Maintenance in myeloma patients achieving complete response after upfront therapy: a pooled analysis

Purpose: Maintenance demonstrated to improve survival in newly diagnosed multiple myeloma (NDMM) patients and the achievement of complete response (CR) is a strong predictor of survival. Nevertheless, the role of maintenance according to response after induction/consolidation has not been investigated so far. To evaluate the impact of maintenance according to response, we pooled together and retrospectively analyzed data from 955 NDMM patients enrolled in two trials (GIMEMA-MM-03-05 and RV-MM-PI-209). Methods: Primary endpoints were progression-free survival (PFS)1, PFS2 and overall survival (OS) of CR patients randomized to maintenance and no maintenance. Secondary endpoints were PFS1, PFS2 and OS in very good partial response/partial response (VGPR/PR) patients. Results: Overall, 213 patients obtained CR after induction/consolidation, 118 received maintenance and 95 no maintenance. In patients achieving CR, maintenance significantly improved PFS1 (HR 0.50, P < 0.001), PFS2 (HR 0.58, P 0.02) and OS (HR 0.51, P 0.02) compared with no maintenance; the advantage was maintained across all the analyzed subgroups according to age, International Staging System (ISS) stage, cytogenetic profile and treatment. Similar features were seen in VGPR/PR patients. Conclusion: Maintenance prolonged survival in CR and in VGPR/PR patients. The benefit in CR patients suggests the importance of continuing treatment in patients with chemo-sensitive disease. Trial registration: The two source studies are registered at ClinicalTrials.gov: identification numbers NCT01063179 and NCT00551928.