A. Expression levels of ER, Bcl2, and PR in UACC812 tumor xenografts grown only in the presence of estrogen (E2; n=6) and treated with lapatinib in the presence of E2 (E2 + L; n=6). L-treated tumors showed a significant increase in the expression of ER, PR, and Bcl2, compared with tumors treated with vehicle.
B. Expression levels of ER, Bcl2, and PR in MCF7 HER2-18 tumor xenografts grown in presence of E2 with (n=9) or without (n=9) HER2-targeted therapy. Tumors treated with lapatinib plus trastuzumab (LT) were harvested either when still sensitive to the treatment (n=4) or at the time of acquired resistance (n=5)(8). LT-sensitive tumors showed a non-significant trend toward increase in ER expression, as well as in Bcl2 and PR levels, compared with control tumors (E2). LT-resistant tumors showed a significant increase in ER, Bcl2, and PR expression compared with control.