The Prognostic Significance of Minimal Residual Disease Detection after Induction and ASCT to the Patients with Multiple Myeloma
Authors: Yao Weiqin , Mingqing Zhu , Feirong Yao , Yan Lingzhi , Jin Song , Shang Jingjing , Yao Ying , Yan Shuang , Wu Depei , Fu ChengCheng 
Published: October 2019

Abstract
Objective: In the last decade the outcome in multiple myeloma in CHINA has greatly improved due to the new, effective therapies including PIs and Imids. But responses to treatment and survival remains heterogeneous because of patient characteristic, disease biology and mechanisms of drug resistance. More and more studies have established the link between depth of response and improved PFS and OS. multiparameter-flow cytometry (MFC) is a main method to detect minimal residual disease(MRD) in myeloma. Sensitivity will be at least at 10-4 to 10-5 by 10-color MFC. Imaging techniques such as PET-CT are important for EMD and bone MRD detection. whole body DWI-MRI is a new imaging technique by mean of the apparent diffusion coefficient(ADC) which can qualify the depth of response to antineoplastic treatment. This study was designed to evaluate the prognostic significance of MRD by 10-color MFC and imaging to the MM patients after induction.Methods: 102 patients with newly diagnosed MM were enrolled at the First Affiliated Hospital of Soochow University from July 2015 to July 2017. All patients were diagnosed and the response were assessed by IMWG criteria. The median of age was 58 (31-75).There were 46 patients with IgG type , 24 IgA , 14 light chain, 18 others. 34 Patients in ISS stageⅠ,34 in stage Ⅱ, 30 in stage Ⅲ. All patients received 4-6 cycles of triplet bortezomib based or lenalidomide based induction therapy. Transplantation available patients received APBSCT with BUCY condition followed by 4-6 cycles of bortezomib based or lenalidomide based consolidation which were given to transplantation unavailable patients too. Lenalidomide and thalidomide were used for over 2y of maintenance therapy. Bone marrow aspirates for MRD imaging MRD assessment were obtained at the end of induction and 1year after ASCT.The median of follow-up was 13 (2-29) months.Results: According to MRD by MFC and imaging after induction therapy and 1 year after ASCT, the patients were divided into different groups. MFC negativity was 33%(29/88) after induction therapy compared with 63%(32/51) after ASCT (X2=11.636,P=0.001). After induction therapy, the median PFS was 22 months for MRD positive group compared with not reached with MRD negative group by MFC (P=0.042) in patients with very good partial remission(VGPR) and above. The 2 years PFS was 100% for those with MRD negative compared with 60% for MRD positive by imaging. The 2 years PFS was 80% for those have multiclonal normal plasma cells compared with 52.6% for those without. The median PFS was not reached for MFC MRD negative patients 1 year after ASCT compared with 20 months for positive patients. (P=0.002). Multivariate analysis including high risk cytogenetics(17p-, t(4;14), t(14;16)), sex, age, ISS, chemotherapy, ASCT, CR/VGPR, normal PCs showed that the MFC MRD and ASCT were independent prognostic factor.Conclusions: Patients with MFC MRD negative after induction therapy or ASCT is a better prognostic marker than CR or even the best marker. Imaging MRD negativity and the appearance of normal plasma cells in the bone marrow suggests a better prognosis.We will have a try to do more research on overall survival(OS),include longer follow-up and a larger number of patients enrolled.
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Disclosures
No relevant conflicts of interest to declare.