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

Abstract

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 < 0.001), higher CR rate (8% vs 0.5%, p < 0.001), and longer TTP and OS (see table), the latter despite crossover to Vc of >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 similar superiority of Vc compared with Dex in ORR (48% vs 29%, p = 0.004), CR rate (6% vs 2%, p > 0.05), and TTP. Among 218 (33%) patients with no prior ASCT (median follow-up in survivors was 21.7 months), Vc was also superior to Dex in ORR (32% vs 18%, p = 0.025), CR rate (4% vs 1%, p > 0.05), and TTP. Conclusions: Vc is consistently superior to Dex in ORR, CR rate, and TTP, regardless of prior ASCT status, and OS is superior in patients who had received prior ASCT. Vc is an effective therapy for myeloma relapsing after ASCT. NE = not estimable. [Table: see text] [Table: see text]