An oncologist that I talk to sees ARRY-380 having to (potentially) compete with Roche's T-DM1. The oncologist thinks T-DMI is a superior drug.
Interestingly, Roche will be presenting data at ESMO on a Phase II controlled, randomized study in HER2+ breast cancer comparing T-DMI to chemotherapy plus Herceptin. This should provide some very interesting data. Roche will also present follow-up data on PFS in the third-line setting with TDM-1.