Selective molecular characterization of organic aerosols using in situ laser desorption ionization mass spectrometry.

RATIONALE: The sources and chemical compositions of organic aerosol (OA) exert a significant influence on both regional and global atmospheric conditions, thereby having far-reaching implications on environmental chemistry. However, existing mass spectrometry (MS) methods have limitations in characterizing the detailed composition of OA due to selective ionization as well as fractionation during cold-water extraction and solid-phase extraction (SPE). METHODS: A comprehensive MS study was conducted using aerosol samples collected on dusty, clean, and polluted days. To supplement the data obtained from electrospray ionization (ESI), a strategy for analyzing OAs collected using the quartz fiber filter directly utilizing laser desorption ionization (LDI) was employed. Additionally, the ESI method was conducted to explore suitable approaches for determining various OA compositions from samples collected on dusty, clean, and polluted days. RESULTS: In situ LDI has the advantages of significantly reducing the sample volume, simplifying sample preparation, and overcoming the problem of overestimating sulfur-containing compounds usually encountered in ESI. It is suitable for the characterization of highly unsaturated and hydrophobic aerosols, such as brown carbon-type compounds with low volatility and high stability, which is supplementary to ESI. CONCLUSIONS: Compared with other ionization methods, in situ LDI helps provide a complementary description of the molecular compositions of OAs, especially for analyzing OAs in polluted day samples. This method may contribute to a more comprehensive MS analysis of the elusive compositions and sources of OA in the atmosphere.

An Overview of Different Vitamin D Compounds in the Setting of Adiposity.

A large body of research shows an association between higher body weight and low vitamin D status, as assessed using serum 25-hydroxyvitamin D concentrations. Vitamin D can be metabolised in adipose tissue and has been reported to influence gene expression and modulate inflammation and adipose tissue metabolism in vitro. However, the exact metabolism of vitamin D in adipose tissue is currently unknown. White adipose tissue expresses the vitamin D receptor and hydroxylase enzymes, substantially involved in vitamin D metabolism and efficacy. The distribution and concentrations of the generated vitamin D compounds in adipose tissue, however, are largely unknown. Closing this knowledge gap could help to understand whether the different vitamin D compounds have specific health effects in the setting of adiposity. This review summarises the current evidence for a role of vitamin D in adipose tissue and discusses options to accurately measure vitamin D compounds in adipose tissue using liquid chromatography tandem mass spectrometry (LC/MS-MS).

Seasonal variation and dissolved organic matter influence on the distribution, transformation, and environmental risk of pharmaceuticals and personal care products in coastal zone: A case study of Tianjin, China.

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants that have raised urgent environmental issues. The dissolved organic matter (DOM) plays a pivotal role on PPCPs' migration and transformation. To obtain a comprehensive understanding of the occurrence and distribution of PPCPs, a seasonal sampling focused on the riverine system in coastal zone, Tianjin, Bohai Rim was conducted. The distribution and transformation of thirty-three PPCPs and their interaction with DOM were investigated, and their sources and ecological risks were further evaluated. The total concentration of PPCPs ranges from 0.01 to 197.20 µg/L, and such value is affected by regional temperature, DOM and land use types. PPCPs migration at soil-water interface is controlled by temperature, sunlight, water flow and DOM. PPCPs have a high affinity to the protein-like DOM, while the humus-like DOM plays a negative influence and facilitates PPCPs' degradation. It is also found that protein-like DOM can represent point source pollution, while humus-like substances indicate non-point source (NPS) emission. Specific PPCPs can be used as markers to trace the source of domestic discharge. Additionally, daily use PPCPs such as ketoprofen, caffeine and iopromide are estimated to be the main risk substances, and their ecological risk varies on space, season and river hydraulic condition.

Surgical complications requiring late surgical revisions after pancreatoduodenectomy increase postoperative morbidity and mortality.

