John D Pfeifer

Washington University in St. Louis, San Luis, Missouri, United States

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Publications (127)439.48 Total impact

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    Dataset: mmc3
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    Dataset: mmc1
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    Dataset: mmc4
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    Dataset: mmc2
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although the presence of the t(12;22)(q13;q12) translocation (the defining molecular feature of malignant melanoma of soft parts/clear cell sarcoma) in cutaneous melanoma has been investigated, no large-scale studies have been performed among mucosal melanoma (MucM). In this study we assessed the prevalence of the EWSR1 rearrangement in primary MucM, and analyzed gross and microscopic features with their potential impact on diagnosis and prognosis. Overall, 132 specimens from 84 patients were included. A total of 55 cases had an intramucosal component. Survival of MucMs of the head and neck was associated with two independent factors: size and histology. Tumors more than 3 cm in greatest dimension had an average survival of 12.75 months; those 3 cm or less had an average survival of 38.3 months (P=0.035). Purely epithelioid tumors had an average worse survival of 16.8 months (P=0.028). A cut-off value of 1 mm for Breslow depth provided a statistically significant difference in survival at both 3 and 5 years (P=-0.02) by multivariate analysis in the gynecologic tract. At the molecular level three cases had a EWSR1 rearrangement by fluorescent in-situ hybridization, but only one with an intramucosal component. None of the 58 cases tested by PCR showed the presence of the EWSR1 rearrangement. With the exception of vulvar melanomas, the prognosis of mucosal-associated melanomas was poor and there was a suggestion that spindle morphology may be more favorable. Our study also showed that the EWSR1 rearrangement was very uncommon among MucM. Though 'clear cell sarcoma' is embedded in the sarcoma literature, the synonym 'melanoma of soft parts' has considerable justification in light of our evolving understanding of the molecular genetics in the family of malignant melanomas.
    Melanoma research. 05/2014;
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    ABSTRACT: The identification of recurrent gene rearrangements in the clinical laboratory is the cornerstone for risk stratification and treatment decisions in many malignant tumors. Studies have reported that targeted next-generation sequencing assays have the potential to identify such rearrangements; however, their utility in the clinical laboratory is unknown. We examine the sensitivity and specificity of ALK and KMT2A (MLL) rearrangement detection by next-generation sequencing in the clinical laboratory. We analyzed a series of seven ALK rearranged cancers, six KMT2A rearranged leukemias, and 77 ALK/KMT2A rearrangement-negative cancers, previously tested by fluorescence in situ hybridization (FISH). Rearrangement detection was tested using publicly available software tools, including Breakdancer, ClusterFAST, CREST, and Hydra. Using Breakdancer and ClusterFAST, we detected ALK rearrangements in seven of seven FISH-positive cases and KMT2A rearrangements in six of six FISH-positive cases. Among the 77 ALK/KMT2A FISH-negative cases, no false-positive identifications were made by Breakdancer or ClusterFAST. Further, we identified one ALK rearranged case with a noncanonical intron 16 breakpoint, which is likely to affect its response to targeted inhibitors. We report that clinically relevant chromosomal rearrangements can be detected from targeted gene panel-based next-generation sequencing with sensitivity and specificity equivalent to that of FISH while providing finer-scale information and increased efficiency for molecular oncology testing.
    The Journal of molecular diagnostics: JMD 05/2014; · 3.48 Impact Factor
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    ABSTRACT: Context.-Genomic medicine is revolutionizing patient care. Physicians in areas as diverse as oncology, obstetrics, and infectious disease have begun using next-generation sequencing assays as standard diagnostic tools. Objective.-To review the role of pathologists in genomic testing as well as current educational programs and future training needs in genomic pathology. Data Sources.-Published literature as well as personal experience based on committee membership and genomic pathology curricular design. Conclusions.-Pathologists, as the directors of the clinical laboratories, must be prepared to integrate genomic testing into their practice. The pathology community has made significant progress in genomics-related education. A continued coordinated and proactive effort will ensure a future vital role for pathologists in the evolving health care system and also the best possible patient care.
