Abstract 2232: Effectiveness evaluation of an in vitro nucleic acid amplification test for quantification of BCR-ABL fusion transcript variants in human whole blood

Abstract

Abstract Quantitative measurement of BCR-ABL fusion gene transcripts in whole blood by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) is a clinically validated method to monitor tyrosine kinase inhibitor drug response in patients diagnosed with chronic myelogenous leukemia (CML). Monitoring of BCR-ABL expression in blood of cML patients under treatment with a tyrosine kinase inhibitor of BCR-ABL is considered standard of care. A three log or greater reduction in BCR-ABL expression from baseline is considered a Maximum Molecular Response (MMR). A subsequent 0.5 log increase in BCR-ABL from MMR is considered a sign of treatment failure sufficient to trigger change in treatment. The challenge is to develop a test with sufficient analytical performance characteristics and quality control to reliably measure BCRABL in MMR samples in which there may be less than 10 molecules in 300 of RNA extracted from whole blood. A method validation protocol was developed using the International Committee on Harmonization (ICH) Q2(R1) international validation guidelines. BCRABL variants b2a2 and b3a2 as well as the housekeeping gene GUSB were measured in KCL22 cell line RNA and Stratagene Universal Human Reference RNA test articles in extreme linear dilution assay, robustness testing conditions, and in multiple laboratories. Quality controls were developed to enable loading as much whole blood RNA into the assay as possible without assay interference. These included a reverse transcription (RT) standardization mixture comprising External RNA Control Consortium (ERCC) reagents to control for RT interference, and controls for genomic DNA contamination, RNA integrity, and PCR interference. Results: This test for b2a2 and b3a2 variants of BCR-ABL meets ICHQ2(R1) guidelines for specificity, linearity, accuracy, LOD and LOQ, imprecision, robustness, and reproducibility. Each analyte comprised by the test was linear (R2 > 0.97) over more than 3 logs10, and demonstrated inter-experimental and inter-laboratory imprecision low enough to enable measurement of a 3-fold difference as significant (P <0.05) from a value as low as five molecules/assay. Experiments are underway to quantify the amount of whole blood RNA that can be loaded into RT reaction without interference. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2232. doi:10.1158/1538-7445.AM2011-2232