Feasibility of risk stratified allocation to single versus tandem autologous SCT in multiple myeloma.

Abstract

e18550 Background: Multiple myeloma (MM) is a plasma cell malignancy with variable prognosis depending on disease features such as β2m and cytogenetics. High dose therapy and stem cell transplantation (SCT) remains the current standard of care for MM, however the role of tandem SCT is controversial, particularly in the era of novel induction therapy. Methods: Our program has a practice of risk-stratified transplant allocation in MM patients referred for SCT, those with high-risk (HR) disease (β2m >5.5, adverse cytogenetics, >1st remission) are preferentially assigned tandem SCT, and those with standard risk (SR), a single SCT. Between 2008 and 2011, 129 MM patients underwent SCT, 43% SR patients received a single SCT (SRS), 22% HR received tandem SCT (HRT) & 36% HR a single SCT (HRS). Median age at SCT was 57 years. Maintenance therapy was administered in 51% SRS, 57% HRT & 67% HRS patients. Results: Complete response (CR) or very good partial response was achieved in 0.68, 0.72 and 0.80 for the HRT, HRS, and SRS groups. The HRT group (0.39) was more likely to achieve CR than HRS (0.20) (P=0.02). At a median follow up of 23.4 months, the overall survival for HRS was inferior to SRS (P=0.01) but there was no difference in the overall survival between HRT and SRS cohorts. Two-year survival rates were 0.81, 0.91 and 0.97 in the HRS, HRT and SRS cohorts (HRS vs. SRS P=0.02). This was attributable to a higher 1-year relapse rate in HRS (0.29) compared to HRT (0.07) and SRS (0.07) (P<0.01). Conclusions: Using a risk-stratified allocation system, we report that HR MM patients undergoing tandem SCT have outcomes comparable to SR patients. However, HR MM patients receiving a single SCT have inferior outcomes compared to those with SR. Notably, higher rate of CR and a lower relapse rate were observed in the HRT cohort when compared to HRS. This suggests that greater depth of remission achieved in HR patients undergoing tandem SCT may result in longer time to relapse and survival advantage compared to HR patients receiving a single SCT. In contrast, a single SCT may suffice for SR MM patients. These results demonstrate that risk-stratification based on disease prognostic features is an important treatment consideration when planning high dose therapy in MM patients.