The authors attach importance to their finding that Lapatinib inhibits insulin-like growth factor I (IGF-I): if this is true for humans it may mean that Lapatinib can prevent or delay one of the ways cancer cells become resistant to Herceptin.
This might also mean that concurrent administration of the two drugs may be better than sequential administration although this is not said in the abstract & may need to be demonstrated in trials.
http://mct.aacrjournals.org/cgi/cont...stract/6/2/667
Lapatinib induces apoptosis in trastuzumab-resistant breast cancer cells: effects on insulin-like growth factor I signaling