Joanne Mason

Assessment of Minimal Residual Disease in Standard-Risk AML.

BACKGROUND Despite the molecular heterogeneity of standard-risk acute myeloid leukemia (AML), treatment decisions are based on a limited number of molecular genetic markers and morphology-based assessment of remission. Sensitive detection of a leukemia-specific marker (e.g., a mutation in the gene encoding nucleophosmin [NPM1]) could improve prognostication by identifying submicroscopic disease during remission. METHODS We used a reverse-transcriptase quantitative polymerase-chain-reaction assay to detect minimal residual disease in 2569 samples obtained from 346 patients with NPM1-mutated AML who had undergone intensive treatment in the National Cancer Research Institute AML17 trial. We used a custom 51-gene panel to perform targeted sequencing of 223 samples obtained at the time of diagnosis and 49 samples obtained at the time of relapse. Mutations associated with preleukemic clones were tracked by means of digital polymerase chain reaction. RESULTS Molecular profiling highlighted the complexity of NPM1-mutated AML, with segregation of patients into more than 150 subgroups, thus precluding reliable outcome prediction. The determination of minimal-residual-disease status was more informative. Persistence of NPM1-mutated transcripts in blood was present in 15% of the patients after the second chemotherapy cycle and was associated with a greater risk of relapse after 3 years of follow-up than was an absence of such transcripts (82% vs. 30%; hazard ratio, 4.80; 95% confidence interval [CI], 2.95 to 7.80; P<0.001) and a lower rate of survival (24% vs. 75%; hazard ratio for death, 4.38; 95% CI, 2.57 to 7.47; P<0.001). The presence of minimal residual disease was the only independent prognostic factor for death in multivariate analysis (hazard ratio, 4.84; 95% CI, 2.57 to 9.15; P<0.001). These results were validated in an independent cohort. On sequential monitoring of minimal residual disease, relapse was reliably predicted by a rising level of NPM1-mutated transcripts. Although mutations associated with preleukemic clones remained detectable during ongoing remission after chemotherapy, NPM1 mutations were detected in 69 of 70 patients at the time of relapse and provided a better marker of disease status. CONCLUSIONS The presence of minimal residual disease, as determined by quantitation of NPM1-mutated transcripts, provided powerful prognostic information independent of other risk factors. (Funded by Bloodwise and the National Institute for Health Research; Current Controlled Trials number, ISRCTN55675535.).

Guidelines for the measurement of BCR-ABL1 transcripts in chronic myeloid leukaemia

Molecular testing for the BCR‐ABL1 fusion gene by real time quantitative polymerase chain reaction (RT‐qPCR) is the most sensitive routine approach for monitoring the response to therapy of patients with chronic myeloid leukaemia. In the context of tyrosine kinase inhibitor (TKI) therapy, the technique is most appropriate for patients who have achieved complete cytogenetic remission and can be used to define specific therapeutic milestones. To achieve this effectively, standardization of the laboratory procedures and the interpretation of results are essential. We present here consensus best practice guidelines for RT‐qPCR testing, data interpretation and reporting that have been drawn up and agreed by a consortium of 21 testing laboratories in the United Kingdom and Ireland in accordance with the procedures of the UK Clinical Molecular Genetics Society.

Presence of multiple recurrent mutations confers poor trial outcome of relapsed/refractory CLL.

Although TP53, NOTCH1, and SF3B1 mutations may impair prognosis of patients with chronic lymphocytic leukemia (CLL) receiving frontline therapy, the impact of these mutations or any other, alone or in combination, remains unclear at relapse. The genome of 114 relapsed/refractory patients included in prospective trials was screened using targeted next-generation sequencing of the TP53, SF3B1, ATM, NOTCH1, XPO1, SAMHD1, MED12, BIRC3, and MYD88 genes. We performed clustering according to both number and combinations of recurrent gene mutations. The number of genes affected by mutation was ≥ 2, 1, and 0 in 43 (38%), 49 (43%), and 22 (19%) respectively. Recurrent combinations of ≥ 2 mutations of TP53, SF3B1, and ATM were found in 22 (19%) patients. This multiple-hit profile was associated with a median progression-free survival of 12 months compared with 22.5 months in the remaining patients (P = .003). Concurrent gene mutations are frequent in patients with relapsed/refractory CLL and are associated with worse outcome.

