Search

Objectives We compared complete blood count (CBC) with differential and markers of inflammation and coagulation in patients with and without coronavirus disease 2019 (COVID-19) presenting to emergency departments in Seattle, WA. Methods We reviewed laboratory values for 1 week following each COVID-19 test for adult patients who received a standard severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) test before April 13, 2020. Results were compared by COVID-19 status and clinical course. Results In total 1,027 patients met inclusion criteria. Patients with COVID-19 (n = 155) had lower leukocytes (P < .0001), lymphocytes (P < .0001), platelets (P < .0001), and higher hemoglobin (P = .0140) than those without, but absolute differences were small. Serum albumin was lower in patients with COVID-19 (P < .0001) and serum albumin, neutrophil to lymphocyte ratio (NLR), and red cell distribution width (RDW) were each associated with disease severity. NLR did not differ between patients with COVID-19 and those without (P = .8012). Conclusions Patients with COVID-19 had modestly lower leukocyte, lymphocyte, and platelet counts and higher hemoglobin values than patients without COVID-19. The NLR, serum albumin, and RDW varied with disease severity, regardless of COVID-19 status.

Warfarin is a narrow therapeutic index anticoagulant drug and its use is associated with infrequent but significant adverse bleeding events. The international normalized ratio (INR) is the most commonly used biomarker to monitor and titrate warfarin therapy. However, INR is derived from a functional assay, which determines clotting efficiency at the time of measurement and is susceptible to technical variability. Protein induced by vitamin K antagonist‐II (PIVKA‐II) has been suggested as a biomarker of long‐term vitamin K status, providing mechanistic insights about variation in the functional assay. However, the currently available antibody‐based PIVKA‐II assay does not inform on the position and number of des‐carboxylation sites in prothrombin. The assay presented in this paper provides simultaneous quantification of carboxy and des‐carboxy prothrombin that are essential for monitoring early changes in INR and, thus, serves as the superior tool for managing warfarin therapy. Additionally, this assay permits the quantification of total prothrombin level, which is affected by warfarin treatment. Prothrombin recovery from plasma was 95% and the liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) assay was linear (r 2 = 0.98) with a dynamic range of 1–100 µg/mL. The assay interday precision was within 20%. A des‐carboxy peptide of prothrombin (GNLER) was negatively correlated with active prothrombin (Pearson r = 0.99, P

Background Venous thromboembolism (VTE) is the third most common cause of cardiovascular illness and is projected to double in incidence by 2050. It is a spectrum of disease that includes deep venous thrombosis (DVT) and pulmonary embolism (PE). In February 2016, the American College of Chest Physicians provided updated management guidelines for DVT and PE to address some of the unresolved questions from the previous version and to provide recommendations related to newer anticoagulants. Content Here we review current concepts for screening, diagnosis, thromboprophylaxis, and management of DVT and PE. We also describe the management of VTE in acute, long-term, and extended phases of treatment. Thrombophilia testing is rarely necessary and should be used judiciously; the laboratory can serve an important role in preventing unnecessary testing. The direct oral anticoagulants are as effective as conventional treatment and are preferred agents except in the case of cancer. The initial management of PE should be based on risk stratification including the use of D-dimer testing. Thrombolysis is used in cases of hemodynamically unstable PE and not for low-risk patients who can be treated on an outpatient basis. Summary This review is intended to provide readers with updated guidelines for screening, testing, prophylaxis, and management from various organizations.

There are no clear and consistent guidelines on how to utilize DOAC assays, and reports on the use of DOAC levels in clinical practice is limited. The objective of this study was to analyze why DOAC levels are ordered, how the results affect clinical decision-making, and to determine if DOAC assays are utilized appropriately. This was a retrospective chart review study analyzing 150 dabigatran, rivaroxaban, and apixaban levels performed at a single institution. The majority of DOAC assays were ordered in situations or special patient populations where confirming absence or detecting presence of drug may be useful. The most common indication for ordering assays was prior to an invasive procedure. Most DOAC levels were timed appropriately but peak levels were most likely to be incorrectly ordered. Clinical decisions following level results depended on indication for ordering and were most commonly used to determine whether or not to proceed with an invasive procedure. The results of our study suggest while DOAC assays are generally ordered for useful indications, there is still a lack of understanding of when levels should be drawn and how to interpret DOAC assay results.

Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. Currently, testing is performed in hospital laboratories or with expensive point-of-care devices limiting the ability to test frequently and affordably. We report a proof-of-concept PT/INR testing system that uses the vibration motor and camera on smartphones to track micro-mechanical movements of a copper particle. The smartphone system computed the PT/INR with inter-class correlation coefficients of 0.963 and 0.966, compared to a clinical-grade coagulation analyzer for 140 plasma samples and demonstrated similar results for 80 whole blood samples using a single drop of blood (10 μl). When tested with 79 blood samples with coagulopathic conditions, the smartphone system demonstrated a correlation of 0.974 for both PT/INR. Given the ubiquity of smartphones in the global setting, this proof-of-concept technology may provide affordable and effective PT and INR testing in low-resource environments.

Analysis of circulating tumor cells (CTCs) by multiparameter immunofluorescence (IF) microscopy allows non-invasive characterization of cancer cell biomarker expression in real time. This information can be helpful in prognosis, treatment selection, and stratification of cancer patients. AccuCyte® is a density-based unbiased isolation method that transfers nucleated cells from whole blood to slides for the characterization of CTCs and other rare cells. RarePlex® panel kits are IF staining reagents used on automated slide staining instruments to label cells to differentiate CTCs from white blood cells (WBC). CyteFinder® is a seven-channel automated fluorescent imaging system that rapidly scans microscope slides and applies machine learning algorithms to identify CTCs. Together, these technologies provide an end-to-end solution for CTC characterization. For analysis, blood is drawn into AccuCyte blood collection tubes (BCTs) containing a preservative which maintains cell properties prior to processing onto slides. Once slides are prepared, they can be stored at -20°C without significant biomarker degradation. This flexible workflow allows investigators to bank samples for batch analysis and to begin sample collection prior to validating the IF assay to be used. This study was designed to evaluate: (1) stability time between collection in the AccuCyte BCT and sample processing; (2) performance of an improved version of the AccuCyte kit with higher nucleated cell isolation capacity; and (3) storage time that AccuCyte prepared slides can be banked frozen prior to staining. The study was performed using model CTCs and cancer patient samples. Metrics to determine performance were CTC recovery and mean fluorescence intensity (MFI) of biomarker expression. Our results demonstrate that the AccuCyte BCT preserves blood components for at least 5 days after collection without significant effect on CTC recovery or biomarker expression. The latest version of the AccuCyte kit demonstrated a higher cell isolation capacity and could collect up to 60% more nucleated blood cells than the previous version, increasing CTC recovery. The increased capacity was demonstrated in patients treated with hematopoietic growth factors, whose WBC count was significantly higher than the normal range. Finally, accelerated-aging study results demonstrated that AccuCyte-prepared slides can be stored at -20°C for at least 4 years without significant effect on most biomarkers tested. In conclusion, enhancements to the AccuCyte-CyteFinder platform reported here increase flexibility and performance for analysis of CTCs in global clinical trials by allowing longer periods of time before collected blood samples need to be processed and by extending the length of time processed slides can be banked before they are stained. Citation Format: Arturo B. Ramirez, Lillian Costandy, Brady S. Gardner, Ryan H. Huston, A Anders Larson Tevis, Casey E. Helmicki, Alisa C. Clein, Daniel E. Sabath, Joshua J. Nordberg, Tad C. George. Validation of enhanced performance of the AccuCyte®-CyteFinder® platform for circulating tumor cell characterization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1952.

Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14–labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.

Objectives To compare the accuracy and reliability of phenotypic activated protein C resistance (aPC-R) assays with a genotypic assay for the factor V Leiden F5 p.R506Q (FVL) mutation. Methods Data were obtained from an electronic data warehouse for FVL testing performed at an academic institution with a large referral laboratory service. In total, 1,596 patients were identified who had undergone both phenotypic aPC-R and genotypic FVL mutation testing. Results Phenotypic testing showed a high level of sensitivity, specificity, and other biostatistical values compared with genotypic testing. Improvements in technology decreased the amount of equivocal phenotypic results. Conclusions Phenotypic assays had close to total concordance with genotypic assays over 16 years of testing. Changing ordering practices could result in up to an 80% reduction in testing costs.

Protein expression of synaptophysin (SYP) is characteristic of neuroendocrine subtype tumors. In prostate cancer, neuroendocrine differentiation is correlated with disease progression, poor prognosis, and treatment resistance. Analysis of circulating tumor cells (CTCs) by multiparameter immunofluorescence (IF) microscopy allows non-invasive characterization of cancer cell biomarker expression in real time. This information can be helpful in prognosis, treatment selection, and patient stratification. Here we describe the validation of a biomarker IF assay for enumeration of CTCs and characterization of their SYP expression. The 0920-VB SYP CTC assay workflow includes processing blood samples to slides (AccuCyte® Sample Preparation System), staining slides with a panel of fluorescent markers (RarePlex® Staining Kit and Ventana® DISCOVERY® ULTRA immunostaining system), and multiparameter imaging and analysis (CyteFinder® Instrument). The panel consists of a nuclear dye, and antibodies against cytokeratins and EpCAM (to identify epithelial CTCs), CD45 (to exclude white blood cells) and SYP. Both clinical and spike-in samples were used for assay validation. The model CTCs used to generate spike-in samples included 22Rv1 (prostate carcinoma, SYP positive) and BT-474 (breast carcinoma, SYP negative). Performance metrics for the assay included accuracy, sensitivity, specificity, repeatability, and intermediate precision of SYP detection and CTC enumeration. Single-cell SYP mean fluorescence intensities (MFI) were analyzed to determine protein expression levels. An MFI threshold for SYP positivity was established by maximizing the classification accuracy of the positive and negative cell lines. Using this threshold, 98.7% of 22Rv1 cells were correctly classified as SYP-positive, and 99.7% of BT474 cells were correctly classified as SYP-negative with an inter-run coefficient of variation of 13.9% for the 22Rv1 cell line. In clinical prostate, breast and colon cancer patient samples, subsets of CTCs were found to be SYP positive with the expected cytoplasmic localization of the marker. In summary, this liquid biopsy assay provides an analytically sensitive and specific method for CTC enumeration and SYP biomarker expression analysis, allowing non-invasive detection of neuroendocrine differentiation. Citation Format: Jennifer Chow, A Anders Tevis, Edward Lo, Alisa Clein, Daniel E. Sabath, Arturo B. Ramirez, Eric P. Kaldjian, Tad George. Liquid biopsy for neuroendocrine differentiation: Validation of a circulating tumor cell assay for synaptophysin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 600.

Objectives To describe the use of molecular diagnostic techniques for patients with hemoglobin disorders. Methods A clinical scenario is presented in which molecular diagnosis is important for genetic counseling. Globin disorders, techniques for their diagnosis, and the role of molecular genetic testing in managing patients with these disorders are described in detail. Results Hemoglobin disorders, including thalassemias and hemoglobinopathies, are among the commonest genetic diseases, and the clinical laboratory is essential for the diagnosis of patients with these abnormalities. Most disorders can be diagnosed with protein-based techniques such as electrophoresis and chromatography. Since severe syndromes can result due to inheritance of combinations of globin genetic disorders, genetic counseling is important to prevent adverse outcomes. Protein-based methods cannot always detect potentially serious thalassemia disorders; in particular, α-thalassemia may be masked in the presence of β-thalassemia. Deletional forms of β-thalassemia are also sometimes difficult to diagnose definitively with standard methods. Conclusions Molecular genetic testing serves an important role in identifying individuals carrying thalassemia traits that can cause adverse outcomes in offspring. Furthermore, prenatal genetic testing can identify fetuses with severe globin phenotypes.

