| Background and objective:Multiple myeloma（MM）is a malignant tumor originated from monoclonal plasma cells,among which IgD MM is a relatively rare type.The incidence of IgD MM varies greatly between domestic and foreign studies,and the incidence in China is higher than that abroad,about 3%to 8.9%of all MM.IgD MM is characterized byλlight chain,extramedullary infiltration,poor prognosis,and the median survival is between 13 and 21 months.At present,most of the clinical data of IgD MM are derived from small retrospective studies,with large differences in clinical characteristics and unclear prognostic factors.In addition,the combination of new drugs and autologous hematopoietic stem cell transplantation can significantly prolong the survival time of MM patients,improve the remission rate and the depth of remission,but its efficacy in IgD MM patients has not been unified.Therefore,systematic and comprehensive research on IgD MM is still needed to help clinicians to further understand its clinical,prognostic and prognostic factors,so as to adopt effective treatment strategies.The purpose of this study is to analyze the clinical information of IgD MM patients in China,analyze the unique clinical characteristics of IgD MM patients in China,and explore the prognosis factors of the disease.Methods:The clinical data of 231 IgD MM diagnosed from July 2006 to June 2021 in 13centers in China were retrospectively analyzed.All statistical analyses were conducted using SPSS software（version 22.0）,Graphpad Prism（version 8.0）and R packages survival and survminer in R/Bioconductor（version 4.0.4）.Baseline clinical characteristics of IgD MM and non-IgD MM were compared by using Chi-square test or Fisher exact probability test.Overall survival（OS）probabilities were estimated using the Kaplan-Meier method.Differences were tested for statistical significance using the（two-sided）log-rank test and hazard ratios（HRs;with two-sided 95%CIs）.Univariate and multivariate survival analyses were performed by Cox regression models.P<0.05 was considered statistically significant.Results:1.Clinical characteristics of IgD MM:Among the 864 cases of newly diagnosed myeloma in Bethune First Hospital of Jilin University,53 cases（6.1%）were IgD MM.The median age of the 231 IgD MM was 58 years.Male was more common,accounting for 64.9%.The light chain ofλtype（92.2%）was more common.ISS stage Ⅲ accounted for 66.4%,R-ISS stage Ⅲ accounted for 33.1%.The incidence of anemia,renal insufficiency,hypercalcemia,osteolytic disease and extramedullary disease were 71%,43.6%,22.9%,95.4%and 23.4%,respectively.The incidence of LDH elevation（≥220U/L）,β2-MG（≥5.5mg/L）,BMPCs（≥60%）,PLT<100×10~9/L,ALB<40g/L,GLB<40g/L and immune paralysis were 40.6%,64.8%,32.7%,22.6%,63.8%81.9%and 77.8%,respectively.The incidence of del（17p）,del（13q）,1q+,t（11;14）,t（4;14）and t（14;16）were 14.3%,40.6%,76%,38.8%,2.5%and 2.6%,respectively.The incidence of SRCA,HRCA,double strike and triple strike were18.3%,81.7%,8.6%and 0%,respectively.2.Comparison of characteristics between IgD MM and non-IgD MM:The median age of IgD MM and non-IgD MM was 58 years and 61 years,respectively.IgD MM patients younger than 65 years was more common than non-IgD MM（74%vs 62.8%,P=0.003）.And ISS stage Ⅲ（66.4%vs 46.8%,P<0.05）,R-ISS stage Ⅲ（33.1%vs 26.5%,P=0.120）,PLT<100×10~9/L（22.6%vs 10.6%,P<0.001）,LDH elevation（40.6%vs 27%,P=0.001）,β2-MG≥5.5mg/L（64.8%vs 46.8%,P<0.001）and renal insufficiency（43.6%vs 21.4%,P<0.001）were higher than those in non-IgD MM.ALB<40g/L was lower than those in non-IgD MM（63.8%vs 84.1%,P<0.001）.The incidence of Hb<100g/L,extramedullary disease,Cs Ca>2.75mmol/L and osteolytic disease had no statistical difference with non-IgD MM.In FISH,1q+and t（11;14）were higher than those in non-IgD MM（76%vs 50.8%,P<0.001,38.8%vs10.3%,P<0.001）,t（4;14）（2.5%vs 15.16%,P=0.001）,HRCA（81.7%vs 100%,P<0.001）,double strike（8.6%vs 