Clinical And Experimental Study On Thalidomide In The Treatment Of Multiple Myeloma

Partâ… Clinical study of 110 patients with multiple myeloma treated with thalidomide based regimensObjective To explore the response rate(RR),progress-free survival(PFS) and overall survival(OS) in Chinese patients with multiple myeloma(MM) treated with thalidomide -based regimens and identify the potential prognostic factors.Methods Our study enrolled 110 patients treated with thalidomide-based regimens and their laboratory and clinical parameters were retrospectively analyzed.Comparisons of RR were performed by x² test.Survival analysis was performed by Kaplan-Meier method and the comparison between groups by Log-rank test.Multivariate analysis was carried out by Cox proportional hazard model.Results The patients received thalidomide alone(5 patients),thalidomide plus dexamethasone(Thal+Dex)(55 patients) or thalidomide plus conventional chemotherapy (Thal+CC)(50 patients).The overall RR was 63.6%(complete response rate 6.4%,partial response rate 57.3%).Patients with age＜65 years,time from diagnosis to the start of thalidomide treatment＜6 months or combined therapy had a significantly higher RR (P＜0.05).In univariate analysis,age＜65 years predicted a longer PFS(P=0.008).Age＜65 years,serum creatinine(Cr)＜176.8μmol/L and serum beta 2 microglobulin(β₂MG)＜3.5mg/L were associated with longer OS(P=0.028,0.045 and 0.019,respectively). Multifactor analysis suggested that serumβ₂MG was the only independent prognostic factor for OS(P=0.025).Most common side effects consisted of constipation(38.2%), somnolence(33.6%),edema(31.8%) and numbness(29%),which was tolerated by majority of the patients.Rare but severe adverse events included bradycardia(2.7%), thromboembolism(1.8%) and mental anomaly(0.9%).Conclusion Thalidomide based therapy proved to have confirmed efficacy for the treatment of myeloma with tolerable side effects by most patients.The RR was associated with age,time of the start of thalidomide therapy and treatment regimens.Age was also a prognostic factor for PFS.Serumβ₂MG was an independent prognostic factor predicting OS. Partâ…¡Effect of CYP2C19 genetic polymorphism on efficacy of thalidomide based regimens for the treatment of multiple myelomaObjective To identify the distribution of different genotypes of CYP2C19 in multiple myeloma(MM) and investigate the effect of its polymorphism on efficacy of thalidomide based regimens for the treatment of MM and discuss the role of antiangiogenesis in MM.Methods The CYP2C19 genotype of 92 patients with multiple myeloma was determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.The incidence rate of poor metabolizer(PM) in MM was compared with healthy Chinese population.After they were treated with thalidomide-based regimens, the response rate was compared between extensive metabolizers(EMs) and PMs.Results Of 92 patients,18 were PMs,giving an incidence rate of 19.5%which was similar to that of healthy ones.The response rate of EMs and PMs was 62.6%and 33.3%, respectively(P＜0.05).When patients were grouped by treatment regimens,the response rate of EMs was statistically higher than PMs(60.8%versus 27.3%) in the thalidomide-dexamethasone cohort and similar results was observed in the thalidomide-chemotherapy group although no statistical difference was observed(65.2% versus 42.7%,P＞0.05).Conclusion CYP2C19 genotype has no relationship with incidence of MM but exhibits an effect on the treatment efficacy of thalidomide for MM.The lower response rate observed in PMs was possibly due to the reduced property to inhibit angiogenesis by thalidomide. Partâ…¢Effect of cytochrome CYP2C19 on the antimyeloma activity of thalidomide in vitroObjective To investigate the effect of human liver microsome on antimyeloma activity of thalidomide in vitro and identify the role of cytochrome CYP2C19.Methods Human multiple myeloma(MM) cell lines U266,NCI-H929,RPMI 8226, LP-1 and CZ-1 were treated with thalidomide alone or thalidomide preincubated with human liver microsome.Cell viability was assessed by MTT assay and cell cycle analysis and detection of apoptosis by flow cytometer(FCM).Results Thalidomide alone has no obviously direct effect on cell viability.However, when preincubated with human liver microsome,thalidomide significantly inhibits the cell viability and the effect was dose dependent.At the concentration of 100μg/ml,thalidomide preincubated with human liver microsome causes a 34.9%～46.3%decrease of cell viability and an increase of 18.5%～32.5%in apoptosis cells.When omeprazole,a specific inhibitor of cytochrome CYP2C19,was added in the incubation mixture,the inhibition of cell viability by thalidomide was weakened.At the concentration of 5μmol/L and 10μmol/L,omeprazole reversed the cell viability by 7.5%～21.9%and 19.1%～38.3%, respectively.Conclusion Metabolism of thalidomide by human liver microsome is required for thalidomide's antimyeloma activity in vitro.Cytochrome CYP2C19 was at least in part responsible for the metabolism of thalidomide to exhibit the activity.Partâ…£Antiangiogenic activities of thalidomide in vitro mediated by cytochrome CYP2C19Objective To investigate the effect of human liver microsome on antiangiogenic activity of thalidomide in vitro and identify the role of cytochrome CYP2C19.Methods Human umbilical vein endothelial cells(HUVECs) were treated with thalidomide alone or thalidomide preincubated with human liver microsome.Cell viability was assessed by MTT assay,cell cycle analysis and detection of apoptosis by flow cytometer(FCM),migration activity by modified Boyden chamber assay and differentiation of HUVEC by tube formation assay,respectively.Results Thalidomide alone had no obviously direct effect on cell viability or apoptosis, mild effect on cell migration and no effect on tube formation.However,when preincubated with human liver microsome,thalidomide significantly inhibited the cell viability and the effect was dose dependent.At the concentration of 100μg/ml,thalidomide preincubated with human liver microsome caused a(11.7±3.9)%decrease of cell viability,an increase of 27.2%in apoptosis cells,significantly inhibited the cell migration and obviously suppressed the tube formation.When omeprazole,a specific inhibitor of cytochrome CYP2C19,was added in the incubation mixture,the effects of thalidomide on cell viability, apoptosis,migration and tube formation were partially reversed.Conclusion Metabolism of thalidomide by human liver microsome is required for thalidomide's antiangiogenic activity in vitro.Cytochrome CYP2C19 was at least in part responsible for the metabolism of thalidomide to exhibit the activity.