Absolute Lymphocyte Count Recovery Following Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma

Introduction Absolute lymphocyte count (ALC) recovery following autologous stem cell transplant(ASCT) has been shown to be an important factor for overall and progression free survival. This is thought to be mediated by improved immune reconstitution resulting in decreased adverse events. Objectives Our primary aim was to investigate the role of ALC recovery at day 30 (D30) following ASCT in the overall survival(OS) and progression free survival(PFS) in patients treated for multiple myeloma(MM). Our secondary aim was to evaluate the correlation between infused CD3 content and ALC D30. Methods Two hundred forty-six patients were identified from our center's CIBMTR database who underwent ASCT between 2000-2010 for MM. Following manual chart review one hundred twenty-five met criteria for inclusion in analysis. ALC D30 was defined as the closest ALC to D30 post ASCT +/- 7 days. Patients who did not have D30 ALC data (n= 87) or underwent tandem ASCT (n=25) were excluded. Descriptive data is available in Table 1. The cohort was split into two groups with ALC ≥ 500 cells x10^6/cu mm or ALC Results ALC D30 failed to show an association with either PFS or OS in the univariable and multivariable analyses. The Median PFS time in ALC ≥500 group was 23.7 months (95%CI: 18.4 - 29.7) compared to 30.1 months (95% CI: 15.5 – 70.5) in the ALC Conclusions Our study failed to show an association between ALC D30 recovery and OS or PFS in patients with MM undergoing ASCT. Previously identified factors such as age also did not show an association with OS and PFS in our study. Data on induction regimens was not collected for this study and maintenance therapy was not administered or data was unavailable for a large portion of our dataset which may contribute to the discrepancy with previously reported studies. CD3+ dose of cells infused showed a weak but statistically significant correlation with ALC D30.