Comparison of MALDI-TOF mass spectrometry analysis of peripheral blood and bone marrow-based flow cytometry for tracking measurable residual disease in patients with multiple myeloma.

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) may soon replace routine electrophoretic methods for monitoring monoclonal proteins in patients with multiple myeloma. To further evaluate the clinical utility of this assay, we compared the performance of MALDI-TOF-MS head-to-head with an established bone marrow-based measurable residual disease assay by flow cytometry (Flow-BM-MRD), using Memorial Sloan Kettering Cancer Center's 10-color, single-tube method. Our results suggest that MALDI-TOF-MS adds value to bone marrow-based MRD testing and may be most useful for early detection of relapse in peripheral blood compared to current electrophoretic methods.

A novel method for the laboratory workup of anaphylactic transfusion reactions in haptoglobin-deficient patients.

BACKGROUND: Patients with congenital haptoglobin deficiency can develop anti-haptoglobin antibodies after exposure to blood products, and they can suffer from life-threatening anaphylactic transfusion reactions. Here, we present a case of a 57-year-old Chinese male with myelodysplastic syndrome who manifested an anaphylactic transfusion reaction during the transfusion of platelets. The only abnormality detected during his reaction laboratory workup was an undetectable haptoglobin level in the absence of evidence of hemolysis. STUDY DESIGN AND METHODS: Surface plasmon resonance (SPR) was explored as a method to be able to detect the presence of anti-haptoglobin antibodies in serum. First, haptoglobin was immobilized to the surface of an SPR sensor chip. The patient's serum sample was injected, and the binding response was monitored in real time. Serum samples from five healthy volunteers were used as negative controls. Binding specificity was assessed in competition experiments using soluble haptoglobin. Anti-IgG, -IgA, -IgM, -IgD and -IgE antibodies were used to identify the antibody isotype. RESULTS: An IgG anti-haptoglobin antibody was detected in the patient's serum with SPR. CONCLUSION: SPR provided a rapid, readily available method for the detection of an IgG anti-haptoglobin antibody in an anhaptoglobinemic individual. This confirmed the underlying etiology of the anaphylactic nonhemolytic transfusion reaction and justified the necessity of stringently washed cellular products for all future transfusions and strong caution for future use of plasma-containing products.

Standard Antithymocyte Globulin Dosing Results in Poorer Outcomes in Overexposed Patients after Ex Vivo CD34+ Selected Allogeneic Hematopoietic Cell Transplantation.

Antithymocyte globulin (ATG) use mitigates the risk of graft rejection and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT), but ATG overexposure in the setting of lymphopenia negatively affects immune recovery. We hypothesized that standard empiric weight-based dosing of ATG, used to prevent graft rejection in ex vivo CD34-selected allo-HCT, may lead to serious adverse consequences on outcomes in certain patients. We evaluated 304 patients undergoing myeloablative-conditioned ex vivo CD34-selected allo-HCT with HLA-matched donors for the treatment of hematologic malignancies. Patients received rabbit ATG at a dose of 2.5 mg/kg/day i.v. on days -3 and/or -2. An ATG dosing cutoff of 450 mg was used for statistical analyses to assess the relationship between ATG and overall survival (OS). Among all patients, median total ATG dose was 360 mg (range, 130 to 510 mg); 279 (92%) received a total dose of ATG ≤450 mg, and 25 (8%) received a total dose >450 mg. On the first day of ATG administration (day -3), the median absolute lymphocyte count was .0 K/µL. For patients who received a total dose of ATG >450 mg or ≤450 mg, the incidences of acute and late-acute GVHD grade II-IV were statistically similar. At 3 years post-HCT, for patients who received a total dose of ATG >450 mg or ≤450 mg, nonrelapse mortality (NRM) rates were 35% and 18%, respectively (P = .029), disease-free survival (DFS) rates were 37% and 61%, respectively (P = .003), and OS rates were 40% and 67%, respectively (P = .001). Among all patient and HCT characteristics in multivariable analyses, receipt of a total dose of ATG >450 mg was associated with an increased risk of NRM (hazard ratio [HR], 2.9; P = .01), shorter DFS (HR, 2.0; P = .03), and inferior OS (HR, 2.1; P = .01). In summary, the use of weight-based ATG at a time of relative lymphopenia before ex vivo CD34-selected allo-HCT results in overdosing in heavier patients, leading to higher NRM and lower DFS and OS. Further pharmacokinetic investigation in this setting is critical to determining the optimal dosing strategy for ATG.

