Antigen escape as a shared mechanism of resistance to BCMA-directed therapies in multiple myeloma.

B-cell maturation antigen (BCMA)-targeting therapeutics have dramatically improved outcomes in relapsed/refractory multiple myeloma (RRMM). However, whether the mechanisms of resistance between these therapies are shared and how the identification of such mechanisms before therapy initiation could refine clinical decision-making remains undefined. We analyzed outcomes for 72 RRMM patients treated with teclistamab, a CD3 x BCMA bispecific antibody (BsAb), 42% (30/72) of whom had prior BCMA-directed therapy exposure. Malignant plasma cell BCMA expression was present in all BCMA therapy-naïve patients. Prior therapy-mediated loss of plasma cell BCMA expression before teclistamab treatment, measured by immunohistochemistry, was observed in 3 patients, none of whom responded to teclistamab, and one of whom also did not respond to ciltacabtagene autoleucel. Whole exome sequencing of tumor DNA from one patient revealed biallelic loss of TNFRSF17 following treatment with belantamab mafodotin. Low-to-undetectable peripheral blood soluble BCMA levels correlated with the absence of BCMA expression by bone marrow plasma cells. Thus, although rare, loss of BCMA expression following TNFRSF17 gene deletions can occur following any BCMA-directed therapy and prevents response to subsequent anti-BCMA-directed treatments, underscoring the importance of verifying the presence of a target antigen.

CD8 effector T cells enhance teclistamab response in BCMA-exposed and -naïve multiple myeloma.

ABSTRACT: Teclistamab, a B-cell maturation antigen (BCMA)- and CD3-targeting bispecific antibody, is an effective novel treatment for relapsed/refractory multiple myeloma (R/RMM), but efficacy in patients exposed to BCMA-directed therapies and mechanisms of resistance have yet to be fully delineated. We conducted a real-world retrospective study of commercial teclistamab, capturing both clinical outcomes and immune correlates of treatment response in a cohort of patients (n = 52) with advanced R/RMM. Teclistamab was highly effective with an overall response rate (ORR) of 64%, including an ORR of 50% for patients with prior anti-BCMA therapy. Pretreatment plasma cell BCMA expression levels had no bearing on response. However, comprehensive pretreatment immune profiling identified that effector CD8+ T-cell populations were associated with response to therapy and a regulatory T-cell population associated with nonresponse, indicating a contribution of immune status in outcomes with potential utility as a biomarker signature to guide patient management.

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.

Complex biological patterns of soluble cytokines and CD163 in childhood necessitating age-specific reference intervals for evidence-based clinical interpretation.

BACKGROUND: Cytokine measurements to support clinical laboratory and research investigations have become increasingly common in pediatrics. However, there is a paucity of accurate pediatric reference intervals (RIs) essential to the interpretation of cytokine results. To address this gap, here, we establish age- and sex-specific pediatric reference values for clinically relevant inflammatory markers including CD163, and the cytokines IL-1ß, IL-6, IL-10, IL-18, TNF-α, IFN-γ, and CXCL-9. METHODS: Healthy children and adolescents (n = 311, 1-19 years) were recruited as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) study. Multi-analyte measurements in plasma and analytical performance verification were conducted on the ProteinSimple® Ella™ automated immunoassay platform (Bio-Techne, MN, USA). Age- and sex-specific RIs were calculated based on Clinical and Laboratory Standards Institute guidelines. Additionally, 75th and 95th percentile cut-offs were determined. RESULTS: Three types of reference value distributions were observed: (a) consistent levels throughout age and sex: IL-6, and IFN-γ, (b) gradual decline in concentration with age: CD163, TNF-α, CXCL-9, and IL-10, (c) significantly higher concentrations during ages 4-14 years than earlier and later ages: IL-1ß and IL-18. Reference values for CXCL-9, IL-10, and TNF-α under 8 years of age differed significantly from older children. CD163, IL-18 and IL-1ß required three age partitions. CD163 demonstrated significant sex differences in ages 8-13 years. CONCLUSION: The circulating profile of cytokines in children is complex and can vary by age and sex. This necessitates careful interpretation of test results based on age and/or sex specific RIs facilitating more accurate clinical decision making.

