Bio

Clinical Focus


  • Gastroenterology
  • Gastrointestinal Endoscopy
  • Gastrointestinal Cancer Prevention

Honors & Awards


  • North American International GI Training Grant, American College of Gastroenterology (2015)

Education & Certifications


  • Board Certification, Gastroenterology, American Board of Internal Medicine (2016)
  • Fellowship, Stanford University (Gastroenterology), CA (2016)
  • Master of Science, Stanford University (Epidemiology and Clinical Research), CA (2016)
  • Board Certification, Internal Medicine, American Board of Internal Medicine (2013)
  • Residency, Yale New Haven Hospital (Internal Medicine), CT (2013)
  • Medical Education, University of Texas Southwestern Medical School, TX (2010)
  • Undergraduate, Harvard College (Biochemical Sciences), MA (2006)

Teaching

Graduate and Fellowship Programs


  • Gastroenterology & Hepatology (Fellowship Program)

Publications

All Publications


  • Efficacy of Video Capsule Endoscopy in the Management of Suspected Small Bowel Bleeding in Patients With Continuous Flow Left Ventricular Assist Devices. Gastroenterology research Zikos, T. A., Pan, J., Limketkai, B., Banerjee, D., Fernandez-Becker, N. 2017; 10 (5): 280?87

    Abstract

    Continuous flow left ventricular assist device (CF-LVAD) patients have a high prevalence of gastrointestinal bleeding from the small bowel. Video capsule endoscopy (VCE) is often used for diagnosis in these patients, but efficacy has yet to be determined. In this study, we evaluated the efficacy of VCE in the management of CF-LVAD patients with suspected small bowel bleeding by comparing to a non-VCE CF-LVAD control group.We retrospectively reviewed the charts of all patients with CF-LVADs implanted at Stanford Hospital from January 2010 to October 2015. Patients were included in the study if there was a clinical suspicion of small bowel bleeding and either a negative upper endoscopy or colonoscopy.A total of 26 patients met inclusion criteria for a total of 15 encounters where VCE was done, and 25 where VCE was not done. There were no statistical differences when comparing these groups in terms of medical therapy use (thalidomide or octreotide), enteroscopy use (double-balloon or push), intervention on lesions, or any 30-day outcomes. There was no advantage to VCE with regard to the composite endpoint time to re-bleed or death related to re-bleeding (median 114 vs. 161 days, P = 0.15) after removing patients who did not get a VCE due to death or critical illness.We did not find VCE changed management or outcomes in CF-LVAD patients with suspected small bowel bleeding at our institution when compared to a non-VCE control group. Our experience is small and single center, and larger, multi-center studies could further elucidate the utility of VCE in this patient population.

    View details for DOI 10.14740/gr908w

    View details for PubMedID 29118868

    View details for PubMedCentralID PMC5667693

  • Association of Aurora-A (STK15) kinase polymorphisms with clinical outcome of esophageal cancer treated with preoperative chemoradiation CANCER Pan, J. Y., Ajani, J. A., Gu, J., Gong, Y., Quin, A., Hung, M., Wu, X., Izzo, J. G. 2012; 118 (17): 4346-4353

    Abstract

    Aurora-A/STK15 is a serine/threonine kinase critical for regulated chromosome segregation and cytokinesis. We investigated the association between 2 nonsynonymous single nucleotide polymorphisms in the coding region of STK15, T91A (Phe31Ile) and G169A (Val57Ile), and clinical outcome of esophageal cancer treated with preoperative chemoradiation.Genotypes at Phe31Ile and Val57Ile were assessed from peripheral blood lymphocytes of 190 esophageal cancer patients and were correlated to response to treatment, recurrence rate, risk of death, disease-free survival (DFS) and median survival time (MTS).All patients had resectable esophageal or gastroesophageal junction cancer and received preoperative chemoradiation followed by esophagectomy. The heterozygous variant Phe31/Ile variant was significantly associated with tumor recurrence (odds ratio [OR] = 4.39; 95% confidence interval [CI], 2.12-8.94; P < .001), shorter DFS (P = .0001), and shorter MTS (P = .012). For patients receiving cisplatin-based therapy, only the variant Phe31/Ile had an adverse effect on response (OR = 2.8; 95% CI, 1.01-5.17; P = .048) and MTS (P = .026). The variant 91A-169G haplotype carried a significant risk for lack of complete response (OR = 2.54; 95% CI, 1.15-5.54) and higher rate of recurrence (OR = 2.73; 95%CI, 1.00-7.29). The presence of at least 1 variant allele at each locus further increased the risk of recurrence (adjusted OR = 6.21; 95% CI, 2.28-17.11; P = <.001), and was associated significantly shorter DFS (P = .003).Our study shows that functional SNPs in the STK15 gene are associated with higher rate of recurrence, higher likelihood of chemoratiotherapy-resistance, shorter DFS, and shorter MTS. Confirmation of our data and understanding the mechanisms through which STK15 functional SNPs mediate resistance to chemoradiotherapy are warranted.