Burkitt lymphoma (BL) is a highly aggressive, B cell non-Hodgkin lymphoma (NHL) that is rare outside Africa. We report a case of HIV-associated BL originating in the right maxillary sinus in a 31-year-old Hispanic male living in Washington, USA. We also highlight the diagnostic challenges in arriving at the diagnosis when the patient initially presented with a painless right facial swelling. Rapid diagnosis and treatment are critical because BL is one of the fastest-growing tumors. Treatment involves brief duration of high intensity chemotherapy and central nervous system prophylaxis. It is important for oral and maxillofacial surgeons to recognize this disease and understand the necessary steps to treat this aggressive tumor. Keywords: Burkitt lymphoma, Lymphoma, Human immunodeficiency virus, Maxillary sinus, Cervical lymph node

Thalassemia is among the most common genetic diseases worldwide. α-Thalassemia is usually caused by deletion of one or more of the duplicated HBA genes on chromosome 16. In contrast, most β-thalassemia results from point mutations that decrease or eliminate expression of the HBB gene on chromosome 11. Deletions within the HBB locus result in thalassemia or hereditary persistence of fetal Hb. Although routine diagnostic testing cannot distinguish thalassemia deletions from point mutations, deletional hereditary persistence of fetal Hb is notable for having an elevated HbF level with a normal mean corpuscular volume. A small number of deletions accounts for most α-thalassemias; in contrast, there are no predominant HBB deletions causing β-thalassemia. To facilitate the identification and characterization of deletions of the HBA and HBB globin loci, we performed array-based comparative genomic hybridization using a custom oligonucleotide microarray. We accurately mapped the breakpoints of known and previously uncharacterized HBB deletions defining previously uncharacterized deletion breakpoints by PCR amplification and sequencing. The array also successfully identified the common HBA deletions --(SEA) and --(FIL). In summary, comparative genomic hybridization can be used to characterize deletions of the HBA and HBB loci, allowing high-resolution characterization of novel deletions that are not readily detected by PCR-based methods.

Enumeration and phenotypic profiling of circulating tumor cells (CTCs) can give important information about tumor progression, presence of therapeutic targets, and metastatic potential. New and informative cancer-specific biomarkers are being discovered at a rapid pace, so there is a strong need for tools that enable investigator driven assays to best study and utilize these biomarkers. Through the RareCyte platform, we provide sensitive and specific assays that are optimized and validated for CTC enumeration and biomarker expression. RarePlex Developer Kits enable the addition of user-selected antibodies against biomarkers of interest to a CTC detection assay. Here we demonstrate the application of RarePlex Developer Kits to study the presence of a variety of cancer related biomarkers. Using the Developer strategy, we present results for several biomarkers, including HER2, ER, PR, EGFR, Ki67, AR, ARv7, PDL1, and PSMA. We also characterized clinical samples from prostate (AR and ARv7) and breast (HER2 and ER) cancer patients. The biomarkers demonstrated proper localization on or within model CTC control cells when using default antigen retrieval and fixation conditions. For each biomarker, fluorescence intensity cut-offs that segregated negative and positive cell lines were statistically defined to maximize classification accuracy. For clinical samples, breast and prostate cancer sample staining showed expected localization based on available clinical information. In conclusion, RarePlex Developer Kits provide a flexible tool for custom CTC assay development that enables researchers to develop assays in their own lab for characterization of phenotypic heterogeneity. Citation Format: Edward Lo, Daniel Campton, Arturo Ramirez, Lillian Costandy, Brady Gardner, Ryan Houston, Heather Itamoto, Jeffery L. Werbin, VK Gadi, Tanisha Mojica, Alisa Clein, Celestia Higano, Daniel E. Sabath, Eric P. Kaldjian, Tad George. Investigation of custom biomarkers on circulating tumor cells from clinical samples using RarePlex® Developer Kits [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6442.

Circulating tumor cells (CTCs) can provide information on drug target expression, response to therapy, and disease prognosis from a non-invasive blood draw. Currently, investigating biomarkers on CTCs is difficult due to challenges of developing multiplexed assays that also identify rare cells. Presence of the androgen receptor splice variant ARv7 in prostate cancer cells is associated with resistance to second generation anti-androgen therapies. We report here the analytical validation of an immunofluorescence assay for characterization of ARv7 protein expression on CTCs using the RareCyte platform - an end-to-end platform that combines CTC sample preparation, multiparameter fluorescence staining, digital imaging, and single cell retrieval. Blood samples spiked with positive and negative cell lines for ARv7 expression were processed using the AccuCyte Sample Preparation System. Slides were auto-stained by immunofluorescence with the RarePlex ARv7 CTC Panel Kit comprised of a three-channel CTC detection base plus an ARv7 biomarker channel. The detection base consists of a nuclear dye, anti-CD45 antibody to exclude white blood cells, and cocktailed antibodies to cytokeratin (CK) and epithelial cell adhesion molecule (EpCAM). Stained slides were imaged with the CyteFinder Instrument. CTCs were identified using machine learning-based algorithms and confirmed by user review. Mean fluorescence intensity (MFI) measurements were used as a metric for ARv7 expression on confirmed CTCs. Analytic validation studies of the AR-V7 CTC assay were performed using 22RV1 (high), LNCaP (low), and BT-474 (negative) cell lines. Performance characteristics tested for ARv7 included accuracy, sensitivity, specificity, repeatability, and inter-stainer run coefficient of variation. Performance metrics for CTC recovery were calculated on spike-in and clinical samples. For recovery calculations, the number of CTCs found with the ARv7 assay was compared to the number of CTCs found with the CTC detection base assay. An ARv7 MFI threshold that segregated negative and positive cell lines was statistically defined. This threshold identified 80% of 22RV1 cells as positive for ARv7, 97% of BT-474 cells as negative, with an overall accuracy of 90%. When the assay was applied to clinical prostate cancer samples, staining with proper nuclear localization was observed. CTC recovery was at least as high with the ARv7 assay as with the base CTC detection assay. Citation Format: Daniel Campton, Edward Lo, Lillian Costandy, Brady Gardner, Ryan Houston, Jeffery L. Werbin, Kyla Teplitz, Daniel E. Sabath, Alisa C. Clein, Celestia S. Higano, Tanisha M. Mojica, Kristin Province, Eric P. Kaldjian, Arturo B. Ramirez, Tad George. Analytic validation of an assay to detect androgen receptor splice variant ARv7 protein expression on circulating tumor cells from prostate cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5384.

