From the 2018 HVPAA National Conference
Kwabena Sarpong (University of Virginia Health System), Joesph Wiencek (University of Virginia Health System)
Background
SPEP is highly utilized in clinical laboratories to diagnose and monitor patients with monoclonal gammopathies. However, with the emergence of IgG kappa therapeutic monoclonal antibodies (t-mAbs) and the use of autologous stem cell transplants (ASCT) to treat multiple myeloma, we have identified several non-consistent patterning with SPEP and immunofixation interpretations.
Objectives
To reduce unnecessary follow-up testing by utilizing patients’ medical history, medications and past protein electrophoresis results in SPEP and immunofixations interpretations.
Methods
Literature review, patient’s medical history and manufacturer’s instructions were used to identify FDA-approved monoclonal antibodies and impacts of ASCT on SPEP banding patterns.
Results
We identified seven monoclonal antibodies that have been either approved by the FDA or are in different phases of clinical trials for the treatment of multiple myeloma. With the exception of M0R202, which is an IgGλ-based t-mAb, the other six t-mAbs (Daratumumab, Elotuzumab, Rituximab, Pembrolizumab, Siltuximab and Isatuximab) are all IgG kappas. Further investigation using patient’s medication list showed that Daratumumab, Elotuzumab and Rituximab were commonly prescribed t-mAbs by clinicians for the patient population served by the University of Virginia Health System (we currently have 35 patients in our health system on Daratumumab). This led to changing the way we report SPEP results for patients on these t-mAbs. For example, for a patient who reports to the clinic for monthly infusion with Daratumumab, our new standard operating procedure now includes notifying the clinician in our reports that the patient is on Daratumumab, which may appear as a restricted IgG kappa on protein electrophoresis and/or immunofixation. We also now report oligoclonal patterning patterns in patients with recent ASCT based on information in the primary literature.
Conclusion
Accurate, succinct and detailed reporting of laboratory results is pertinent for appropriate interpretation and clinical diagnosis. We utilize patients’ medical history, t-mAb usage and procedures such as ASCT to provide clinician awareness of interferences in SPEP and Immunofixation. Our enhanced interpretations has eliminated ambiguity in these patients.
Implications for the Patient
Monoclonal antibodies (especially Daratumumab) are being considered first line therapies for multiple myeloma in newly diagnosed patients. Without high resolution methods to identify bands due to t-mAbs or oligoclonal bands, it becomes imperative to provide interpretive results to clinicians that reflect medical history, medications and past protein electrophoresis results.