    Archives of pathology & laboratory medicine 04/2014; 138(4):498-504. · 2.78 Impact Factor
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    ABSTRACT: Precision medicine uses individually determined genomic information to guide treatment in cancer and other diseases. We have implemented a clinical genomics assay that uses targeted next-generation sequencing of 25 cancer-related genes to guide the use of targeted therapies in diverse malignancies. We report the case of a 55-year-old woman with a poorly differentiated squamous cell carcinoma of thymic origin, with disease progression after standard treatment. Targeted tumor sequencing revealed the presence of a KIT codon 579 deletion (p.D579del). This specific mutation has not previously been associated with thymic tumors, but has been reported in gastrointestinal stromal tumors and has been associated with response to imatinib. Imatinib therapy was instituted for and resulted in stabilization of disease. This case illustrates the potential of clinical next-generation sequencing to open unexpected avenues for treatment and thereby improve patient outcomes.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2014; 9(2):e12-6. · 4.55 Impact Factor
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    ABSTRACT: The microcystic elongated and fragmented (MELF) pattern of myoinvasion is a feature of some well-differentiated endometrial endometrioid adenocarcinomas that has been associated with poor prognosis. The myoinvasion in MELF-pattern tumors can be subtle and lead to underestimation of the depth of myometrial invasion resulting in tumor understaging; the presence of lymphvascular space invasion (LVSI) and lymph node metastasis in MELF-pattern tumors can also be subtle and lead to tumor understaging. To investigate the association of MELF-pattern invasion and lymph node metastasis, we reviewed a series of well-differentiated endometrioid adenocarcinomas and correlated the presence of MELF-pattern myoinvasion and LVSI with lymph node metastasis. Cases of T1 stage well-differentiated endometrioid adenocarcinomas with LVSI and a concurrent lymph node dissection were identified from departmental files. Hematoxylin and eosin-stained slides from the hysterectomy specimen and lymph nodes were reviewed for the presence of MELF-pattern myoinvasion, LVSI, and nodal metastasis. MELF-pattern myoinvasion was identified at least focally in 36% of cases. The pattern of LVSI differed between cases with MELF-pattern invasion and conventional-type invasion, as did the pattern of nodal metastasis. A statistically significantly higher rate of lymph node metastasis was present in cases with MELF-pattern invasion than in cases with conventional invasion, and the rate stratified with the proportion of MELF-pattern adenocarcinomas. MELF-pattern cases carry an increased rate of lymph node metastasis even within the subset of endometrioid tumors with LVSI, which has implications in routine clinical practice as it signals the importance of recognizing MELF-pattern myoinvasion.
    International journal of gynecological pathology: official journal of the International Society of Gynecological Pathologists 01/2014; · 2.07 Impact Factor
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    ABSTRACT: Targeted next-generation sequencing (NGS) provides predictive and prognostic information in the routine care of patients with cancer. However, with increasing knowledge of the biological basis of cancer, NGS of the same gene sets can also provide diagnostic information in challenging cases, on the basis of identification of both known and novel variants, including single-nucleotide variants, insertions and deletions, copy number alterations, and translocations. Here, we present 3 clinical cases in which targeted NGS of hybrid-capture-enriched DNA from formalin-fixed, paraffin-embedded tumor samples provided unique and clinically important diagnostic and/or staging information in 3 different challenging clinical scenarios. In the first patient, NGS played a key role in both diagnosis and staging in a patient with multiple tumors of the same histologic type. The second case demonstrates the ability of NGS to clarify the tumor tissue type in a single mass involving multiple organs, and thereby guide appropriate chemotherapy. The third case illustrates that information regarding susceptibility to targeted therapeutics can also clarify the original histologic diagnosis.
    The American journal of surgical pathology 01/2014; · 4.06 Impact Factor
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    ABSTRACT: Merkel cell carcinoma is a highly aggressive cutaneous neuroendocrine tumor that has been associated with Merkel cell polyomavirus in up to 80% of cases. Merkel cell polyomavirus is believed to influence pathogenesis, at least in part, through expression of the large T antigen, which includes a retinoblastoma protein-binding domain. However, there appears to be significant clinical and morphological overlap between polyomavirus-positive and polyomavirus-negative Merkel cell carcinoma cases. Although much of the recent focus of Merkel cell carcinoma pathogenesis has been on polyomavirus, the pathogenesis of polyomavirus-negative cases is still poorly understood. We hypothesized that there are underlying human somatic mutations that unify Merkel cell carcinoma pathogenesis across polyomavirus status, and to investigate we performed whole exome sequencing on five polyomavirus-positive cases and three polyomavirus-negative cases. We found that there were no significant differences in the overall number of single-nucleotide variations, copy number variations, insertion/deletions, and chromosomal rearrangements when comparing polyomavirus-positive to polyomavirus-negative cases. However, we did find that the retinoblastoma pathway genes harbored a high number of mutations in Merkel cell carcinoma. Furthermore, the retinoblastoma gene (RB1) was found to have nonsense truncating protein mutations in all three polyomavirus-negative cases; no such mutations were found in the polyomavirus-positive cases. In all eight cases, the retinoblastoma pathway dysregulation was confirmed by immunohistochemistry. Although polyomavirus-positive Merkel cell carcinoma is believed to undergo retinoblastoma dysregulation through viral large T antigen expression, our findings demonstrate that somatic mutations in polyomavirus-negative Merkel cell carcinoma lead to retinoblastoma dysregulation through an alternative pathway. This novel finding suggests that the retinoblastoma pathway dysregulation leads to an overlapping Merkel cell carcinoma phenotype and that oncogenesis occurs through either a polyomavirus-dependent (viral large T antigen expression) or polyomavirus-independent (host somatic mutation) mechanism.Modern Pathology advance online publication, 10 January 2014; doi:10.1038/modpathol.2013.235.