Prognostic significance of baseline metabolic tumor volume in relapsed and refractory Hodgkin lymphoma.

Identification of prognostic factors for patients with relapsed/refractory Hodgkin lymphoma (HL) is essential for optimizing therapy with risk-adapted approaches. In our phase 2 study of positron emission tomography (PET)-adapted salvage therapy with brentuximab vedotin (BV) and augmented ifosfamide, carboplatin, and etoposide (augICE), we assessed clinical factors, quantitative PET assessments, and cytokine and chemokine values. Transplant-eligible patients with relapsed/refractory HL received 2 (cohort 1) or 3 (cohort 2) cycles of weekly BV; PET-negative patients (Deauville score ≤2) proceeded to autologous stem cell transplantation (ASCT) whereas PET-positive patients received augICE before ASCT. Serum cytokine and chemokine levels were measured at baseline and after BV. Metabolic tumor volume (MTV) and total lesion glycolysis were measured at baseline, after BV, and after augICE. Sixty-five patients enrolled (45, cohort 1; 20, cohort 2); 49 (75%) achieved complete response and 64 proceeded to ASCT. Three-year overall survival and event-free survival (EFS) were 95% and 82%, respectively. Factors predictive for EFS by multivariable analysis were baseline MTV (bMTV) (P < .001) and refractory disease (P = .003). Low bMTV (<109.5 cm3) and relapsed disease identified a favorable group (3-year EFS, 100%). For patients who received a transplant, bMTV and pre-ASCT PET were independently prognostic; 3-year EFS for pre-ASCT PET-positive patients with low bMTV was 86%. In this phase 2 study of PET-adapted therapy with BV and augICE for relapsed/refractory HL, bMTV and refractory disease were independent prognostic factors for EFS. Furthermore, bMTV improved the predictive power of pre-ASCT PET. Future studies should optimize efficacy and tolerability of salvage therapy by stratifying patients according to risk factors such as bMTV.

Comparison of Information-Dependent Acquisition on a Tandem Quadrupole TOF vs a Triple Quadrupole Linear Ion Trap Mass Spectrometer for Broad-Spectrum Drug Screening.

BACKGROUND: Liquid chromatography high-resolution mass spectrometry (LC-HRMS) with untargeted data collection is especially attractive for general unknown drug screening owing to its ability to identify unexpected compounds. LC-HRMS offers several advantages over traditional selected reaction monitoring (SRM) techniques and could be an ideal screening platform as long as its analytical performance is comparable to that of SRM-based methods. METHODS: We developed a broad-spectrum drug screen on a high-resolution mass spectrometer [tandem quadrupole time-of-flight (QqTOF)] that collected data in an untargeted manner and compared its performance to a nominal mass instrument [triple quadrupole linear ion trap (QqLIT)] that collected data in a targeted manner. Both methods used information-dependent acquisition of product ion spectra. We evaluated the lower limits of detection and matrix effects for each method and compared their ability to identify drugs in 100 routine clinical urine samples. Additional information (patient prescription history, drug screening results, etc.) was used to confirm discordant results. RESULTS: QqLIT was slightly more analytically sensitive than QqTOF; however, this difference did not significantly affect compound identification in patient samples. QqLIT identified 596 drugs in the urine samples, of which 531 (89%) were confirmed. QqTOF identified 515 drugs, of which 500 (97%) were confirmed. There were 562 instances of a confirmed drug (68 unique drugs) in the 100 urine samples; the methods were concordant in 469 of these instances. CONCLUSIONS: Overall, QqTOF performed similarly to QqLIT and could serve as an alternative method for general unknown screening.

