Second Autologous Stem Cell Transplant (ASCT) as Salvage Therapy for Relapsed Multiple Myeloma.

Introduction: Autologous stem cell transplant (ASCT) as part of initial therapy has been shown to prolong survival of patients with multiple myeloma, with some achieving durable complete remission. However, the majority of patients ultimately relapse after ASCT and require salvage treatment. Options for the treatment of such patients have increased significantly over recent years, including not only novel chemotherapeutic and biological agents but also additional ASCTs. We performed a retrospective analysis of our experience with salvage ASCT for multiple myeloma to determine which clinical variables influence outcome.

Methods: Between October 1992 and February 2005, we performed 342 ASCTs for multiple myeloma. Twenty-six of these were salvage transplants for relapsed disease after prior ASCT, and all were included in the analysis. Patients who received two planned (tandem) ASCTs were not included.

Results: The median age at diagnosis was 47 (range 25–66), and median ISS and DS stages at diagnosis were 1 and 2, respectively. The initial ASCT was melphalan-based in 21/26; six (23%) achieved a complete response (CR) to the initial transplant, and fifteen (58%) achieved a partial response (PR). The median event-free survival (EFS) after the initial transplant was 19.5 months (range 2–60). The median time between initial and salvage ASCT was 2.6 years (range 0.3–7.6). Twenty-two patients (85%) received non-transplant therapy between ASCTs, and the median number of lines of therapy prior to salvage ASCT was 3. At the time of salvage ASCT, the median age was 52.5 (range 28–69). Fourteen patients received melphalan alone, eight received melphalan/TBI, and four received other regimens. Eleven patients (42%) achieved a response to therapy (1 CR, 10 PR). One patient (4%) died of transplant-related toxicity. The median follow-up after salvage ASCT is 12 months (range 0.2–58). Median EFS is 9 months, and median overall survival (OS) is 36 months. The 2-year EFS is 14%, and 2-year OS is 52%. On univariate analysis, both response to and EFS after initial transplant significantly predict improved EFS after salvage transplant (p=0.0008 and p=0.0065 respectively). Both also predict improved OS (p=0.03 and 0.0005 respectively). A greater than 12 month interval between first and second transplant also correlated with OS (p=0.04). There was no significant difference in EFS or OS by preparative regimen. Interestingly, type of response to the salvage transplant (CR/PR or less than PR) did not predict improved EFS or OS.

Conclusion: This study suggests that salvage ASCT after relapse from initial ASCT is a feasible therapy for patients with heavily treated multiple myeloma, particularly those with a prolonged response to the first transplant.