Targeted resequencing analysis of 31 genes commonly mutated in myeloid disorders in serial samples from myelodysplastic syndrome patients showing disease progression

Targeted resequencing analysis of 31 genes commonly mutated in myeloid disorders in serial samples from myelodysplastic syndrome patients showing disease progression

Monitoring of chimerism following allogeneic haematopoietic stem cell transplantation (HSCT): Technical recommendations for the use of Short Tandem Repeat (STR) based techniques, on behalf of the United Kingdom National External Quality Assessment Service for Leucocyte Immunophenotyping Chimerism Working Group

Analysis of short tandem repeats (STR) is the predominant method for post‐transplant monitoring of donor engraftment. It can enable early detection of disease relapse, level of engraftment and provide useful information on the graft‐versus‐host disease (GVHD)/graft‐versus‐tumour (GVT) effect, facilitating therapeutic intervention. Harmonization and standardization of techniques and result interpretation is essential to reduce the impact of laboratory variability on both clinical management and the results of multi‐centre clinical trials. However, the United Kingdom National External Quality Assessment Service for Leucocyte Immunophenotyping (UK NEQAS LI) has highlighted significant issues inherent in STR testing that impact upon inter‐ and intra‐ laboratory variation. We present here consensus best practice guidelines and recommendations for STR chimerism testing, data interpretation and reporting that have been drawn up and agreed by a consortium of 11 UK and Eire clinical laboratories. This document uses data obtained from the UK NEQAS LI Post‐Stem Cell Transplant (SCT) Chimerism Monitoring Programme.

NUP98-NSD1 Fusion in Association with FLT3-ITD Mutation Identifies a Prognostically Relevant Subgroup of Pediatric Acute Myeloid Leukemia Patients Suitable for Monitoring by Real Time Quantitative PCR

The cytogenetically cryptic t(5;11)(q35;p15) leading to the NUP98‐NSD1 fusion is a rare but recurrent gene rearrangement recently reported to identify a group of young AML patients with poor prognosis. We used reverse transcription polymerase chain reaction (PCR) to screen retrospectively diagnostic samples from 54 unselected pediatric AML patients and designed a real time quantitative PCR assay to track individual patient response to treatment. Four positive cases (7%) were identified; three arising de novo and one therapy related AML. All had intermediate risk cytogenetic markers and a concurrent FLT3‐ITD but lacked NPM1 and CEBPA mutations. The patients had a poor response to therapy and all proceeded to hematopoietic stem cell transplant. These data lend support to the adoption of screening for NUP98‐NSD1 in pediatric AML without otherwise favorable genetic markers. The role of quantitative PCR is also highlighted as a potential tool for managing NUP98‐NSD1 positive patients post‐treatment.

Targeted deep sequencing reveals clinically relevant subclonal IgHV rearrangements in chronic lymphocytic leukemia

The immunoglobulin heavy-chain variable region gene (IgHV) mutational status is considered the gold standard of prognostication in chronic lymphocytic leukemia (CLL) and is currently determined by Sanger sequencing that allows the analysis of the major clone. Using next-generation sequencing (NGS), we sequenced the IgHV gene from two independent cohorts: (A) 270 consecutive patient samples obtained at diagnosis and (B) 227 patients from the UK ARCTIC-AdMIRe clinical trials. Using complementary DNA from purified CD19+CD5+ cells, we demonstrate the presence of multiple rearrangements in independent experiments and showed that 24.4% of CLL patients express multiple productive clonally unrelated IgHV rearrangements. On the basis of IgHV-NGS subclonal profiles, we defined five different categories: patients with (a) multiple hypermutated (M) clones, (b) 1 M clone, (c) a mix of M-unmutated (UM) clones, (d) 1 UM clone and (e) multiple UM clones. In population A, IgHV-NGS classification stratified patients into five different subgroups with median treatment-free survival (TFS) of >280(a), 131(b), 94(c), 29(d), 15(e) months (P<0.0001) and a median OS of >397(a), 292(b), 196(c), 137(d) and 100(e) months (P<0.0001). In population B, the poor prognosis of multiple UM patients was confirmed with a median TFS of 2 months (P=0.0038). In conclusion, IgHV-NGS highlighted one quarter of CLL patients with multiple productive IgHV subclones and improves disease stratification and raises important questions concerning the pre-leukemic cellular origin of CLL.

