title: Analysis of CLLU1 expression levels before and after therapy in patients with chronic lymphocytic leukemia.
abstract: OBJECTIVE
  Chronic lymphocytic leukemia (CLL) is incurable, but therapy leading to eradication of minimal residual disease (MRD) in CLL is associated with improved clinical outcomes. CLL upregulated gene 1 (CLLU1) is solely upregulated in CLL patient samples. We hypothesized that CLLU1 could be used to monitor for residual disease in CLL patient samples after therapy.
  
  
  METHODS
  We examined whether the CLLU1 real-time quantitative PCR (RQ-PCR) could detect small numbers of CLL cells in mixtures of normal peripheral blood mononuclear (PBMC) cells. We then performed a retrospective analysis on time-matched cryo-preserved specimens from patients who achieved MRD-negative remissions that underwent serial marrow biopsies for evaluation of residual disease by 4-color flow cytometry. RNA from PBMC samples collected at the time of the marrow assessments was analyzed for CLLU1. Nine patients underwent a total of 46 paired blood and marrow evaluations (median 5 assessments per patient).
  
  
  RESULTS
  CLLU1 RQ-PCR on PBMCs of healthy donors reconstituted with varying amounts of CLL cells demonstrated leukemia cells could be reliably detected with high sensitivities depending on the CLLU1 expression level. Analysis of time-matched samples assessed for CLLU1 levels in the blood by RQ-PCR and residual disease of the marrow determined by 4-color flow cytometry revealed a correlation coefficient of 0.96 (P < 0.0001).
  
  
  CONCLUSIONS
  The CLLU1 RQ-PCR is a sensitive and specific assay for detecting residual CLL cells after therapy. Assessment of blood CLLU1 levels can be used as a reliable marker of tumor burden and has the potential to complement currently used techniques for MRD monitoring in patients with CLL.
authors.affiliation: Department of Hematology, Rigshospitalet, Copenhagen, Denmark.|Division of Hematology/Oncology, Department of Medicine, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA.
authors.forename: Anne Mette
authors.initials: AM
authors.lastname: Buhl
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA.|The CLL Research Consortium, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Danelle F
authors.initials: DF
authors.lastname: James
authors.affiliation: The CLL Research Consortium, Dana-Farber Cancer Institute, Boston, MA.|Department of Biostatics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Donna
authors.initials: D
authors.lastname: Neuberg
authors.affiliation: Division of Biostatistics and Bioinformatics, UCSD, La Jolla, CA, USA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Jain
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA.|The CLL Research Consortium, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Laura Z
authors.initials: LZ
authors.lastname: Rassenti
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA.|The CLL Research Consortium, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kipps
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics; D001853:Bone Marrow / Q000473:pathology; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000097:blood / Q000235:genetics*; D018365:Neoplasm, Residual / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods / Q000706:statistics & numerical data; D062085:RNA, Long Noncoding; D012016:Reference Values; D012189:Retrospective Studies; D047368:Tumor Burden / Q000235:genetics; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; C510032:CLLU1 lncRNA, human; D009363:Neoplasm Proteins; D062085:RNA, Long Noncoding