BACKGROUND: Pancreatoduodenectomies are complex surgical procedures with considerable postoperative morbidity and mortality. Here, we describe complications and outcomes in patients requiring surgical revisions following pancreatoduodenectomy. METHODS: A total of 1048 patients undergoing a pancreatoduodenectomy at our institution between 2002 and 2019 were analyzed retrospectively. All patients with surgical revisions were included. Revisions were divided into early and late using a cut-off of 5 days after the first surgery. Statistical significance was examined by using chi-square tests and Fisher's exact tests. Survival analysis was performed using Kaplan-Meier curves and log-rank tests. RESULTS: A total of 150 patients with at least 1 surgical revision after pancreatoduodenectomy were included. Notably, 64 patients had a revision during the first 5 days and were classified as early revision. Compared with the 86 patients with late revisions, we found no differences concerning wound infections, delayed gastric emptying, or acute kidney failure. After late revisions, we found significantly more cases of sepsis (31.4% late versus 15.6% early, p = 0.020) and reintubation due to respiratory failure (33.7% versus 18.8%, p = 0.031). Postoperative mortality was significantly higher within the late revision group (23.2% versus 9.4%, p = 0.030). CONCLUSION: Arising complications after pancreatoduodenectomy should be addressed as early as possible as patients requiring late surgical revisions frequently developed septic complications and multiorgan failure.

Characterizing lignins from various sources and treatment processes after optimized sample preparation techniques and analysis via ESI-HRMS and custom mass defect software tools.

Sample preparation of complex, natural mixtures such as lignin prior to mass spectrometry analysis, however minimal, is a critical step in ensuring accurate and interference-free results. Modern shotgun-MS techniques, where samples are directly injected into a high-resolution mass spectrometer (HRMS) with no prior separation, usually still require basic sample pretreatment such as filtration and appropriate solvents for full dissolution and compatibility with atmospheric pressure ionization interfaces. In this study, sample preparation protocols have been established for a unique sample set consisting of a wide variety of degraded lignin samples from numerous sources and treatment processes. The samples were analyzed via electrospray (ESI)-HRMS in negative and positive ionization modes. The resulting information-rich HRMS datasets were then transformed into the mass defect space with custom R scripts as well as the open-source Constellation software as an effective way to visualize changes between the samples due to the sample preparation and ionization conditions as well as a starting point for comprehensive characterization of these varied sample sets. Optimized conditions for the four investigated lignins are proposed for ESI-HRMS analysis for the first time, giving an excellent starting point for future studies seeking to better characterize and understand these complex mixtures.

Detecting Early-Stage Intermediates of Free-Radical Oxidative Degradation in Charged Aqueous Microdroplets.

We report the detection of early-stage intermediates of spontaneous free-radical oxidation of organic pollutants such as aliphatic amino alcohols and diamines in charged aqueous microdroplets in the ambient atmosphere. We propose that the intrinsic formation of reactive oxygen species at the air-water interface is responsible for the radical oxidation of the sp3 carbon. We suggest that our work will aid the understanding of the degradation mechanisms of organic molecules in the environment.

2-fluoro-1-methylpyridinium p-toluene sulfonate: a new LC-MS/MS derivatization reagent for vitamin D metabolites.

Vitamin D analysis by MS faces several analytical challenges, including inefficient ionization, nonspecific fragmentation, interferences from epimers, isomers, and isobars, as well as very low concentration levels. In this study, we used 2-fluoro-1-methylpyridinium (FMP) p-toluene sulfonate for derivatization of vitamin D3 metabolites to increase detection sensitivity and allow for full chromatographic separation of vitamin D isomers and epimers. UHPLC-MS/MS was used for measurement of five vitamin D3 metabolites in human serum. Compared with Amplifex and 4-phenyl-1,2,4-triazolin-3,5-dion, the FMP p-toluene sulfonate reaction required less time to be performed. The method was optimized and validated to ensure accuracy, precision, and reliability. In-house and commercial quality control samples were used to assure the quality of the results for 25-hydroxyvitamin D3. The method showed very good linearity and intraday and interday accuracy and precision; coefficients of determination (r2) ranged between 0.9977 and 0.9992, relative recovery from 95 to 111%, and coefficient of variation from 0.9 to 11.3. Stability tests showed that the extracted derivatized serum samples were stable for 24 h after storage at -20°C; 24,25-dihydroxyvitamin D3 and 1,25-dihydroxyvitamin D3-FMP derivatives were stable for 1 week at -80°C. The method was applied to samples of healthy individuals for quantitative determination of vitamin D3, the two epimers of 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.

Clinical characteristics and long-term outcomes following pancreatic injury - An international multicenter cohort study.