There is increasing interest in sequence analysis of circulating tumor cells (CTCs) to identify actionable mutations that may complement circulating tumor DNA (ctDNA) findings. Because the amount of DNA present in a single cell is miniscule (~6 pg), whole genome amplification (WGA) is typically performed prior to next generation sequencing (NGS) library preparation. Existing WGA methods have inherent amplification biases leading to non-uniform genome coverage that can cause dropout of desired targets, as well as replication errors that can lead to false positive results. Targeted sequencing is an alternative approach that does not require WGA. We modified the CleanPlex® OncoZoom® Cancer Hotspot Panel protocol to perform targeted sequencing of single CTCs isolated by the RareCyte platform using A549 cell line spike-in and patient samples. We also used the CleanPlex panel to evaluate ctDNA from plasma isolated by blood collection tubes from two manufacturers (RareCyte and Streck). In both cases we compared OncoZoom results with and without prior WGA. Increased uniformity of coverage with decreased target dropout was observed when CleanPlex NGS libraries were prepared directly from cell lysates without WGA. Median read depth increased 48-fold when compared to the WGA method. On average, 23 out of 29 (79%) variants present in bulk A549 genomic DNA were observed without WGA in single model CTCs, while 15 of 29 (52%) were observed after WGA. Additionally, the false positive error frequency of non-WGA samples was 8-fold lower than in the WGA samples. CTCs and cell-free DNA from two metastatic breast cancer patients were also sequenced using OncoZoom. In one patient, PIK3CA E542K, a well-documented oncogenic mutation, was observed in 3 of 5 CTCs. In the other, ERBB2 L755S, a known HER2-reactivating mutation associated with chemoresistance, was found in 3 of 5 CTCs. Both patients' variants were present at similar allelic frequencies in plasma isolated from RareCyte and Streck cell-free DNA BCT tubes. Single-cell CleanPlex amplicon-based sequencing without prior WGA resulted in libraries with more complete and consistent coverage and lower error frequencies, enabling efficient and accurate assessment of somatic mutations in CTCs. This approach shows promise for cell-based liquid biopsy diagnostic applications. Citation Format: Nolan G. Ericson, Vidushi Kapoor, Guoying Liu, Alisa C. Clein, Daniel E. Sabath, Eric P. Kaldjian, Tad George. A direct amplicon-based targeted sequencing assay for mutation analysis of single circulating tumor cells and correlation with circulating tumor DNA [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5363.

This commentary highlights the article by Kim et al that suggests use of two different next-generation sequencing-based assays for detection of fusion RNAs in patients with acute leukemia.

Chronic fatigue syndrome (CFS) is characterized by prolonged fatigue and other physical and neurocognitive symptoms. Some studies suggest that CFS is accompanied by disruptions in the number and function of various lymphocytes. However, it is not clear which lymphocytes might influence CFS symptoms.To determine if patient reported fatigue symptoms and physical functioning scores significantly changed across time with lymphocyte counts as evidence of a relation among chronic fatigue symptoms and the immune response.The current longitudinal, naturalistic study assessed the cellular expression of three lymphocyte subtypes -- natural killer (NK) cells (CD3-CD16+ and CD3-CD56+) and naïve T cells (CD4+CD45RA+) -- to determine whether changes in lymphocytes at 4 time points across 18 months were associated with clinical outcomes, including CFS symptoms, physical functioning, and vitality, among patients with chronic fatigue.. Latent growth curve models were used to examine the longitudinal relationship between lymphocytes and clinical outcomes.Ninety-three patients with Fukuda-based CFS and seven with non-CFS fatigue provided study data. Results indicated that higher proportions of naïve T cells and lower proportions of NK cells were associated with worse physical functioning, whereas higher proportions of NK cells (CD3-CD16+) and lower proportions of naïve T cells were associated with fewer CFS symptoms.These findings suggest that lymphocytes are modestly related to clinical outcomes over time.

The goal of cancer therapy is to eliminate all cancer cells in a patient by surgery, radiation therapy, and/or chemotherapy. If residual cancer cells remain after therapy, the patient is more likely to have recurrent disease. Thus, detection of small amounts of residual cancer is predictive of relapse. Methods for detecting small amounts of cancer may include microscopy, cytogenetic studies, immunohistochemical or immunofluorescent staining, or sensitive molecular techniques. Although very sensitive methods are available to detect residual cancer, there is no agreement as to whether and how to treat patients with minimal residual disease.

Viscoelastic testing to assess the overall clotting ability of a patient’s whole blood, such as thromboelastography (TEG), has risen in popularity over the past several years due its holistic assessment and rapid turnaround time, most notably in the realm of liver transplants and complex cardiac surgery. In the setting of trauma and assessing the concomitant coagulopathy, the rapid turnaround time and ability to assess for hyperfibrinolytic states had led to it being requested at our institution despite variable result interpretation and lack of reproducibility in previous studies. In response, our institution’s laboratory made this available at our hospital, which includes a large level 1 trauma center serving multiple states, with the aim of reassessing its utility after a 1-year period. Following the first year of use, data that were evaluated included TEG values and conventional laboratory testing temporally associated with the TEG order, including platelet count and fibrinogen level. Retrospective chart review was also performed to determine indication and context of testing, as well as for assessment of resulting interventions. Seventy-three samples from 58 patients were tested during the 1-year period, 30 of whom were admitted for trauma and 20 of whom were evaluated during the critical initial acute resuscitation period. Among the trauma patients, the majority of TEG samples (75.6%) did not demonstrate any abnormality. A primary reason cited by trauma surgeons for the need for TEG was its ability to accurately identify states of hyperfibrinolysis to determine the need for therapeutic agents such as tranexamic acid. In this regard, no evidence of hyperfibrinolysis was identified in any of the trauma patients. In fact, only a single hyperfibrinolytic sample was identified, corresponding to a nontrauma patient who had received a thrombolytic agent (alteplase) prior to TEG testing. Additionally, 75% of acute trauma patients received tranexamic acid, which was nearly always administered prior to the TEG sample being drawn. No evidence of TEG results affecting patient management was identified. As a result of the retrospective review of the data, use of TEG in the trauma population at our institution dramatically declined. We present this institutional review as an example of performing data review to influence test utilization practices.

