Minimal Residual Disease Status as a Surrogate Endpoint for Progression-free Survival in Newly Diagnosed Multiple Myeloma Studies: A Meta-analysis

Low circulating tumor cell levels correlate with favorable outcomes and distinct biological features in multiple myeloma

There is growing interest in multiple myeloma (MM) circulating tumor cells (CTCs), but their rareness in peripheral blood (PB) and inconsistency in cutoffs question their clinical utility. Herein, we applied next-generation flow cytometry in 550 bone marrow (BM) and matched PB samples to define an optimal CTC cutoff for both transplant-eligible and transplant-ineligible newly diagnosed MM (NDMM) patients. Deep phenotyping was performed to investigate unique microenvironmental features associated with CTC dissemination. CTCs were detected in 90% of patients (median 0.01%; range: 0.0002%-12.6%) and increased levels associated with adverse features. Correlations were observed between high CTC percentages and a diffused MRI pattern, a distinct BM composition characterized by altered B-cell differentiation together with an expansion of effector cells and tumor-associated macrophages, as well as a greater phenotypic dissimilarity between BM and PB clonal cells. Progression-free survival (PFS) and overall survival (OS) gradually worsened with each logarithmic increment of CTCs. Conversely, NDMM patients without CTCs showed unprecedented outcomes, with 5-year PFS and OS rates of 83% and 97%, respectively. A cutoff of 0.02% CTCs was independent of the ISS, LDH, and cytogenetics in a multivariate analysis of risk factors for PFS. The 0.02% CTC cutoff synergized with the MGUS-like phenotype and the R-ISS for improving the risk stratification systems. MRD negativity was less frequent if CTCs were ≥0.02% at diagnosis, but whenever achieved, the poor prognosis of these patients was abrogated. This study shows the clinical utility of CTC assessment in MM and provides evidence toward a consensus cutoff for risk stratification.

Isatuximab, lenalidomide, dexamethasone and bortezomib in transplant-ineligible multiple myeloma: the randomized phase 3 BENEFIT trial

CD38-targeting immunotherapy is approved in combination with lenalidomide and dexamethasone in patients with newly diagnosed multiple myeloma (NDMM) that are transplant ineligible (TI) and is considered the best standard of care (SOC). To improve current SOC, we evaluated the added value of weekly bortezomib (V) to isatuximab plus lenalidomide and dexamethasone (IsaRd versus Isa-VRd). This Intergroupe Francophone of Myeloma phase 3 study randomized 270 patients with NDMM that were TI, aged 65-79 years, to IsaRd versus Isa-VRd arms. The primary endpoint was a minimal residual disease (MRD) negativity rate at 10-5 by next-generation sequencing at 18 months from randomization. Key secondary endpoints included response rates, MRD assessment rates, survival and safety. The 18-month MRD negativity rates at 10-5 were reported in 35 patients (26%, 95% confidence interval (CI) 19-34) in IsaRd versus 71 (53%, 95% CI 44-61) in Isa-VRd (odds ratio for MRD negativity 3.16, 95% CI 1.89-5.28, P < 0.0001). The MRD benefit was consistent across subgroups at 10-5 and 10-6, and was already observed at month 12. The proportion of patients with complete response or better at 18 months was higher with Isa-VRd (58% versus 33%; P < 0.0001), as was the proportion of MRD negativity and complete response or better (37% versus 17%; P = 0.0003). At a median follow-up of 23.5 months, no difference was observed for survival times (immature data). The addition of weekly bortezomib did not significantly affect the relative dose intensity of IsaRd. Isa-VRd significantly increased MRD endpoints, including the 18-month negativity rate at 10-5, the primary endpoint, compared with IsaRd. This study proposes Isa-VRd as a new SOC for patients with NDMM that are TI. ClinicalTrials.gov identifier: NCT04751877 .

Recovery of uninvolved heavy/light chain pair immunoparesis in newly diagnosed transplant-eligible myeloma patients complements the prognostic value of minimal residual disease detection

Immunoparesis (IP) in multiple myeloma (MM) patients can be measured by classic assessment of immunoglobulin (Ig) levels or by analysis of the uninvolved heavy/light chain pair of the same immunoglobulin (uHLC) by the Hevylite® assay. In this study we evaluate the prognostic value of recovery from IP measured by classic total Ig and uHLC assessment in newly diagnosed MM transplant-eligible (NDMM-TE) patients with intensive treatment and its association with minimal residual disease (MRD). Patients were enrolled and treated in the PETHEMA/GEM2012MENOS65 trial and continued in the PETHEMA /GEM2014MAIN trial. Total Ig (IgG, IgA and IgM) and uHLC were analyzed in a central laboratory at diagnosis, after consolidation treatment and after the first year of maintenance. MRD was analyzed by next-generation flow cytometry after consolidation (sensitivity level 2x10-6). We found no differences in progression-free survival (PFS) between patients who recovered and patients who didn't recover from IP after consolidation when examining classic total Ig and uHLC. However, after the first year of maintenance, in contrast to patients with classic IP, patients with recovery from uHLC IP had longer PFS than patients without recovery, with hazard ratio of 0.42 (95% confidence interval [CI]: 0.21-0.81; P=0.008). Multivariate analysis with Cox proportional-hazards regression models confirmed recovery from uHLC IP after the first year of maintenance as an independent prognostic factor for PFS, with an increase in C-statistic of 0.05 (95% CI: -0.04 to 0.14; P<0.001) when adding uHLC IP recovery. Moreover, we observed that MRD status and uHLC IP recovery affords complementary information for risk stratification. In conclusion, recovery from uHLC IP after 1 year of maintenance is an independent prognostic factor for PFS in NDMM-TE patients who receive intensive treatment. Immune reconstitution, measured as recovery from uHLC IP, provides complementary prognostic information to MRD assessment (clinicaltrials gov. Identifiers: NCT01916252 and NCT02406144).

Clinical consensus on treatments for transplant-ineligible newly diagnosed multiple myeloma: double-blinded Delphi panel

Aim: Obtain clinical consensus on factors impacting first-line prescribing for transplant-ineligible (TIE) patients with newly diagnosed multiple myeloma (NDMM). Materials & methods: A double-blinded, modified Delphi panel was employed. USA-based hematologists/oncologists who treat TIE patients with NDMM were selected as expert panelists. Results: Consensus was reached that patient frailty, performance status, comorbidities, treatment efficacy, and adverse event profile affect first-line prescribing. All panelists agreed it is important to use the most efficacious treatment first; 88% of panelists considered daratumumab-containing regimens the most efficacious. Panelists agreed treatment should be continued until progression while benefits outweigh risk. Conclusion: Findings reinforce the importance of using the most efficacious regimen upfront for TIE NDMM, and nearly all panelists considered daratumumab-containing regimens the most efficacious treatment.