Background: Trauma to the pancreas is rare but associated with significant morbidity. Currently available management guidelines are based on low-quality evidence and data on long-term outcomes is lacking. This study aimed to evaluate clinical characteristics and patient-reported long-term outcomes for pancreatic injury. Methods: A retrospective cohort study evaluating treatment for pancreatic injury in 11 centers across 5 European nations over >10 years was performed. Data relating to pancreatic injury and treatment were collected from hospital records. Patients reported quality of life (QoL), changes to employment and new or ongoing therapy due to index injury. Results: In all, 165 patients were included. The majority were male (70.9%), median age was 27 years (range: 6-93) and mechanism of injury predominantly blunt (87.9%). A quarter of cases were treated conservatively; higher injury severity score (ISS) and American Association for the Surgery of Trauma (AAST) pancreatic injury scores increased the likelihood for surgical, endoscopic and/or radiologic intervention. Isolated, blunt pancreatic injury was associated with younger age and pancreatic duct involvement; this cohort appeared to benefit from non-operative management. In the long term (median follow-up 93; range 8-214 months), exocrine and endocrine pancreatic insufficiency were reported by 9.3% of respondents. Long-term analgesic use also affected 9.3% of respondents, with many reported quality of life problems (QoL) potentially attributable to side-effects of opiate therapy. Overall, impaired QoL correlated with higher ISS scores, surgical therapy and opioid analgesia on discharge. Conclusions: Pancreatic trauma is rare but can lead to substantial short- and long-term morbidity. Near complete recovery of QoL indicators and pancreatic function can occur despite significant injury, especially in isolated, blunt pancreatic injury managed conservatively and when early weaning off opiate analgesia is achieved.

Improved quantitative LC-MS/MS analysis of vitamin D metabolites in serum after one-pot double derivatization.

In this study, we report a one-pot double derivatization scheme, which used acetylation after a Diels-Alder reaction using 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) to improve separation efficiency and provide baseline separations of the five vitamin D metabolites 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 24,25-dihydroxyvitamin D3 (24,25(OH)2D3), 3ß-25-hydroxyvitamin D3 (3ß-25(OH)D3), 3α-25-hydroxyvitamin D3 (3α-25(OH)D3) and vitamin D3 on a C-18 stationary phase. Vitamin D metabolites are often very challenging to measure quantitatively using mass spectrometry, due to their low serum concentration levels and low ionization efficiencies. Moreover, some of these species are isomers with virtually identical mass spectral dissociation behavior. To overcome the low ionization efficiency and unspecific fragmentation behavior, derivatization using Diels-Alder reactions with Cookson-type reagents such as PTAD are common. These derivatization reactions generally result in more complicated liquid chromatography separations, because both 6R- and 6S-isomers are formed during Diels-Alder reactions. It has been shown that separations have been particularly challenging for the 3α-25(OH)D3 and 3ß-25(OH)D3 epimers. Here, we optimized the PTAD derivatization and the esterification using acetic anhydride. By utilizing the esterification catalyst 4-dimethylaminopyridine, we avoided quenching and evaporation between the two derivatization steps, but were also able to perform the esterification at room temperature without heating. The optimized one-pot double derivatization LC-MS/MS assay was validated with respect to inter/intra-day precision, accuracy, recovery and linear dynamic range and applied to metabolic fingerprinting of vitamin D3 metabolites in serum samples. The metabolites 3α-25(OH)D3, 3ß-25(OH)D3 and 24,25(OH)2D3, were readily quantified in all investigated samples. The method was, in principle, also fit for purpose for quantification of the native vitamin D3 species; the relatively high blank concentration of the commercial vitamin D-depleted serum used for calibration, however, limited the limits of quantification for this metabolite. The method provided insufficient limits of quantification for serum levels of 1,25(OH)2D3.

Comparing derivatization reagents for quantitative LC-MS/MS analysis of a variety of vitamin D metabolites.

