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Drugs of interest to pathologists

Drugs related to surgical pathology

Lapatinib ditosylate


Author: Him G. Kwee, M.D. (see Reviewers/Authors page)
Revised: 24 November 2011, last major update November 2011
Copyright: (c) 2011, PathologyOutlines.com, Inc.

General
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● A dual kinase inhibitor targeting the ErbB-1 (HER1) and Erb-2 (HER2) receptors

Trade name
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● Tykerb (in USA), Tyverb (in Europe)

Clinical information
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Approved by US Food and Drug Administration for:
● Advanced or metastatic breast carcinoma that overexpress HER2, in combination with capecitabine (Xeloda) in patients who had received prior treatment with an anthracycline, a taxane or trastuzumab (Herceptin, approved March 13, 2007)
● First line therapy for advanced or metastatic breast carcinomas that are triple positive (ER+, EGFR+ and HER2+) combined with letrozole (Femara) in post menopausal women (February 2010, source: drug package insert)

● Approximate cost: $5,000 to 6,000 per month in 2010 (Diseases, Drugs, Health News Dec 10, 2010)

Pathophysiology
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● Lapatinib reversibly binds to the cytoplasmic ATP-binding site of the tyrosine kinase domain and blocks receptor phosphorylation and activation, thereby blocking downstream signaling pathways, namely, activation of extracellular signal-related kinase 1/2 and phosphatidylinositol 3 kinase / Akt (Oncologist 2007;12:756)
● Lapatinib is a small molecule able to penetrate the blood-brain barrier, and may be effective for CNS metastases
● Lapatinib appears to have clinical activity in inflammatory HER2 positive breast carcinoma
● There is no cross-resistance between lapatinib and trastuzumab
● A common side effect is a characteristic skin rash with inflammatory papules and pustules, usually on the face, neck and back, which may resemble folliculitis and acneiform drug eruption; rash differs from classic acne vulgaris because it lacks comedones
● Histologically, there is suppurative folliculitis and superficial perifolliculitis with no microcomedones
● Similar rash can be seen with erlotinib, gefitinib and cetuximab (Oncologist 2007;12:756)
● Patients who developed such a rash survived twice as long as those who did not develop a rash (RxPG News June 5, 2006)

End of Drugs > Drugs related to surgical pathology > Lapatinib ditosylate


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