Background. RareCyte has developed platform technology for visual identification and single cell retrieval of rare cells in blood, including circulating tumor cells (CTCs). There is increasing interest in mutational analysis of circulating tumor cells (CTCs) as a liquid biopsy application. Because of the minuscule amount of DNA present in a single cell (~6 pg), whole genome amplification (WGA) is typically performed prior to next generation sequencing (NGS) library preparation. Existing WGA methods have inherent amplification biases leading to non-uniform genome coverage that can cause dropout of desired targets, as well as elevated error rates that can lead to false positive mutations. Amplicon-based next generation sequencing (abNGS) is a high-throughput method which enables genetic confirmation of malignancy and discovery of de novo pathogenic mutations. Here we present a method for performance of single cell abNGS on model CTCs without prior WGA using a commercially available pan-cancer hotspot panel. Methods. A549 lung cancer cells as model CTCs (mCTCs) were spiked into whole blood, which was processed by AccuCyte® separation onto slides. After formalin fixation, multi-parameter immunofluorescence and automated imaging (CyteFinder®) were used to identify CTCs - visualized as nucleated cells expressing epithelial markers (cytokeratin or EpCAM) and not expressing white blood cell markers. mCTCs were mechanically retrieved by CytePicker® into PCR tubes and either amplified by WGA (PicoPLEX®) or lysed in a PCR-compatible lysis buffer. WGA products or cell lysates were used as template for the AmpliSeq™ Cancer HotSpot Panel v2 for Illumina® library preparation; additional PCR cycles were added during target amplification to compensate for low DNA input in the non-WGA samples. Libraries were sequenced on an Illumina MiSeq and analyzed using the BaseSpace bioinformatics suite. Results. Single mCTCs that underwent amplicon-based NGS library prep direct from cell lysate (non-WGA) displayed increased uniformity of coverage with decreased target dropout when compared to WGA cells. Median read depth increased 7-fold with the non-WGA method. On average, 8 of 15 variants present in bulk A549 genomic DNA were observed in single mCTCs sequenced after WGA, while 12 out of 15 were observed with the non-WGA method. Additionally, the false positive error frequency of non-WGA samples was < 5% of the WGA samples. The non-WGA method was applied to CTCs identified in blood from a prostate cancer patient and confirmed presence of PTEN and TP53 mutations identified by cell-free DNA analysis. Conclusions. Amplicon-based targeted single-cell sequencing without prior WGA resulted in libraries with more complete and consistent coverage and lower error frequencies, enabling efficient and accurate assessment of somatic mutations in CTCs. Citation Format: Nolan G. Ericson, Arturo B. Ramirez, Alisa C. Clein, Celestia S. Higano, Daniel E. Sabath, Eric P. Kaldjian. Targeted single cell DNA sequencing without prior whole genome amplification for mutational analysis of circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 439.

Background. The presence and number of circulating tumor cells (CTCs) are prognostic for breast cancer treatment outcome. Direct imaging assays traditionally employ four markers to identify canonical epithelial CTCs: nucleus, exclusion (CD45), and inclusion (EpCAM and cytokeratin). There is intense interest in the ability to phenotype CTCs in order to provide a noninvasive means by which to predict treatment benefit from endocrine therapy and/or HER2-directed therapy in breast cancer. To address this, a 6-parameter assay for detection of ER and HER2 expression on CTCs was developed. We applied this assay to four well characterized breast cancer cell lines representative of various ER and HER2 phenotypes. Methods. BT474, MCF-7, SKBR3, or MDA-MB-231 cells were spiked into peripheral blood from healthy donors and processed using the AccuCyte® sample preparation system; nucleated cells, including CTCs, are captured onto glass slides (8 slides per 7.5 mL blood sample) for subsequent immunofluorescent staining. Slides were stained using the combined epithelial marker and ER/HER2 CTC assay and then analyzed with the CyteFinder® imaging system. CTCs were identified as nucleated cells with positive EpCAM and/or cytokeratin staining, and negative CD45 staining. ER and HER2 expression were assessed as present or absent. Results. All cell lines expressed both cytokeratin and EpCAM, except for MDA-MB-231 which was EpCAM-negative. The ER / HER2 expression patterns observed were consistent with reported phenotype: BT474 (+/+), MCF-7 (+/–), SKBR3 (–/+), and MDA-MB-231 (–/–). Conclusions. Identification of epithelial CTCs and phenotypic characterization of ER and HER2 status are feasible in a combined assay applied to a single blood sample. This approach has implications for efficiency and cost effectiveness, which are of particular importance given the interest in longitudinal testing. Assay evaluation is currently underway using blood samples from breast cancer patients with known receptor status, treatment history, and clinical outcomes. Results will be available for presentation at the meeting. Citation Format: Liu MC, Sun Y, Ramirez A, Campton D, George T, Haselkorn KE, Clein A, Gadi V, Sabath D, Kaldjian E. A novel six-parameter assay for comprehensive phenotyping of circulating tumor cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-11.

Recurrent mutations in JAK2 and MPL genes are genetic hallmarks of BCR-ABL1–negative myeloproliferative neoplasms. Detection of JAK2 and MPL mutations has been incorporated into routine diagnostic algorithms for these diseases. This Special Article summarizes results from a nationwide laboratory survey of JAK2 and MPL mutation analysis. Based on the current practice pattern and the literature, this Special Article provides recommendations and guidelines for laboratory practice for detection of mutations in the JAK2 and MPL genes, including clinical manifestations for prompting the mutation analysis, current and recommended methodologies for testing the mutations, and standardization for reporting the test results. This Special Article also points to future directions for genomic testing in BCR-ABL1–negative myeloproliferative neoplasms.

Enumeration of circulating tumor cells (CTCs) has proved valuable for early detection and prognosis in cancer treatment. This paper describes an automated high-throughput counting method for CTCs based on microfluidics and line-confocal microscopy. Peripheral blood was directly labeled with multiple antibodies, each conjugated with a different fluorophore, pneumatically pumped through a microfluidic channel, and interrogated by a line-confocal microscope. On the basis of the fluorescence signals and labeling schemes, the count of CTCs was automatically reported. Due to the high flow rate, 1 mL of whole blood can be analyzed in less than 30 min. We applied this method in analyzing CTCs from 90 stage IV breast cancer patient samples and performed a side-by-side comparison with the results of the CellSearch assay, which is the only method approved by the U.S. Food and Drug Administration at present for enumeration of CTCs. This method has a recovery rate for cultured breast cancer cells of 94% (n = 9), with an average of 1.2 counts/mL of background level of detected CTCs from healthy donors. It detected CTCs from breast cancer patients ranging from 15 to 3375 counts/7.5 mL. Using this method, we also demonstrate the ability to enumerate CTCs from breast cancer patients that were positive for Her2 or CD44(+)/CD24(-), which is a putative cancer stem cell marker. This automated method can enumerate CTCs from peripheral blood with high throughput and sensitivity. It could potentially benefit the clinical diagnosis and prognosis of cancer.

