title: Measuring cereblon as a biomarker of response or resistance to lenalidomide and pomalidomide requires use of standardized reagents and understanding of gene complexity.
abstract: Cereblon, a member of the cullin 4 ring ligase complex (CRL4), is the molecular target of the immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide and is required for the antiproliferative activity of these agents in multiple myeloma (MM) and immunomodulatory activity in T cells. Cereblon's central role as a target of lenalidomide and pomalidomide suggests potential utility as a predictive biomarker of response or resistance to IMiD therapy. Our studies characterized a cereblon monoclonal antibody CRBN65, with high sensitivity and specificity in Western analysis and immunohistochemistry that is superior to commercially available antibodies. We identified multiple cereblon splice variants in both MM cell lines and primary cells, highlighting challenges with conventional gene expression assays given this gene complexity. Using CRBN65 antibody and TaqMan quantitative reverse transcription polymerase chain reaction assays, we showed lack of correlation between cereblon protein and mRNA levels. Furthermore, lack of correlation between cereblon expression in MM cell lines and sensitivity to lenalidomide was shown. In cell lines made resistant to lenalidomide and pomalidomide, cereblon protein is greatly reduced. These studies show limitations to the current approaches of cereblon measurement that rely on commercial reagents and assays. Standardized reagents and validated assays are needed to accurately assess the role of cereblon as a predictive biomarker.
authors.affiliation: Celgene Corporation, Summit, NJ, USA.
authors.forename: Anita K
authors.initials: AK
authors.lastname: Gandhi
authors.forename: Derek
authors.initials: D
authors.lastname: Mendy
authors.forename: Michelle
authors.initials: M
authors.lastname: Waldman
authors.forename: Gengxin
authors.initials: G
authors.lastname: Chen
authors.forename: Emily
authors.initials: E
authors.lastname: Rychak
authors.forename: Karen
authors.initials: K
authors.lastname: Miller
authors.forename: Svetlana
authors.initials: S
authors.lastname: Gaidarova
authors.forename: Yan
authors.initials: Y
authors.lastname: Ren
authors.forename: Maria
authors.initials: M
authors.lastname: Wang
authors.forename: Michael
authors.initials: M
authors.lastname: Breider
authors.forename: Gilles
authors.initials: G
authors.lastname: Carmel
authors.forename: Afshin
authors.initials: A
authors.lastname: Mahmoudi
authors.forename: Pilgrim
authors.initials: P
authors.lastname: Jackson
authors.forename: Mahan
authors.initials: M
authors.lastname: Abbasian
authors.forename: Brian E
authors.initials: BE
authors.lastname: Cathers
authors.forename: Peter H
authors.initials: PH
authors.lastname: Schafer
authors.forename: Tom O
authors.initials: TO
authors.lastname: Daniel
authors.forename: Antonia
authors.initials: A
authors.lastname: Lopez-Girona
authors.forename: Anjan
authors.initials: A
authors.lastname: Thakurta
authors.forename: Rajesh
authors.initials: R
authors.lastname: Chopra
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017398:Alternative Splicing; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006801:Humans; D009101:Multiple Myeloma / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D059368:RNA Isoforms; D013792:Thalidomide / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C502543:CRBN protein, human; D059368:RNA Isoforms; D013792:Thalidomide; C467566:pomalidomide; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases
keywords: DNA damage binding protein 1; cereblon; cullin 4 ring ligase complex; immunomodulatory drugs; myeloma