Serial quantitation of BCR-ABL IntroductionReverse-transcription real-time quantitative polymerase chain reaction (RQ-PCR) is used routinely to quantify levels of BCR-ABL mRNA in peripheral blood and bone marrow samples from chronic myelogenous leukemia (CML) patients undergoing therapy. The technique can accurately determine response to treatment and is particularly valuable for patients who have achieved a complete cytogenetic response. The National Comprehensive Cancer Network (NCCN) 1 and the European LeukemiaNet (ELN) 2 recommend similar monitoring schedules for patients treated with imatinib and the ELN defines an optimal response as the attainment of a major molecular response (MMR) after 18 months of therapy. Monitoring of BCR-ABL mRNA levels is also useful for gauging therapeutic response for patients with Philadelphia chromosomepositive acute lymphoblastic leukemia (Ph ϩ ALL). The CML meeting at the National Institutes of Health in Bethesda in October 2005 made several recommendations for the harmonization of minimal residual disease (MRD) assessment and proposed an international scale (IS) for BCR-ABL RQ-PCR measurements. 8 Importantly, the IS is essentially identical to that used in the International Randomized Study of Interferon and STI571 (IRIS) study, 9 with the IRIS standardized baseline defined as 100% BCR-ABL IS and MMR (3-log reduction relative to the standardized baseline) defined as 0.1% BCR-ABL IS . The original standards used for the IRIS trial are no longer available, however traceability to the IRIS scale is provided by the extensive quality control data generated by the Adelaide laboratory over a period of several years. 10,11 To enable testing centers to gain access to the IS, the Adelaide laboratory initiated a process to develop and validate laboratoryspecific conversion factors (CFs) that can be used to convert local values to IS values. 11 The strength of this approach is that testing centers can continue to use their existing assay conditions and continue to express results according to local preferences in addition to expressing results on the IS. The concept of the IS is analogous to established procedures for other quantitative assays, for example the International Normalized Ratio (INR) for prothrombin time. 12 Many laboratories with validated CFs have established themselves as national or regional reference laboratories and are in the process of propagating CFs to local centers. 13 While this process has generally worked well, it is apparent that the establishment of CFs is time-consuming, complex, expensive, and open to only a limited number of laboratories at any given time. Furthermore, it is unclear how frequently any individual CF will need to be revalidated. We sought therefore to develop an alternative means for testing laboratories to access the IS by developing calibrated, accredited primary reference reagents for BCR-ABL RQ-PCR analysis. StrategyIdeally, the formulation for primary reference reagents should be as close as possible to the usual analyte, should cove...

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Background Treatment with anti-PD1 monoclonal antibodies improves the survival of metastatic melanoma patients but only a subgroup of patients benefits from durable disease control. Predictive biomarkers for durable benefit could improve the clinical management of patients. Methods Plasma samples were collected from patients receiving anti-PD1 therapy for ctDNA quantitative assessment of BRAF V600 and NRAS Q61/G12/G13 mutations. Results After a median follow-up of 84 weeks 457 samples from 85 patients were analyzed. Patients with undetectable ctDNA at baseline had a better PFS (Hazard ratio (HR) = 0.47, median 26 weeks versus 9 weeks, p = 0.01) and OS (HR = 0.37, median not reached versus 21.3 weeks, p = 0.005) than patients with detectable ctDNA. Additionally, the HR for death was lower after the ctDNA level became undetectable during follow-up (adjusted HR: 0.16 (95% CI 0.07–0.36), p-value < 0.001). ctDNA levels > 500 copies/ml at baseline or week 3 were associated with poor clinical outcome. Patients progressive exclusively in the central nervous system (CNS) had undetectable ctDNA at baseline and at subsequent assessments. In multivariate analysis adjusted for LDH, CRP, ECOG and number of metastatic sites, the ctDNA remained significant for PFS and OS. A positive correlation was observed between ctDNA levels and total metabolic tumor volume (TMTV), number of metastatic sites and total tumor burden. Conclusions Assessment of ctDNA baseline and during therapy was predictive for tumor response and clinical outcome in metastatic melanoma patients and reflected the tumor burden. ctDNA evaluation provided reliable complementary information during anti-PD1 antibody therapy.

ObjectiveRecently, Next Generation Sequencing (NGS) has begun to supplant other technologies for gene mutation testing that is now required for targeted therapies. However, transfer of NGS technology to clinical daily practice requires validation.MethodsWe validated the Ion Torrent AmpliSeq Colon and Lung cancer panel interrogating 1850 hotspots in 22 genes using the Ion Torrent Personal Genome Machine. First, we used commercial reference standards that carry mutations at defined allelic frequency (AF). Then, 51 colorectal adenocarcinomas (CRC) and 39 non small cell lung carcinomas (NSCLC) were retrospectively analyzed.ResultsSensitivity and accuracy for detecting variants at an AF >4% was 100% for commercial reference standards. Among the 90 cases, 89 (98.9%) were successfully sequenced. Among the 86 samples for which NGS and the reference test were both informative, 83 showed concordant results between NGS and the reference test; i.e. KRAS and BRAF for CRC and EGFR for NSCLC, with the 3 discordant cases each characterized by an AF <10%.ConclusionsOverall, the AmpliSeq colon/lung cancer panel was specific and sensitive for mutation analysis of gene panels and can be incorporated into clinical daily practice.