Composite lymphoma is a rarely reported entity, defined as two or more morphologically distinct types of lymphoma at the same anatomic site, occurring either synchronously or metachronously. Since 1978, about 100 case reports of composite lymphoma have been cited, many involving combinations of low-grade B-cell lymphomas. To our knowledge, no cases of large-cell transformation of composite lymphoma have yet been described. We report the case of a patient who presented with diffuse large B-cell lymphoma (DLBCL) fifteen years after successful treatment for a mature B-cell lymphoma. Reassessment of the patient's lymph node from 1995, using techniques not previously available, resulted in a revised diagnosis of composite lymphoma, comprising both follicular lymphoma (FL) and small lymphocytic lymphoma (SLL). Analysis of B-cell gene rearrangement studies using BIOMED-2-based PCR, and of t(14;18) rearrangements by both FISH and PCR, provided evidence that the DLBCL evolved from transformation of the composite lymphoma, specifically from its FL component. B-cell gene rearrangement studies also supported a clonal relationship between the FL and SLL components of the composite lymphoma.

Background. Androgen receptor (AR) signaling is the primary driver of prostate cancer. Expression of the AR splice variant AR-V7, is predictive of resistance to anti-androgen therapies enzalutimide and abiratirone. There is great interest to non-invasively identify circulating tumor cells (CTCs) and investigate their expression of AR and AR-V7 and monitor them over time. RareCyte has developed a platform for automated visual identification of CTCs by immunofluorescence (IF) that allows up to 6-parameter assessment. We have developed a set of prototype assays using tyramide amplification to detect AR and AR-V7 individually and in combination with prostate membrane-specific antigen (PSMA). Using a novel method, we also developed an assay to identify AR and AR-V7 simultaneously. Methods. Normal human whole blood samples were spiked with prostate cancer lines serving as model CTCs (mCTCs). Prostate cancer blood from a patient with advanced and known high CTC count were collected under an IRB-approved protocol. Blood was processed onto microscope slides and stained on an automated stainer with CTC detection assays incorporating 4 core parameters (nuclear dye, CD45, pan-cytokeratin, EpCAM) plus the following markers: (1) AR; (2) AR-V7; (3) AR and PSMA; (4) AR-V7 and PSMA; (5) AR and AR-V7. Each assay was applied to the cancer cell lines PC3, LNCaP, and 22RV1 and to the patient sample. An antibody denaturing process was used to sequentially amplify two rabbit monoclonals for the assay containing both AR and AR-V7. No-primary (diluent only) staining controls were run to confirm success of the denaturing step. Results. Staining of spike-in CTC models confirmed the reported AR and AR-V7 phenotype of the cell lines, supporting the specificity of the assays. When applied to an equivalent volume of the patient sample, the assays identified a mean (SD) of 36 (11) CTCs. In the assays staining AR, the mean percent of AR+ CTCs was 70% (range 61 - 86) and for the assays staining AR-V7, the percent of AR-V7+ CTCs was 30% (range 26 - 39). In the assay staining both AR and AR-V7, 10 of 38 CTCs were AR-V7+ (26%); all of these were AR+; 15 CTCs were only AR+ (39%). Conclusions. We have developed multi-parameter IF assays for detection of AR and AR-V7 in prostate CTCs, including the first assay we are aware of to simultaneously visualize AR and AR-V7. It has been validated in prostate cancer CTC models. The percentages of AR and AR-V7-positive CTCs identified in a patient sample with the assay are consistent with the percentages observed when AR and AR-V7 are detected in independent assays, supporting the accuracy of the simultaneous detection assay. All AR-V7-positive CTCs were also AR-positive, supporting specificity of AR-V7 staining. Citation Format: Yao Sun, Daniel Campton, Arturo Ramirez, Tanisha Mojica, Alisa Clein, Celestia Higano, Daniel Sabath, Stephen Plymate, Eric Kaldjian. Development of a multi-parameter immunofluorescence assay for simultaneous detection of androgen receptor and androgen receptor variant 7 in prostate cancer circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5230.

Background. The epithelial-mesenchymal transition (EMT) is understood to be an important step in invasion and metastasis of cancer. It is of increasing investigational interest to identify circulating tumor cells (CTCs) that express mesenchymal markers that indicate entrance into EMT. Such cells may not express surface epithelial markers (such as EpCAM) that are often used to capture CTCs. RareCyte has developed a platform for automated visual identification and retrieval of rare cells in blood by immunofluorescence (IF) that does not rely on surface marker capture. We developed a 5-parameter assay to identify epithelial CTCs with or without mesenchymal differentiation. Methods. Buffy coats isolated from blood by AccuCyte® separation were spread onto slides. A 5-parameter IF assay was developed with the following markers: Sytox orange (nuclear dye) / cytokeratin and EpCAM (epithelial) / vimentin (mesenchymal) / CD45, CD11b and CD105 (exclusion) / EGFR (investigational biomarker). Slides were stained with the assay on an auto-stainer, and were scanned and imaged with CyteFinder®. Specificity of the assay was validated on positive and negative control cell lines spiked into normal donor blood. It was applied to a pilot set of blood samples from 3 prostate and 3 breast cancer patients that were collected under an IRB-approved protocol. Nucleated cells that were epithelial marker-positive and exclusion marker-negative were identified as CTCs. CTCs were categorized as epithelial (epiCTC) if they were vimentin-negative and epithelial-mesenchymal (E-M) if they were vimentin-positive. In a sample from a patient with known mutation in TP53 (G244S) from tissue tumor analysis, individual epiCTCs, E-M CTCs and WBC control cells were mechanically retrieved by CytePicker® and whole genome amplification was performed. The resulting DNA was PCR amplified at the TP53 mutation site and sequenced. Results. Between 15 and 193 CTCs were counted in the patient samples. The average percentage of epiCTCs was 74% (range 33 - 100%) and of E-M CTCs was 26% (range 0 - 67%). E-M CTC fraction was higher in breast than in prostate cancer samples. EGFR-positive epiCTCs and E-M CTCs were identified. In the patient with the tumor-associated TP53 G244S mutation, 2 of 2 epiCTC, 6 of 7 E-M CTC and 0 of 6 WBC contained the mutation. Conclusions. We have developed a multi-parameter immunofluorescence assay for identification of circulating tumor cells with epithelial-mesenchymal phenotype and applied it to cancer patient samples. Confirmation of malignancy of epiCTCs and E-M CTCs by single cell mutational analysis was demonstrated. The expression of EGFR on CTCs in prostate and breast cancer confirms literature reports. Citation Format: Arturo Ramirez, Nolan Ericson, Daniel Campton, Melinda Duplessis, Tanisha Mojica, Alisa Clein, Celestia Higano, VK Gadi, Daniel E. Sabath, Eric Kaldjian. Development of a multi-parameter immunofluorescence assay for identification of circulating tumor cells with epithelial-mesenchymal phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5190.

