Project description:The sensitivity of conventional techniques for the quantification of minimal/measurable residual disease (MRD) in chronic lymphocytic leukemia (CLL) is limited to MRD 10-4. Measuring MRD <10-4 could help to further distinguish between CLL patients with durable remission and those at risk of early relapse. We here present a novel, academically developed IGHV leader-based next-generation sequencing (NGS) assay for the quantification of MRD in CLL. We demonstrate, based on measurements in contrived MRD samples, that the linear range of detection and quantification of our novel assay reaches beyond MRD 10-5. If provided with sufficient DNA input, MRD can even be detected down to MRD 10-6. There was high inter-assay concordance between measurements of the IGHV leader-based NGS assay and allele-specific oligonucleotide quantitative PCR (r=0.92, [95%CI 0.86-0.96]) and droplet digital PCR (r=0.93, [95%CI 0.88-0.96]) on contrived MRD samples. In a cohort of 37 patients from the CLL11 trial, using MRD 10-5 as a cut-off, MRD undetectability was associated with superior progression-free survival (PFS) and time to next treatment. Importantly, deeper MRD measurement allowed for additional stratification of patients with MRD <10-4 but ≥10‑5. Whereas the PFS of these patients was significantly shorter, compared to patients with MRD <10-5 (HR 4.9, [95%CI 1.3-17.9], P=0.017), their PFS was superior to those with MRD ≥10‑4 (HR 0.18, [95%CI 0.06-0.46], P<0.001). These results clearly demonstrate the clinical utility of the novel IGHV-leader based NGS assay.
Project description:N6-Methyladenosine (m6A) in mRNA regulates almost every stage in the mRNA life cycle, and the development of the high throughput detection of methylated sites in mRNA using MeRIPSeq or miCLIP revolutionized the m6A research field. Both methods are based on immunoprecipitation of fragmented mRNA. However, it is well documented that antibodies often have nonspecific activities, thus verification of identified m6A sites using an antibody-independent method would be highly desirable. Currently such approaches are limited. Here we present RedBaron, an improved biochemical method for the site-specific detection and quantification of m6A in RNA. We demonstrate that the RedBaron method is able to accurately quantify m6A levels at specific transcripts in vivo. We used this assay for the site-specific detection and quantification of m6A within the chicken β-actin (ACTB) zipcode sequence in chicken embryos and in fibroblast cells. We demonstrate that methylation of this site in the β-actin zipcode enhances ZBP1 binding in vitro, whilst methylation of a nearby adenosine abolishes
Project description:Measuring minimal residual disease (MRD) in cancer has clinical applications for prognosis, monitoring treatment, and detection of recurrence. Simple sequence-based methods to detect nucleotide substitution variants have error rates (about 10^-3) that limit sensitive detection. We developed and characterize the performance of MASQ (Multiplex Accurate Sensitive Quantitation), a method with an error rate on the order of 10^-6. MASQ counts variant templates accurately in the presence of millions of host genomes by using tags to identify each template and demanding consensus over multiple reads of each template. At least 50 target loci can be multiplexed and quantified accurately over a wide range of genomic DNA input amounts. Simultaneously assaying many target variants allows for efficient use of sample, high sensitivity, robustness, and the ability to distinguish subpopulations of variants. We tested MASQ in a small pilot study measuring residual disease in acute myeloid leukemia (AML) patients who entered remission following induction therapy. We detect leukemic variants in the blood and bone marrow samples of all five patients, after induction therapy. We observe evidence of subclonal structure following treatment and find higher target variant frequencies in patients who go on to relapse.