Isatuximab-Specific Immunofixation Electrophoresis Assay to Remove Interference in Serum M-Protein Measurement in Patients with Multiple Myeloma.

BACKGROUND: Isatuximab, an IgG-kappa (IgGκ) anti-cluster of differentiation 38 (CD38) monoclonal antibody approved for use in patients with relapsed or refractory multiple myeloma (MM), can potentially interfere with the visualization of endogenous monoclonal protein (M-protein) on standard immunofixation electrophoresis (IFE) and lead to inaccurate classification of a patient's response to therapy. The Hydrashift 2/4 isatuximab IFE assay (Hydrashift isatuximab assay) removes isatuximab interference from IFE. Using samples from patients enrolled in clinical trials of isatuximab-based therapy for MM, we demonstrate how the Hydrashift isatuximab assay improves the ability to detect residual M-protein and offer recommendations for when the assay is most useful. METHODS: Samples from 141 patients with a variety of known M-protein isotypes were selected and analyzed by standard IFE and the Hydrashift isatuximab assay. A positive control containing isatuximab was run on every standard IFE and Hydrashift gel. RESULTS: The Hydrashift isatuximab assay reliably shifted the migration of isatuximab in patient samples. Standard IFE was adequate for determining 104 patients' M-protein status, and the Hydrashift isatuximab assay confirmed these results. In samples from 37 patients with a history of IgGκ MM and a single IgGκ band visible on standard IFE near the isatuximab migration site, the Hydrashift isatuximab assay was able to separate isatuximab from endogenous M-protein, identifying residual M-protein in 17 samples and preventing false-positive interpretations of standard IFE in 20 samples. CONCLUSIONS: The Hydrashift isatuximab assay is most useful in patients with known IgGκ MM when a single IgGκ band appears near the isatuximab migration site on standard IFE during isatuximab-based therapy. CLINICALTRIALS.GOV REGISTRATION NUMBERS: NCT03275285 and NCT03319667.

Charge requirements for proton gradient-driven translocation of anthrax toxin.

Anthrax lethal toxin is used as a model system to study protein translocation. The toxin is composed of a translocase channel, called protective antigen (PA), and an enzyme, called lethal factor (LF). A proton gradient (ΔpH) can drive LF unfolding and translocation through PA channels; however, the mechanism of ΔpH-mediated force generation, substrate unfolding, and establishment of directionality are poorly understood. One recent hypothesis suggests that the ΔpH may act through changes in the protonation state of residues in the substrate. Here we report the charge requirements of LF's amino-terminal binding domain (LF(N)) using planar lipid bilayer electrophysiology. We found that acidic residues are required in LF(N) to utilize a proton gradient for translocation. Constructs lacking negative charges in the unstructured presequence of LF(N) translocate independently of the ΔpH driving force. Acidic residues markedly increase the rate of ΔpH-driven translocation, and the presequence is optimized in its natural acidic residue content for efficient ΔpH-driven unfolding and translocation. We discuss a ΔpH-driven charge state Brownian ratchet mechanism for translocation, where glutamic and aspartic acid residues in the substrate are the "molecular teeth" of the ratchet. Our Brownian ratchet model includes a mechanism for unfolding and a novel role for positive charges, which we propose chaperone negative charges through the PA channel during ΔpH translocation.

The unfolding story of anthrax toxin translocation.

