VS38 Identifies Myeloma Cells With Dim CD38 Expression and Plasma Cells Following Daratumumab Therapy, Which Interferes With CD38 Detection for 4 to 6 Months

Abstract Objectives We report our institutional experience using VS38 to evaluate plasma cells by flow cytometry. Methods Flow cytometry data were reanalyzed to compare plasma cell percentages between the standard panel and VS38 panel. Natural killer (NK) and plasma cell CD38 median fluorescence int...

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Bibliographic Details
Published in:American journal of clinical pathology 2020-02, Vol.153 (2), p.221-228
Main Authors: Courville, Elizabeth L, Yohe, Sophia, Shivers, Paula, Linden, Michael A
Format: Article
Language:English
Subjects:
ADP-ribosyl Cyclase 1 - analysis
Adult
Aged
Aged, 80 and over
Antibodies, Monoclonal - analysis
Antibodies, Monoclonal - therapeutic use
CD38 antigen
Diagnosis
Drug therapy
Female
Flow Cytometry
Glycoproteins
Health aspects
Humans
Immunodiagnosis
Immunotherapy
Killer Cells, Natural - chemistry
Male
Methods
Middle Aged
Monoclonal antibodies
Multiple myeloma
Multiple Myeloma - drug therapy
Multiple Myeloma - immunology
Multiple Myeloma - pathology
Myeloma
Natural killer cells
Patient outcomes
Plasma
Plasma cells
Plasma Cells - chemistry
Targeted cancer therapy
Time Factors
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Summary:Abstract Objectives We report our institutional experience using VS38 to evaluate plasma cells by flow cytometry. Methods Flow cytometry data were reanalyzed to compare plasma cell percentages between the standard panel and VS38 panel. Natural killer (NK) and plasma cell CD38 median fluorescence intensity (MFI) values were calculated. Results Our cohort included 63 specimens from 38 patients. Twenty-six had received daratumumab (monoclonal anti-CD38 therapy) between less than 1 month and 17 months prior. For NK and plasma cells, CD38 MFI values were suppressed for 0 to 4 months and started to increase 4 to 6 months after last exposure. There was no significant difference in clonal plasma cell percentage calculated by the VS38 and standard panels; however, identification and quantification using the VS38 panel were easier. Conclusions VS38 is a viable alternative to bright CD38 to identify plasma cells and particularly helpful in myeloma cases with dim CD38 and after daratumumab. Daratumumab interference with CD38 identification persists 4 to 6 months after the last exposure.
ISSN:0002-9173
1943-7722
DOI:10.1093/ajcp/aqz153