Identifying biochemical relapse earlier
Section 01 — The clinical challenge
Conventional monitoring may delay relapse detection in multiple myeloma
Per the International Myeloma Working Group (IMWG), absence of detectable monoclonal protein (M-protein) by immunofixation electrophoresis (IFE) is required to assign complete response (CR) in multiple myeloma.1 However, electrophoretic methods may lack the analytical sensitivity needed to detect low-level M-proteins that persist after treatment, potentially leading to missed residual disease, inaccurate response classification, or delayed detection of relapse. This case study examines how enhanced sensitivity of mass spectrometry in patient monitoring may address this.
Electrophoretic methods may miss low-level M-proteins still present after treatment, potentially missing residual disease or delaying the detection of relapse.
In this case study, a patient who achieved CR by conventional criteria was monitored using both SPE and the EXENTTM GAM assay, revealing significant differences in detection sensitivity.
AT A GLANCE
Patient presentation: 68-year-old with IgGκ multiple myeloma
Baseline M-protein (SPE): 11.7 g/L
CR confirmed by IFE: Month 5
EXENT GAM assay residual M-protein detection: 14 additional months post-CR
EXENT GAM assay relapse detection: 4 months before SPE
Section 02 — The patient
Monitoring an IgGκ M-protein through treatment and complete response
A 68-year-old patient with multiple myeloma presented with an IgGκ M-protein quantified at 11.7 g/L by SPE and 11.93 g/L by the EXENT GAM assay.2 The patient started therapy and was monitored regularly with SPE. At monitoring month 5, the IgGκ M-protein was undetectable by SPE, and CR was confirmed by IFE.2
Section 03 — The breakthrough
EXENT GAM assay detected residual M-protein and relapse earlier than SPE
Despite CR confirmation by IFE, the EXENT GAM assay identified a persistent monoclonal peak for an additional 14 months after conventional methods indicated CR.2 The M-protein became undetectable by the EXENT GAM assay at month 19 (Figure 1).
After more than 2.5 years in remission, SPE detected M-protein re-appearance at month 40 but the EXENT GAM assay had already identified the re-emergence at month 36 - four months earlier.2 (Figure 1).
Figures referenced on this page are available in the full case study PDF.
PDF · 2 pages
Identifying biochemical relapse earlier
Includes Figures 1–2 and full references
EXENT GAM ASSAY FINDINGS
4 months before SPE
The EXENT GAM assay identified the re-emergence of the patient's IgGκ M-protein four months before it was detectable by SPE.2
Section 04 — Hear from the experts
Serum monitoring may guide the timing of MRD assessment
Podcast 5
Podcast episode
Listen to our podcast episode where our scientists discuss how the EXENT GAM assay can support more sensitive monitoring of M-proteins beyond electrophoresis.
"We can measure to those lower levels for longer before you might need to consider a bone marrow biopsy, which gives you a better indication of when clinicians might want to do an MRD test."
—Dr. Nick Paciaroni, Medical Science Liaison, Binding Site, part of Thermo Fisher Scientific
Section 05 — Broader clinical validation
M-protein dynamics predict progression-free survival
In a study by Puig et al., the EXENTTM System was used to evaluate M-protein dynamics and the association with disease progression in patients undergoing maintenance therapy.3 Mass spectrometry (MS) status was assessed at several time points during the study period.
Patients who transitioned from MS negative to MS positive had a median progression-free survival (mPFS) of 0.76 years.3 Those who remained MS negative or converted from MS positive to MS negative had the best outcomes, with mPFS not reached within the study period.3 (Figure 2).
mPFS not reached
Patients who either remained MS negative or converted from MS positive to MS negative had the best outcomes (mPFS not reached).
Section 06 — Implications
Key points for clinical practice
01
The EXENT GAM assay's enhanced analytical sensitivity may enable earlier detection of biochemical relapse compared to electrophoretic methods, providing a wider window for clinical decision-making.
02
Using the EXENT GAM assay may reduce the need for early bone marrow biopsy while maintaining sensitivity below the threshold of SPE and IFE.
03
Conversion from mass spectrometry negative to positive status carries significant prognostic implications, suggesting serial MS monitoring may help to quickly identify patients at highest risk of progression.
Section 07 – Next Steps
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References
- Kumar S, et al. Lancet Oncol 2016; 17:e328-46
- Berlanga O, et al. Clinical Chemistry 2023; 69.
- Puig N, et al. Blood 2024; 144:2432-2438.
The EXENT system combines EXENT analyzer with the Immunoglobulin Isotypes (GAM) for the EXENT analyzer. EXENT GAM assay refers to Immunoglobulin Isotypes (GAM) for the EXENT analyzer