The essential cellular functions of secretion and protein degradation require a molecular machine to unfold and translocate proteins either across a membrane or into a proteolytic complex. Protein translocation is also critical for microbial pathogenesis, namely bacteria can use translocase channels to deliver toxic proteins into a target cell. Anthrax toxin (Atx), a key virulence factor secreted by Bacillus anthracis, provides a robust biophysical model to characterize transmembrane protein translocation. Atx is comprised of three proteins: the translocase component, protective antigen (PA) and two enzyme components, lethal factor (LF) and oedema factor (OF). Atx forms an active holotoxin complex containing a ring-shaped PA oligomer bound to multiple copies of LF and OF. These complexes are endocytosed into mammalian host cells, where PA forms a protein-conducting translocase channel. The proton motive force unfolds and translocates LF and OF through the channel. Recent structure and function studies have shown that LF unfolds during translocation in a force-dependent manner via a series of metastable intermediates. Polypeptide-binding clamps located throughout the PA channel catalyse substrate unfolding and translocation by stabilizing unfolding intermediates through the formation of a series of interactions with various chemical groups and α-helical structure presented by the unfolding polypeptide during translocation.

Lethal factor unfolding is the most force-dependent step of anthrax toxin translocation.

Cellular compartmentalization requires machinery capable of translocating polypeptides across membranes. In many cases, transported proteins must first be unfolded by means of the proton motive force and/or ATP hydrolysis. Anthrax toxin, which is composed of a channel-forming protein and two substrate proteins, is an attractive model system to study translocation-coupled unfolding, because the applied driving force can be externally controlled and translocation can be monitored directly by using electrophysiology. By controlling the driving force and introducing destabilizing point mutations in the substrate, we identified the barriers in the transport pathway, determined which barrier corresponds to protein unfolding, and mapped how the substrate protein unfolds during translocation. In contrast to previous studies, we find that the protein's structure next to the signal tag is not rate-limiting to unfolding. Instead, a more extensive part of the structure, the amino-terminal beta-sheet subdomain, must disassemble to cross the unfolding barrier. We also find that unfolding is catalyzed by the channel's phenylalanine-clamp active site. We propose a broad molecular mechanism for translocation-coupled unfolding, which is applicable to both soluble and membrane-embedded unfolding machines.

Myeloma precursor disease (MGUS) among rescue and recovery workers exposed to the World Trade Center disaster.

An elevated risk of myeloma precursor disease, monoclonal gammopathy of undetermined significance (MGUS), was identified among Fire Department of the City of New York (FDNY) World Trade Center (WTC)-exposed firefighters. Further investigation was needed to determine if these findings were reproducible in a more heterogeneous WTC-exposed rescue/recovery workers cohort, the Stony Brook University-General Responder Cohort GRC (SBU-GRC). MGUS risk was compared between the cohorts and to published general population estimates from Olmsted County, MN, USA. In this observational seroprevalence study, odds ratios (OR) and age-standardized risk ratios (RR) of MGUS (M-spike and light-chain-MGUS combined), M-spike, and light-chain-MGUS were estimated using logistic regression. Age-standardized prevalences were calculated for white males aged 50-79; RRs were estimated by comparing risk in the WTC-exposed cohort with the Olmsted County screened cohort. SBU-GRC had elevated odds of MGUS compared with FDNY (OR = 1.38; 95%CI = 1.00-1.89). The age-standardized prevalence of MGUS was 9.0/100 persons (95%CI = 7.5-10.6), over two-fold higher than the general population (RR = 2.08; 95%CI = 1.72-2.51); the age-standardized prevalence of light-chain-MGUS was 3.5-fold higher (RR = 3.54; 95%CI = 2.52-4.97). This study adds to mounting evidence supporting an association between WTC/environmental exposures and MGUS among rescue/recovery workers. Access to MGUS screenings for the entire WTC-exposed cohort could allow for treatment interventions that improve survival.

Use of a Daratumumab-Specific Immunofixation Assay to Assess Possible Immunotherapy Interference at a Major Cancer Center: Our Experience and Recommendations.