Background: Canonical methods for CTC identification (such as CellSearch®) have typically relied on co-expression of surface (EpCAM) and cytoplasmic (cytokeratin, CK) epithelial markers to separate them from white blood cells. RareCyte has developed AccuCyte®-CyteFinder®, a platform for automated visual identification and retrieval of rare cells in blood by immunofluorescence (IF). For CTC detection, EpCAM and CK are placed in individual fluorescence channels, allowing for identification of CTCs that may be EpCAM(-) /CK(+) as well as EpCAM(+)/CK(-). Recently we have developed technology that increases the number of markers from 4 to 6 to allow for biomarker phenotypic analysis in the additional two channels. Given that our platform does not require co-expression of EpCAM and CK, we hypothesized that we could gain a third biomarker channel by combining detection reagents for EpCAM and CK into a cocktail within a single channel. We tested feasibility of epithelial marker cocktailing with an assay to detect androgen receptor (AR) in prostate CTCs. Methods: Normal human whole blood samples were spiked with prostate cancer lines PC3, LNCaP, and 22RV1 as model CTCs (mCTCs). Blood samples from University of Washington patients with advanced cancer were collected under an IRB-approved protocol. Blood was processed onto microscope slides and stained on an automated stainer using a CTC assay for detection of AR in which anti-cytokeratin and anti-EpCAM antibodies were combined in a reagent cocktail into a single channel; the CD45 WBC marker and a nuclear dye were included in the assay. After development using spike-in models, the assay was applied to a patient sample. Results: No CTCs were identified in non-spiked normal donor blood samples. In spike-in models, the epithelial cocktail assay performed as well as the non-cocktail assay in identifying CTCs. AR fluorescence signal was present in LNCaP and 22RV1 mCTCs (which express AR) and absent in PC3 mCTCs (which do not express AR), confirming specificity of AR staining. When the assay was applied to a blood sample from a prostate cancer patient with known high CTC count, 160 CTCs per mL were identified; of these, 114 were observed to be AR-positive (71%). Conclusions: Combining the epithelial markers cytokeratin and EpCAM into a single-wavelength cocktail is feasible for IF identification of CTCs, allowing an additional channel for phenotypic investigation. In a patient with advanced prostate cancer with high CTC count, there was high incidence (71%) of AR expression in identified CTCs. Citation Format: Yao Sun, Arturo Ramirez, Daniel Campton, Tanisha Mojica, Alisa Clein, Celestia Higano, Daniel Sabath, Eric Kaldjian. Increased phenotypic depth for automated visual identification of biomarkers on circulating tumor cells by cocktailing epithelial markers EpCAM and cytokeratin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1561.

Improved methods for diagnosing small B-cell lymphomas (SBCLs) and predicting patient response to therapy are likely to result from the ongoing discovery of molecular markers that better define these malignancies. In this report, we identify 120 genes whose expression patterns differed between reactive lymph node tissue and three types of SBCL: follicular lymphoma, mantle cell lymphoma, and chronic lymphocytic leukemia/small lymphocytic lymphoma. Whereas previously published studies have generally analyzed the gene expression profiles of one type of SBCL, work presented in this paper was intended to identify genes that are differentially expressed between three SBCL subtypes. This analysis was performed using mRNA pooled from multiple specimens representing each tissue type. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to validate the differential expression of 23 of these genes. Among the 23 validated genes were cyclin D1 (CCND1) and B-cell CLL/lymphoma 2, which have well-known roles in lymphoma pathogenesis. The remaining 21 genes have no currently established role in lymphoma development. Using qRT-PCR, the expression of CCND1 and seven additional genes was further studied in a panel of individual specimens. Genes identified in this study are of biological interest and represent candidate diagnostic markers.

Whether persons with multiple chemical sensitivity syndrome (MCS) have immunological abnormalities is unknown. To assess the reliability of selected immunological tests that have been hypothesized to be associated with MCS, replicate blood samples from 19 healthy volunteers, 15 persons diagnosed with MCS, and 11 persons diagnosed with autoimmune disease were analyzed in five laboratories for expression of four T-cell surface activation markers (CD25, CD26, CD38, and HLA-DR) and in four laboratories for autoantibodies (to smooth muscle, thyroid antigens, and myelin). For T-cell activation markers, the intralaboratory reproducibility was very good, with 90% of the replicates analyzed in the same laboratory differing by ≤3%. Interlaboratory differences were statistically significant for all T-cell subsets except CD4 + cells, ranging from minor to eightfold for CD25 + subsets. Within laboratories, the date of analysis was significantly associated with the values for all cellular activation markers. Although reproducibility of autoantibodies could not be precisely assessed due to the rarity of abnormal results, there were inconsistencies across laboratories. The effect of shipping on all measurements, while sometimes statistically significant, was very small. These results support the reliability of fresh and shipped samples for detecting large (but perhaps not small) differences between groups of donors in the T-cell subsets tested. When comparing markers that are not well standardized, it may be important to distribute samples from different study groups evenly over time.

alpha-Thalassemia trait is the most common inherited abnormality worldwide. Diagnosis of alpha-thalassemia trait can be difficult as there are no abnormalities detectable by hemoglobin electrophoresis or high-performance liquid chromatography. Detection of individuals with alpha-thalassemia trait, particularly the type present in many Asian populations, is important for genetic counseling purposes, because these individuals are at risk for having offspring with hemoglobin Bart's hydrops fetalis, a fatal condition. The best routine diagnostic method to detect individuals with alpha-thalassemia trait is staining reticulocyte-enriched red cell preparations with brilliant cresyl blue to detect hemoglobin H inclusions. Current methods use centrifugation of microhematocrit tubes to enrich for reticulocytes, which presents a laboratory safety hazard. In this report, we describe an alternative technique to enrich for reticulocytes that does not require glass capillary tubes, but is as effective as the capillary tube method for reticulocyte enrichment and detection of cells containing hemoglobin H inclusions.

