title: Analysis of circulating tumor cells in patients with multiple myeloma during the course of high-dose therapy with peripheral blood stem cell transplantation.
abstract: In multiple myeloma (MM) circulating CD19+ cells have been considered as myeloma precursors. As these cells are also possibly a reservoir of treatment resistant disease evaluation of the CD19+ cells during the course of high-dose therapy has to be a major concern. We determined the number of tumor cells in the CD19+ as well as CD19- fractions of PB of eight patients with disease sensitive to VA[I]D chemotherapy, of 10 patients who achieved partial or complete remission post-high-dose therapy (HDT) with peripheral blood stem cell transplantation (PBSCT) and of a further seven patients with disease progression post-transplantation. CD19+ cell fractions were obtained by preparative sequential magnetic and fluorescence activated cell sorting with a median purity of 97.1%. In addition, PB samples of seven patients post-transplantation were sorted for CD20+ cells (median purity, 98.7%). The number of tumor cells in the CD19+, the CD19- and the CD20+ fractions were determined using a quantitative CDR3 PCR assay. The number of CD19+ tumor cells in patients in remission post-HDT was similar to those of the patients post-VA[I]D (median, 1.05 vs 0.92 CD19+ tumor cells/ml PB, P = 0.72) providing evidence for the persistence of this tumor cell fraction during the course of HDT. This was in contrast to the CD19- compartment, in which the number of tumor cells was significantly reduced in those patients in remission post-transplantation (median, 53 vs 0 CD19- tumor cells/ml PB; P = 0.006). In patients with progressive disease the number of tumor cells in both cell fractions was significantly higher (CD19+: median, 1.05 vs 21 tumor cells/ml PB, P = 0.05; CD19-: 0 vs 63 tumor cells/ml PB, P = 0.008). While the absolute number of CD19+ cells was reduced in the group of patients after VA[I]D treatment, a polyclonal CD19+ reconstitution had occurred in patients responding to HDT. The tumor cell content in the CD19+ fractions could be confirmed by the results obtained analyzing the CD20+ cell fractions. In conclusion, these results indicate that disease progression after PBSCT in MM is accompanied by an expansion of tumor cells in both the CD19+ and CD19- fractions. Similar numbers of CD19+ clonotypic cells post-HDT suggest that these cells persist and thus, contribute to disease dissemination and relapse.
authors.affiliation: Department of Internal Medicine V, University of Heidelberg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kiel
authors.forename: F W
authors.initials: FW
authors.lastname: Cremer
authors.forename: C
authors.initials: C
authors.lastname: Rottenburger
authors.forename: C
authors.initials: C
authors.lastname: Kallmeyer
authors.forename: E
authors.initials: E
authors.lastname: Ehrbrecht
authors.forename: A
authors.initials: A
authors.lastname: Atzberger
authors.forename: U
authors.initials: U
authors.lastname: Hegenbart
authors.forename: H
authors.initials: H
authors.lastname: Goldschmidt
authors.forename: M
authors.initials: M
authors.lastname: Moos
mesh_terms: D000328:Adult; D000368:Aged; D018941:Antigens, CD19 / Q000097:blood; D018951:Antigens, CD20 / Q000097:blood; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology; D002452:Cell Count; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007135:Immunoglobulin Variable Region; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood* / Q000276:immunology / Q000628:therapy*; D009360:Neoplastic Cells, Circulating / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D016133:Polymerase Chain Reaction; D014182:Transplantation, Autologous; D014410:Tumor Stem Cell Assay
chemical_list: D018941:Antigens, CD19; D018951:Antigens, CD20; D007135:Immunoglobulin Variable Region