Identification and Validation of a Biomarker Signature in Patients With Resectable Pancreatic Cancer via Genome-Wide Screening for Functional Genetic Variants

Importance

Surgery currently offers the only chance for a cure in pancreatic ductal adenocarcinoma (PDAC), but it carries a significant morbidity and mortality risk and results in varying oncologic outcomes. At present, to our knowledge, there are no tests available before surgical resection to identify tumors with an aggressive biological phenotype that could guide personalized treatment strategies.

Objective

Identification of noninvasive genetic biomarkers that could direct therapy in patients whose cases are amenable to pancreatic cancer resection.

Design, Setting, and Participants

This multicenter study combined a prospective European cohort of patients with PDAC who underwent pancreatic resection (from University Hospital of Zurich, Zurich, Switzerland; Cantonal Hospital of Winterthur, Winterthur, Switzerland; and University Clinic of Ulm, Ulm, Germany) with data from the Cancer Genome Atlas database in the United States, which includes prospectively registered patients with PDAC. A genome-wide screening for functional single-nucleotide polymorphisms (SNPs) that affect PDAC survival was conducted using the European cohort for identification and the Cancer Genome Atlas cohort for validation. We used Cox proportional hazards models to screen for high-frequency polymorphic variants that are associated with allelic differences in tumor-associated survival and either result in an altered protein structure and function or reside in known regulatory noncoding genomic regions. The false-discovery rate method was applied for multiple hypothesis-testing corrections. Data analysis occurred from November 2017 to May 2018.

Exposures

Pancreatic resection.

Main Outcomes and Measures

Tumor-associated survival.

Results

A total of 195 patients in the European cohort were included, as well as 136 patients in the Cancer Genome Atlas cohort (overall median [range] age, 66 [19-87] years; 156 [47.1%] were women, and 175 [52.9%] were men). Two SNPs in noncoding, functional regions of genes that regulate cancer progression, invasion, and metastasis were identified (CHI3L2 SNP rs684559 and CD44 SNP rs353630). These were associated with survival after PDAC resection; patients who carry the risk alleles at 1 of both SNP loci had a 2.63-fold increased risk for tumor-associated death compared with those with protective genotypes (hazard ratio for survival, 0.38 [95% CI, 0.27-0.53]; P = 1.0 × 10-8).

Conclusions and Relevance

The identified polymorphisms may serve as a noninvasive biomarker signature of prospective survival after pancreatic resection that is readily available at the time of PDAC diagnosis. This signature can be used to identify a subset of high-risk patients with PDAC with very low survival probability who might be eligible for inclusion in clinical trials of new therapeutic strategies, including neoadjuvant chemotherapy protocols. In addition, the biological knowledge about these SNPs could help guide the development of individualized genomic strategies for PDAC therapies.

Alternate splicing of the p53 inhibitor HDMX offers a superior prognostic biomarker than p53 mutation in human cancer

Conventional high-grade osteosarcoma is the most common primary bone malignancy. Although altered expression of the p53 inhibitor HDMX (Mdmx/Mdm4) is associated with cancer risk, progression, and outcome in other tumor types, little is known about its role in osteosarcoma. High expression of the Hdmx splice variant HDMX-S relative to the full-length transcript (the HDMX-S/HDMX-FL ratio) correlates with reduced HDMX protein expression, faster progression, and poorer survival in several cancers. Here, we show that the HDMX-S/HDMX-FL ratio positively correlates with less HDMX protein expression, faster metastatic progression, and a trend to worse overall survival in osteosarcomas. We found that the HDMX-S/HDMX-FL ratio associated with common somatic genetic lesions connected with p53 inhibition, such as p53 mutation and HDM2 overexpression in osteosarcoma cell lines. Interestingly, this finding was not limited to osteosarcomas as we observed similar associations in breast cancer and a variety of other cancer cell lines, as well as in tumors from patients with soft tissue sarcoma. The HDMX-S/HDMX-FL ratio better defined patients with sarcoma with worse survival rates than p53 mutational status. We propose a novel role for alternative splicing of HDMX, whereby it serves as a mechanism by which HDMX protein levels are reduced in cancer cells that have already inhibited p53 activity. Alternative splicing of HDMX could, therefore, serve as a more effective biomarker for p53 pathway attenuation in cancers than p53 gene mutation.

Long-term outcome after total parathyroidectomy for the management of secondary hyperparathyroidism

