Lapatinib Side Effects

Some side effects of lapatinib may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to lapatinib: oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking lapatinib: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using lapatinib and call your doctor at once if you have a serious side effect such as:

• fast or pounding heartbeats;

• extreme dizziness or tired feeling;

• feeling like you might pass out;

• severe diarrhea;

• dry cough, feeling short of breath;

• white patches or sores inside your mouth or on your lips;

• nosebleeds; or

• nausea, pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects of lapatinib may include:

• mild diarrhea, upset stomach;

• pain or redness on the palms of your hands or the soles of your feet;

• dry skin, mild rash;

• unusual hair loss; or

• problems with your fingernails or toenails.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to lapatinib: oral tablet

General

All clinical trial data were from trials of lapatinib in combination with capecitabine.

To report suspected adverse reactions, contact GlaxoSmithKline at 1-888-825-5249 or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Gastrointestinal

Gastrointestinal side effects including diarrhea (65%), nausea (44%), vomiting (26%), stomatitis (14%), and dyspepsia (11%) have been reported.

Diarrhea was the most common adverse reaction resulting in discontinuation of study medication.

Hematologic

Hematologic side effects have included laboratory abnormalities in hemoglobin (56%), neutrophils (22%), and platelets (18%).

Dermatologic

Dermatologic side effects including palmar plantar erythrodysesthesia (53%) (also called hand-foot syndrome or acral erythema), rash (28%), dry skin (10%), and nail disorders including paronychia have been reported.

Hepatic

Hepatic side effects have included laboratory abnormalities in AST (49%), total bilirubin (45%), and ALT (37%).

Hepatotoxicity may be severe and deaths have been reported. Causality of the deaths is uncertain. The hepatotoxicity may occur days to several months after initiation of treatment. Liver function tests (transaminases, bilirubin, and alkaline phosphatase) should be monitored before initiation of treatment, every 4 to 6 weeks during treatment, and as clinically indicated. If changes in liver function are severe, therapy with lapatinib should be discontinued and patients should not be retreated with lapatinib. If lapatinib is to be administered to patients with severe preexisting hepatic impairment, dose reduction should be considered. In patients who develop severe hepatotoxicity while on therapy, lapatinib should be discontinued and should not be retreated with lapatinib.

Cardiovascular

Cardiovascular side effects including decreases in left ventricular ejection fraction and QT prolongation have been reported.

Due to potential cardiac toxicity with HER2 (ErbB2) inhibitors, left ventricular ejection fraction (LVEF) was monitored in clinical trials at approximately eight-week intervals. LVEF decreases were defined as signs or symptoms of deterioration in left ventricular cardiac function that are grade 3 (NCI CTCAE), or a 20% decrease in left ventricular cardiac ejection fraction relative to baseline which is below the institution's lower limit of normal. Among 198 patients who received lapatinib/capecitabine combination treatment, three experienced Grade 2 and one had Grade 3 LVEF adverse reactions (NCI CTC 3.0).

The QT prolongation potential of lapatinib was assessed as part of an uncontrolled, open-label dose escalation study in advanced cancer patients. Eighty-one patients received daily doses of lapatinib ranging from 175 mg/day to 1800 mg/day. Serial ECGs were collected on day 1 and day 14 to evaluate the effect of lapatinib on QT intervals. Thirteen of the 81 subjects were found to have either QTcF (corrected QT by the Friedericia method) greater than 480 msec or an increase in QTcF greater than 60 msec by automated machine-read evaluation of ECG. Analysis of the data suggested a relationship between lapatinib concentration and the QTc interval.

Other

Other side effects including mucosal inflammation (15%), pain in the extremity (12%), dyspnea (12%), back pain (11%), and insomnia (10%) have been reported.

Oncologic

Oncologic side effects including genotoxicity have been reported. An impurity in the drug product was genotoxic when tested alone in both in vitro and in vivo assays.

Respiratory

It is recommended that patients be monitored for pulmonary symptoms indicative of interstitial lung disease or pneumonitis. Lapatinib should be discontinued in patients who experience pulmonary symptoms indicative of interstitial lung disease/pneumonitis which are greater than or equal to grade 3 (NCI CTCAE).

Respiratory side effects have been reported including interstitial lung disease and pneumonitis in monotherapy or in combination with other chemotherapies.

Hypersensitivity

Hypersensitivity side effects including anaphylaxis have been reported.

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