Abstract
Hevylite™ is a recently developed method for the quantification of heavy chain immunoglobulins and the corresponding light chain (IgG k, IgGλ , IgAk, IgAλ , IgMk,and IgMλ ), specifically quantifying heavy chain and light chain ratios. The current study looks to assess the value of Hevylite™ analysis as it applies to the routine screening and monitoring of suspected or known cases of Plasma Cell Neoplasms at Rush University Medical Center.
We performed the current testing algorithm used at Rush University Medical Center for suspected or known Plasma Cell Myeloma patients for 206 patient specimens. This algorithm includes a Serum Protein Electrophoresis (SPE) and Free Light Chain (FLC) analysis. The method used for SPE analysis is capillary electrophoresis (Sebia™). The FLCs are quantified by immunoassay (The Binding Site™). In the event of identifying abnormal results further reflex testing is added to identify the specific paraprotein present (Immunotyping Electrophoresis and/or Immunofixation Electrophoresis). We performed Hevylite™ assays on all patient specimens in an attempt to assess any additional clinical value.
The 206 patient results were categorized into two subsets – 1) No Monoclonal Protein Present (NMPP); and 2) Monoclonal Protein Present (MPP). In the 111 patients included in the NMPP subset, there exists a large discordance between our testing algorithm and the quantitation of the Hevylite™ method. Discordance was assessed when our algorithm identifying no abnormal paraprotein and the Hevylite™ method showed an elevation for one of the immunoglobulins. There were 51 concordant patient results in the 111 total NMPP subset (46%).
In the 95 patient included in the MPP subset, there were 30 patients (31.6%) that the Hevylite™ results did not match the paraprotein(s) identified with our current algorithm. The mismatched patients were further categorized into the individual immunoglobulins identified: IgMk- total of 13 patients with 11 concordant results (92.3%), IgMλ- total of 4 patients with 4 concordant results (100%), IgAk- total of 13 patients with 13 concordant results (100%), IgAλ- total of 6 patients with 5 concordant results (83.3%), IgGk- total of 33 patients with 19 concordant results (57.6%), IgGλ- total of 26 patients with 13 concordant results (50%).
When compared to the current testing algorithm for patients with suspected or known Plasma Cell Neoplasms at Rush University Medical Center, the Hevylite™ assay showed wide discordance in the patient population our current testing algorithm identified as NMPP. However, we recognize the need for further investigation into the nature of this discordance. Our data shows that the Hevylite™ analysis in the subset of the MPPs showed a greater concordance with our testing algorithm results for IgM and IgA immunoglobulins, whereas IgG immunoglobulin results showed much lower concordance (approximately 50%). Based on our findings Hevylite™ may not be well suited as a generalized screening test.
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
