Katrina Pedersen

Leukocyte DNA Methylation Signature Differentiates Pancreatic Cancer Patients from Healthy Controls

Pancreatic adenocarcinoma (PaC) is one of most difficult tumors to treat. Much of this is attributed to the late diagnosis. To identify biomarkers for early detection, we examined DNA methylation differences in leukocyte DNA between PaC cases and controls in a two-phase study. In phase I, we measured methylation levels at 1,505 CpG sites in treatment-naïve leukocyte DNA from 132 never-smoker PaC patients and 60 never-smoker healthy controls. We found significant differences in 110 CpG sites (false discovery rate <0.05). In phase II, we tested and validated 88 of 96 phase I selected CpG sites in 240 PaC cases and 240 matched controls (p≤0.05). Using penalized logistic regression, we built a prediction model consisting of five CpG sites (IL10_P348, LCN2_P86, ZAP70_P220, AIM2_P624, TAL1_P817) that discriminated PaC patients from controls (C-statistic = 0.85 in phase I; 0.76 in phase II). Interestingly, one CpG site (LCN2_P86) alone could discriminate resectable patients from controls (C-statistic  = 0.78 in phase I; 0.74 in phase II). We also performed methylation quantitative trait loci (methQTL) analysis and identified three CpG sites (AGXT_P180_F, ALOX12_E85_R, JAK3_P1075_R) where the methylation levels were significantly associated with single nucleotide polymorphisms (SNPs) (false discovery rate <0.05). Our results demonstrate that epigenetic variation in easily obtainable leukocyte DNA, manifested by reproducible methylation differences, may be used to detect PaC patients. The methylation differences at certain CpG sites are partially attributable to genetic variation. This study strongly supports future epigenome-wide association study using leukocyte DNA for biomarker discovery in human diseases.

Prevalence of CDKN2A mutations in pancreatic cancer patients: implications for genetic counseling

Germline mutations in CDKN2A have been reported in pancreatic cancer families, but genetic counseling for pancreatic cancer risk has been limited by lack of information on CDKN2A mutation carriers outside of selected pancreatic or melanoma kindreds. Lymphocyte DNA from consecutive, unselected white non-Hispanic patients with pancreatic adenocarcinoma was used to sequence CDKN2A. Frequencies of mutations that alter the coding of p16INK4 or p14ARF were quantified overall and in subgroups. Penetrance and likelihood of carrying mutations by family history were estimated. Among 1537 cases, 9 (0.6%) carried germline mutations in CDKN2A, including three previously unreported mutations. CDKN2A mutation carriers were more likely to have a family history of pancreatic cancer (P=0.003) or melanoma (P=0.03), and a personal history of melanoma (P=0.01). Among cases who reported having a first-degree relative with pancreatic cancer or melanoma, the carrier proportions were 3.3 and 5.3%, respectively. Penetrance for mutation carriers by age 80 was calculated to be 58% for pancreatic cancer (95% confidence interval (CI) 8–86%), and 39% for melanoma (95% CI 0–80). Among cases who ever smoked cigarettes, the risk for pancreatic cancer was higher for carriers compared with non-carriers (HR 25.8, P=2.1 × 10−13), but among nonsmokers, this comparison did not reach statistical significance. Germline mutations in CDKN2A among unselected pancreatic cancer patients are uncommon, although notably penetrant, especially among smokers. Carriers of germline mutations of CDKN2A should be counseled to avoid tobacco use to decrease risk of pancreatic cancer in addition to taking measures to decrease melanoma risk.

