Limitations of VS38c labeling in the detection of plasma cell myeloma by flow cytometry

Context Flow cytometry is often applied to minimal residual disease (MRD) testing in hematolymphoid neoplasia. Because flow-based MRD tests are developed in the laboratory, testing methodologies and lower levels of detection (LODs) are laboratory dependent. Objectives To broadly survey flow cytometry laboratories about MRD testing in laboratories, if performed, including indications and reported LODs. Design Voluntary supplemental questions were sent to the 549 laboratories participating in the College of American Pathologists (CAP) FL3-A Survey (Flow Cytometry—Immunophenotypic Characterization of Leukemia/Lymphoma) in the spring of 2014. Results A total of 500 laboratories (91%) responded to the supplemental questions as part of the FL3-A Survey by April 2014; of those 500 laboratories, 167 (33%) currently perform MRD for lymphoblastic leukemia, 118 (24%) for myeloid leukemia, 99 (20%) for chronic lymphocytic leukemia, and 91 (18%) for plasma cell myeloma. Other indications include non-Hodgkin lymphoma, hairy cell leukemia, neuroblastoma, and myelodysplastic syndrome. Most responding laboratories that perform MRD for lymphoblastic leukemia reported an LOD of 0.01%. For myeloid leukemia, chronic lymphocytic leukemia, and plasma cell myeloma, most laboratories indicated an LOD of 0.1%. Less than 3% (15 of 500) of laboratories reported LODs of 0.001% for one or more MRD assays performed. Conclusions There is major heterogeneity in the reported LODs of MRD testing performed by laboratories subscribing to the CAP FL3-A Survey. To address that heterogeneity, changes to the Flow Cytometry Checklist for the CAP Laboratory Accreditation Program are suggested that will include new requirements that each laboratory (1) document how an MRD assay's LOD is measured, and (2) include the LOD or lower limit of enumeration for flow-based MRD assays in the final diagnostic report.

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Flow cytometry quality requirements for monitoring of minimal disease in plasma cell myeloma

Cytometry Part B Clinical Cytometry ◽

10.1002/cyto.b.21276 ◽

2015 ◽

Vol 90 (1) ◽

pp. 40-46 ◽

Cited By ~ 14

Author(s):

Teri A. Oldaker ◽

Paul K. Wallace ◽

David Barnett

Keyword(s):

Flow Cytometry ◽

Plasma Cell ◽

Plasma Cell Myeloma ◽

Quality Requirements ◽

Minimal Disease

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Evaluation of a 5-Color Flow Cytometric Technique for Immunophenotyping and Quantitation of Plasma Cell Myeloma in Post-Therapy Bone Marrows.

Blood ◽

10.1182/blood.v108.11.5036.5036 ◽

2006 ◽

Vol 108 (11) ◽

pp. 5036-5036

Author(s):

Tove Isaacson ◽

Andrzej Jakubowiak ◽

Lloyd Stoolman ◽

Usha Kota ◽

William Finn ◽

...

Keyword(s):

Bone Marrow ◽

Flow Cytometry ◽

Minimal Residual Disease ◽

Plasma Cell ◽

Plasma Cells ◽

Residual Disease ◽

Plasma Cell Myeloma ◽

Color Flow ◽

Flow Cytometric ◽

Minimal Residual

Abstract Multiparameter flow cytometry is a useful tool for comprehensive immunophenotyping of plasma cell myeloma, and has been proposed as a sensitive method for the evaluation of minimal residual disease in patients following treatment. This study aimed to assess the value of flow cytometry in quantitation of residual disease, in comparison to routine morphologic examination of first-pull bone marrow aspirate smears, in myeloma patients post-therapy. Heparinized bone marrow aspirates were obtained from 27 treated patients with plasma cell myeloma. Cells were prepared for 5-color flow cytometric analysis within 24-hours of specimen draw. Surface membrane staining with anti-CD19, CD20, CD38, CD45, CD56, and CD138 was followed by ammonium chloride lysis of red cells. Fixed and permeabilized cells were analyzed for cytoplasmic light chains to confirm clonality. Data were acquired using an FC500 flow cytometer (Beckman-Coulter), analyzed with CXP software with plasma cells isolated based on bright CD38+ or CD138+ expression. A median of 97,639 cellular events (range 14,279 to 262,508) were collected per analysis. Flow cytometric enumeration of plasma cells was compared to 500-cell differential counts of Wright-Giemsa-stained first-pull aspirate smears from the same cases. The median plasma cell count as determined by flow cytometry was 0.5% (range 0–7.9%). The median plasma cell count estimated by morphologic review was 8.0% (range 0–84.4%). Flow cytometry underestimated the plasma cell content in all but one case. Clonal plasma cells expressed CD38 and CD138 in all cases; 87.5% (21/24) coexpressed CD56, 25% (6/24) coexpressed CD45, and 4.2% (1/24) coexpressed CD19. None was positive for CD20. Although detection of minimal residual disease after therapy for acute leukemia is routinely achieved by flow cytometric analysis, successful quantitation of minimal residual disease in treated myeloma patients using flow cytometry remains limited as it usually underestimates the plasma cell content of bone marrow samples compared to routine morphology of first-pull aspirates. We have observed that this holds true for both pre-treatment and post-treatment specimens. Causes for the discrepancy may include hemodilution of second-pull aspirates used for flow cytometry, fragility and loss of plasma cells during preparation for flow cytometry, and incomplete disaggregation of plasma cells from bone marrow spicules. With improved outcome of treatments, better and more reliable methods of detection of minimal residual disease are needed for optimal prognostic stratification. We are currently validating alternative methods, which may offer more sensitivity while at the same time allow more objectivity, for assessing the amount of minimal residual disease in myeloma patients.

