Impact of prior autologous stem cell transplant (ASCT) in patients receiving bortezomib or dexamethasone for relapsed/refractory multiple myeloma in the APEX trial

7546 Background: The phase 3 international APEX trial demonstrated significantly superior overall survival (OS), time to progression (TTP), and overall response rate (ORR: CR+PR, EBMT criteria) with bortezomib (VELCADE [Vc]) therapy for relapsed myeloma compared with dexamethasone (Dex). ASCT is a common component of initial therapy and may affect the outcome of salvage therapies. Methods: This analysis aimed to evaluate the impact of prior ASCT on the APEX results. TTP, OS, and ORR were analyzed by prior ASCT treatment. Results: Of 669 randomized patients, 451 (67%) had received prior ASCT (median follow-up in survivors was 21.9 months); in this group, Vc led to higher ORR compared with Dex (41% vs 18%, p 62% of patients originally assigned to Dex. A subset of 156 (23%) patients had ASCT as their only prior line of therapy (median follow-up in survivors was 20.0 months), with simila...