Stuart D Scott1,2, Matthew Fletcher1, Helen Whitehouse1, Liam Whitby1, Constance Yuan3, Silvia Mazzucchelli4, Pei Lin5, Ruth de Tute6, Pranav Dorwal7, Paul K Wallace8, Prashant Tembhare9, Maria Arroz10, John A Snowden2,11, Andrew D Chantry2,11, David Barnett1,2,11. 1. UK NEQAS for Leucocyte Immunophenotyping, Sheffield Teaching Hospitals, Sheffield, UK. 2. Department of Oncology and Metabolism, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, UK. 3. Clinical Flow Cytometry Laboratory, Laboratory of Pathology, CCR, NCI, NIH, Bethesda, Maryland. 4. Department of Haematology and Flow Cytometry, Synlab Suisse SA, Bioggio, Switzerland. 5. Department of Hematopathology, MD Anderson Cancer Center, Houston, Texas. 6. HMDS, Department of Haematology, St. James's Institute of Oncology, Leeds, UK. 7. Flow Cytometry Laboratory, Waikato Hospital, Hamilton, New Zealand. 8. Department of Flow and Image Cytometry, Roswell Park Cancer Institute, Buffalo, New York. 9. Hematopathology Laboratory, Tata Memorial Center, Mumbai, Maharashtra, India. 10. Flow Cytometry Laboratory, Department of Clinical Pathology, CHLO S. Francisco Xavier Hospital, Lisbon, Portugal. 11. Department of Haematology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
Abstract
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.
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.
Authors: Alexander Schmitz; Rasmus Froberg Brøndum; Hans Erik Johnsen; Ulf-Henrik Mellqvist; Anders Waage; Peter Gimsing; Davine Hofste Op Bruinink; Vincent van der Velden; Bronno van der Holt; Markus Hansson; Niels Frost Andersen; Ulf Christian Frølund; Carsten Helleberg; Fredrik H Schjesvold; Lucia Ahlberg; Nina Gulbrandsen; Bjorn Andreasson; Birgitta Lauri; Einar Haukas; Julie Støve Bødker; Anne Stidsholt Roug; Martin Bøgsted; Marianne T Severinsen; Henrik Gregersen; Niels Abildgaard; Pieter Sonneveld; Karen Dybkær Journal: BMC Cancer Date: 2022-02-05 Impact factor: 4.430
Authors: Davine Hofste op Bruinink; Stefania Oliva; Lucie Rihova; Alexander Schmitz; Milena Gilestro; Jeroen Te Marvelde; Romana Kralova; Helle Høholt; Annemiek Broijl; Hans Erik Johnsen; Roman Hajek; Mario Boccadoro; Pieter Sonneveld; Paola Omedè; Vincent H J Van der Velden Journal: Haematologica Date: 2020-10-05 Impact factor: 9.941