    Modern Pathology 01/2014; · 5.25 Impact Factor
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    ABSTRACT: The identification of recurrent gene rearrangements in the clinical laboratory is the cornerstone for risk stratification and treatment decisions in many malignant tumors. Studies have reported that targeted next-generation sequencing assays have the potential to identify such rearrangements; however, their utility in the clinical laboratory is unknown. We examine the sensitivity and specificity of ALK and KMT2A (MLL) rearrangement detection by next-generation sequencing in the clinical laboratory. We analyzed a series of seven ALK rearranged cancers, six KMT2A rearranged leukemias, and 77 ALK/KMT2A rearrangement–negative cancers, previously tested by fluorescence in situ hybridization (FISH). Rearrangement detection was tested using publicly available software tools, including Breakdancer, ClusterFAST, CREST, and Hydra. Using Breakdancer and ClusterFAST, we detected ALK rearrangements in seven of seven FISH-positive cases and KMT2A rearrangements in six of six FISH-positive cases. Among the 77 ALK/KMT2A FISH-negative cases, no false-positive identifications were made by Breakdancer or ClusterFAST. Further, we identified one ALK rearranged case with a noncanonical intron 16 breakpoint, which is likely to affect its response to targeted inhibitors. We report that clinically relevant chromosomal rearrangements can be detected from targeted gene panel–based next-generation sequencing with sensitivity and specificity equivalent to that of FISH while providing finer-scale information and increased efficiency for molecular oncology testing.
    The Journal of Molecular Diagnostics. 01/2014;
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    ABSTRACT: Background Clinical outcome of papillary thyroid carcinoma (PTC) in children differs significantly from that of adults. There is no clear explanation of this difference although previous studies have demonstrated a lower prevalence of the BRAFV600E mutation in PTC of children. However, data are limited due to the rarity of this diagnosis. BRAFV600E mutation prevalence and its relationship with outcome in pediatric PTC remain unclear.ProcedureBRAFV600E mutational status was determined in 27 PTC patients less than 22 years of age using restriction fragment length polymorphism (RFLP) analysis. The relationship between BRAFV600E mutation status, patient and tumor characteristics as well as progression-free survival (PFS) were analyzed.ResultsBRAFV600E was present in 63% of patients and occurred more often in male patients versus females (P = 0.033). Presence of the mutation did not correlate with any difference in extent of disease at diagnosis, tumor size, capsular invasion, vascular invasion, soft tissue invasion, or margin status. At 10 years, PFS for BRAFV600E positive versus negative patients was 55.5% versus 70.0%, respectively (P = 0.48). Overall survival was 100% and median follow-up was 13.9 years.Conclusions This study of pediatric PTC demonstrates that BRAFV600E mutations occur in children at a rate comparable to adults. We found a correlation of BRAFV600E with the male gender, but no evidence that the mutation correlates with more extensive or aggressive disease. This analysis suggests that differences in disease course of PTC in children versus adults are not strongly dependent upon the presence of the BRAFV600E mutation. Pediatr Blood Cancer © 2014 Wiley Periodicals, Inc.