BACKGROUND: The incorporation of monoclonal antibodies, such as daratumumab, into multiple myeloma treatment regimens has led to the issue of false-positive interference in both serum protein electrophoresis (SPEP) and immunofixation (IF). The Hydrashift assay removes daratumumab interference from IF, allowing for correct interpretation. Here, we retrospectively examined the use of the Hydrashift assay at a large cancer center and provide guidelines on its most appropriate use. METHODS: 38 patients with distinct daratumumab peaks on their SPEP were selected and were used to quantify the daratumumab peak on SPEP using the Sebia Phoresis software. A retrospective review of all Hydrashift assays ordered at our institution from July 2018 to March 2020 was performed. Data collected included patient clone type, IF migration patterns, and Hydrashift result. Serial quantification of SPEP results was performed as the corresponding IF transitioned from a true positive to a false positive. RESULTS: Daratumumab adds a maximum magnitude of 0.20 g/dL on SPEP. Serial SPEP quantification showed IF transitioned from true positive to false positive when M-spikes ranged from 0.09 g/dL to 0.11 g/dL. Over 20 months, our laboratory performed 280 Hydrashift assays on 96 patients, 43/96 of whom had comigrating daratumumab/IgG-K IF bands. CONCLUSIONS: The Hydrashift assay is typically unnecessary in patients with large M-spikes, >0.25 g/dL, regardless of clone type. When patient history is available, we recommend the Hydrashift assay be used in patients with comigrating daratumumab/IgG-K bands with M-spikes of <0.25 g/dL.

Immunotyping Provides Equivalent Results to Immunofixation in a Population with a High Prevalence of Monoclonal Gammopathies.

BACKGROUND: Serum immunofixation (IF) is a common laboratory test used to diagnose and monitor patients with monoclonal gammopathies. Similarly, immunotyping (IT) by capillary electrophoresis can confirm the presence of a monoclonal protein (M-protein) and determine its isotype. The goal of this study was to compare the ability of IT and IF to detect M-proteins. METHODS: IT and IF results for 1000 waste clinical serum samples were obtained. All results were interpreted blindly by reviewers who were experienced in each technique. Results were compared by band. Results were also compared to patient history to determine if the original clone was present. We determined the sensitivity of IT and IF alone and in combination with additional tests. Finally, we evaluated the impact of reviewer training on the sensitivity of IT. RESULTS: IT and IF were concordant in 721/773 (93%) samples with a history of an intact M-protein and in 143/172 (83%) samples with a history of a free light chain (FLC) M-protein. IF was significantly more sensitive than IT for the detection of FLC M-proteins (P < 0.0001). However, IF was not more sensitive than IT for detection of intact M-proteins (P = 0.1272) or when each test was combined with the FLC ratio or urine immunofixation (P = 0.2812 and P = 0.6171, respectively). Finally, after training, inexperienced reviewers improved their IT sensitivity by 19%. CONCLUSION: IT provides equivalent results to IF for the detection of monoclonal proteins. Training and experience are critical to the accurate interpretation of IT.

Minimal residual disease in multiple myeloma: defining the role of next generation sequencing and flow cytometry in routine diagnostic use.

For patients diagnosed with multiple myeloma (MM) there have been significant treatment advances over the past decade, reflected in an increasing proportion of patients achieving durable remissions. Clinical trials repeatedly demonstrate that achieving a deep response to therapy, with a bone marrow assessment proving negative for minimal residual disease (MRD), confers a significant survival advantage. To accurately assess for minute quantities of residual cancer requires highly sensitive methods; either multiparameter flow cytometry or next generation sequencing are currently recommended for MM response assessment. Under optimal conditions, these methods can detect one aberrant cell amongst 1,000,000 normal cells (a sensitivity of 10-6). Here, we will review the practical use of MRD assays in MM, including challenges in implementation for the routine diagnostic laboratory, standardisation across laboratories and clinical trials, the clinical integration of MRD status assessment into MM management and future directions for ongoing research.

Defining the undetectable: The current landscape of minimal residual disease assessment in multiple myeloma and goals for future clarity.