The present study systematically compares the sensitivity and selectivity of the analysis of multiple vitamin D metabolites after chemical derivatization using different reagents for liquid chromatography-tandem mass spectrometry (LC-MS/MS). Generally, chemical derivatization is applied to vitamin D metabolites to increase the ionization efficiency, which is particularly important for very low abundant metabolites. Derivatization can also improve the selectivity of the LC separation. A wide variety of derivatization reagents has been reported in recent years, but information on their relative performance and applicability to different vitamin D metabolites is, unfortunately, not available in the literature. To fill this gap, we investigated vitamin D3, 3ß-25-hydroxyvitamin D3 (3ß-25(OH)D3), 3α-25-hydroxyvitamin D3 (3α-25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and compared response factors and selectivity after derivatizing with several important reagents, including four dienophile reagents (4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), 4-[2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalinyl)ethyl]-1,2,4-triazoline-3,5-dione (DMEQ-TAD), Amplifex, 2-nitrosopyridine (PyrNO)) as well as two reagents targeting hydroxyl groups: isonicotinoyl chloride (INC) and 2-fluoro-1-methylpyridinium-p-toluenesulfonate (FMP-TS). In addition, a combination of dienophiles and hydroxyl group reagents was examined. For LC separations, reversed-phase C-18 and mixed-mode pentafluorophenyl HPLC columns using different compositions of the mobile phase were compared. With respect to detection sensitivity, the optimum derivatization reagent for the profiling of multiple metabolites was Amplifex. Nevertheless, FMP-TS, INC, PTAD, or PTAD combined with an acetylation reaction showed very good performance for selected metabolites. These reagent combinations provided signal enhancements on the order of 3- to 295-fold depending on the compound. Chromatographic separation of the dihydroxylated vitamin D3 species was readily achieved using any of the derivatization reactions, while for 25(OH)D3 epimers, only PyrNO, FMP, INC, and PTAD combined with acetylation enabled complete separation. In conclusion, we believe this study can serve as a useful reference for vitamin D laboratories, to help analytical and clinical scientists decide which derivatization reagent to choose for their application.

Identification of Trace Components in Sauce-Flavor Baijiu by High-Resolution Mass Spectrometry.

Sauce-flavor Baijiu is one of the most complex and typical types of traditional Chinese liquor, whose trace components have an important impact on its taste and quality. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is one of the most favorable analytical tools to reveal trace molecular components in complex samples. This study analyzed the chemical diversity of several representative sauce-flavor Baijiu using the combination of electrospray ionization (ESI) and FT-ICR MS. The results showed that ESI+ and ESI- exhibited different chemical features characteristic of trace components. Overall, sauce-flavor Baijiu was dominated by CHO class compounds, and the main specific compound types were aliphatic, highly unsaturated with low oxygen, and peptide-like compounds. The mass spectral parameters resolved by FT-ICR MS of several well-known brands were relatively similar, whereas the greatest variability was observed from an internally supplied brand. This study provides a new perspective on the mass spectrometry characteristics of trace components of sauce-flavor Baijiu and offers a theoretical foundation for further optimization of the gradients in Baijiu.

Miniaturized Protein Digestion Using Acoustic Levitation with Online High Resolution Mass Spectrometry.

The combination of acoustically levitated droplets, mid-IR laser evaporation, and subsequent post-ionization by secondary electrospray ionization was applied for monitoring the enzymatic digestion of various proteins. Acoustically levitated droplets are an ideal, wall-free model reactor, readily allowing compartmentalized microfluidic trypsin digestions. Time-resolved interrogation of the droplets yielded real-time information on the progress of the reaction and thus provided insights into reaction kinetics. After 30 min of digestion in the acoustic levitator, the obtained protein sequence coverages were identical to the reference overnight digestions. Importantly, our results clearly demonstrate that the applied experimental setup can be used for the real-time investigation of chemical reactions. Furthermore, the described methodology only uses a fraction of the typically applied amounts of solvent, analyte, and trypsin. Thus, the results exemplify the use of acoustic levitation as a green analytical chemistry alternative to the currently used batch reactions.

New algorithms demonstrate untargeted detection of chemically meaningful changing units and formula assignment for HRMS data of polymeric mixtures in the open-source constellation web application.

The field of high-resolution mass spectrometry (HRMS) and ancillary hyphenated techniques comprise a rapidly expanding and evolving area. As popularity of HRMS instruments grows, there is a concurrent need for tools and solutions to simplify and automate the processing of the large and complex datasets that result from these analyses. Constellation is one such of these tools, developed by our group over the last two years to perform unsupervised trend detection for repeating, polymeric units in HRMS data of complex mixtures such as natural organic matter, oil, or lignin. In this work, we develop two new unsupervised algorithms for finding chemically-meaningful changing units in HRMS data, and incorporate a molecular-formula-finding algorithm from the open-source CoreMS software package, both demonstrated here in the Constellation software environment. These algorithms are evaluated on a collection of open-source HRMS datasets containing polymeric analytes (PEG 400 and NIST standard reference material 1950, both metabolites in human plasma, as well as a swab extract containing polymers), and are able to successfully identify all known changing units in the data, including assigning the correct formulas. Through these new developments, we are excited to add to a growing body of open-source software specialized in extracting useful information from complex datasets without the high costs, technical knowledge, and processor-demand typically associated with such tools.

Analysis of vitamin D metabolic markers by mass spectrometry: Recent progress regarding the "gold standard" method and integration into clinical practice.

