialysis. Close monitoring is recommended.