In this study, we evaluated the prognostic significance of multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF4) expression in B-cell chronic lymphocytic leukemia (B-CLL). Our results demonstrated that the absence of MUM1/IRF4 expression showed the highest relative risk among the factors analyzed in determining the probability for death in patients with B-CLL using univariate and multivariate Cox regression analysis. Patients without MUM1/IRF4 expression had significantly worse overall survival than did those with MUM1/IRF4 expression (52% cumulative survival, 63 months vs not reached, Kaplan-Meier survival analysis; P

Studies elsewhere have suggested that immune dysfunction may be common in patients with chronic fatigue syndrome (CFS). The objective of this study was to assess the nature and extent of abnormalities in lymphocyte cell surface markers and NK cell activity in patients with CFS while controlling for genetic factors. A co-twin control study of immune system parameters was conducted for 22 pairs of monozygotic twins discordant for CFS and 9 healthy pairs of twins. The CFS twins had greater numbers of CD62L(+) T cells in several T cell subsets, although these differences did not achieve statistical significance. Significantly greater variability was noted in twins discordant for CFS than in the concordant healthy twins for 20 of 48 variables examined. The monozygotic co-twin control design is of unique value because of its ability to control for genetic influences on CFS; however, additional studies will be required to further assess immune dysregulation in this illness.

Background: Baseline and post-treatment counts of circulating tumor cells (CTCs) are prognostic of patient outcome in cancer. The FDA-cleared CellSearch® system has defined CTC count as the number of cells per 7.5 mL of blood, with poor prognosis being 5 or more for breast and prostate cancers, and 3 or more for colon cancer. There are little reported data on whether it is reasonable to extrapolate CTC counts from smaller blood volumes, particularly when CTC count is low, given sampling variability. The AccuCyte - CyteFinder system (RareCyte) collects 7.5 mL of blood for analysis, isolates the buffy coat and smears it onto 8 slides, which are then stained with markers for CTCs that are identified by fluorescence microscopy. We investigated the statistical accuracy of extrapolation of total CTC count from fewer than 8 slides. Methods: 172 blood samples from various cancers were processed to microscope slides, stained, and analyzed by CyteFinder. Counts were made on a per slide basis, with total “true” CTC count being the sum of all 8 slides. Samples with no CTCs were excluded. To extrapolate the total CTC count from k slides, all possible combination of k slides were used to estimate the total count of 8 slides. This was done for k = 1-7 for all 172 samples and extrapolated counts were rounded to the nearest integer. The proportion of times that extrapolated counts fell within a specified percentage of the true CTC count was calculated across the entire sample set, as well as for 6 sub-categories defined by true CTC count range. Results: The 6 CTC count categories were: 1-4 (N=39), 5-10 (N=21), 11-25 (N=21), 26-50 (N=14), 51-100 (N=24), more than 100 (N=53). Cumulative proportions within 5, 10, 25 and 50% of the true total CTC count were determined for the entire sample set as well as by category. In the entire sample set, the proportion of extrapolated counts that fell within 25% of the true count ranged from 0.448 (1 slide) to 0.723 (4 slides) to 0.951 (7 slides). Generally, the lower the true total count, the lower the fraction of extrapolated counts that fell within the specified percentage of the true count. For example, for true count 5-10, the fraction that fell within 25% of the true count ranged from 0.208 (1 slide) to 0.513 (4 slides) to 0.951 (7 slides). In contrast, for true count more than 100, the fraction that fell within 25% of the true count ranged from 0.751 (1 slide) to 0.968 (4 slides) to 1.000 (7 slides). Conclusions: In this sample set, nearly three quarters of cases could be estimated within 25% of the true CTC count by extrapolating from 4 AccuCyte slides. Estimating each slide to represent ~1 mL of processed whole blood, our analysis suggests that a ~4 mL sample will have this level of accuracy relative to a CTC count from 7.5 mL. At low true CTC counts the accuracy of extrapolation decreases, indicating that a larger volume of blood is required for this level of accuracy. Citation Format: Jeffrey L. Werbin, Paulina Varshavskaya, Arturo B. Ramirez, Jackie L. Stilwell, Daniel E. Sabath, Ping-Yu Liu, Eric Kaldjian. Accuracy of extrapolation of circulating tumor cell count from small blood volumes: statistical estimation using the AccuCyte - CyteFinder system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1732. doi:10.1158/1538-7445.AM2017-1732

Background Circulating tumor cells (CTCs) are malignant cells that have migrated from solid cancers into the blood, where they are typically present in rare numbers. There is great interest in using CTCs to monitor response to therapies, to identify clinically actionable biomarkers, and to provide a non-invasive window on the molecular state of a tumor. Here we characterize the performance of the AccuCyte® – CyteFinder® system, a comprehensive, reproducible and highly sensitive platform for collecting, identifying and retrieving individual CTCs from microscopic slides for molecular analysis after automated immunofluorescence staining for epithelial markers. Methods All experiments employed a density-based cell separation apparatus (AccuCyte) to separate nucleated cells from the blood and transfer them to microscopic slides. After staining, the slides were imaged using a digital scanning microscope (CyteFinder). Precisely counted model CTCs (mCTCs) from four cancer cell lines were spiked into whole blood to determine recovery rates. Individual mCTCs were removed from slides using a single-cell retrieval device (CytePicker™) for whole genome amplification and subsequent analysis by PCR and Sanger sequencing, whole exome sequencing, or array-based comparative genomic hybridization. Clinical CTCs were evaluated in blood samples from patients with different cancers in comparison with the CellSearch® system. Results AccuCyte – CyteFinder presented high-resolution images that allowed identification of mCTCs by morphologic and phenotypic features. Spike-in mCTC recoveries were between 90 and 91%. More than 80% of single-digit spike-in mCTCs were identified and even a single cell in 7.5 mL could be found. Analysis of single SKBR3 mCTCs identified presence of a known TP53 mutation by both PCR and whole exome sequencing, and confirmed the reported karyotype of this cell line. Patient sample CTC counts matched or exceeded CellSearch CTC counts in a small feasibility cohort. Conclusion The AccuCyte – CyteFinder system is a comprehensive and sensitive platform for identification and characterization of CTCs that has been applied to the assessment of CTCs in cancer patient samples as well as the isolation of single cells for genomic analysis. It thus enables accurate non-invasive monitoring of CTCs and evolving cancer biology for personalized, molecularly-guided cancer treatment. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1383-x) contains supplementary material, which is available to authorized users.