Effect of complete response pre- and post- autologous stem cell transplantation in multiple myeloma

Abstract

7604 Background: The value of achieving a complete response (CR) pre or post high dose therapy and autologous stem cell transplant (HDT-ASCT) in multiple myeloma is still uncertain. Knowing the impact of achieving a CR prior to HDT-ASCT on survival, may lead to the incorporation of novel therapeutic agents into the front line treatment of this disease. The aim of our study was to determine whether achieving a CR before or after HDT-ASCT affects overall survival (OS) in multiple myeloma patients. Methods: We performed a retrospective analysis of 88 consecutive myeloma patients receiving HDT-ASCT at our center from 1993 to 2004. The OS of patients achieving at least 90% reduction in their M-protein, i.e. complete response and very good partial response (CR/VGPR), pre or post HDT-ASCT, was compared to that of patients achieving a partial response or less (<90% reduction in M-protein). OS, defined as the number of months from HDT-ASCT to death or last follow up, was estimated by the Kaplan-Meier method. Response status was evaluated pre and at 100 days post HDT-ASCT. Results: Prior to HDT-ASCT, twenty-two (25%) patients achieved a CR/VGPR. Median follow-up time was 39 months for patients in CR/VGPR and 18 months for non-CR/VGPR group. OS at 5 years was 58% (95% CI: 21%-82%) for patients in CR/VGPR, compared to 69% (95% CI: 51%-81%) for all patients in PR or less prior to stem cell collection. Post HDT-ASCT, 48 (55%) patients achieved a CR/VGPR. Their OS estimate at 5 years was 67% (95% CI: 44%-82%) compared to 71% (95% CI: 27%-92%) for all other patients. Overall, 30% more patients achieved CR/VGPR post HDT-ASCT. However, the survival curves did not differ by response status pre or post HDT-ASCT (log-rank test p=0.58 and 0.57 respectively). Conclusions: Our results suggest that achieving a clinical CR/VGPR pre or post HDT-ASCT does not appear to impact OS. These results might have been influenced by the small sample size and the possible need for a longer follow-up time. A more robust definition of CR at the molecular level, plus the use of novel therapeutic agents in front-line treatment, may better define the impact of achieving CR in multiple myeloma. No significant financial relationships to disclose.