Validation of ZAP-70 methylation and its relative significance in predicting outcome in chronic lymphocytic leukemia.

Abstract

ZAP-70 methylation 223 nucleotides downstream of transcription start (CpG+223) predicts outcome in chronic lymphocytic leukemia (CLL), but its impact relative to CD38 and ZAP-70 expression or immunoglobulin heavy chain variable region (IGHV) status is uncertain. Additionally, standardizing ZAP-70 expression analysis has been unsuccessful. CpG+223 methylation was quantitatively determined in 295 untreated CLL cases using MassARRAY. Impact on clinical outcome vs CD38 and ZAP-70 expression and IGHV status was evaluated. Cases with low methylation (<20%) had significantly shortened time to first treatment (TT) and overall survival (OS) (P < .0001). For TT, low methylation defined a large subset of ZAP-70 protein-negative cases with significantly shortened TT (median, 8.0 vs 3.9 years for high vs low methylation; hazard ratio [HR] = 0.43; 95% confidence interval [CI], 0.25-0.74). Conversely, 16 ZAP-70 protein-positive cases with high methylation had poor outcome (median, 1.1 vs 2.3 years for high vs low methylation; HR = 1.62; 95% CI, 0.87-3.03). For OS, ZAP-70 methylation was the strongest risk factor; CD38 and ZAP-70 expression or IGHV status did not significantly improve OS prediction. A pyrosequencing assay was established that reproduced the MassARRAY data (κ coefficient > 0.90). Thus, ZAP-70 CpG+223 methylation represents a superior biomarker for TT and OS that can be feasibly measured, supporting its use in risk-stratifying CLL.

• Authors: Rainer Claus, David M Lucas, Amy S Ruppert, Katie E Williams, Daniel Weng, Kara Patterson, Manuela Zucknick, Christopher C Oakes, Laura Z Rassenti, Andrew W Greaves, Susan Geyer, William G Wierda, Jennifer R Brown, John G Gribben, Jacqueline C Barrientos, Kanti R Rai, Neil E Kay, Thomas J Kipps, Peter Shields, Weiqiang Zhao, Michael R Grever, Christoph Plass, John C Byrd
• Journal: Blood (Blood) Vol. 124 Issue 1 Pg. 42-8 (Jul 03 2014) ISSN: 1528-0020 [Electronic] United States
• PMID: 24868078 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Validation Study)
• Copyright: © 2014 by The American Society of Hematology.

Chemical References

• Biomarkers, Tumor
• Immunoglobulin Variable Region
• ZAP-70 Protein-Tyrosine Kinase
• ZAP70 protein, human

Topics

• Adult
• Aged
• Aged, 80 and over
• Biomarkers, Tumor (analysis)
• DNA Methylation (genetics)
• Female
• Humans
• Immunoglobulin Variable Region (genetics)
• Kaplan-Meier Estimate
• Leukemia, Lymphocytic, Chronic, B-Cell (genetics, metabolism, mortality)
• Male
• Middle Aged
• Prognosis
• Proportional Hazards Models
• Reverse Transcriptase Polymerase Chain Reaction
• ZAP-70 Protein-Tyrosine Kinase (genetics, metabolism)