There are 4 hers (or EGFRs or ERBBs)
one can have any combination or permutation of the four ie, -+++, -++-,
+--+, +-+-, -+-+. etc. Assuming one is her2+ that leaves three other "hers" that can be + or - . Her4 positivity is actually associated with a better prognosis (vs her 1, her2 or her3). Lapatinib works vs. her1 and her2 but does not require one to be both. In fact they hope it will work for those who are her1 but not her2. Her1 (also known as EGFR or ERBB1) is the target of the oral drugs (tyrosine kinase inhibitors) Iressa and Tarceva and of the monoclonal antibody Erbitux (of Martha Stewart fame) There are monoclonal antibodies underdevelopment that target her 3 and her2, etc.
Hope this helps!
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