BRCA2‐associated pancreatic cancer and current screening guidelines

As is previously known, germline mutations have been identified in a few known cancer genes, such as BRCA2, that predispose individuals to developing pancreatic adenocarcinoma. Based on advancements made in the understanding of the function of these genetic alterations, the identification of these mutations not only has clinical implications for the individual patient but also for their family. Identification of carrier status has led to the development of very clear guidelines for screening and/or management with respect to breast cancer and ovarian cancer. However, to the best of our knowledge, a clear-cut consensus has not been reached with regard to screening highrisk individuals for pancreatic adenocarcinoma. We know from prior studies that BRCA2 carriers are at a higher risk of developing pancreatic cancer. However, the standard incidence ratios (SIRs) quoted by Mersch et al for pancreatic cancer when compared with breast, ovarian, prostate, and other cancer subtypes are striking and a cause for concern (males: SIR, 82.559; 95% confidence interval, 39.524-151.84 [P< .001]; females: SIR, 13.809; 95% confidence interval, 6.301-26.216 [P< .001]). Despite recent therapeutic advances for pancreatic cancer and potential individualized therapy for BRCA2 mutation carriers in the form of DNA-damaging agents (such as platinum compounds) or poly (ADPribose) polymerase (PARP) inhibitors, clinical outcomes are still dismal. There have been studies evaluating the role of endoscopic ultrasound (EUS) in high-risk individuals leading to the identification of both malignant and premalignant lesions. The majority of the studies that defined “highrisk” individuals for pancreatic cancer were not limited to BRCA2, and despite the small heterogeneous groups studied, EUS did lead to the identification of clinically significant pancreatic lesions in a sizeable percentage (up to 42%) of asymptomatic individuals. Based on the accumulating data and the relative safety and feasibility of EUS, especially in tertiary care centers, germline BRCA2 mutation carriers represent a high-risk subset of patients who would potentially benefit from more intense surveillance in the form of EUS and/or other surveillance methods (eg, magnetic resonance cholangiopancreatography), as noted by a majority of the 49expert multidisciplinary international consortium (International Cancer of the Pancreas Screening [CAPS]). However, the impact of early detection on overall survival would still need to be determined. Nevertheless, these results open the debate regarding the need for aggressive surveillance in these individuals. What type of surveillance and age parameters have yet to be determined. Minimization of controllable risk factors such as smoking and obesity in at-risk patients is also likely important. Within the subset of pancreatic cancers identified in the study by Mersch et al, it would be important to discuss the age distribution at the time of diagnosis to help guide some of these screening guidelines.

A 64-Year-Old Man With Progressive Dyspnea and Cough Productive of Copious Amounts of Clear Sputum

A 64-year-old man was admitted for evaluation of progressive dyspnea and cough productive of copious amounts of clear sputum. About 3 months prior to presentation he had developed dyspnea and cough while traveling in Texas and Arizona. He was hospitalized and treated with antibiotics for presumed left lower lobe pneumonia. A diagnosis of left lower extremity DVT was also made, for which anticoagulation with warfarin was initiated. After discharge, he felt well for some days but subsequently noted recurrence of dyspnea and cough, along with fevers, prompting a second hospital admission. Chest imaging with CT scan at that time showed extensive bilateral ground-glass opacities. The patient required noninvasive respiratory support and was started on broad-spectrum antibiotics. Exten sive infectious work-up was unrevealing. He was discharged feeling slightly improved on supplemental oxygen and an empirical antibiotic course. His medical history was otherwise notable for coronary artery disease, hypertension, hyperlipidemia, chronic compensated systolic heart failure with an ejection fraction of 39%, COPD (FEV 1 , 74%), type 2 diabetes mellitus, and chronic kidney disease. On admission, the patient complained of progressive dyspnea as well as an increase in oxygen requirements and sputum production over a 2-week period. He denied constitutional symptoms, weight changes, or hemoptysis.

Pacritinib to inhibit JAK/STAT signaling in refractory metastatic colon and rectal cancer

Background Treatment options for patients with refractory colorectal cancer are limited and typically provide a chance of only modest benefit. The goal of this study was to evaluate the benefit of inhibiting the JAK/STAT inflammatory pathway with single agent pacritinib in patients with metastatic refractory colorectal adenocarcinoma. Methods A single arm institutional trial was initiated and enrolled patients with metastatic colorectal cancer refractory to at least two standard lines of treatment. Pacritinib 400 mg daily was administered orally continuously in 28 day cycles. Results The trial was discontinued prior to reaching the planned accrual due to an FDA hold on pacritinib and a lack of treatment benefit. Eleven patients were enrolled and seven were evaluated for response. Median baseline C-reactive protein level was 12.1 (2.1-147) mg/L. One patient had stable disease at eight weeks by RECIST criteria and six progressed. There were no grade 4 or 5 adverse events while patients were on study. The grade 2 and lower AE events experienced were consistent with prior pacritinib trials. Conclusions In seven evaluable patients there were no objective responses. The trial was discontinued prior to completing planned accrual based on a low likelihood that the progression free survival goal of 4 months would be met.

A phase I/II study combining tosedostat with capecitabine in patients with metastatic pancreatic ductal adenocarcinoma (PDAC).

TPS471 Background: Metastatic pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. Recent advances with fluorouracil in combination with oxaliplatin and irinotecan (FOLFIRINOX) and nab-paclitaxel combined with gemcitabine (AG) have improved survival in patients with PDAC. A fluorouracil-based regimen is recommended for patients who progress after a gemcitabine-based regimen. Tosedostat is an oral aminopeptidase inhibitor shown to have anti-proliferative effects in malignancies. Aminopeptidase inhibitors disrupt the cleavage of amino acids from peptides downstream of proteasomal degradation, preventing the recycling of amino acids needed for new protein synthesis. This leads to intracellular depletion of amino acids, resulting in a cellular stress response known as the amino acid deprivation response, which leads to apoptosis. Because pancreatic cancer cells frequently upregulate expression of these aminopeptidases, aminopeptidases inhibitors hold therapeutic promise. Methods: This is a single i...