Patterns of Relapse Among Myeloma Patients Post-Autologous Stem Cell Transplant

Introduction: In younger patients that are transplant-eligible, autologous stem cell transplant (ASCT) prolongs overall survival based on several prospective randomized control trials. Nevertheless, ASCT is not a curative approach and majority of the patient's relapse, requiring further salvage therapeutic options. However, in the face of an ongoing paradigm shift in myeloma therapeutics, there is a significant knowledge gap regarding how patients relapse following ASCT. We analyzed the patterns of relapse among myeloma patients after ASCT.

Methodology: We have evaluated a total of 975 patients that underwent ASCT during the period January 2008 through June 2014 from our myeloma database. 273 patients had documented evidence of first relapse post-ASCT on the laboratory parameters, radiologic or pathologic findings based on IMWG criteria for relapse. We categorized the relapses as biochemical vs symptomatic, and described their frequencies and characteristics. Median time of follow up from diagnosis is 68 months and from ASCT is 54 months. We used IBM SPSS version 23.0 to generate the survival statistics.

Results: Median time from ASCT to relapse is 20 months. A total of 182 (66.7%) patients (105M, 77F) experienced biochemical relapse, while 91 (33.3%) patients (50M, 41F) had symptomatic relapse. More IgA patients (30.8% vs 23.1%, p=0.06) relapsed as symptomatic myeloma. While characterizing relapses, we did not find any differences in symptomatic relapses by the risk group [high risk (31.3%) vs standard risk (31.9%), p=0.193, ISS stage I (29.3%) vs II (32.9%) vs III (32.8%), p=0.807] or by maintenance [yes (30.7%) vs no (38.1%), p=0.211]. Among the patients that had a symptomatic relapse, presence of new bone lesions (52%) and anemia (42%) are the most common forms of relapse seen. Only 4% presented as hypercalcemia and 1% presented as renal failure illustrating the benefits of closer follow up. Overall survival is similar among patients that relapsed as biochemical or symptomatic relapse (log rank, p=0.105). More importantly, impressive median OS of 145 months from the ASCT among this entire cohort (at median follow up 54 months, figure 1).

Conclusions: Two-thirds of the patients relapse as a biochemical relapse post-ASCT. The patterns of biochemical vs symptomatic relapses were similar among patients by maintenance, by risk status and also by the ISS stage. The significant improvement in OS among the entire cohort emphasizes the power of the new therapeutic salvage strategies aimed at gaining the survival advantage even among this selected group of patients undergoing early relapses.

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