Outcomes with early response to first-line treatment in patients with newly diagnosed multiple myeloma.

We evaluated the impact of achieving a rapid response in 840 newly diagnosed multiple myeloma patients from 2004 to 2015. Rates of very good partial response (VGPR) or better were 29% (240/840) after 2 cycles of treatment, 42% (350/840) after 4 cycles of treatment, and 66% (552/840) as best response. Early responders after 2 cycles of treatment had higher rates of light chain disease, anemia, renal failure, International Staging System (ISS) stage III disease, and high-risk cytogenetics, especially t(4;14), and were more likely to have received triplet therapy and undergo transplant. Median progression-free survival (PFS) and overall survival (OS) were not different among patients with ≥VGPR and <VGPR after 2 cycles (PFS, 28 vs 30 months, P = .6; OS, 78 vs 96 months, P = .1) and 4 cycles (PFS, 31 vs 29 months; OS, 89 vs 91 months, P = .9), although both were improved, with ≥VGPR as best response (PFS, 33 vs 22 months, P < .001; OS, 102 vs 77 months, P = .003). On multivariate analysis stratified by transplant status, achievement of ≥VGPR after 2 cycles was not associated with improved PFS (hazard ratio [95% confidence interval]; transplant cohort, 1.1 [0.7-1.6]; nontransplant cohort, 1.2 [0.8-1.7]) or OS (transplant cohort, 1.6 [0.9-2.9]; nontransplant cohort, 1.5 [1.0-2.4]). Covariates in the model included high-risk cytogenetics, ISS stage III, triplet therapy, creatinine ≥2 mg/dL, light chain disease, and age. Although patients with high-risk disease are more likely to achieve early response, a rapid achievement of a deep response by itself does not affect long-term outcomes.