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.

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.

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.

Pesticide use and kidney function among farmers in the Biomarkers of Exposure and Effect in Agriculture study.

BACKGROUND: Pesticides have been reported to be associated with malignant and non-malignant kidney disease. Few studies have examined the relationship between individual pesticides and kidney dysfunction. OBJECTIVE: We evaluated the associations of pesticide use with measured kidney function among male pesticide applicators in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study, a subcohort in the Agricultural Health Study. METHODS: Serum creatinine was measured in 1545 BEEA participants and estimated glomerular filtration rate (eGFR) was calculated with the chronic kidney disease epidemiology collaboration (CKD-EPI) equation. Using reported information on lifetime use of 41 pesticides, multivariable linear and logistic regression was used to examine associations with eGFR modeled continuously and with CKD (eGFR <60 mL/min/1.73 m2), respectively. Models were adjusted for possible confounding factors related to kidney function and correlated pesticides. RESULTS: Lower eGFR was observed among pesticide applicators who ever used the herbicides pendimethalin (-3.7%, 95% confidence interval (CI): 5.8%, -1.5%), atrazine (-3.7%, 95% CI: 6.9%, -0.4%), and dicamba (-2.8%, 95% CI: 5.3%, -0.2%) compared with never users of each pesticide. Ever use of pendimethalin (odds ratio (OR)=1.6, 95% CI: 1.1, 2.2) and atrazine (OR=1.8, 95% CI: 1.0, 3.0) was also associated with elevated odds of CKD, with an exposure-response association between intensity-weighted lifetime days of pendimethalin use and CKD among active farmers (N=1302; ptrend=0.04). Atrazine use within the last year was associated with lower eGFR and elevated odds of CKD when compared with never users, and we observed exposure-response associations with intensity-weighted lifetime days among recent users. Use of several other pesticides was associated with higher eGFR. DISCUSSION: These results suggest that two widely used herbicides, pendimethalin and atrazine, may be associated with altered kidney function among pesticide applicators. Our findings for these herbicides are consistent with observed associations with end-stage renal disease in the Agricultural Health Study.

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.

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.

Identification of gamma heavy chain disease using MALDI-TOF mass spectrometry.

We describe the use of MALDI-TOF mass spectrometry in the analysis of a suspected case of gamma heavy chain disease. The patient had an abnormal serum immunofixation result where a monoclonal gamma heavy chain band was present without a corresponding light chain. Analysis by MALDI-TOF mass spectrometry revealed large peaks in the spectrum following IgG-specific purification. The m/z values of the peaks were outside the expected range for normal heavy chains or light chains. Corresponding peaks were not present in mass spectra of the kappa- or lambda-specific purifications. MALDI-TOF MS confirmed the presence of a truncated heavy chain without associated light chains. This case report demonstrates the value of mass spectrometry in interpreting challenging cases such as the identification of heavy chain disease.

Association of Immune Marker Changes With Progression of Monoclonal Gammopathy of Undetermined Significance to Multiple Myeloma.