    Pediatric Blood & Cancer 01/2014; · 2.35 Impact Factor
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    ABSTRACT: Next-generation sequencing (NGS) is becoming a common approach for clinical testing of oncology specimens for mutations in cancer genes. Unlike inherited variants, cancer mutations may occur at low frequencies because of contamination from normal cells or tumor heterogeneity and can therefore be challenging to detect using common NGS analysis tools, which are often designed for constitutional genomic studies. We generated high-coverage (>1000×) NGS data from synthetic DNA mixtures with variant allele fractions (VAFs) of 25% to 2.5% to assess the performance of four variant callers, SAMtools, Genome Analysis Toolkit, VarScan2, and SPLINTER, in detecting low-frequency variants. SAMtools had the lowest sensitivity and detected only 49% of variants with VAFs of approximately 25%; whereas the Genome Analysis Toolkit, VarScan2, and SPLINTER detected at least 94% of variants with VAFs of approximately 10%. VarScan2 and SPLINTER achieved sensitivities of 97% and 89%, respectively, for variants with observed VAFs of 1% to 8%, with >98% sensitivity and >99% positive predictive value in coding regions. Coverage analysis demonstrated that >500× coverage was required for optimal performance. The specificity of SPLINTER improved with higher coverage, whereas VarScan2 yielded more false positive results at high coverage levels, although this effect was abrogated by removing low-quality reads before variant identification. Finally, we demonstrate the utility of high-sensitivity variant callers with data from 15 clinical lung cancers.
    The Journal of molecular diagnostics: JMD 11/2013; · 3.48 Impact Factor
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    ABSTRACT: Currently, oncology testing includes molecular studies and cytogenetic analysis to detect genetic aberrations of clinical significance. Next-generation sequencing (NGS) allows rapid analysis of multiple genes for clinically actionable somatic variants. The WUCaMP assay uses targeted capture for NGS analysis of 25 cancer-associated genes to detect mutations at actionable loci. We present clinical validation of the assay and a detailed framework for design and validation of similar clinical assays. Deep sequencing of 78 tumor specimens (≥1000× average unique coverage across the capture region) achieved high sensitivity for detecting somatic variants at low allele fraction (AF). Validation revealed sensitivities and specificities of 100% for detection of single-nucleotide variants (SNVs) within coding regions, compared with SNP array sequence data (95% CI = 83.4-100.0 for sensitivity and 94.2-100.0 for specificity) or whole-genome sequencing (95% CI = 89.1-100.0 for sensitivity and 99.9-100.0 for specificity) of HapMap samples. Sensitivity for detecting variants at an observed 10% AF was 100% (95% CI = 93.2-100.0) in HapMap mixes. Analysis of 15 masked specimens harboring clinically reported variants yielded concordant calls for 13/13 variants at AF of ≥15%. The WUCaMP assay is a robust and sensitive method to detect somatic variants of clinical significance in molecular oncology laboratories, with reduced time and cost of genetic analysis allowing for strategic patient management.
    The Journal of molecular diagnostics: JMD 11/2013; · 3.48 Impact Factor
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    ABSTRACT: Mutations in exon 2 of the MED12 gene have been reported in 50% to 70% of uterine leiomyomas. To determine the frequency of MED12 mutations in various types of smooth muscle tumors as well as normal uterine myometrium adjacent to a leiomyoma, we selected a total of 143 cases for analysis of MED12 exon 2 mutations by polymerase chain reaction and Sanger sequencing. MED12 mutations were detected in 54% of classical uterine leiomyomas (15/28) and in 15% of cases in myometrium adjacent to leiomyomas (2/13); 34% of leiomyoma/leiomyomatosis in pelvic/retroperitoneal sites (10/29); 0% of extrauterine leiomyomas (0/29); 8% of smooth muscle tumor of uncertain malignant potential (1/12); 30% of uterine leiomyosarcomas (6/20); and 4% of extrauterine leiomyosarcomas (1/25). Mutations were clustered around codons 44, 40, 41, and 36, and consisted primarily of single nucleotide substitutions and small in-frame deletions. Our results confirm the findings of similar recent studies and further show that pelvic and retroperitoneal leiomyomas harbor an increased frequency of MED12 mutations (34%) as compared with other extrauterine sites (0%; P = 0.0006), and that histologically unremarkable adjacent myometrium can harbor similar MED12 mutations. These findings suggest that smooth muscle tumors in pelvic/retroperitoneal sites are subject to the same mutational changes as those of uterine myometrium, and that these mutations may precede the gross or histological development of a leiomyoma.