Multiple Myeloma, the second most prevalent hematologic malignancy, yet lacks an established curative therapy. However, overall response rate to modern four-drug regimens approaches 100%. Major efforts have thus focused on the measurement of minute quantities of residual disease (minimal residual disease or MRD) for prognostic metrics and therapeutic response evaluation. Currently, MRD is assessed by flow cytometry or by next generation sequencing to track tumor-specific immunoglobulin V(D)J rearrangements. These bone marrow-based methods can reach sensitivity thresholds of the identification of one neoplastic cell in 1,000,000 (10-6). New technologies are being developed to be used alone or in conjunction with established methods, including peripheral blood-based assays, mass spectrometry, and targeted imaging. Data is also building for MRD as a surrogate endpoint for overall survival. Here, we will address the currently utilized MRD assays, challenges in validation across labs and clinical trials, techniques in development, and future directions for successful clinical application of MRD in multiple myeloma.

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 IgGκ monoclonal antibody, interferes with electrophoretic techniques making it difficult to reliably define residual disease versus CR, especially in patients with IgGκ 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 MALDI-TOF 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.

Lifetime Pesticide Use and Monoclonal Gammopathy of Undetermined Significance in a Prospective Cohort of Male Farmers.

BACKGROUND: Farmers have a higher incidence of multiple myeloma, and there is suggestive evidence of an elevated prevalence of its precursor, monoclonal gammopathy of undetermined significance (MGUS), relative to the general population. Pesticide exposures are suspected to play a role; however, the biologic plausibility for associations with multiple myeloma remains unclear. OBJECTIVES: Our objectives were to examine the prevalence of MGUS and evaluate associations with a wide range of pesticides in a large sample of farmers. METHODS: We obtained sera and assessed MGUS among 1,638 male farmers ≥50 years of age in the Agricultural Health Study (AHS), a prospective cohort in Iowa and North Carolina. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed to estimate associations with MGUS for recent use (within the 12 months before phlebotomy) and cumulative intensity-weighted lifetime days of use of specific pesticides. RESULTS: The age-standardized MGUS prevalence was significantly elevated among AHS farmers (7.7%) compared with demographically similar men in the National Health and Nutrition Examination Survey (2.8%) or Olmsted County, Minnesota (3.8%; p<0.001). Recent use of permethrin was associated with MGUS [recent use vs. no recent use, OR=1.82 (95% CI: 1.06, 3.13)], especially among those who had also used it in the past [recent and past use vs. never use, OR=2.49 (95% CI: 1.32, 4.69)]. High intensity-weighted lifetime use of the organochlorine insecticides aldrin and dieldrin was associated with MGUS relative to those who never used either of these pesticides [OR=2.42 (95% CI: 1.29, 4.54); ptrend=0.006]. We also observed a positive association with high lifetime use of petroleum oil/distillates as an herbicide, as well as an inverse association with fonofos use. DISCUSSION: This is the largest investigation of MGUS in farmers and the first to identify an association with MGUS for permethrin, a pyrethroid insecticide previously associated with multiple myeloma. Given the continued widespread use of permethrin in various residential and commercial settings, our findings may have important implications for exposed individuals in the general population. https://doi.org/10.1289/EHP6960.

Dynamics of minimal residual disease in patients with multiple myeloma on continuous lenalidomide maintenance: a single-arm, single-centre, phase 2 trial.