Carfilzomib, daratumumab, and dexamethasone (KdD) vs. lenalidomide-sparing pomalidomide-containing triplet regimens for relapsed/refractory multiple myeloma: an indirect treatment comparison

Nearly all patients with multiple myeloma eventually relapse or become refractory to treatment. Lenalidomide is increasingly administered in the frontline until disease progression or intolerance to therapy, resulting in the need for highly effective, lenalidomide-sparing options. In this study, carfilzomib plus daratumumab and dexamethasone were evaluated against lenalidomide-sparing, pomalidomide-containing triplets using matching-adjusted indirect comparison in the absence of head-to-head data. The analyses utilized long-term follow-up data from the CANDOR study (NCT03158688). Treatment with carfilzomib, daratumumab, and dexamethasone resulted in significantly longer progression-free survival (hazard ratio 0.60 [95% confidence interval: 0.37, 0.88])vs. pomalidomide plus bortezomib and dexamethasone, and numerically longer progression-free survival (hazard ratio 0.77 [95% confidence interval: 0.50, 1.08]) vs. daratumumab plus pomalidomide and dexamethasone in patients with relapsed/refractory multiple myeloma and previous lenalidomide exposure, the majority of whom were lenalidomide refractory. Carfilzomib plus daratumumab and dexamethasone offers a highly effective, lenalidomide-sparing treatment option for this population.

Monitoring Minimal Residual Disease in Patients with Multiple Myeloma by Targeted Tracking Serum M-Protein Using Mass Spectrometry (EasyM)

PURPOSE

We investigated both the clinical utilities and the prognostic impacts of the clonotypic peptide mass spectrometry (MS)-EasyM, a blood-based minimal residual disease (MRD) monitoring protocol in multiple myeloma.

EXPERIMENTAL DESIGN

A total of 447 sequential serum samples from 56 patients with multiple myeloma were analyzed using EasyM. Patient-specific M-protein peptides were sequenced from diagnostic samples; sequential samples were quantified by EasyM to monitor the M-protein. The performance of EasyM was compared with serum immunofixation electrophoresis (IFE), bone marrow multiparameter flow cytometry (MFC), and next-generation flow cytometry (NGF) detection. The optimal balance of EasyM sensitivity/specificity versus NGF (10-5 sensitivity) was determined and the prognostic impact of MS-MRD status was investigated.

RESULTS

Of the 447 serum samples detected and measured by EasyM, 397, 126, and 92 had time-matching results for comparison with serum IFE, MFC-MRD, and NGF-MRD, respectively. Using a dotp >0.9 as the MS-MRD positive, sensitivity was 99.6% versus IFE and 100.0% versus MFC and NGF. Using an MS negative cutoff informed by ROC analysis (<1.86% of that at diagnosis), EasyM sensitivity remained high versus IFE (88.3%), MFC (85.1%), and NGF (93.2%), whereas specificity increased to 90.4%, 55.8%, and 93.2%, respectively. In the multivariate analysis, older diagnostic age was an independent predictor for progression-free survival [PFS; high risk (HR), 3.15; 1.26-7.86], the best MS-MRD status (MS-MRD negative) was independent predictor for both PFS (HR, 0.25; 0.12-0.52) and overall survival (HR, 0.16; 0.06-0.40).

CONCLUSIONS

EasyM is a highly sensitive and minimal invasive method of MRD monitoring in multiple myeloma; MS-MRD had significant predictive ability for survival outcomes.

Predictors of unsustained measurable residual disease negativity in transplant-eligible patients with multiple myeloma

ABSTRACT

The role of measurable residual disease (MRD) negativity as a biomarker to stop treatment is being investigated in transplant-eligible patients with multiple myeloma (MM). Thus, it is important to identify risk factors of MRD resurgence and/or progressive disease (PD) among patients achieving undetectable MRD to avoid undertreating them. Here, we studied 267 newly diagnosed transplant-eligible patients with MM enrolled in the GEM2012MENOS65 and GEM2014MAIN clinical trials who achieved MRD negativity by next-generation flow cytometry. After a median follow-up of 73 months since the first MRD negative assessment, 111 of the 267 (42%) patients showed MRD resurgence and/or PD. The only prognostic factors at diagnosis that predicted MRD resurgence and/or PD were an International Staging System (ISS) 3 and the presence of ≥0.01% circulating tumor cells (CTCs). Failure to achieve MRD negativity after induction also predicted higher risk of MRD resurgence and/or PD. Patients having 0 vs 1 vs ≥2 risk factors (ISS 3, ≥0.01% CTCs, and late MRD negativity) showed 5-year rates of MRD resurgence and/or PD of 16%, 33%, and 57%, respectively (P < .001). Thus, these easily measurable risk factors could help refine the selection of patients for whom treatment cessation after MRD negativity is being investigated in clinical trials. This trial was registered at www.clinicaltrials.gov as NCT01916252 and NCT02406144.

M-protein detection by mass spectrometry for minimal residual disease in multiple myeloma

Multiple myeloma (MM) is characterized by excessive production of monoclonal immunoglobulins (M proteins). Routine screening methods for M proteins to assess prognosis are unable to detect low levels of M proteins produced by residual tumor cells, ie, minimal residual disease (MRD). Assessment of MRD can be conducted by examining residual tumor cells in bone marrow or circulating M proteins. Advances in mass spectrometry have enabled reliable and highly sensitive detection of low abundance serum biomarkers making it a viable and significantly less invasive approach. Mass spectrometry can achieve dynamic monitoring of MRD and identify therapeutic monoclonal antibodies as well as oligoclonal proteins. In this review we summarize mass spectrometry methods in M protein detection and their applications of MRD detection in MM.

Isatuximab, Carfilzomib, Lenalidomide, and Dexamethasone for the Treatment of High-Risk Newly Diagnosed Multiple Myeloma

PURPOSE

The GMMG-CONCEPT trial investigated isatuximab, carfilzomib, lenalidomide, and dexamethasone (Isa-KRd) in transplant-eligible (TE) and transplant-noneligible (TNE) patients with newly diagnosed multiple myeloma (NDMM) with exclusively high-risk disease for whom prospective trials are limited, aiming to induce minimal residual disease (MRD) negativity.

METHODS

This academic, investigator-initiated, multicenter, phase II trial enrolled patients with high-risk NDMM (HRNDMM) defined by mandatory International Staging System stage II/III combined with del17p, t(4;14), t(14;16), or more than three 1q21 copies as high-risk cytogenetic aberrations (HRCAs). Patients received Isa-KRd induction/consolidation and Isa-KR maintenance. TE patients received high-dose melphalan. TNE patients received two additional Isa-KRd cycles postinduction. This prespecified interim analysis (IA) reports the primary end point, MRD negativity (<10-5, next-generation flow), at the end of consolidation. The secondary end point was progression-free survival (PFS).

RESULTS

Among 125 patients with HRNDMM (TE-intention-to-treat [ITT]-IA, 99; TNE-ITT, 26) of the IA population for the primary end point, the median age was 58 (TE-ITT-IA) and 74 (TNE-ITT) years. Del17p was the most common HRCA (TE, 44.4%; TNE, 42.3%); about one third of evaluable TE/TNE patients presented two or more HRCAs, respectively. The trial met its primary end point with MRD negativity rates after consolidation of 67.7% (TE) and 54.2% (TNE) of patients. Eighty-one of 99 TE-ITT-IA patients reached MRD negativity at any time point (81.8%). MRD negativity was sustained for ≥1 year in 62.6% of patients. With a median follow-up of 44 (TE) and 33 (TNE) months, median PFS was not reached in either arm.