Pitfalls in molecular diagnosis in haemato-oncology

Molecular techniques can contribute to establishing the correct diagnosis, prognostic stratification and predicting and assessing response to treatment in haematological malignancy. For instance, presence of the JAK2 V617F mutation confirms a suspected diagnosis of a myeloproliferative neoplasm (MPN), PML-RARA confirms acute promyelocytic leukaemia (APML), BCR-ABL1 confirms chronic myeloid leukaemia (CML) and FIP1L1-PDGFRA confirms chronic eosinophilic leukaemia (CEL).1 Examples of specific molecular markers on which targeted therapies depend include PML-RARA in APML, which responds to all-trans retinoic acid, and BCR-ABL1 in CML and FIP1L1-PDGFRA in chronic CEL which both respond to imatinib. This brief review will illustrate with examples some of the common problems that may be encountered when using molecular techniques in the field of clinical molecular haemato-oncology. A major difference between genetic diagnosis of constitutional disorders and acquired neoplasia is the background of normal cells, which are invariably present in a tumour specimen. With blood cancer, this can be particularly problematic. For example, in systemic mastocytosis (SM), a MPN associated with a point mutation (D816V) in the KIT gene,2 the mutation may not be reliably detected in blood if there are insufficient mast cells.3 Literature discrepancies regarding the prevalence of KIT mutations in SM can be partly explained by differences among studies in the type of tissue screened. Marrow is recommended when referring samples for molecular diagnosis of SM,4 although cell selection using CD117 for enrichment of mast cells from blood may improve sensitivity. The presence of normal cells is also an issue in the diagnosis of JAK2 V617F-positive MPN, although the clinical significance of detecting a low level mutation-positive clone is questionable. Assays based on allele-specific oligonucleotide (ASO) PCR or amplification-refractory mutation system (ARMS) PCR have limited sensitivity, which can be compounded by the visualisation method (agarose gel electrophoresis being less sensitive than …

Clinical whole-genome sequencing from routine formalin-fixed, paraffin-embedded specimens: pilot study for the 100,000 Genomes Project

PurposeFresh-frozen (FF) tissue is the optimal source of DNA for whole-genome sequencing (WGS) of cancer patients. However, it is not always available, limiting the widespread application of WGS in clinical practice. We explored the viability of using formalin-fixed, paraffin-embedded (FFPE) tissues, available routinely for cancer patients, as a source of DNA for clinical WGS.MethodsWe conducted a prospective study using DNAs from matched FF, FFPE, and peripheral blood germ-line specimens collected from 52 cancer patients (156 samples) following routine diagnostic protocols. We compared somatic variants detected in FFPE and matching FF samples.ResultsWe found the single-nucleotide variant agreement reached 71% across the genome and somatic copy-number alterations (CNAs) detection from FFPE samples was suboptimal (0.44 median correlation with FF) due to nonuniform coverage. CNA detection was improved significantly with lower reverse crosslinking temperature in FFPE DNA extraction (80 °C or 65 °C depending on the methods). Our final data showed somatic variant detection from FFPE for clinical decision making is possible. We detected 98% of clinically actionable variants (including 30/31 CNAs).ConclusionWe present the first prospective WGS study of cancer patients using FFPE specimens collected in a routine clinical environment proving WGS can be applied in the clinic.

Detection of Minimal Residual Disease in Leukaemia by RT-PCR

Reverse transcription-PCR (RT-PCR) describes a technique whereby RNA is first reverse transcribed into complementary DNA (cDNA) using the enzyme reverse transcriptase, and the resulting cDNA amplified in either a single-step or a two-step nested PCR reaction. It is particularly useful for detecting molecular markers associated with leukaemia, as it enables a single assay to be used for many patients, each with unique genomic translocation breakpoints, but who have common fusion points in mRNA. This molecular method can not only detect aberrations that are cytogenetically cryptic, such as t(12;21)(p13;q22) in paediatric acute lymphoblastic leukaemia (ALL), but is also very sensitive, and as such can be used to monitor minimal residual disease (MRD). Detecting and measuring MRD is important because it can be a guide to determining prognosis and relapse risk, predict recurrence of leukaemia, and enable individualization of treatment.