Detection of minimal residual disease in patients with B lymphoblastic leukemia by high-throughput sequencing of IGH.

Publication Type:

Journal Article

Source:

Clinical cancer research : an official journal of the American Association for Cancer Research (2014)

Keywords:

2014, July 2014, Public Health Sciences Division

Abstract:

Purpose: High-throughput sequencing (HTS) of immunoglobulin heavy chain genes (IGH) in unselected clinical samples for minimal residual disease (MRD) in B lymphoblastic leukemia (B-ALL) has not been tested. As current methods for MRD detection, such as flow cytometry or patient-specific qPCR are complex or difficult to standardize in the clinical laboratory, sequencing may enhance clinical prognostication. Experimental design: We sequenced IGH in paired pre- and day 29 post-treatment samples using residual material from consecutive, unselected samples from Children's Oncology Group AALL0932 trial to measure MRD as compared to flow cytometry. We assessed the impact of on-going recombination at IGH on MRD detection in post-treatment samples. Lastly, we evaluated a subset of cases with discordant MRD results between flow cytometry and sequencing. Results: We find clonal IGH rearrangements in 92 of 98 pre-treatment patient samples. Further, while on-going recombination of IGH was evident, index clones typically prevailed in MRD-positive post-treatment samples, suggesting that clonal evolution at IGH does not contribute substantively to tumor fitness. MRD was detected by sequencing in all flow cytometry positive cases with no false negative results. Additionally, in a subset of patients, MRD was detected by sequencing, but not by flow cytometry, including a fraction with MRD levels within the sensitivity of flow cytometry. We provide data that suggest that this discordance in some patients may be due to the phenotypic maturation of the transformed cell. Conclusion: Our results provide strong support for high-throughput sequencing of IGH to enhance clinical prognostication in B-ALL.