CONCLUSION

Isa-KRd effectively induces high rates of sustainable MRD negativity in the difficult-to-treat HRNDMM population, regardless of transplant status, translating into a median PFS that was not yet reached after 44/33 months.

Upfront or Deferred Autologous Stem Cell Transplantation for Newly Diagnosed Multiple Myeloma in the Era of Triplet and Quadruplet Induction and Minimal Residual Disease/Risk-Adapted Therapy

The standards of care for the initial treatment of patients with newly diagnosed multiple myeloma (NDMM) who are eligible for high-dose melphalan and autologous stem cell transplantation (HDM-ASCT) include highly active triplet and quadruplet regimens based on proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies. These regimens are resulting in improved outcomes and increasingly high rates of minimal residual disease (MRD)-negative responses without HDM-ASCT as part of the upfront therapy. Furthermore, recent randomized studies have shown that, while transplant-based approaches as a frontline therapy result in significantly longer progression-free survival compared to non-transplant approaches, this has not translated into an overall survival benefit. Given these developments, and in the context of the treatment burden of undergoing HDM-ASCT, in addition to the acute toxicities and long-term sequelae of HDM, which are associated with the genotoxicity of melphalan, there is an increasing rationale for considering deferring upfront HDM-ASCT in select transplant-eligible patients and saving it as a treatment option for later salvage therapy. Here, we review the latest clinical trial data on upfront or deferred HDM-ASCT and on the activity of quadruplet induction regimens, including rates of MRD-negative responses, and summarize emerging treatment approaches in the upfront setting such as the use of MRD-directed therapy and alternatives to HDM-ASCT.

Multiple myeloma following bone metastasis of renal cell carcinoma: a case report

Background

The clinical manifestations of multiple myeloma (MM) and bone metastatic tumor are both systemic bone pain, which is difficult to distinguish from imaging manifestations, leading to misdiagnosis and missed diagnosis.

Case summary

We reported a man with a unique case whose tumors were MM with bone metastatic tumor of clear cell renal cell carcinoma (CCRCC). Computed tomography (CT) showed multifocal osteolytic bone destruction, while magnetic resonance imaging (MRI) showed multifocal bone marrow infiltration with soft tissue mass. Pathology and immunohistochemistry established the diagnosis of the coexistence of myeloma with bone metastatic tumor of CCRCC in the spine. Immunotherapy and systemic chemotherapy were adopted in the clinic, and vertebral decompression was performed after anemia was corrected. This case with MM and bone metastatic tumor of CCRCC received radiotherapy and immunotherapy and acquired satisfying outcome after 1 year of follow-up.

Conclusion

It is difficult to differentiate MM and bone metastatic tumor on imaging, especially when there are bone lesions at the same time, which is an easily missed diagnosis and needs to be comprehensively evaluated in combination with functional procedures, clinical laboratory tests, and histopathology.

Potential future direction of measurable residual disease evaluation in multiple myeloma

Multiple myeloma remains an incurable disease plagued by high relapse rates. Deeper and more sustainable responses, however, have been consistently shown to improve outcomes and could eventually pave the way to achieving a cure. Our understanding of disease response has surpassed complete response (CR), because the current definitions are suboptimal, and the treatment goal should aim even beyond stringent CR, toward molecular and flow CR, that is, measurable residual disease (MRD) negativity. It has been more than 20 years since the discrepancy in the outcome between patients in CR with and without MRD has been demonstrated, and the field has come a long way from multiparameter flow cytometry to next-generation flow and next-generation sequencing, able to detect up to a limit of detection of a single myeloma cell from 1 million healthy counterparts. This review aims to summarize the current available data regarding MRD but also its potential future use as a coprimary outcome both in clinical and trial settings as a survival surrogate as well as its use to evaluate treatment efficacy and for adaptive response-based and early-rescue therapy. Furthermore, we discuss whether these concepts are applicable in different settings (eg, newly diagnosed and relapsed/refractory myeloma, patients who are eligible and ineligible for tansplant, and standard- and high-risk disease).

Aiming for the cure in myeloma: Putting our best foot forward

Frontline therapy for multiple myeloma (MM) is evolving to include novel combinations that can achieve unprecedented deep response rates. Several treatment strategies exist, varying in induction regimen composition, use of transplant and or consolidation and maintenance. In this sea of different treatment permutations, the overarching theme is the powerful prognostic factors of disease risk and achievement of minimal residual disease (MRD) negativity. MM has significant inter-patient variability that requires treatment to be individualized. Risk-adapted and response-adapted strategies which are increasingly being explored to define the extent and duration of therapy, and eventually aim for functional curability. In addition, with T-cell redirection therapies rapidly revolutionizing myeloma treatments, the current standard of care for myeloma will change. This review analyzes the current relevant literature in upfront therapy for fit myeloma patients and provides suggestions for treatment approach while novel clinical trials are maturing.

Enhanced clinical assessment of hematologic malignancies through routine paired tumor and normal sequencing

Genomic profiling of hematologic malignancies has augmented our understanding of variants that contribute to disease pathogenesis and supported development of prognostic models that inform disease management in the clinic. Tumor only sequencing assays are limited in their ability to identify definitive somatic variants, which can lead to ambiguity in clinical reporting and patient management. Here, we describe the MSK-IMPACT Heme cohort, a comprehensive data set of somatic alterations from paired tumor and normal DNA using a hybridization capture-based next generation sequencing platform. We highlight patterns of mutations, copy number alterations, and mutation signatures in a broad set of myeloid and lymphoid neoplasms. We also demonstrate the power of appropriate matching to make definitive somatic calls, including in patients who have undergone allogeneic stem cell transplant. We expect that this resource will further spur research into the pathobiology and clinical utility of clinical sequencing for patients with hematologic neoplasms.

Current and Future PET Imaging for Multiple Myeloma

Positron emission tomography (PET) is an imaging modality used for the noninvasive assessment of tumor staging and response to therapy. PET with 18F labeled fluorodeoxyglucose (18F-FDG PET) is widely used to assess the active and inactive lesions in patients with multiple myeloma (MM). Despite the availability of 18F-FDG PET for the management of MM, PET imaging is less sensitive than next-generation flow cytometry and sequencing. Therefore, the novel PET radiotracers 64Cu-LLP2A, 68Ga-pentixafor, and 89Zr-daratumumab have been developed to target the cell surface antigens of MM cells. Furthermore, recent studies attempted to visualize the tumor-infiltrating lymphocytes using PET imaging in patients with cancer to investigate their prognostic effect; however, these studies have not yet been performed in MM patients. This review summarizes the recent studies on PET with 18F-FDG and novel radiotracers for the detection of MM and the resulting preclinical research using MM mouse models and clinical studies. Novel PET technologies may be useful for developing therapeutic strategies for MM in the future.

