Katie L. Thoren

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.

Hallucinogens causing seizures? A case report of the synthetic amphetamine 2,5-dimethoxy-4-chloroamphetamine.

Although traditional hallucinogenic drugs such as marijuana and lysergic acid diethylamide (LSD) are not typically associated with seizures, newer synthetic hallucinogenic drugs can provoke seizures. Here, we report the unexpected consequences of taking a street-bought hallucinogenic drug thought to be LSD. Our patient presented with hallucinations and agitation progressing to status epilepticus with a urine toxicology screen positive only for cannabinoids and opioids. Using liquid chromatography high-resolution mass spectrometry, an additional drug was found: an amphetamine-derived phenylethylamine called 2,5-dimethoxy-4-chloroamphetamine. We bring this to the attention of the neurologic community as there are a growing number of hallucinogenic street drugs that are negative on standard urine toxicology and cause effects that are unexpected for both the patient and the neurologist, including seizures.

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.

Optimization and Validation of High-Resolution Mass Spectrometry Data Analysis Parameters

High-resolution mass spectrometry (HRMS) has gained recognition as a valuable tool for comprehensive drug screening in a variety of biological matrices. HRMS instruments collect untargeted, accurate mass data, which permit identification of known and unknown compounds in a single analytical run. One of the most challenging aspects of implementing an HRMS drug screen is establishing appropriate data analysis parameters for identifying compounds. Unlike other types of mass spectrometry data, guidelines for HRMS data analysis and acceptability criteria have not been established. Although many laboratories have published on the utility of HRMS for drug screening, few have included details on how they determined allowable errors and set positivity criteria. Previously, we developed and validated a comprehensive 169-compound drug screen on a high-resolution quadrupole time of flight mass spectrometer. Here we report the detailed procedure that we used to determine appropriate positivity criteria for our screening procedure. Our approach was empirical; we collected data and analyzed it with commonly available software. We found that a combined scoring approach using a threshold of 70, with 70% weight given to library match and 10% weight given to each of mass error, retention time error and isotope pattern difference provided optimum drug identification efficiency of 99.2%. Our results demonstrate the importance of library matching in accurately identifying compounds, and underscore the utility of robust product ion spectra that contain information on the lineage, mass and relative abundance of fragments. The method we describe is easily adaptable to include alternative parameters that may be available in software associated with a variety of HRMS platforms. With careful selection of error limits and positivity criteria, HRMS instruments are capable of producing high-quality, high-confidence results that may reduce the need for confirmatory testing.

Mass spectrometry methods for detecting monoclonal immunoglobulins in multiple myeloma minimal residual disease

Mass spectrometry methods that can detect low levels of monoclonal immunoglobulin in serum have recently been developed. These assays are based on the principle that each immunoglobulin has a unique amino acid sequence and therefore, has a unique mass. This mass can be used as a surrogate marker in order to monitor a patients disease over time and at low levels. Here, we explain these methods, discuss their advantages and disadvantages and how they may be used to monitor monoclonal immunoglobulins for minimal residual disease detection in multiple myeloma.

Multiple Myeloma and Its Precursor Disease Among Firefighters Exposed to the World Trade Center Disaster

Importance The World Trade Center (WTC) attacks on September 11, 2001, created an unprecedented environmental exposure to known and suspected carcinogens suggested to increase the risk of multiple myeloma. Multiple myeloma is consistently preceded by the precursor states of monoclonal gammopathy of undetermined significance (MGUS) and light-chain MGUS, detectable in peripheral blood. Objective To characterize WTC-exposed firefighters with a diagnosis of multiple myeloma and to conduct a screening study for MGUS and light-chain MGUS. Design, Setting, and Participants Case series of multiple myeloma in firefighters diagnosed between September 11, 2001, and July 1, 2017, together with a seroprevalence study of MGUS in serum samples collected from Fire Department of the City of New York (FDNY) firefighters between December 2013 and October 2015. Participants included all WTC-exposed FDNY white, male firefighters with a confirmed physician diagnosis of multiple myeloma (n = 16) and WTC-exposed FDNY white male firefighters older than 50 years with available serum samples (n = 781). Exposures WTC exposure defined as rescue and/or recovery work at the WTC site between September 11, 2001, and July 25, 2002. Main Outcomes and Measures Multiple myeloma case information, and age-adjusted and age-specific prevalence rates for overall MGUS (ie, MGUS and light-chain MGUS), MGUS, and light-chain MGUS. Results Sixteen WTC-exposed white male firefighters received a diagnosis of multiple myeloma after September 11, 2001; median age at diagnosis was 57 years (interquartile range, 50-68 years). Serum/urine monoclonal protein isotype/free light-chain data were available for 14 cases; 7 (50%) had light-chain multiple myeloma. In a subset of 7 patients, myeloma cells were assessed for CD20 expression; 5 (71%) were CD20 positive. In the screening study, we assayed peripheral blood from 781 WTC-exposed firefighters. The age-standardized prevalence rate of MGUS and light-chain MGUS combined was 7.63 per 100 persons (95% CI, 5.45-9.81), 1.8-fold higher than rates from the Olmsted County, Minnesota, white male reference population (relative rate, 1.76; 95% CI, 1.34-2.29). The age-standardized prevalence rate of light-chain MGUS was more than 3-fold higher than in the same reference population (relative rate, 3.13; 95% CI, 1.99-4.93). Conclusions and Relevance Environmental exposure to the WTC disaster site is associated with myeloma precursor disease (MGUS and light-chain MGUS) and may be a risk factor for the development of multiple myeloma at an earlier age, particularly the light-chain subtype.

Suspect Screening Using LC–QqTOF Is a Useful Tool for Detecting Drugs in Biological Samples

High-resolution mass spectrometers (HRMS), including quadrupole time of flight mass analyzers (QqTOF), are becoming more prevalent as screening tools in clinical and forensic toxicology laboratories. Among other advantages, HRMS instruments can collect untargeted, full-scan mass spectra. These datasets can be analyzed retrospectively using a combination of techniques, which can extend the drug detection capabilities. Most laboratories using HRMS in production settings perform untargeted data collection, but analyze data in a targeted manner. To perform targeted analysis, a laboratory must first analyze a reference standard to determine the expected characteristics of a given compound. In an alternate technique known as suspect screening, compounds can be tentatively identified without the use of reference standards. Instead, predicted and/or intrinsic characteristics of a compound, such as the accurate mass, isotope pattern, and product ion spectrum are used to determine its presence in a sample. The fact that reference standards are not required a priori makes this data analysis approach very attractive, especially for the ever-changing landscape of novel psychoactive substances. In this work, we compared the performance of four data analysis workflows (targeted and three suspect screens) for a panel of 170 drugs and metabolites, detected by LC-QqTOF. We found that retention time was not required for drug identification; the suspect screen using accurate mass, isotope pattern, and product ion library matching was able to identify more than 80% of the drugs that were present in human urine samples. We showed that the inclusion of product ion spectral matching produced the largest decrease in false discovery and false negative rates, as compared to suspect screening using mass alone or using just mass and isotope pattern. Our results demonstrate the promise that suspect screening holds for building large, economical drug screens, which may be a key tool to monitor the use of emerging drugs of abuse, including novel psychoactive substances.