AffiCHECK® BCR-ABL IS p210 Linearity Panel
The AffiCHECK® BCR-ABL IS p210 Linearity Panel is a meticulous tool crafted to assess the accuracy of detecting BCR-ABL1 translocation mRNA e14a2/b3a2 transcripts and the ABL1 endogenous control mRNA. This evaluation takes place within the Xpert® BCR-ABL Ultra assay, integrated into Cepheid GeneXpert® Instrument Systems.
At its core lies the enigmatic Philadelphia chromosome, a genetic fusion between chromosome 9's ABL1 gene and chromosome 22's BCR gene (t(9;22)). This fusion births the consequential BCR-ABL1 gene, prevalent among most chronic myelogenous leukemia (CML) cases. Monitoring BCR-ABL1 transcripts in patient blood is pivotal in evaluating therapy response.
In a pivotal 2009 initiative, the World Health Organization (WHO) established four primary BCR-ABL1 standards, forming the international scale (IS). This standardized system portrays assay outcomes as a ratio of fusion transcripts to control gene transcripts (%IS), often denoted as molecular response (MR), depicting the logarithmic reduction from a standardized 100% baseline on the IS. The AffiCHECK® BCR-ABL IS p210 Linearity Panel traces its origins to the esteemed WHO International Genetic Reference Panel for Quantitation of BCR-ABL Translocation (WHO Reference Panel), identified by the revered NIBSC code 09/138. Tailored for the Xpert BCR-ABL Ultra assay, this panel facilitates international alignment, ensuring consistent patient care standards across diverse laboratory settings.
The AffiCHECK® BCR-ABL IS p210 Linearity Panel comprises six components, each featuring a progressive concentration of BCR-ABL1 (e14a2/b3a2) RNA transcript blended with a consistent concentration of ABL1 RNA transcript. This concoction generates six distinct levels: 0.01%IS, 0.1%IS, 1%IS, 10%IS, 20%IS, and 50%IS. These levels are evaluated using the GeneXpert system in conjunction with the Xpert BCR-ABL Ultra assay. The %IS values, aligning with the WHO Reference Panel traced back to NIBSC code 09/138, are attributed to every batch of the AffiCHECK® BCR-ABL IS p210 Linearity Panel following the guidelines set forth by NIBSC Instructions for Use3.
Validation and value assignment procedures involved AffiGEN's production of three lots of the Xpert BCR-ABL IS p210 Linearity Panel. These lots underwent assessment alongside the WHO Reference Panel, utilizing a specific cartridge lot of the Xpert BCR-ABL Ultra assay. The evaluation involved employing Grubb’s outlier analysis and regression techniques to determine lot-specific Correction Factors (CF). This process culminated in the assignment of WHO-traceable %IS/MR values for each level of the AffiCHECK® BCR-ABL IS p210 Linearity Panel across all three lots, following the protocols outlined in NIBSC Instructions for Use3. Figure 1 depicts a comparative analysis between the three lots of the AffiCHECK® BCR-ABL IS p210 Linearity Panel and the four constituents of the WHO Reference Panel. Subsequent batches of the AffiCHECK® BCR-ABL IS p210 Linearity Panel will undergo a similar process to allocate lot-specific %IS/MR values.
The AffiCHECK® BCR-ABL IS p210 Linearity Panel contiens 12 vials, featuring a pair of bottles for each %IS level. Enclosed within these vials is a 4mL composition of artificially created BCR-ABL1 RNA transcript and synthetic ABL1 control gene RNA transcript. These substances are enveloped within a stabilizing matrix infused with non-infectious buffers and preservatives, guaranteeing stability and safety in handling.
AffiCHECK® BCR-ABL IS p210 Linearity Panel must be sored at -20°C. Unopened package remains stable until the indicated expiration date.