Response adaptive salvage with KTd and ASCT for functional high-risk multiple myeloma-The Australasian Leukemia and Lymphoma Group (ALLG) MM17 Trial

We evaluated re-induction incorporating carfilzomib-thalidomide-dexamethasone (KTd) and autologous stem cell transplantation (ASCT) for newly diagnosed multiple myeloma (NDMM) refractory, or demonstrating a suboptimal response, to non-IMID bortezomib-based induction. KTd salvage consisted of thalidomide 100 mg daily and dexamethasone 20 mg orally combined with carfilzomib 56 mg/m² days 1, 2, 8, 9, 15 and 16, of each 28-day cycle. Following four cycles, patients achieving a stringent complete response proceeded to ASCT whereas those who did not received a further two cycles then ASCT. Consolidation consisted of two cycles of KTd then Td to a total of 12 months post-ASCT therapy. Primary end-point was the overall response rate (ORR) with KTd prior to ASCT. Fifty patients were recruited. The ORR was 78% with EuroFlow MRD negativity of 34% in the intention-to-treat population and 65% in the evaluable population at 12 months post-ASCT. With follow-up >38 months median PFS and OS have not been reached with PFS and OS at 36 months of 64% and 80%, respectively. KTd was well tolerated with grade 3 and grade ≥4 adverse events rates of 32% and 10%, respectively. Response adaptive utilisation of KTd with ASCT is associated with both high-quality responses and durable disease control in functional high-risk NDMM.

Efficacy and safety of isatuximab plus bortezomib, lenalidomide, and dexamethasone in patients with newly diagnosed multiple myeloma ineligible/with no immediate intent for autologous stem cell transplantation

Patients with newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation (ASCT) have lower survival rates and may benefit from frontline regimens that include novel agents. This Phase 1b study (NCT02513186) evaluated preliminary efficacy, safety, and pharmacokinetics (PK) of isatuximab, an anti-CD38 monoclonal antibody, combined with bortezomib-lenalidomide-dexamethasone (Isa-VRd) in patients with NDMM ineligible for/with no intent for immediate ASCT. Overall, 73 patients received four 6-week induction cycles of Isa-VRd, then maintenance with Isa-Rd in 4-week cycles. In the efficacy population (n = 71), the overall response rate was 98.6%, with 56.3% achieving a complete response or better (sCR/CR), and 36/71 (50.7%) patients reaching minimal residual disease negativity (10^-5 sensitivity). Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 79.5% (58/73) of patients but TEAEs leading to permanent study treatment discontinuation were reported in 14 (19.2%) patients. Isatuximab PK parameters were within the previously reported range, suggesting that VRd does not alter the PK of isatuximab. These data support additional studies of isatuximab in NDMM, such as the Phase 3 IMROZ study (Isa-VRd vs VRd).

Overall and complete response rates as potential surrogates for overall survival in relapsed/refractory multiple myeloma

Aim: The correlation between response and survival has not been well-studied in relapsed or refractory multiple myeloma (RRMM). Materials & methods: A systematic literature review of Medline, Embase and Cochrane databases (2010-06/2020) and relevant congresses (2018-2020) was performed to identify randomized clinical trials in RRMM reporting median overall survival (mOS), progression-free survival and response endpoints. The relationship between mOS and response endpoints was analyzed using Pearson's product-moment correlation. Results: A total of 81 records for 65 original studies, representing 12,827 patients were included. The correlation was moderate for mOS with overall response rate (Pearson r = 0.79), very good partial response (r = 0.73) and duration of response (r = 0.78); all were statistically significant. In linear regression models, estimated mOS gain was 0.48, 0.47 and 1.94 months per percentage point of overall response rate, very good partial response and complete response, respectively (all p < 0.001). Significance was maintained after adjustment for age, relapsed versus refractory multiple myeloma and study year. The analysis was limited by small sample sizes and inconsistent reporting of study-level covariates. Conclusion: These findings support short-term response-based endpoints as surrogates to survival in RRMM.

Integrated analysis of next generation sequencing minimal residual disease (MRD) and PET scan in transplant eligible myeloma patients

Minimal residual disease (MRD) assays allow response assessment in patients with multiple myeloma (MM), and negativity is associated with improved survival outcomes. The role of highly sensitive next generation sequencing (NGS) MRD in combination with functional imaging remains to be validated. We performed a retrospective analysis on MM patients who underwent frontline autologous stem cell transplant (ASCT). Patients were evaluated at day 100 post-ASCT with NGS-MRD and positron emission tomography (PET-CT). Patients with ≥ 2 MRD measurements were included in a secondary analysis for sequential measurements. 186 patients were included. At day 100, 45 (24.2%) patients achieved MRD negativity at a sensitivity threshold of 10-6. MRD negativity was the most predictive factor for longer time to next treatment (TTNT). Negativity rates did not differ according to MM subtype, R-ISS Stage nor cytogenetic risk. PET-CT and MRD had poor agreement, with high rates of PET-CT negativity in MRD-positive patients. Patients with sustained MRD negativity had longer TTNT, regardless of baseline risk characteristics. Our results show that the ability to measure deeper and sustainable responses distinguishes patients with better outcomes. Achieving MRD negativity was the strongest prognostic marker and could help guide therapy-related decisions and serve as a response marker for clinical trials.

Time-to-event surrogate end-points in multiple myeloma randomised trials from 2005 to 2019: A surrogacy analysis

Use of surrogate end-points such as progression-free survival (PFS) and other time-to-event (TTE) end-points is common in multiple myeloma (MM) clinical trials. This systematic review characterises all published randomised controlled trials (RCTs) in MM using PFS or other TTE end-points between 2005 and 2019 and assesses strength of surrogacy of PFS for overall survival (OS). The association between OS hazard ratios (HRs) and PFS HRs was evaluated with linear regression, and the coefficient of determination with Pearson's correlation. We identified 88 RCTs of which 67 (76%) used PFS as the primary/co-primary end-point. One trial indicated whether progression was biochemical or clinical. Of the variance in OS, 39% was due to variance in PFS. Correlation between PFS and OS was weak (0.62, 95% confidence interval [CI] 0.38-0.78). In newly diagnosed MM, 43% of the variance in OS was due to changes in PFS. The correlation between PFS and OS was weak (0.65, 95% CI 0.30-0.84). In relapsed/refractory MM, 58% of the variance in OS was due to changes in PFS. Correlation between PFS and OS was medium (0.76, 95% CI 0.42-0.91). We demonstrate that PFS and progression characteristics are characterised poorly in MM trials and that PFS is a poor surrogate for OS in MM.

Reproducibility of low-level residual myeloma immunoglobulin detection using ultra-deep sequencing

Multiple myeloma, a mature B-cell neoplasm, is the second most common hematologic malignancy. Despite advancements in treatment, the disease remains incurable, with more than 100,000 annual deaths worldwide. As recommended by the International Myeloma Working Group, measurable residual disease (MRD) should be addressed at a 10^-5 sensitivity level or beyond for practical purposes. Next-generation sequencing (NGS) has provided new opportunities with deep sequencing of clonal rearrangements of the immunoglobulin heavy chain (IGH) locus in B-cell malignancies. Although the ability to resolve one cancerous cell in a million other B cells is becoming attractive as a prognostic indicator in sustained patients who are MRD-negative, reaching consistent sensitivity levels is challenging because of sample stochasticity and the substantial amount of deoxyribonucleic acid (DNA) required for library preparation. Thus, in the presented study, we implemented ultra-deep sequencing of rearranged IGH to investigate the reproducibility and consistency aimed at the 10^-5 sensitivity level. In this controlled setup, our data provided stable MRD detection of 1.2 clonal cells per 100,000 analyzed cells and longitudinal reproducibility. We also demonstrated a low false-negative rate using 4-5 replicates and 700-800 ng DNA per sequencing replicate. In conclusion, adding an internal control to the replicates enabled clonal cell normalization for MRD evaluation as a stable reference. These findings may guide MRD-level reporting and comparisons between laboratories.