Background Lenalidomide maintenance improves progression-free survival for patients with multiple myeloma, although its optimal duration is unknown. Clearance of minimal residual disease (MRD) in the bone marrow results in superior outcomes, although its attainment or sustainment does not alter clinical decision-making. Studies that have evaluated MRD serially are limited in length. We therefore aimed to evaluate longitudinal changes in MRD-status (dynamics) and their association with progression-free survival in patients with multiple myeloma. METHODS: In this single-centre, single-arm, phase 2 study, we enrolled patients aged 18 years and older from the Memorial Sloan Kettering Cancer Center (New York, NY, USA) who had newly diagnosed multiple myeloma following unrestricted frontline therapy and an Eastern Cooperative Oncology Group Performance Status of 2 or lower, including patients who started maintenance before study enrolment. All participants received lenalidomide maintenance at 10 mg for 21 days of 28-day cycles until progression or unacceptable toxic effects for up to 5 years on protocol. The primary endpoint was progression-free survival at 60 months per protocol and key secondary endpoints were MRD rates after completion of the 12th, 24th, and 36th cycle of maintenance and the association between progression-free survival and annual measurement of MRD status. MRD was assessed from first-pull bone marrow aspirates at baseline and annually by flow cytometry per International Myeloma Working Group criteria, (limit of detection of at least 1 × 10-5) up to a maximum of 5 years. Patients who completed at least four cycles of treatment were included in the analysis of the primary endpoint, and patients who had completed at least one dose of treatment on protocol were assessable for secondary endpoints. The study was registered at ClinicalTrials.gov, NCT02538198, and is now closed to accrual. FINDINGS: Between Sept 8, 2015, and Jan 25, 2019, 108 patients (100 evaluable for the primary endpoint) were enrolled. Median follow-up was 40·7 months (95% CI 38·7-45·0). At 60 months, progression-free survival was 64% (95% CI 52-79). Median progression-free survival was unreached (95% CI unreached-unreached). MRD dynamics were assessed using 340 MRD assessments done over 5 years for 103 evaluable patients. Patients who sustained MRD negativity for 2 years (n=34) had no recorded disease progression at median 19·8 months (95% CI 15·8-22·3) past the 2-year maintenance landmark. By contrast, patients who lost their MRD-negative responses (n=10) were more likely to progress than those with sustained MRD negativity (HR infinite; p<0·0001) and those with persistent MRD positivity (HR 5·88, 95% CI 1·18-33·33; p=0·015) at the 2-year landmark. Haematological and non-haematological serious adverse events occurred in 19 patients (18%). The most common adverse events of grade 3 or worse were decreased lymphocyte count in 48 (44%) patients and decreased neutrophil count in 47 (44%) patients. One death occurred on study due to sepsis and heart failure and was considered unrelated to the study drug. INTERPRETATION: Serial measurements of MRD allow for dynamic assessment of risk for disease progression. Early intervention should be investigated for patients with loss of MRD negativity. Sustained MRD positivity is not categorically an unfavourable outcome and might portend prolonged stability of low-level disease. FUNDING: Memorial Sloan Kettering and Celgene.

Safety and Effectiveness of Weekly Carfilzomib, Lenalidomide, Dexamethasone, and Daratumumab Combination Therapy for Patients With Newly Diagnosed Multiple Myeloma: The MANHATTAN Nonrandomized Clinical Trial.