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Increased Circulating Plasma Cells Predicts Poor Overall Survival in Symptomatic Plasma Cell Myeloma Patients

Blood ◽

10.1182/blood.v126.23.4205.4205 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4205-4205

Author(s):

Mi Hyun Bae ◽

Sang Hyuk Park ◽

Chan-Jeoung Park ◽

Bo Hyun Kim ◽

Young-Uk Cho ◽

...

Keyword(s):

Flow Cytometry ◽

Overall Survival ◽

Plasma Cell ◽

Peripheral Blood ◽

Plasma Cells ◽

Survival Curve ◽

Plasma Cell Myeloma ◽

Newly Diagnosed ◽

Kaplan Meier ◽

Meier Survival Curve

Abstract Backgrounds Flow cytometry can rapidly determine immunophenotypes of neoplastic plasma cells (PCs) and quantify PCs in patients with plasma cell myeloma. Flow cytometric immunophenotyping and quantification of neoplastic plasma cells is sensitive and reliable tool for diagnosis and disease monitoring in patients with monoclonal gammopathy. Circulating PCs (cPCs) in peripheral blood (PB) after autologous hematopoietic stem cell transplantation is a marker of high-risk disease in patients with plasma cell myeloma. We assessed the utility of quantification of cPCs using flow cytometry for risk stratification in newly diagnosed plasma cell myeloma patients in the era of novel agents. Methods PB and bone marrow (BM) aspirates of 85 newly diagnosed patients with symptomatic plasma cell myeloma from August 2013 to July 2014 were analyzed by five-color flow cytometry using monoclonal antibodies against CD45, CD19, CD56, CD38, and CD138. The gating strategy employed first used the expression of CD38 and CD138 to identify plasma cells among 100,000 to 200,000 events. cPCs in PB was determined according to the patient's specific immunophenotype of neoplastic PCs in BM. Results The median age of the patient population was 68 years (45~87) and 58% were female. Median follow-up duration was 19.2 months. Six out of 85 patients (7%) did not show cPCs. Among 79 patient (93%) who had detectable cPCs, the median cPCs was 0.09% (0.006~3.612%). Patients without cPCs or cPCs under 0.05% were assigned to low cPCs group (n=32, 38%) and others to high cPCs group (n=53, 62%) according to receiver operating characteristics analysis. High cPCs group showed higher level of BM neoplastic PCs detected by both methodologys of morphology and flow cytometry (P=0.002, 0.033, respectively), higher BM cellularity (P=0.011), higher serum M protein level (P=0.013), lower hemoglobin (P=0.008), and lower platelet level (P=0.034) than low cPCs group. High cPCs group was associated with adverse cytogenetics such as t(4;14) and monosomy 13 (P=0.008), and CD45 negative immunophenotype (P=0.007). In survival analysis, high cPCs presented shorter overall survival (OS) than low cPCs group (P=0.013) (Fig. 1). It was independent with patient age and cytogenetic risks (P =0.011). Conclusion By flow cytometry cPCs was detected in most symptomatic plasma cell myeloma patients. Increased cPCs ≥0.05% among PB leukocytes could be an independent prognostic factor showing adverse effect in overall survival in symptomatic plasma cell myeloma patients. Figure 1. Kaplan-Meier survival curve of patients with plasma cell myeloma who showed 0.05% or more circulating plasma cells in peripheral blood and patients with circulating plasma cells less than 0.05%. Figure 1. Kaplan-Meier survival curve of patients with plasma cell myeloma who showed 0.05% or more circulating plasma cells in peripheral blood and patients with circulating plasma cells less than 0.05%. Disclosures No relevant conflicts of interest to declare.

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