Predicting long-term (≥ 5 years) event-free survival in multiple myeloma patients following planned tandem autotransplants

Although outcome in multiple myeloma (MM) patients has improved significantly with the introduction of autotransplants (AT), the curability of this approach remained to be demonstrated. Therefore, we analysed outcome and prognostic factors using a logistic regression model in 515 consecutive newly diagnosed and previously treated patients intended to receive melphalan-based tandem transplants with follow up of greater than or equal to 5 years. One quarter of patients had event-free survivals (EFS) greater than or equal to 5 years with no further relapses seen after 7 years (46 patients on plateau). On multivariate analysis, factors associated with EFS greater than or equal to 5 years were absence of chromosome 11 and 13 abnormalities (odds ratio: 6.1), less than or equal to 12 months of preceding standard-dose therapy (SDT) (OR: 2.6) and beta-2 microglobulin (B2M) level less than or equal to 2.5 mg/l at time of first AT (OR: 1.7). Patients with only favourable variables (25%) had a 7-year EFS in excess of 35%, compared with 15% and 10%, respectively, with one (43%) or two unfavourable variables (27%), and 0% for 5% of patients with three unfavourable variables (P < 0.0001). Using a 1-year landmark analysis to allow for guaranteed time and thereby excluding early treatment failures, attaining a complete remission (CR) had no significant effect on long-term survival. Our data are consistent with cure in MM patients with a CR duration >= 7 years and re-establishment of a monoclonal gammopathy of undetermined significance (MGUS) phase in those with persistent evidence of disease post transplantation, but without disease progression >= 7 years.