IMPORTANCE: Multiple myeloma is consistently preceded by monoclonal gammopathy of undetermined significance (MGUS). Risk models that estimate the risk of progression from MGUS to multiple myeloma use data from a single time point, usually the initial workup. OBJECTIVE: To longitudinally investigate the alterations of serum immune markers with stable vs progressive MGUS. DESIGN, SETTING, AND PARTICIPANTS: This prospective cross-sectional cohort study included 77 469 adult participants aged 55 to 74 years in the screening arm of the National Cancer Institute Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial who had a diagnosis of progressing MGUS (n = 187) or stable MGUS (n = 498), including light-chain subtype, from November 1993, through December 2011. For each participant, all available serially stored prediagnostic serum samples (N = 3266) were obtained. Data analysis was performed from April 2018, to December 2018. MAIN OUTCOMES AND MEASURES: Serum protein and monoclonal immunoglobulin levels, serum free light chains, and serum light chains within each immunoglobulin class were measured. RESULTS: Of 685 individuals included in the study, 461 (67.3%) were men; the mean (SD) age was 69.1 (5.6) years. In cross-sectional modeling, risk factors associated with progressive MGUS were IgA isotype (adjusted odds ratio [OR], 1.80; 95% CI, 1.03-3.13; P = .04), 15 g/L or more monoclonal spike (adjusted OR, 23.5; 95% CI, 8.9-61.9; P < .001), skewed (<0.1 or >10) serum free light chains ratio (adjusted OR, 46.4; 95% CI, 18.4-117.0; P < .001), and severe immunoparesis (≥2 suppressed uninvolved immunoglobulins) (adjusted OR, 19.1; 95% Cl, 7.5-48.3; P < .001). Risk factors associated with progressive light-chain MGUS were skewed serum free light chains ratio (adjusted OR, 44.0; 95% CI, 14.2-136.3; P < .001) and severe immunoparesis (adjusted OR, 48.6; 95% CI, 9.5-248.2; P < .001). In longitudinal analysis of participants with serial samples prior to progression, 23 of 43 participants (53%) had high-risk MGUS before progression; 16 of these 23 (70%) experienced conversion from low-risk or intermediate-risk MGUS within 5 years. Similar results were found for light-chain MGUS. CONCLUSIONS AND RELEVANCE: The findings of evolving risk patterns support annual blood testing and risk assessment for patients with MGUS or light-chain MGUS.

Donor-specific Antibodies, Immunoglobulin-free Light Chains, and BAFF Levels in Relation to Risk of Late-onset PTLD in Liver Recipients.

BACKGROUND: Posttransplant lymphoproliferative disorder (PTLD) is a neoplastic complication of transplantation, with early cases largely due to immunosuppression and primary Epstein-Barr virus infection. Etiology may differ for later-onset cases, but the contributions of immunosuppression, immune reactivity to the donor organ, and chronic B cell activation are uncertain. METHODS: We conducted a case-control study of late-onset PTLD (diagnosed >1 year posttransplant) in a cohort of liver recipients. We assessed serum samples (obtained >6 months before diagnosis in cases) from N = 60 cases and N = 166 matched controls for donor-specific antibodies (DSAs, evaluable for N = 221 subjects), immunoglobulin kappa and lambda free light chains (FLCs, N = 137), and B cell activating factor (BAFF, N = 226). Conditional or unconditional logistic regression was used to calculate adjusted odds ratios (aORs). RESULTS: Circulating DSAs were less common in PTLD cases than controls (18% vs 30%), although this difference was borderline significant (aOR, 0.51; 95% confidence interval [CI], 0.24-1.10; P = 0.09). Donor-specific antibodies against class II HLA antigens predominated and likewise showed a borderline inverse association with PTLD (aOR, 0.58; 95% CI, 0.27-1.24). The FLC levels were less frequently abnormal in cases than controls, but measurements were available for only a subset and confidence intervals were wide (elevated kappa: aOR, 0.57; 95% CI, 0.15-2.12; P = 0.40; elevated lambda: aOR, 0.68; 95% CI, 0.30-1.50; P = 0.34). B cell-activating factor levels were not associated with PTLD. CONCLUSIONS: Our results suggest that circulating DSAs are associated with decreased risk of late-onset PTLD. Because DSAs may develop in the setting of underimmunosuppression, the inverse association with DSAs supports a role for immunosuppression in the etiology of late-onset PTLD.

Data from the analytical performance of the Abaxis Piccolo Xpress point of care analyzer in whole blood, serum, and plasma.

The objective of this study was to examine the analytical performance of 14 comprehensive metabolic panel analytes on the Abaxis Piccolo Xpress® Point of Care analyzer in serum, plasma, and whole blood. A method comparison was performed on all three specimen types intended for use on the Piccolo Xpress®: serum, heparinized plasma, and whole blood. This data is also presented in Murata et al. (2015) [1]. This article includes the actual Bland-Altman bias plots of the difference in results obtained for analytes in the comprehensive metabolic panel from the Abaxis Piccolo Xpress and the comparison instrument, the Ortho Vitros.

