Single-point and kinetics of peripheral residual disease by mass spectrometry to predict outcome in patients with high risk smoldering multiple myeloma included in the GEM-CESAR trial.

The value of quantitative immunoprecipitation mass spectrometry (QIP-MS) to identify the M-protein is being investigated in patients with monoclonal gammopathies but no data are yet available in high-risk smoldering myeloma (HRsMM). We have therefore investigated QIP-MS to monitor peripheral residual disease (PRD) in 62 HRsMM patients enrolled in the GEM-CESAR trial. After 24 cycles of maintenance, detecting the M-protein by MS or clonal plasma cells by NGF identified cases with a significantly shorter median PFS (mPFS; MS: not reached vs 1,4 years, p=0.001; NGF: not reached vs 2 years, p=0.0002) but reaching CR+sCR did not discriminate patients with different outcome. With NGF as a reference, the combined results of NGF and MS showed a high negative predictive value (NPV) of MS: 81% overall and 73% at treatment completion. When sequential results were considered, sustained negativity by MS or NGF was associated with a very favorable outcome with a mPFS not yet reached vs 1.66 years and 2.18 years in cases never attaining PRD or minimal residual disease (MRD) negativity, respectively. We can thus conclude that 1) the standard response categories of the IMWG do not seem to be useful for treatment monitoring in HRsMM patients, 2) MS could be used as a non-invasive, clinical valuable tool with the capacity of guiding timely bone marrow evaluations (based on its high NPV with NGF as a reference) and 3) similarly to NGF, sequential results of MS are able identify a subgroup of HRsMM patients with long-term disease control. This study was registered at www.clinicaltrials.gov (ClinicalTrials.gov identifier: NCT02415413).

Mass Spectrometry as Alternative Method to Identify and Monitor Non-Secretory Progressive Disease in Patients with Multiple Myeloma.

INTRODUCTION: After receiving different lines of treatment, multiple myeloma patients tend to present with less secretory and more frequent extramedullary disease. These features make treatment monitoring and follow-up very complex since they have to be based on the use of imaging methods and/or bone marrow aspirations or biopsies. OBJECTIVE: To present the case of a patient with myeloma progressing with non-secretory bone disease and to discuss the potential impact of mass spectrometry as a new highly sensitive method able to identify the monoclonal protein (MP) in the serum of these types of patients. MATERIALS AND METHODS: Informed consent was signed by the patient prior to receiving each line of treatment. The clinical information and images were obtained from anonymized electronic files. The mass spectrometry was performed with the Immunoglobulin Isotypes (GAM) assay for the mass spectrometry EXENT® Analyser Technology from Binding Site, part of Thermofisher. RESULTS: A 73-year-old male with IgG kappa multiple myeloma progressing with a new lytic lesion after receiving 14 cycles of Talquetamab as a third line of therapy who, due to the non-secretory nature of the disease at this point, could not be enrolled in a clinical trial, thus limiting his therapeutic options. The mass spectrometry was able to identify and quantify the presence of the patient's MP when the serum protein electrophoresis and immunofixation were still negative and therefore could have been used to confirm the progression, to permit the inclusion of the patient in a clinical trial and to further monitor the disease response. CONCLUSIONS: The higher sensitivity of the mass spectrometry methods to detect the MP in patients with myeloma and other monoclonal gammopathies translates into better identification of the disease progression, permits the inclusion of more patients in clinical trials and facilitates treatment monitoring.

Serum mass spectrometry for treatment monitoring in patients with multiple myeloma receiving ARI0002h CAR T-cells.

Chimeric antigen receptor (CAR) T-cell therapies have increased the patients with relapsed/refractory multiple myeloma (RRMM) in whom standard electrophoretic techniques fail to detect the M-protein. Quantitative immunoprecipitation mass spectrometry (QIP-MS) can accurately measure serum M-protein with high sensitivity, and identify interferences caused by therapeutic monoclonal antibodies. Here, we investigate the outcome of QIP-MS in 33 patients treated with the academic BCMA-directed CAR T-cell ARI0002h (Cesnicabtagene Autoleucel). QIP-MS offered more detailed insights than serum immunofixation (sIFE), identifying glycosylated M-proteins and minor additional peaks. Moreover, the potential interferences owing to daratumumab or tocilizumab treatments were successfully detected. When analysing different assay platforms during patient's monitoring after ARI0002h administration, we observed that QIP-MS showed a high global concordance (78.8%) with sIFE, whereas it was only moderate (55.6%) with bone marrow (BM)-based next-generation flow cytometry (NGF). Furthermore, QIP-MS consistently demonstrated the lowest negativity rate across the different timepoints (27.3% vs. 60.0% in months 1 and 12, respectively). Patients with QIP-MS(+)/BM-based NGF(-) showed a non-significant shorter median progression free survival than those with QIP-MS(-)/BM-based NGF(-). In summary, we show the first experience to our knowledge demonstrating that QIP-MS could be particularly useful as a non-invasive technique when evaluating response after CAR T-cell treatment in MM.

Mass spectrometry vs immunofixation for treatment monitoring in multiple myeloma.

Monitoring of the monoclonal protein (M-protein) by electrophoresis and/or immunofixation (IFE) has long been used to assess treatment response in multiple myeloma (MM). However, with the use of highly effective therapies, the M-protein becomes frequently undetectable, and more sensitive methods had to be explored. We applied IFE and mass spectrometry (EXENT&FLC-MS) in serum samples from newly diagnosed MM patients enrolled in the PETHEMA/GEM2012MENOS65 obtained at baseline (n = 223), and after induction (n = 183), autologous stem cell transplantation (n = 173), and consolidation (n = 173). At baseline, the isotypes identified with both methods fully matched in 82.1% of samples; in the rest but 2 cases, EXENT&FLC-MS provided additional information to IFE with regards to the M-protein(s). Overall, the results of EXENT&FLC-MS and IFE were concordant in >80% of cases, being most discordances due to EXENT&FLC-MS+ but IFE- cases. After consolidation, IFE was not able to discriminate 2 cohorts with different median progression-free survival (PFS), but EXENT&FLC-MS did so; furthermore, among IFE- patients, EXENT&FLC-MS identified 2 groups with significantly different median PFS (P = .0008). In conclusion, compared with IFE, EXENT&FLC-MS is more sensitive to detect the M-protein of patients with MM, both at baseline and during treatment, and provides a more accurate prediction of patients' outcome. This trial was registered at www.clinicaltrials.gov as #NCT01916252.