Liquid chromatography/tandem mass spectrometry is firmly established today as the gold standard technique for analysis of vitamin D, both for vitamin D status assessments as well as for measuring complex and intricate vitamin D metabolic fingerprints. While the actual mass spectrometry technology has seen only incremental performance increases in recent years, there have been major, very impactful changes in the front- and back-end of MS-based vitamin D assays; for example, the extension to new types of biological sample matrices analyzed for an increasing number of different vitamin D metabolites, novel sample preparation techniques, new powerful chemical derivatization reagents, as well the continued integration of high resolution mass spectrometers into clinical laboratories, replacing established triple-quadrupole instruments. At the same time, the sustainability of mass spectrometry operation in the vitamin D field is now firmly established through proven analytical harmonization and standardization programs. The present review summarizes the most important of these recent developments.

Mass spectrometry-based methods for the advanced characterization and structural analysis of lignin: A review.

Lignin is currently one of the most promising biologically derived resources, due to its abundance and application in biofuels, materials and conversion to value aromatic chemicals. The need to better characterize and understand this complex biopolymer has led to the development of many different analytical approaches, several of which involve mass spectrometry and subsequent data analysis. This review surveys the most important analytical methods for lignin involving mass spectrometry, first looking at methods involving gas chromatography, liquid chromatography and then continuing with more contemporary methods such as matrix assisted laser desorption ionization and time-of-flight-secondary ion mass spectrometry. Following that will be techniques that directly ionize lignin mixtures-without chromatographic separation-using softer atmospheric ionization techniques that leave the lignin oligomers intact. Finally, ultra-high resolution mass analyzers such as FT-ICR have enabled lignin analysis without major sample preparation and chromatography steps. Concurrent with an increase in the resolution of mass spectrometers, there have been a wealth of complementary data analyses and visualization methods that have allowed researchers to probe deeper into the "lignome" than ever before. These approaches extract trends such as compound series and even important analytical information about lignin substructures without performing lignin degradation either chemically or during MS analysis. These innovative methods are paving the way for a more comprehensive understanding of this important biopolymer, as we seek more sustainable solutions for our human species' energy and materials needs.

An advanced LC-MS/MS protocol for simultaneous detection of pharmaceuticals and personal care products in the environment.

RATIONALE: The development of appropriate analytical screening techniques for pharmaceuticals and personal care products (PPCPs) is the basis for studying the distribution and environmental impact of emerging contaminants (ECs). Mass spectrometry-based screening methods vary with the complexity of the target compounds. It is challenging to balance both positive and negative ion quantification with a low detection limit. To establish a set of experimental methods including extraction, chromatography-separation and mass spectrometry screening is one of the most important topics in PPCP research. This paper describes a universal and efficient qualification and quantification protocol for the simultaneous detection of 34 PPCPs in different environmental samples in a single analytical data acquisition run. METHODS: Thirty-four representative PPCPs, which are widely distributed in the environment with high ecological toxicity and complex chemical structures, were selected as representative target ECs. The extraction of the target PPCPs was achieved using only one solid-phase extraction cartridge without the need to adjust the pH of samples. The enriched samples were detected by LC-MS/MS in both positive and negative ion modes simultaneously. The protocol was evaluated based on the accuracy, precision, detection limits and matrix effects. RESULTS: This method achieved simultaneous detection of PPCPs in both positive and negative ion modes, with a single analytical cycle of 12 min. The observed SPE recoveries were between 40% and 115%. The instrumental detection limits (IDL) varied from 0.01 to 1 pg, and the method detection limits (MDL) were between 0.002 and 3.323 ng/l in different matrices. Most of the PPCPs were subjected to matrix suppression below 30%. The method was successfully applied for quantitative analysis of the PPCPs in different environmental samples, including river samples, wastewater treatment plant (WWTP) samples and soil samples. CONCLUSIONS: This protocol developed a rapid and efficient detection method to simultaneous qualitative and quantitative 34 representative PPCPs in the environment. The IDL ranged from 0.01 to 1 pg and the MDL ranged from 0.002 to 3.323 ng/l in different matrices. The detection limit was one order of magnitude lower compared to previous studies. The protocol also provided a wide application range for different environmental matrices, which permitted the migration and transformation of PPCPs to be explored.

Stability of sample extracts of vitamin D3 metabolites after chemical derivatization for LC-MS/MS analysis.