Treatment of multiple myeloma with monoclonal antibodies and the dilemma of false positive M-spikes in peripheral blood.

OBJECTIVES: To characterize the effect of three humanized IgG κ monoclonal antibodies (daratumumab, isatuximab, and elotuzumab) on the interpretation of results generated by protein electrophoresis, immunofixation, free light chain, and heavy/light chain assays performed on human serum. METHODS: Healthy volunteer serum and serum from multiple myeloma patients were supplemented with clinically relevant concentrations of each of the three monoclonal antibodies. These specimens then underwent analysis via serum protein electrophoresis, immunofixation, serum free light chain quantification, heavy/light chain quantification, total IgG, and total protein. In addition, serum specimens from patients who had undergone treatment with elotuzumab for multiple myeloma underwent similar analysis. RESULTS: Addition of the study drugs to serum from both the healthy donor as well as multiple myeloma patients resulted in a visible and quantifiable M-protein on SPEP and a visible IgGκ band by IFE. Increases were also noted in total IgG, IgGκ, and IgGκ/IgGλ-ratios. Analysis of serum from multiple myeloma patients receiving study drug showed similar findings with an additional IgGκ band and quantifiable M-protein with similar migration patterns in specimens drawn after administration. CONCLUSION: The treatment of multiple myeloma patients with monoclonal antibodies results in a visible and quantifiable M-protein that has the potential to falsely indicate poor response to therapy.

The Case for Laboratory Developed Procedures: Quality and Positive Impact on Patient Care.

An explosion of knowledge and technology is revolutionizing medicine and patient care. Novel testing must be brought to the clinic with safety and accuracy, but also in a timely and cost-effective manner, so that patients can benefit and laboratories can offer testing consistent with current guidelines. Under the oversight provided by the Clinical Laboratory Improvement Amendments, laboratories have been able to develop and optimize laboratory procedures for use in-house. Quality improvement programs, interlaboratory comparisons, and the ability of laboratories to adjust assays as needed to improve results, utilize new sample types, or incorporate new mutations, information, or technologies are positive aspects of Clinical Laboratory Improvement Amendments oversight of laboratory-developed procedures. Laboratories have a long history of successful service to patients operating under Clinical Laboratory Improvement Amendments. A series of detailed clinical examples illustrating the quality and positive impact of laboratory-developed procedures on patient care is provided. These examples also demonstrate how Clinical Laboratory Improvement Amendments oversight ensures accurate, reliable, and reproducible testing in clinical laboratories.

Generation of a novel, multi-stage, progressive, and transplantable model of plasma cell neoplasms.

Multiple myeloma is a plasma cell neoplasm with an extremely variable clinical course. Animal models are needed to better understand its pathophysiology and for preclinical testing of potential therapeutic agents. Hematopoietic cells expressing the hypermorphic Rad50(s) allele show hematopoietic failure, which can be mitigated by the lack of a transcription factor, Mef/Elf4. However, we find that 70% of Mef(-/-)Rad50(s/s) mice die from multiple myeloma or other plasma cell neoplasms. These mice initially show an abnormal plasma cell proliferation and monoclonal protein production, and then develop anemia and a decreased bone mineral density. Tumor cells can be serially transplanted and according to array CGH and whole exome sequencing, the pathogenesis of plasma cell neoplasms in these mice is not linked to activation of a specific oncogene, or inactivation of a specific tumor suppressor. This model recapitulates the systemic manifestations of human plasma cell neoplasms, and implicates cooperativity between the Rad50(s) and Mef/Elf4 pathways in initiating myelomagenic mutations that promote plasma cell transformation.

Development of an Assay for Methotrexate and Its Metabolites 7-Hydroxy Methotrexate and DAMPA in Serum by LC-MS/MS.