    Human pathology 11/2013; · 3.03 Impact Factor
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    ABSTRACT: Antibody-mediated rejection (AMR) after cardiac transplantation is associated with significant mortality, and the optimal treatment of this condition is poorly defined. Rituximab has been used successfully for the treatment for antibody-mediated diseases; however, its role in AMR is unclear. We review our experience with rituximab in patients with cardiac allograft AMR. We conducted a retrospective analysis of cardiac transplant patients with a diagnosis of AMR from 2001 to 2011. Inclusion criteria were clinical suspicion of rejection with the presence of C4d complement staining on endomyocardial biopsy and the absence of cellular rejection of grade 2R or greater. Patients were divided into Rituximab and NoRituximab groups. The primary endpoint was all-cause mortality. Secondary endpoints were infection, change in ejection fraction (EF), and rehospitalization. Thirty-three patients met inclusion criteria, of whom 13 received rituximab and 20 did not. Baseline characteristics were similar between groups. Kaplan-Meier curves for a three-yr follow-up period demonstrate improved survival in the Rituximab group (p = 0.0089). There were no differences in secondary endpoints. We found that rituximab therapy was associated with improved survival in cardiac allograft AMR. Further prospective, randomized studies in larger patient populations are needed to confirm this finding and to define ideal timing for rituximab administration.
    Clinical Transplantation 11/2013; 27(6):961-7. · 1.63 Impact Factor
  • Mark R Wick, Oscar Nappi, John D Pfeifer
    Seminars in Diagnostic Pathology 11/2013; 30(4):263-83. · 1.62 Impact Factor
  • John D Pfeifer
    Cancer Genetics 10/2013; · 1.92 Impact Factor
  • James Mathews, Eric J Duncavage, John D Pfeifer
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    ABSTRACT: Mesenchymal hamartoma of the liver (MHL) is an uncommon benign primary liver tumor that typically occurs in the pediatric population, although cases have been described in adults. MHL is sometimes associated with the highly malignant undifferentiated embryonal sarcoma (UES), and the synchronous or metachronous occurrence of MHL and UES suggests they share a common genetic link. Although the exact mechanism of tumorigenesis has not been identified, MHL cases harbor recurring chromosomal rearrangements involving 19q13. Design In order to provide more detail on the genetic events of MHL tumorigenesis, capture-based next generation sequencing (NGS) targeted to loci recently shown to be involved in a translocation in a case of UES arising in MHL (specifically, the MALAT1 gene on chromosome 11 and a gene poor region termed MHLB1 on chromosome 19) was performed on formalin fixed paraffin embedded tissue from seven cases of MHL. Chromosome rearrangements involving the MHLB1 locus were identified in three of the seven cases, including the translocation t(11,19)(q13.1;q13.42) involving the MALAT1 gene; the translocation t(2,19)(q31.1;q13.42) involving AK023515, an uncharacterized noncoding gene; and the inversion inv(19,19)(q13.42;q13.43) involving the PEG3 gene encoding a Kruppel-type zinc-finger protein. Rearrangements were exclusively identified in pediatric tumors. In each case, the presence of the rearrangement was confirmed by PCR and interphase FISH. Interphase FISH also demonstrated that the arrangements occur within the spindle cell component but not the epithelial components of the tumor. Since the MHLB1 locus contains a CpG-rich region whose methylation regulates C19MC miRNA genes, rearrangements that disrupt this region may contribute to MHL development through alteration of miRNA expression. The demonstration that the loose stromal cells harbor the rearrangements indicates that (some cases of) MHL are a neoplastic process due to a somatic genetic change and not a germline abnormality.
    Experimental and Molecular Pathology 10/2013; · 2.13 Impact Factor

Publication Stats

2k Citations
439.48 Total Impact Points

Institutions

  • 1993–2014
    • Washington University in St. Louis
      • • Department of Pathology and Immunology
      • • Division of Biology and Biomedical Sciences
      • • Department of Obstetrics and Gynecology
      • • Department of Molecular Microbiology
      San Luis, Missouri, United States
  • 1992–2013
    • University of Washington Seattle
      • • Department of Pathology
      • • Department of Immunology
      Seattle, WA, United States
  • 2011–2012
    • Postgraduate Institute of Medical Education and Research
      • Department of NeuroSurgery
      Chandīgarh, Union Territory of Chandigarh, India
  • 2010–2011
    • University of Utah
      • Department of Pathology
      Salt Lake City, UT, United States
  • 2002–2011
    • Barnes Jewish Hospital
      San Luis, Missouri, United States
  • 2009
    • University of Alabama at Birmingham
      Birmingham, Alabama, United States
  • 2005
    • University of British Columbia - Vancouver
      Vancouver, British Columbia, Canada
  • 1996
    • St. Luke's Hospital (MO, USA)
      Saint Louis, Michigan, United States
  • 1995–1996
    • Lund University
      Lund, Skåne, Sweden
    • Case Western Reserve University
      • Institute of Pathology
      Cleveland, OH, United States