Liquid chromatography/tandem mass spectrometry (LC-MS/MS) is widely used to determine vitamin D3 metabolites in biological samples. The ionization efficiencies of these metabolites, however, are poor under electrospray ionization conditions. Moreover, the chromatographic separation of multiple vitamin D metabolites and their epimers can be challenging. For these reasons, chemical derivatization reagents are often used to improve sensitivity and selectivity of analysis. While the derivatization schemes have been proven to be very effective, one missing aspect is the investigation of the stability of the chemical derivatization products in stored sample extracts. In this study, we investigated the long-term stability of several vitamin D3 metabolites after 1 and 3 months of storage at - 20 °C. Five vitamin D3 metabolites were examined after derivatization with seven different derivatization reagents. Generally, Amplifex products were the most stable in the long term in our study with 11-20% degraded after 1 month of storage and 14-35% after 3 months. The stabilities for some of the metabolites' 4-[2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalyl)ethyl]-1,2,4-triazoline-3,5-dione (DMEQ-TAD), 2-fluoro-1-methylpyridinium p-toluenesulfonate (FMP-TS), isonicotinoyl chloride (INC) and 4-phenyl-1,2,4-triazoline-3,5-dione acetylated (PTAD-Ac) products were also acceptable after 1 month of storage. Other derivatized metabolites, however, degraded extensively already after 1 month of storage, such as 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) (54-72% degradation) and 2-nitrosopyridine (PyrNO) (32-100% degradation). Importantly, for every metabolite, there was an optimum derivatization reagent that met the criteria of stability proposed by international regulatory bodies after 1 month of storage. Some derivatives were stable for even up to 3 months of storage, with degradation of less than 15%.

Epigenetics in Pancreatic Ductal Adenocarcinoma: Impact on Biology and Utilization in Diagnostics and Treatment.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with high potential of metastases and therapeutic resistance. Although genetic mutations drive PDAC initiation, they alone do not explain its aggressive nature. Epigenetic mechanisms, including aberrant DNA methylation and histone modifications, significantly contribute to inter- and intratumoral heterogeneity, disease progression and metastasis. Thus, increased understanding of the epigenetic landscape in PDAC could offer new potential biomarkers and tailored therapeutic approaches. In this review, we shed light on the role of epigenetic modifications in PDAC biology and on the potential clinical applications of epigenetic biomarkers in liquid biopsy. In addition, we provide an overview of clinical trials assessing epigenetically targeted treatments alone or in combination with other anticancer therapies to improve outcomes of patients with PDAC.

Extensive preclinical validation of combined RMC-4550 and LY3214996 supports clinical investigation for KRAS mutant pancreatic cancer.

Over 90% of pancreatic cancers present mutations in KRAS, one of the most common oncogenic drivers overall. Currently, most KRAS mutant isoforms cannot be targeted directly. Moreover, targeting single RAS downstream effectors induces adaptive resistance mechanisms. We report here on the combined inhibition of SHP2, upstream of KRAS, using the allosteric inhibitor RMC-4550 and of ERK, downstream of KRAS, using LY3214996. This combination shows synergistic anti-cancer activity in vitro, superior disruption of the MAPK pathway, and increased apoptosis induction compared with single-agent treatments. In vivo, we demonstrate good tolerability and efficacy of the combination, with significant tumor regression in multiple pancreatic ductal adenocarcinoma (PDAC) mouse models. Finally, we show evidence that 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to assess early drug responses in animal models. Based on these results, we will investigate this drug combination in the SHP2 and ERK inhibition in pancreatic cancer (SHERPA; ClinicalTrials.gov: NCT04916236) clinical trial, enrolling patients with KRAS-mutant PDAC.

Laser Ablation Secondary Electrospray Ionization for In Situ Mass Spectrometric Interrogation of Acoustically-Levitated Droplets.

The composition of acoustically levitated droplets was probed by a novel combination of mid-IR laser evaporation and subsequent postionization via secondary electrospray ionization. The combination of microliter samples and subnanoliter sampling provided time-resolved interrogation of droplets and allowed for a kinetic investigation of the laser-induced release of the analyte, which was found to strongly depend on the analytes. The observed substance-specific delayed release of the analytes permitted baseline-separated discrimination of the analytes, ideal for the study of complex samples. The additionally applied postionization scheme was found to enable efficient detection of small volatile compounds as well as peptides. The detection of small molecules and peptides occurred under very different sampling geometries, pointing to two distinct underlying ionization mechanisms. Overall, our results suggest that the experimental setup presented in this study can serve as a widely applicable platform to study chemical reactions in acoustically levitated droplets as model reactors.