16%,P=0.021）were lower than those in non-IgD MM patients.The incidence of three strikes was similar between them（0%vs 1.3%,P=0.348）.3.Therapeutic response of IgD MM:The median PFS and OS of IgD MM were19 and 41 months respectively,which were significantly lower than those of non-IgD MM were 24（P=0.001）and 53 months（P<0.001）.In IgD MM,86.2%achieved disease remission and 62.9%achieved deep remission.The deep remission in patients with PI as the main treatment was higher than the general population（72.5%vs62.6%）,and patients with IMiD as the main treatment was lower than the general population（46.7%vs 62.6%）.The ORR rate,deep response rate and CR rate of 11transplanted patients were 100%,81.8%and 63.6%,respectively.The median PFS of patients with IMiD-based treatment,PI-based treatment and PI-combined IMID-based treatment was 13 months,22 months and 23 months,respectively.Median OS was 14months,37 months and 48 months,respectively.PI-based and PI-combined IMID-based regimens had significantly better survival than IMID-based regimens（mPFS:22 months vs 13 months,P=0.043,23 months vs 13 months,P=0.008,mOS:37 months vs 14 months,P=0.014,48 months vs 14 months,P<0.001）,patients treated with ASCT had better survival than those not treated with ASCT（mPFS:27months vs 18 months,P=0.072,mOS:68 months vs 41.6 months,P=0.373）.4.Prognostic factors for IgD MM:Univariate analysis showed that male,ISS stage Ⅲ,β2-MG≥5.5mg/L,LDH elevation,and BMPCs≥60%were all adverse prognostic factors for PFS;In addition to the above factors,PLT<100×10~9/L,ALB<40g/L and extramedullary disease were also adverse prognostic factors affecting OS.Multivariate analysis showed thatβ2-MG≥5.5mg/L（HR=2.043,95%CI=1.148-3.636,P=0.015）and BMPCs≥60%（HR=1.910,95%CI=1.146-3.185,P=0.013）were independent prognostic factors of PFS.Extramedullary disease（HR=2.151,95%CI=1.029-4.495,P=0.042）and BMPCs≥60%（HR=2.094,95%CI=1.098-3.993,P=0.025）were independent adverse prognostic factors for OS.5.Early mortality in IgD MM:The incidence of EM6,EM12 and EM24 in IgD MM was 14.1%,18.8%and 28.3%,respectively.The incidence of EM6,EM12 and EM24 in non-IgD MM was 5.6%,8.5%and 15.8%,respectively,the differences were statistically significant（P<0.001）.Univariate analysis:male,β2-MG≥5.5mg/L and BMPCs≥60%were the adverse prognostic factors of EM6,EM12 and EM24.In addition to the above factors,ISS stage Ⅲ was an adverse prognostic factor of EM6.LDH elevation and extramedullary disease were the adverse prognostic factors of EM12.ISS stage Ⅲ and extramedullary disease were the adverse prognostic factors of EM24.Multivariate analysis showed BMPCs≥60%（HR=3.302,95%CI=1.147-9.508,P=0.027）was the independent prognostic factor of EM6.LDH elevation（HR=3.773,95%CI=1.326-10.733,P=0.013）,extramedullarydisease（HR=3.505,95%CI=1.160-10.592,P=0.026）,BMPCs≥60%（HR=3.335,95%CI=1.110-10.016,P=0.032）were the independent prognostic factors of EM12.LDH elevation（HR=2.999,95%CI=1.180-7.621,P=0.021）and BMPCs≥60%（HR=3.373,95%CI=1.282-8.876,P=0.014）were the independent prognostic factors of EM24.Conclusions:1.IgD MM is a rare type of myeloma,with an incidence of 6.1%in this study.Compared with non-IgD MM,IgD MM is younger at diagnosis,with a dominant light chainλ,the stage of IgD MM was poor,and high tumor load,1q+and t（11;14）were common.2.Compared with non-IgD MM,IgD MM has a poorer prognosis and shorter survival time.3.The independent prognostic factors of PFS wereβ2-MG≥5.5mg/L and BMPCs≥60%.The independent prognostic factors of OS were extramedullary disease and BMPCs≥60%.4.Compared with non-IgD MM,IgD MM was more likely to early death.The independent prognostic factors of EM6 were BMPCs≥60%.The independent prognostic factors of EM12 were increased LDH,extramedullary disease and BMPCs≥60%.The independent prognostic factors of EM24 were elevated LDH and BMPCs≥60%. |
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