IMPORTANCE: Recently, the benefit of adding daratumumab to the proteasome inhibitor-based, 3-drug combination of bortezomib, lenalidomide, and dexamethasone for patients with newly diagnosed multiple myeloma who underwent high-dose melphalan chemotherapy and autologous hemopoietic cell transplant was assessed. Here, we examine the addition of daratumumab to the second-generation proteasome inhibitor-based, 3-drug combination of carfilzomib, lenalidomide, and dexamethasone. OBJECTIVE: To assess the safety and effectiveness of carfilzomib-lenalidomide-dexamethasone-daratumumab combination therapy for patients with newly diagnosed multiple myeloma, in the absence of high-dose melphalan chemotherapy and autologous hemopoietic cell transplant. DESIGN, SETTING, AND PARTICIPANTS: Clinical and correlative pilot study at the Memorial Sloan Kettering Cancer Center in New York, New York. Patients with newly diagnosed multiple myeloma were enrolled between October 1, 2018, and November 15, 2019. The median follow-up from start of treatment was 20.3 months (95% CI, 19.2-21.9 months). INTERVENTIONS: Eight 28-day cycles with intravenous carfilzomib, 20/56 mg/m2 (days 1, 8, and 15); oral lenalidomide, 25 mg, (days 1-21); dexamethasone, 40 mg weekly, orally or intravenously (cycles 1-4), and 20 mg after cycle 4; and intravenous daratumumab, 16 mg/kg (days 1, 8, 15, and 22 [cycles 1-2]; days 1 and 15 [cycles 3-6]; and day 1 [cycles 7 and 8]). MAIN OUTCOMES AND MEASURES: The primary end point was the minimal residual disease (MRD) rate, in the absence of high-dose melphalan chemotherapy and autologous hemopoietic cell transplant. Secondary end points included determining safety and tolerability, evaluating rates of clinical response per the International Myeloma Working Group, and estimating progression-free survival (PFS) and overall survival (OS) rates. RESULTS: Forty-one evaluable patients were enrolled (median age, 59 years; range, 30-70 years); 25 (61%) were female, and 20 (49%) had high-risk multiple myeloma. The primary end point (MRD negativity in the bone marrow; 10-5 sensitivity) was achieved in 29 of 41 patients (71%; 95% CI, 54%-83%), and therefore the trial was deemed successful. Median time to MRD negativity was 6 cycles (range, 1-8 cycles). Secondary end points of the overall response rate and the very good partial response or complete response rate were 100% (41 of 41 patients) and 95% (39 of 41 patients), respectively. At 11 months of the median follow-up, the 1-year PFS rate and the OS rate were 98% (95% CI, 93%-100%) and 100%, respectively. Most common (≥2 patients) grade 3 or 4 adverse events were neutropenia (12 patients [27%]), rash (4 patients [9%]), lung infection (3 patients [7%]), and increased alanine aminotransferase level (2 patients [4%]). There were no deaths. CONCLUSIONS AND RELEVANCE: In this nonrandomized clinical trial, carfilzomib-lenalidomide-dexamethasone-daratumumab combination therapy was associated with high rates of MRD negativity in patients with newly diagnosed multiple myeloma and high rates of PFS.

Minimal Residual Disease in Myeloma: Application for Clinical Care and New Drug Registration.

The development of novel agents has transformed the treatment paradigm for multiple myeloma, with minimal residual disease (MRD) negativity now achievable across the entire disease spectrum. Bone marrow-based technologies to assess MRD, including approaches using next-generation flow and next-generation sequencing, have provided real-time clinical tools for the sensitive detection and monitoring of MRD in patients with multiple myeloma. Complementary liquid biopsy-based assays are now quickly progressing with some, such as mass spectrometry methods, being very close to clinical use, while others utilizing nucleic acid-based technologies are still developing and will prove important to further our understanding of the biology of MRD. On the regulatory front, multiple retrospective individual patient and clinical trial level meta-analyses have already shown and will continue to assess the potential of MRD as a surrogate for patient outcome. Given all this progress, it is not surprising that a number of clinicians are now considering using MRD to inform real-world clinical care of patients across the spectrum from smoldering myeloma to relapsed refractory multiple myeloma, with each disease setting presenting key challenges and questions that will need to be addressed through clinical trials. The pace of advances in targeted and immune therapies in multiple myeloma is unprecedented, and novel MRD-driven biomarker strategies are essential to accelerate innovative clinical trials leading to regulatory approval of novel treatments and continued improvement in patient outcomes.

Tracking of low disease burden in multiple myeloma: Using mass spectrometry assays in peripheral blood.

Efforts over the last 5 years have demonstrated that it is technically feasible to detect low levels of monoclonal proteins in peripheral blood using mass spectrometry. These methods are based on the fact that an M-protein has a specific amino acid sequence, and therefore, a specific mass. This mass can be tracked over time and can serve as a surrogate marker of the presence of clonal plasma cells. This review describes the use of mass spectrometry to detect M-proteins in multiple myeloma to date, identifies the challenges of using this biomarker, and describes potential strategies to overcome these challenges. We discuss the work that must be done for these techniques to be incorporated into clinical practice for tracking of low disease burden in multiple myeloma.