Association of Minimal Residual Disease Negativity Rates With Progression Free Survival in Frontline Therapy Trials for Newly Diagnosed Multiple Myeloma: A Meta-analysis

Current frontline therapies for newly diagnosed multiple myeloma patients have significantly prolonged progression-free survival (PFS). This has led to interest in minimal residual disease negativity (MRDng) as an efficacy-response biomarker and possible surrogate endpoint. A meta-analysis was conducted to explore the surrogacy of MRD for PFS and quantify the relationship between MRDng rates and PFS at the trial level. A systematic search was conducted on phase II and III trials reporting MRDng rates along with median PFS (mPFS) or PFS hazard ratios (HR). Weighted linear regressions were conducted relating mPFS to MRDng rates, and relating PFS HRs to either odds ratios (OR) or rate differences (RD) for MRDng in comparative trials. A total of 14 trials were available for the mPFS analysis. log(MRDng rate) was moderately associated with log (mPFS), with a slope of β = 0.37 (95% CI, 0.26-0.48) and R² = 0.62. A total of 13 trials were available for the PFS HR analysis. Treatment effects on MRDng rates were correlated with the corresponding effects on PFS: log (PFS HR) and log (MRDng OR) had a moderate association with β = -0.36 (95% CI, -0.56 to -0.17) and R² = 0.53 (95% CI, 0.21-0.77); log (PFS HR) and the MRDng RD had a stronger association with slope β = -0.03 (95% CI, -0.04 to -0.02) and R² = 0.67 (95% CI, 0.31 to 0.86). MRDng rates moderately associate with PFS outcomes. MRDng RDs are more strongly associated with HRs than MRDng ORs, with evidence suggestive of potential surrogacy.

Standardizing Clinical Workflow for Assessing Minimal Residual Disease by Flow Cytometry in Multiple Myeloma

INTRODUCTION

Minimal residual disease (MRD) status is an established prognostic biomarker for patients with multiple myeloma. Commonly used MRD testing techniques such as next generation sequencing or next generation flow cytometry can detect as little as one or two multiple myeloma plasma cells in 106 normal bone marrow cells. Early pull of bone marrow aspirates (BMA), necessary to achieve such level of sensitivity, can be difficult to secure in routine clinical practice due to the competing need for early pull samples for clinical response assessment, therefore introducing the risk of analytical interference during MRD testing.

METHODS

To overcome this challenge, we standardized our workflow for collecting specimens by using a technical first pull after needle repositioning for MRD testing. To capture a comprehensive picture of MRD assay performance and specimen adequacy, we tested for MRD on 556 technical first pull bone marrow aspirates by next generation flow cytometry. Among the specimens, several key multiple myeloma treatment milestones were represented: end of induction therapy, two to three months post-autologous stem cell transplant, early and late stages of maintenance therapy.

RESULTS

By using the technical first pull bone marrow aspirate, we achieved an analytical assay input of 10 million nucleated cells for 97.5% of specimens. Our analytical sensitivity reached 10-6; (i.e., 10 multiple myeloma plasma cells in 10 × 106 bone marrow cells). Twenty-four percent of specimens were significantly hemodiluted. Low assay input or hemodilution quantifiably lowered the assay sensitivity.

CONCLUSION

Specimen adequacy is, therefore, an important metric to incorporate into MRD status reporting.

Clinical implications of measurable residual disease assessment in multiple myeloma in the era of quadruplet therapy

Multiple myeloma is a complex hematological malignancy with substantial heterogeneity in its clinical manifestations, biological processes, and patient outcomes. Although many biomarkers with have been identified to assist with disease monitoring and prognostication, predictive markers that inform treatment decisions remain elusive. As treatments become more effective, assays for measurable residual disease (MRD) below the level of detection of traditional assays have emerged as an essential component of disease assessment with powerful prognostic value for dynamic risk assessment. As its role as a potentially predictive biomarker continues to evolve, it is increasingly clear that MRD assessment has substantial clinical utility in the evaluation of patients with myeloma. In this review, we will summarize the evidence supporting the role of MRD as a prognostic biomarker and highlight the current clinical implications and future applications of MRD assessment in multiple myeloma.

Steps towards a Multiple Myeloma Cure?

Multiple myeloma survival has increased in last 20 years because of new treatments, better clinical management due to novel diagnostic tools such as imaging, and better understanding of the disease, biologically and genetically. Novel drugs have been introduced that act with different therapeutic mechanisms, but so have novel therapeutic strategies such as consolidation and maintenance after autologous stem cell transplant. Imaging (such as PET-CT and MRI) has been applied at diagnosis and after therapy for minimal residual disease monitoring. Multiparametric flow and molecular NGS may detect, with high-sensitivity, residual monoclonal plasma cells in the bone marrow. With this novel therapeutic and biological approach, a considerable fraction of multiple myeloma patients can achieve durable remission or even MGUS-like regression, which can ultimately lead to disease disappearance. The big dogma, “Myeloma is an incurable disease”, is hopefully fading.

Minimal Residual Disease After Autologous Stem-Cell Transplant for Patients With Myeloma: Prognostic Significance and the Impact of Lenalidomide Maintenance and Molecular Risk

PURPOSE

Minimal residual disease (MRD) can predict outcomes in patients with multiple myeloma, but limited data are available on the prognostic impact of MRD when assessed at serial time points in the context of maintenance therapy after autologous stem-cell transplant (ASCT) and the interaction between MRD and molecular risk.

METHODS

Data from a large phase III trial (Myeloma XI) were examined to determine the relationship between MRD status, progression-free survival (PFS), and overall survival (OS) in post-ASCT patients randomly assigned to lenalidomide maintenance or no maintenance at 3 months after ASCT. MRD status was assessed by flow cytometry (median sensitivity 0.004%) before maintenance random assignment (ASCT + 3) and 6 months later (ASCT + 9).

RESULTS

At ASCT + 3, 475 of 750 (63.3%) patients were MRD-negative and 275 (36.7%) were MRD-positive. MRD-negative status was associated with improved PFS (hazard ratio [HR] = 0.47; 95% CI, 0.37 to 0.58 P < .001) and OS (HR = 0.59; 95% CI, 0.40 to 0.85; P = .0046). At ASCT + 9, 214 of 326 (65.6%) were MRD-negative and 112 (34.4%) were MRD-positive. MRD-negative status was associated with improved PFS (HR = 0.20; 95% CI, 0.13 to 0.31; P < .0001) and OS (HR = 0.33; 95% CI, 0.15 to 0.75; P = .0077). The findings were very similar when restricted to patients with complete response/near complete response. Sustained MRD negativity from ASCT + 3 to ASCT + 9 or the conversion to MRD negativity by ASCT + 9 was associated with the longest PFS/OS. Patients randomly assigned to lenalidomide maintenance were more likely to convert from being MRD-positive before maintenance random assignment to MRD-negative 6 months later (lenalidomide 30%, observation 17%). High-risk molecular features had an adverse effect on PFS and OS even for those patients achieving MRD-negative status. On multivariable analysis of MRD status, maintenance therapy and molecular risk maintained prognostic impact at both ASCT + 3 and ASCT + 9.

