Gene expression profiling of plasma cells at myeloma relapse from tandem transplantation trial Total Therapy 2 predicts subsequent survival

We report on prognostic implications for postrelapse survival (PRS) of a gene expression profiling (GEP)-defined risk score at relapse available in 120 myeloma patients previously enrolled in tandem transplantation trial Total Therapy 2. Among the 71 patients with additional GEP baseline information, 3-year PRS was 71% in 40 patients with low risk present both at baseline and relapse contrasting with only 17% in 28 patients with high risk at relapse, 12 of whom with baseline low-risk status fared better than the remainder (P = .08). On multivariate analysis of relapse parameters available in 104 patients, high risk conferred short PRS (hazard ratio = 4.00, P < .001, R² = 33%), whereas relapse hyperdiploidy predicted long PRS (hazard ratio = 0.37, P = .022, cumulative R² = 41%). In case the initial partial response lasted less than 2 years, relapse low-risk identi-fied 26 patients with superior 3-year PRS of 61% versus 9% among 32 with relapse high-risk (P < .001). Based on its PRS predictive power, GEP analysis should be an integral part of new agent trials in search of better therapy for high-risk myeloma.