Methotrexate (MTX) is a folic acid antagonist that is widely used as an immunosuppressant and chemotherapeutic agent. After high-dose administration of MTX serum levels must be monitored to determine when to administer leucovorin, a folic acid analog that bypasses the enzyme inhibition caused by MTX and reverses its toxicity. We describe a rapid and simple turbulent flow liquid chromatography (TFLC) method implementing positive heated electrospray ionization (HESI) for the accurate and precise determination of MTX, 7-hydroxymethotrexate (7-OH MTX), and 4-amino-4-deoxy-N(10)-methylpteroic acid (DAMPA) concentrations in serum. MTX is isolated from serum samples (100 µL) after protein precipitation with a methanolic solution containing internal standard (MTX-D3) followed by centrifugation. The supernatant is injected into the turbulent flow liquid chromatography which is followed by electrospray positive ionization tandem mass spectrometry (TFLC-ESI-MS/MS) and quantified using a six-point calibration curve. For MTX, 7-OH MTX, and DAMPA the assays were linear from 20 to 1000 nmol/L. Dilutions of 10-, 100-, and 1000-fold were validated giving a clinically reportable range of 20 to 1.0 × 10(6) nmol/L. Within-day and between-day precisions at concentrations spanning the analytical measurement ranges were less than 10 % for all three analytes.

Development and validation of a turbulent flow chromatography and tandem mass spectrometry method for the quantitation of methotrexate and its metabolites 7-hydroxy methotrexate and DAMPA in serum.

A rapid and simple turbulent flow liquid chromatography (TFC-LC) method implementing positive heated electrospray ionization (HESI) for the accurate and precise determination of methotrexate (MTX), 7-hydroxy methotrexate (7-OH MTX), and 4-amino-4-deoxy-N(10)-methylpteroic acid (DAMPA) concentrations in serum was developed. MTX was isolated from serum samples (100µL) after protein precipitation with methanol containing formic acid and internal standard (MTX-D3) followed by centrifugation. The supernatant was injected into the turbulent flow liquid chromatography which is followed by electrospray positive ionization tandem mass spectrometry (TFC-LC-MS/MS) and quantified using a six-point calibration curve. For MTX and DAMPA the assays were linear from 10 to 1000nmol/L and for 7-OH MTX from 20 to 2000nmol/L. Dilutions of 10, 100 and 1000-fold were validated giving a clinically reportable range of 10nmol/L to 5×10(5)nmol/L. Within-day and between-day precisions at concentrations spanning the analytical measurement ranges were less than 10% for all three analytes. MTX, DAMPA and 7-OH MTX were sufficiently stable under all relevant analytical conditions. No significant matrix effect was observed during the method validation. The TFC-LC-MS/MS MTX method was also compared with three other clinically validated MTX assays: a dihydrofolate reductase (DHFR) inhibition assay, an immunoassay based on fluorescence polarization and a previously developed LC-MS/MS assay.

Analytical performance of the Abaxis Piccolo Xpress® point of care analyzer in whole blood, serum, and plasma.

OBJECTIVES: To examine the analytical performance of 14 comprehensive metabolic panel analytes on the Abaxis Piccolo Xpress® Point of Care analyzer in serum, plasma, and whole blood. DESIGN AND METHODS: Precision was evaluated by running two levels of control material over multiple days. Linearity was evaluated using material provided by the manufacturer and the College of American Pathologists (CAP) linearity surveys. Accuracy was evaluated by comparing the results from 60 patient specimens on the Piccolo Xpress® with the Ortho Vitros® 5600 analyzer. The method comparison was performed on all three specimen types intended for use on the Piccolo Xpress®: serum, heparinized plasma, and whole blood. Manufacturer suggested reference ranges for all 14 analytes were tested in serum and plasma specimens from 23 healthy volunteers. RESULTS: High precision (CV ≤ 10%) was noted for all the analytes. Linearity was found to span the clinically useful range for all analytes. The method comparison demonstrated minimal proportional bias and good correlation for most of the analytes in all three matrices tested. The only exceptions were for sodium and total CO2, for which either significant proportional bias and/or poor correlation was noted in all three matrices. Significant bias was noted for AST in serum as well as for total bilirubin in plasma and whole blood. CONCLUSION: The Piccolo Xpress® allows for the delivery of CMP results in a footprint small enough to be stored in a biological safety cabinet, while providing satisfactory performance for the majority of analytes.