CONCLUSION

In patients with multiple myeloma, MRD status at both ASCT + 3 and ASCT + 9 is a powerful predictor of PFS and OS.

The Utility of Euroflow MRD Assessment in Real-World Multiple Myeloma Practice

Measurable residual disease (MRD) is being recognised as an optimal method for assessing depth of response, identifying higher risk of relapse, and guiding response-based treatment paradigms for multiple myeloma (MM). Although MRD negativity is increasingly replacing complete response as the surrogate endpoint in clinical trials, its role in real-world practice is less established. We retrospectively analyzed EuroFlow MRD results from patients with newly diagnosed MM (NDMM) who underwent bortezomib, cyclophosphamide and dexamethasone (VCD) induction and high dose melphalan conditioned autologous stem cell transplant (ASCT) at the Alfred Hospital between January 2016 and December 2020. Next generation flow MRD evaluation was performed 3 months following ASCT using the standardised EuroFlow platform. 112 patients with available MRD data were identified to have received VCD induction followed by ASCT. Post ASCT MRD was undetectable in 28.6% of patients. Those who achieved MRD negativity had significantly longer progression free survival (PFS) than those with persisting MRD (24-month PFS of 85% [95% CI: 72.4-99.9%] vs 63% [95% CI: 52.9-75.3%], p = 0.022). Maintenance therapy was associated with improved PFS regardless of MRD status (24-month PFS of 100% [95% CI: NA, p = 0.02] vs 73% [95% CI: 53.1-99.6%] in MRD negative, and 75% [95% CI: 64.2-88.6%] vs 36% [95% CI: 20.9-63.2%, p = 0.00015] in MRD positive patients). Results from this retrospective study of real-world practice demonstrate that Euroflow MRD analysis following standard VCD induction and ASCT in NDMM is feasible and allows more accurate prognostication, providing a platform for response adaptive therapies.

Response rates and minimal residual disease outcomes as potential surrogates for progression-free survival in newly diagnosed multiple myeloma

Progression-free survival (PFS) is a common primary endpoint in newly diagnosed multiple myeloma (NDMM). Patients with NDMM typically have longer PFS and are more likely to achieve minimal residual disease (MRD) or complete response (CR) compared to patients with relapsed or refractory multiple myeloma. Response-based surrogate endpoints may hold value given the longer follow-up time required to evaluate PFS in NDMM. In this work, systematic literature reviews of Medline, Embase, and Cochrane databases (2010-06/2020) and relevant congresses (2018–2020) were performed to identify randomized clinical trials (RCTs) and real-world studies in NDMM reporting median PFS and objective response. Associations between PFS and each response endpoint were evaluated using Pearson’s product-moment correlation weighted by sample size in each RCT arm. Unadjusted and adjusted weighted linear regression models were applied to estimate the gain in median PFS associated with each response endpoint. Statistically significant correlations were identified for median PFS with overall response rate (ORR; Pearson r = 0.59), CR (r = 0.48), stringent CR (sCR; r = 0.68), and MRD (r = 0.69). The unadjusted models estimated 0.50 (95% CI: 0.36, 0.64; p<0.001), 0.42 (95% CI: 0.25, 0.58; p<0.001), 1.05 (95% CI: 0.58, 1.52; p<0.001), and 0.35 (95% CI: 0.12, 0.58; p = 0.006) months of median PFS gained per point of ORR, CR, sCR, and MRD, respectively. Associations for median PFS remained statistically significant in models adjusted for age and treatment type with ORR (0.35, 95% CI: 0.21, 0.49; p<0.001), and adjusted for age and International Staging System risk stage with CR (0.29, 95% CI: 0.16, 0.41; p<0.001). Due to small sample size, adjusted models could not be constructed for sCR or MRD. Nevertheless, evidence of significant survival benefit (p<0.05) associated with MRD negativity and sCR was identified across real-world studies. These findings provide support for the use of response outcomes as surrogate endpoints to estimate PFS benefit in NDMM.

The potential role of mass spectrometry for the identification and monitoring of patients with plasma cell disorders: Where are we now and which questions remain unanswered?

Mass spectrometry (MS) techniques provide a highly sensitive methodology for the assessment and monitoring of paraproteins compared to standard electrophoretic techniques. The International Myeloma Working Group (IMWG) recently approved the use of intact light chain matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) in lieu of immunofixation in the clinical assessment of patients and the assessment of patients enrolled on clinical trials. The increased sensitivity of these assays may help to detect and monitor monoclonal proteins (MP) in many patients with previously non-measurable disease, will reduce complete response (CR) rates and increase detection of low-level MP. The ability to track the unique mass or amino acid sequence of the MP also eliminates interference from therapeutic monoclonal antibodies (tmAbs) in most patients with IgG kappa myeloma. The intact light chain assays also provide structural information about the monoclonal light chain, including the presence of N-linked glycosylation, which has been shown to be commoner on amyloidogenic light chains and may have prognostic significance in monoclonal gammopathy of undetermined significance (MGUS). In this review, we discuss these issues alongside differences in the analytical and practical aspects related to the different MS assays under development and the challenges for MS.

Real-world data on prognostic value of measurable residual disease assessment by fragment analysis or next-generation sequencing in multiple myeloma

Measurable residual disease (MRD) negativity is a strong prognostic indicator in multiple myeloma (MM). However, the optimal use of MRD in daily clinical practice has been hampered by the limited feasibility of MRD testing. Therefore, we examined the clinical relevance of commercially available MRD modalities based on clonality assays by fragment analysis with IdentiClone® (n = 73 patients) and next-generation sequencing (NGS) with LymphoTrack® (n = 116 patients) in newly diagnosed patients with MM who received autologous stem cell transplantation (ASCT). MRD was assessed at the end of induction (pre-ASCT) and/or at 100 days after ASCT (post-ASCT). MRD could not predict survival when assessed by fragment analysis. However, NGS-based MRD negativity at pre- or post-ASCT was beneficial in terms of progression-free and overall survival. Moreover, NGS-based MRD negativity was independently associated with improved progression-free and overall survival, and MRD-positive patients both pre- and post-ASCT had worst outcome. Indeed, initial adverse prognostic features by high-risk cytogenetics could be mitigated upon achieving MRD negativity by NGS. We demonstrate the feasibility and clinical benefit of achieving MRD negativity by commercially available clonality-based MRD assays in MM and support incorporating NGS, but not fragment analysis, to tailor therapeutic strategies in real-world practice.

Prognostic impact of natural killer cell recovery on minimal residual disease after autologous stem cell transplantation in multiple myeloma

INTRODUCTION

Natural killer cells are a potent effector lymphocyte subset that can induce cytotoxicity without the need for antigen sensitization or presentation. NK cells are a tempting target -for immune therapy, monoclonal antibody, or genetic engineering-to enhance immune surveillance mechanisms against myeloma cells.

