Using MALDI-TOF mass spectrometry in peripheral blood for the follow up of newly diagnosed multiple myeloma patients treated with daratumumab-based combination therapy

Background: Daratumumab-based combination therapies have shown high rates of complete response (CR) and minimal residual disease negativity in patients with multiple myeloma. However, daratumumab, an IgGx monoclonal antibody, interferes with electrophoretic techniques making it difficult to reliably define residual disease versus CR, especially in patients with IgGx multiple myeloma. Methods: Enrichment with polyclonal sheep antibody-coated magnetic microparticles combined with MALDI-TOF mass spectrometry (MALDI-TOF MS) analysis was used to detect M-proteins in serial samples from newly diagnosed multiple myeloma patients treated with daratumumab-based therapy. The performance of the MALDITOF MS assay was compared to that of a routine test panel (serum protein electrophoresis (SPEP), immunofixation (IFE) and serum free light chain (FLC)). Results: Comparison of MALDI-TOF MS to SPEP/IFE/FLC showed a concordance of 84.9% (p < 0.001). When MALDI-TOF MS and FLC results were combined, the M -protein detection rate was the same or better than the routine test panel. For the 9 patients who obtained CR during follow-up, MALDI-TOF MS detected an M -protein in 46% of subsequent samples. Daratumumab could be distinguished from the M-protein in 215/222 samples. Conclusion: MALDI-TOF MS is useful in assessing CR in patients treated with monoclonal antibody-based therapies.

Automated summary

The use of MALDI-TOF MS for detecting M-proteins is helpful in assessing complete response in patients treated with monoclonal antibody therapies.