    View details for DOI 10.1002/cncr.26581

    View details for Web of Science ID 000307845200033

    View details for PubMedID 22213102

  • Genetic susceptibility to esophageal cancer: the role of the nucleotide excision repair pathway CARCINOGENESIS Pan, J., Lin, J., Izzo, J. G., Liu, Y., Xing, J., Huang, M., Ajani, J. A., Wu, X. 2009; 30 (5): 785-792

    Abstract

    In this case-control study with 387 White esophageal patients and 462 White controls matched to cases by age and sex, we evaluated the associations between 13 potential functional polymorphisms in eight major nucleotide excision repair (NER) genes and esophageal cancer risk. In individual single nucleotide polymorphism analysis, after adjustment for multiple comparisons, the heterozygous GT genotype of the ERCC1 3' untranslated region (UTR) was associated with an increased risk, whereas the homozygous variant genotype TT was associated with 60% reduction in risk with an odds ratio (OR) of 0.40 (95% confidence interval [CI] = 0.19-0.86). The heterozygous AG genotype of XPA 5' UTR was at 2.11-fold increased risk (95% CI = 1.33-3.35) and the risk reached 3.10-fold (95% CI = 1.94-4.95) for the homozygous variant GG genotype. These associations were also significant when restricted the analyses in patients with esophageal adenocarcinoma. Further, the CT genotype of the RAD23B Ala249Val was associated with increased esophageal cancer risk (OR = 1.44; 95% CI = 1.05-1.97), whereas the poly-AT-/+ genotype of the XPC intron 9 conferred a decreased risk (OR = 0.71, 95% CI = 0.51-0.97). In joint analysis, individuals carrying 1 (OR = 2.64, 95% CI = 1.57-4.52) and > or = 2 (OR = 2.74, 95% CI = 1.58-4.75) unfavorable genotypes exhibited significantly increased risk for esophageal cancer risk with significant dose-response trend (P for trend = 0.006). The pathway-based risk was more evident in ever smokers, overweight/obese individuals, men and ever drinkers. Our results support the hypothesis that increasing numbers of unfavorable genotypes in the NER predispose susceptible individuals to increased risk of esophageal cancer. These findings warrant further replications in different populations.

    View details for DOI 10.1093/carcin/bgp058

    View details for Web of Science ID 000265740000010

    View details for PubMedID 19270000

  • Cyclin D1 guanine/adenine 870 polymorphism with altered protein expression is associated with genomic instability and aggressive clinical biology of esophageal adenocarcinoma JOURNAL OF CLINICAL ONCOLOGY Izzo, J. G., Wu, T., Wu, X., Ensor, J., Luthra, R., Pan, J., Correa, A., Swisher, S. G., Chao, C. K., Hittelman, W. N., Ajani, J. A. 2007; 25 (6): 698-707

    Abstract

    Altered cyclin D1 (CD1), a cell cycle regulator, may play an important role in imparting aggressive nature to esophageal adenocarcinoma (EAC). CD1 gene single nucleotide polymorphism G/A870 results in two alternatively spliced transcripts, CD1a and CD1b. CD1b, preferentially encoded by the A870 allele, is putatively oncogenic. We hypothesized that CD1 A870 allele would be associated with higher CD1 protein expression, and increased genomic instability during EAC evolution, leading to more aggressive phenotype.One hundred twenty-four archival specimens of EAC, and 39 associated Barrett's esophagus (BE) specimens were examined for CD1 genotype, CD1 protein expression, and chromosome 9 polysomy (representing genomic instability). We correlated CD1 genotypes with CD1 protein expression, genomic instability, age at diagnosis of EAC, and overall survival (OS).The A870 allele was associated with higher levels of CD1 protein expression in EAC (P = .032); in BE (P = .01) where it was associated with concomitant increased chromosome 9 polysomy (P = .002); and with a younger age at diagnosis (P < .001) and poor OS (P = .0003) of EAC patients.Our data suggest that CD1 A870 background may be imparting aggressive phenotype to EAC. It provides a molecular basis to explain the clinical biology associated with CD1 polymorphism whereas aberrant nuclear accumulation of CD1 protein enhances the acquisition of genomic instability (ie, clonal diversity), thus leading to early age of EAC diagnosis and poor OS. CD1 genotyping with other biomarkers may help create a biomarker-based prognostic model for EAC and CD1 may also serve as a therapeutic target.

    View details for DOI 10.1200/JCO.2006.08.0283

    View details for Web of Science ID 000244384000015

    View details for PubMedID 17308274

  • Monovalent ligation of the B cell receptor induces receptor activation but fails to promote antigen presentation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Kim, Y. M., Pan, J. Y., Korbel, G. A., Peperzak, V., Boes, M., Ploegh, H. L. 2006; 103 (9): 3327-3332

    Abstract

    We explored the role of antigen valency in B cell receptor (BCR) activation and rearrangement of intracellular MHC class II compartments as factors that contribute to the efficacy of antigen presentation. Using primary B cells that express a hen egg lysozyme (HEL)-specific BCR, we found that oligomeric HEL more efficiently promoted both BCR activation and internalization than did monovalent HEL, although monovalent HEL, unlike monovalent Fab fragments of anti-Ig, readily triggered the BCR. Nonetheless, oligovalent ligation positions the BCR in a membrane microdomain that is distinct from one engaged in the course of monovalent ligation, as judged by detergent extraction of the BCR. Furthermore, oligovalent HEL induced more pronounced rearrangement of MHC class II-containing antigen-processing compartments. Using videomicroscopy we observed in real time the rearrangement of MHC class II compartments as well as delivery of antigen in primary B cells. The observed increase in rearrangement of MHC class II-positive compartments and the disposition of antigen-bound BCRs therein correlates with improved presentation of a HEL-derived epitope. Although monomeric HEL efficiently engages the BCR, presentation of HEL-derived epitopes is impaired compared to oligovalent antigens. This trait may help explain the known ability of soluble, disaggregated antigen to induce a state of B cell tolerance.

    View details for DOI 10.1073/pnas.0511315103

    View details for Web of Science ID 000235780700059

    View details for PubMedID 16492756

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