Minimal residual disease analysis in multiple myeloma: A single-center experience

Abstract

BACKGROUND: Over the years, with changes in treatment approaches, it has been possible to achieve higher complete response (CR) rates with chemotherapies or chemoimmunotherapies in multiple myeloma (MM). However, a subset of patients in CR still relapse owing to the presence of residual tumor cells in the bone marrow not detectable by conventional methods. Residual disease detection by flow cytometry (FCM) has been proven to be highly sensitive and prognostically significant in a number of clinical studies. AIMS AND OBJECTIVES: In this study, we compared FCM minimal residual disease (FCM MRD) in MM cases post-chemotherapy/autologous stem cell transplant with morphology and biochemical methods. We also tried to correlate the pre-therapy stage of the disease and cytogenetics with MRD. MATERIALS AND METHODS: Twenty eight samples from 26 patients were evaluated for MRD on 6 color 3 tube panel over the period of 2 years. RESULTS: MRD was detectable in 19 samples (67.9%). FCM had a sensitivity of 95% compared to immunohistochemistry (IHC). 100% of cases with MRD positivity had abnormalities in at least three surface antigens. The high risk cytogenetics and high risk stage groups had a higher frequency of MRD positivity compared to the low risk groups. CONCLUSION: FCM MRD analysis is able to risk stratify the patients in CR and stringent CR. Routine use of FCM to detect residual disease posttherapy in MM should be implemented.