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.

Assessment of plasma cell myeloma minimal residual disease testing by flow cytometry in an international inter-laboratory study: Is it ready for primetime use?

BACKGROUND: Minimal/measurable residual disease (MRD) testing by flow cytometry (FC) has been proposed as a potential surrogate clinical endpoint in plasma cell myeloma (PCM) clinical trials. As a result, effort has gone into standardizing this approach on PCM patients. AIMS: To assess inter-laboratory variation in FC MRD testing of PCM patients in an independent inter-laboratory study. METHODS: A dilution series of five stabilized bone marrow samples manufactured to contain 0%, 0.1%, 0.01%, 0.001%, and 0.0001% neoplastic plasma cells (PCs) were tested blind, using standardized FC PCM MRD assays by 10 international laboratories. RESULTS: Laboratories' assays broadly adhered to the consensus guidelines; however, some deviations were identified in panel design, fluorochrome conjugates, and lysis reagents. Despite this, all laboratories that returned results detected neoplastic PCs down to 0.001% of leucocytes. 6/8 laboratories detected neoplastic PCs at a level of 0.0001%. Quantitative data returned by laboratories showed good consensus and linearity with increasing variation at lower levels of MRD. However, examples of analytical and post analytical error were identified. SUMMARY/CONCLUSION: Broadly standardized PCM MRD FC assays can attain the lower limit of detection (LOD) required by current and future clinical trials, an important consideration in establishing PCM MRD testing as a surrogate clinical marker in PCM clinical trials. Laboratories' assays showed good linearity, encouraging the prediction of survival based on log reduction in neoplastic PC populations in future clinical trials. However, the deviations from consensus guidelines identified in this study would suggest that if PCM MRD assays are further standardized interlaboratory variation could be reduced. © 2018 International Clinical Cytometry Society.

Dysregulated expression of adamalysin-thrombospondin genes in human breast carcinoma.

The adamalysin-thrombospondin (ADAMTS) proteinases are a relatively newly described branch of the metzincin family that contain metalloproteinase, disintegrin, and thrombospondin motifs. They have been implicated in various cellular events, including cleavage of proteoglycans, extracellular matrix degradation, inhibition of angiogenesis, gonadal development, and organogenesis. However, in many cases, their normal physiological roles and their potential for dysregulation in malignancy remain to be established. The expression profile of ADAMTS1-20 in human breast carcinoma was undertaken by real-time PCR using RNA isolated from malignant tumors, nonneoplastic mammary tissue, and breast cancer cell lines to identify altered regulation that may have potential pathogenetic and prognostic significance. Our studies show that seven of the ADAMTS genes (ADAMTS1, 3, 5, 8, 9, 10, and 18) are consistently down-regulated in breast carcinomas with respect to nonneoplastic mammary tissue, irrespective of the heterogeneity of the samples and the tumor type or grade (Mann-Whitney U test, P < 0.0001 for each gene). Conversely, ADAMTS4, 6, 14, and 20 are consistently up-regulated in breast carcinomas (P = 0.005, P < 0.0001, P = 0.003, and P = 0.001, respectively). ADAMTS2, 7, 12, 13, 15, 16, 17, and 19 show no significant difference between the sample types. ADAMTS1, 2, 7, 8, 10, and 12 are expressed predominantly in stromal fibroblasts. ADAMTS3, 4, 5, 6, 9, and 13-20 inclusive are expressed predominantly in myoepithelial cells; all appear to be relatively poorly expressed in luminal epithelial cells. ADAMTS15 has emerged as being an independent predictor of survival, with RNA expression levels significantly lower (P = 0.007) in grade 3 breast carcinoma compared with grade 1 and 2 breast carcinoma.