MATERIALS AND METHODS

We hypothesized an association between natural killer cell recovery after autologous stem cell transplantation (ASCT) and disease outcomes in multiple myeloma patients. We concluded a prospective study that started enrolling patients in January 2020 to identify the association between absolute NK cell count two to three after ASCT and disease outcomes after autologous stem cell transplantation in multiple myeloma using univariate and multivariate analysis.

RESULTS

Natural killer cell recovery was evaluated during the third month after ASCT, day +60 to +90 post-ASCT. Our patients had a mean NK cell count of 90.53, ranging from 14 to 282 Cell/μL (Std Dev 84.64 Cell/μL). The odds of having a minimal residual disease (MRD-positivity) among patients with partial remission before transplantation is four times higher than patients with very good partial response or better (95% confidence interval 0.45-35.79). Our patients were classified into two groups based on MRD status after ASCT, an MRD-negative group of eight participants and an MRD-positive group of seven participants. The mean absolute NK cell count was significantly higher in the MRD-negative cohort, 131.38 Cell/μL, versus 43.86 Cell/μL in the MRD-positive group (p = 0.049).

CONCLUSION

We conclude that for multiple myeloma patients treated with ASCT, high absolute NK cell counts two to three months after ASCT is an independent predictor for MRD negativity.

Mass-Fix better predicts for PFS and OS than standard methods among multiple myeloma patients participating on the STAMINA trial (BMT CTN 0702 /07LT)

Measuring response among patients with multiple myeloma is essential for the care of patients. Deeper responses are associated with better progression free survival (PFS) and overall survival (OS). To test the hypothesis that Mass-Fix, a mass spectrometry-based means to detect monoclonal proteins, is superior to existing methodologies to predict for survival outcomes, samples from the STAMINA trial (NCT01109004), a trial comparing three transplant approaches, were employed. Samples from 575 patients from as many as three time points (post-induction [post-I; pre-maintenance [pre-M]; 1 year post enrollment [1YR]) were tested when available. Four response parameters were assessed: Mass-Fix, serum immunofixation, complete response, and measurable residual disease (MRD) by next generation flow cytometry. Of the four response measures, only MRD and Mass-Fix predicted for PFS and OS at multiple testing points on multivariate analyses. Although MRD drove Mass-Fix from the model for PFS at post-I and pre-M, 1YR Mass-Fix was independent of 1YR MRD. For OS, the only prognostic pre-I measure was Mass-Fix, and the only 1YR measures that were prognostic on multivariate analysis were 1YR MRD and 1YR Mass-Fix. SIFE and CR were not. Mass-Fix is a powerful means to track response.

Tumor Reduction in Multiple Myeloma: New Concepts for New Therapeutics

The development of new resources for a more accurate diagnosis and response assessment in multiple myeloma has been a long process for decades, mainly since the middle of the 20th century. During this time, the succession of technical advances has run parallel to the better knowledge of disease biology and the availability of novel therapeutic strategies. The cornerstone of standardized criteria to uniformly evaluate the disease response in myeloma dates back to the 1990s when the key role of complete remission was established. Since then, different updates have been implemented according to available scientific evidences not always without certain controversies. The progressive improvements in survival results of myeloma patients and the growing quality of responses due to the novel therapies have led to the need of developing new tools for better monitoring of tumor burden. In this way, the concept of minimal residual disease and its key value based on the prognostic significance and the clinical relevance has been consolidated during the last years, overcoming the value of conventional response criteria or classical adverse prognosis markers. Nevertheless, its precise role in the clinical management of myeloma patients to detect early treatment failure and trigger early rescue strategies is still pending to be defined. In this review, we revisit the major milestones in the understanding of tumor reduction in multiple myeloma until the most recent imaging techniques or liquid biopsy approaches, including a critical view of conventional response criteria, whose backbone has remained unchanged during the last 20 years.

How I Treat Relapsed Multiple Myeloma

Despite recent advances multiple myeloma remains an incurable disease for most of the patients and initial remission will be followed by relapses requiring therapy. For many, there will be several remissions and relapses until resistance develops to all available therapies. With the introduction of several new agents, myeloma treatment has changed drastically and there are new options for the management of relapsed or refractory disease, including new drug classes with distinct mechanisms of action and cellular therapies. However, resistance to major drug classes used in first line remain the most critical factor for the choice of treatment at relapse. Continuous lenalidomide-based therapy is used extensively at first line and resistance to lenalidomide has become the key factor for the choice of salvage therapy. Daratumumab is increasingly used in first line and soon patients that relapse while on daratumumab will become a common challenge. Three-drug regimens are standard approach to manage relapsed disease. Adding drugs with new mechanisms of activity can improves outcomes and overcomes class resistance but, until now, while the biology is important, can offer only limited guidance for the choice of therapy.

A Cost Impact Analysis of clonoSEQ® as a Valid and CE-Certified Minimal Residual Disease (MRD) Diagnostic Compared to No MRD Testing in Multiple Myeloma in Germany

INTRODUCTION

The measurement of minimal residual disease (MRD) with clonoSEQ® can be used in the assessment of B-cell lymphoid tumor burden throughout treatment with accuracy, sensitivity and standardization when compared to traditional cytomorphology. With the approval of novel treatments, standardized MRD assessment with improved performance is increasingly important. The aim of this analysis is to estimate the cost-effectiveness of MRD testing with clonoSEQ® compared to no MRD testing for patients with multiple myeloma (MM) on maintenance therapy in Germany.

METHODS

The cost impact of clonoSEQ® was analyzed from the German statutory insurance perspective. Clinical data were derived from the literature and expert opinions. Cost input was utilized based on publicly available data and literature. Patients in the MRD arm were tested every 6 months. The deterministic Markov model consists of six health states, and every patient begins at the start of maintenance. Included therapies are lenalidomide for maintenance and carfilzomib, lenalidomide and dexamethasone for relapse.

RESULTS

For a time horizon of 10 years, the deterministic cost impact analysis shows total cost of €279,483 for patients using clonoSEQ® in comparison to €356,623 for simulated patients without MRD testing. The main drivers of the cost differences are saved cost of drug holiday. The savings per patient in 1 year are €18,396. Savings after 3 years are €69,991 per patient. Savings after 10 years are €77,140 per patient.

CONCLUSIONS

Based on the underlying model, clonoSEQ® can support German health insurance funds to use high-cost drugs more efficiently in the treatment of myeloma.

Clinical implications of loss of bone marrow minimal residual disease negativity in multiple myeloma

MRD conversion occurs in 39% of MRD⁻ MM patients and reliably predicts future relapse.

MRD conversion within 10 years of diagnosis confers an inferior overall survival and progress-free survival.

Multiple myeloma (MM) patients frequently attain a bone marrow (BM) minimal residual disease (MRD) negativity status in response to treatment. We identified 568 patients who achieved BM MRD negativity following autologous stem cell transplantation (ASCT) and maintenance combination therapy with an immunomodulatory agent and a proteasome inhibitor. BM MRD was evaluated by next-generation flow cytometry (sensitivity of 10⁻⁵ cells) at 3- to 6-month intervals. With a median follow-up of 9.9 years from diagnosis (range, 0.4-30.9), 61% of patients maintained MRD negativity, whereas 39% experienced MRD conversion at a median of 6.3 years (range, 1.4-25). The highest risk of MRD conversion occurred within the first 5 years after treatment and was observed more often in patients with abnormal metaphase cytogenetic abnormalities (95% vs 84%; P = .001). MRD conversion was associated with a high risk of relapse and preceded it by a median of 1.0 years (range, 0-4.9). However, 27% of MRD conversion-positive patients had not yet experienced a clinical relapse, with a median follow-up of 9.3 years (range, 2.2-21.2). Landmark analyses using time from ASCT revealed patients with MRD conversion during the first 3 years had an inferior overall and progression-free survival compared with patients with sustained MRD negativity. MRD conversion correctly predicted relapse in 70%, demonstrating the utility of serial BM MRD assessment to complement standard laboratory and imaging to make informed salvage therapy decisions.

Harmonization of Flow Cytometric Minimal Residual Disease Assessment in Multiple Myeloma in Centers of Polish Myeloma Consortium

Minimal residual disease (MRD) status is now considered as one of the most relevant prognostic factors in multiple myeloma (MM) while MRD negativity became an important endpoint in clinical trials. Here, we report the results of the first study evaluating the reproducibility of high-sensitivity flow cytometry MM MRD assessment in four laboratories in Poland. EuroFlow protocols for instrument setting standardization and sample preparation in MM MRD assessment were implemented in each laboratory. In the inter-laboratory reproducibility study, 12 bone marrow samples from MM patients were distributed and processed in participant laboratories. In the inter-operator concordance study, 13 raw data files from MM MRD measurements were analyzed by five independent operators. The inter-laboratory study showed high 95% overall concordance of results among laboratories. In the inter-operator study, 89% of MRD results reported were concordant, and the highest immunophenotype interpretation differences with regard to expression of CD27, CD45, CD81 were noticed. We confirmed the applicability and feasibility of the EuroFlow protocol as a highly sensitive method of MRD evaluation in MM. Results of our inter-center comparison study demonstrate that the standardization of MM MRD assessment protocols is highly desirable to improve quality and comparability of results within and between different clinical trials.

The 2020 BMT CTN Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma

The fifth annual Blood and Marrow Transplant Clinical Trials Network Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma was conducted as one of the American Society of Hematology Annual Meeting Scientific Workshops on Thursday December 3, 2020. This workshop focused on four main topics: (1) integrating minimal residual disease into clinical trial design and practice; (2) the molecular and immunobiology of disease evolution and progression in myeloma; (3) adaptation of next-generation sequencing, next-generation flow cytometry, and cytometry by time of flight techniques; and (4) chimeric antigen receptor T-cell and other cellular therapies for myeloma. In this report, we provide a summary of the workshop presentations and discuss future directions in the field.

Minimal Residual Disease in Multiple Myeloma: Ready for Prime Time?

ABSTRACT

Minimal residual disease (MRD) techniques are essential to identify the small clonal fraction within and outside the bone marrow. In the last years, evidence regarding their prognostic role for the evaluation of the depth of response of current treatment strategies has grown rapidly. Consequently, MRD was incorporated in an increasing number of clinical trials for multiple myeloma patients, also as primary endpoint, and even to guide therapeutic choices. A robust correlation between MRD negativity and survival was established. Yet, several issues regarding MRD evaluation remain to be addressed: from the optimal and more cost-effective techniques for its assessment and its harmonization worldwide to its use in clinical practice to its impact on treatment modulation. This review focuses on the available evidence supporting the use of MRD status for the management of multiple myeloma patients and on open issues that still need an answer.

Prognostic and predictive biomarker developments in multiple myeloma

New approaches to stratify multiple myeloma patients based on prognosis and therapeutic decision-making, or prediction, are needed since patients are currently managed in a similar manner regardless of individual risk factors or disease characteristics. However, despite new and improved biomarkers for determining the prognosis of patients, there is currently insufficient information to utilise biomarkers to intensify, reduce or altogether change treatment, nor to target patient-specific biology in a so-called predictive manner. The ever-increasing number and complexity of drug classes to treat multiple myeloma have improved response rates and so clinically useful biomarkers will need to be relevant in the era of such novel therapies. Therefore, the field of multiple myeloma biomarker development is rapidly progressing, spurred on by new technologies and therapeutic approaches, and underpinned by a deeper understanding of tumour biology with individualised patient management the goal. In this review, we describe the main biomarker categories in multiple myeloma and relate these to diagnostic, prognostic and predictive applications.

Minimal Residual Disease in Multiple Myeloma: Potential for Blood-Based Methods to Monitor Disease

In recent years, the life expectancy of Multiple Myeloma (MM) patients has substantially improved, but this cancer remains incurable with increasing incidence in the developed world. Most MM patients will eventually relapse due to residual drug-resistant cancerous cells that survive treatment, commonly referred to as minimal residual disease (MRD). Methods to improve MRD detection in MM patients are generating considerable interest as a means of monitoring patients' response to treatment. In clinical laboratories, these methods currently require bone marrow aspirates which are invasive and frequently miss detection of localised disease due to the spatial heterogeneity of disease infiltration. By simplifying serial sampling and allowing for the detection of extramedullary disease, a blood-based method could significantly impact treatment duration and intensity and minimise chemotherapy-induced toxicity. This review will describe the current blood-based techniques available to detect MRD in MM and compare their potential to evaluate patient prognosis and drive therapeutic decisions.

Prognostic value of minimal residual disease negativity in myeloma: combined analysis of POLLUX, CASTOR, ALCYONE, MAIA

We explored minimal residual disease (MRD) in relapsed/refractory multiple myeloma (RRMM) and transplant-ineligible newly diagnosed multiple myeloma (TIE NDMM) using data from four phase 3 studies (POLLUX, CASTOR, ALCYONE, and MAIA). Each study previously demonstrated that daratumumab-based therapies improved MRD-negativity rates and reduced the risk of disease progression or death by approximately half versus standards of care. We conducted a large-scale pooled analysis for associations between patients achieving complete response (CR) or better with MRD-negative status, and progression-free survival (PFS). MRD was assessed via next-generation sequencing (10‒5 threshold). Patient-level data were pooled from all four studies, and for patients with TIE NDMM plus patients with RRMM who received ≤2 prior lines of therapy (≤2PL). PFS was evaluated by response and MRD status. Median follow-up (months) was: POLLUX, 54.8; CASTOR, 50.2; ALCYONE, 40.1; and MAIA, 36.4. Patients who achieved ≥CR and MRD negativity had improved PFS versus those who failed to reach CR or were MRD positive (TIE NDMM and RRMM hazard ratio [HR] 0.20, P < .0001; TIE NDMM and RRMM ≤2PL HR 0.20, P < .0001). This benefit occurred irrespective of therapy or disease setting. A time-varying Cox proportional hazard model confirmed that ≥CR with MRD negativity was associated with improved PFS. Daratumumab-based treatment was associated with more patients reaching ≥CR and MRD negativity. These findings represent the first large-scale analysis with robust methodology to support ≥CR with MRD negativity as a prognostic factor for PFS in RRMM and TIE NDMM. These trials were registered at www.ClinicalTrials.gov: NCT02076009/NCT02136134/NCT02195479/NCT02252172.