In patients with chronic renal failure, secondary hyperparathyroidism (sHPT) is a common problem requiring surgical parathyroidectomy (PTX) if medical treatment with active vitamin D and calcimimetics fails. To minimize the risk for recurrence, we perform total PTX (tPTX) without autotransplantation. From October 1997 to January 2004, 46 patients (31 men and 15 women) underwent tPTX without autotransplantation (median age 51 years; range 19-80 years; median dialysis time before PTX 5 years; range 0-25 years). Indications for PTX were hyperparathyroid bone disease in 41 cases and calciphylaxis in 5 cases. Postoperatively, all patients were supplemented with vitamin D analogues, both calcitriol and cholecalciferol. Patients were followed up for 4-107 months (median 63 months). Although tPTX was intended in all cases, we saw recurrent or persistent hyperparathyroidism in 26% and supernumerary glands in 15% of cases. In 7 patients (15%), five or more glands were documented and in another four suspected confirming the clinical relevance of intraoperative parathyroid hormone (PTH) measurement. In our study, the positive predictive value of a low intraoperative PTH (<20 pg/ml) for a successful tPTX was 92%. 15 patients received a renal transplant after tPTX without autotransplantation. Here, an uncomplicated hypocalcaemia was noted in 3 patients. Last available calcium levels were between 1.72 and 2.66 mmol/l (median 2.35 mmol/l). After follow-up, active vitamin D was given in a median daily dose of 0.5 microg calcitriol (range 0-2.5 microg/day). There was no evidence of clinical bone disease and no pathological fractures after tPTX after a median observation period of 63 months. tPTX still offers the highest percentage of cure for sHPT, it is safe and postoperatively easily manageable. It allows for adequate supplementation with active vitamin D, and it is the most cost-effective procedure. It should be reconsidered an option for the treatment of sHPT.

Multiple gastrointestinal stromal tumors and bilateral pheochromocytoma in neurofibromatosis

The coincidence of a gastrointestinal stromal tumor (GIST) and a neuroendocrine tumor (NET) in neurofibromatosis type 1 (NF1) is described only five times within the literature. We report on a 63 year old Caucasian female with the rare condition of neurofibromatosis type 1 coinciding with recurrent gastrointestinal stromal tumor plus bilateral pheochromocytoma (PCC). After a history of palpitations and dizziness that lasted for years, a left adrenal mass was detected by CT. Laparotomy revealed a pheochromocytoma of the left adrenal gland while an ileoterminal GIST was found incidentally intraoperatively. After six months contralateral PCC and multiple recurrent GIST were resected again. After four years the patient is doing well without any signs of further recurrent tumors. Discussion includes review of the literature.

Esophageal perforation: principles of diagnosis and surgical management

PURPOSE

Esophageal perforation (EP) is still associated with a high mortality rate, even after surgical repair. We reviewed 17 cases of EP to evaluate the management of this major surgical problem.

METHODS

We reviewed the medical records of all patients treated for EP in our department between November 2001 and November 2004. Therapy was based on various patient-related factors.

RESULTS

Seventeen patients, with a mean age of 63 years, presented with EP mostly caused by iatrogenic incidents (11/17). In nine patients, the perforation was located in the thoracic segment, with a mean size of 2.5 +/- 0.6 cm. Thoracic computed tomography (CT) was performed in all patients to assess the periesophageal inflammation precisely. More than 50% showed signs of systemic inflammation indicative of sepsis, reflected by a dramatic increase in serum C-reactive protein and leukocytosis. Treatment consisted of debridement and drainage (n = 3), primary repair (n = 3), reinforced repair (n = 4), esophageal resection (n = 5), and conservative measures (n = 2). All patients, except for three with pre-existing liver dysfunction and other comorbidities, survived, representing a mortality rate of 17.6% (14/17). An analysis of the literature (2000-2005) revealed an overall mortality rate of 19.7% (101/521), ranging from 3% to 67%.

CONCLUSION

Our data support the individualized surgical management of EP, based on careful evaluation of various patient-related factors, including CT findings.

MDM2 SNP309 Accelerates Tumor Formation in a Gender-Specific and Hormone-Dependent Manner

The importance of the p53 stress response pathway in the suppression of tumor formation is well documented. In a previous report, a single nucleotide polymorphism (SNP309 T/G) was found in the promoter of the MDM2 gene resulting in higher levels of MDM2 RNA and protein and, consequently, in the attenuation of the p53 pathway both in vitro and in vivo. As the SNP309 locus is found in a region of the MDM2 promoter, which is regulated by hormonal signaling pathways, and the G-allele of SNP309 increases the affinity of a well-described cotranscriptional activator of nuclear hormone receptors (i.e., Sp1), the hypothesis that the SNP309 locus could alter the effects of hormones on tumorigenesis was tested in vivo in humans. Data obtained from patients with three different sporadic cancers, from four independent case studies, support this hypothesis, providing an example for the genetic basis of gender differences in cancer and showing that the genotype at a specific locus can affect how hormones, like estrogen, affect tumorigenesis in humans.

A single nucleotide polymorphism in the MDM2 promoter attenuates the p53 tumor suppressor pathway and accelerates tumor formation in humans

The tumor suppressor p53 gene is mutated in minimally half of all cancers. It is therefore reasonable to assume that naturally occurring polymorphic genetic variants in the p53 stress response pathway might determine an individual's susceptibility to cancer. A central node in the p53 pathway is the MDM2 protein, a direct negative regulator of p53. In this report, a single nucleotide polymorphism (SNP309) is found in the MDM2 promoter and is shown to increase the affinity of the transcriptional activator Sp1, resulting in higher levels of MDM2 RNA and protein and the subsequent attenuation of the p53 pathway. In humans, SNP309 is shown to associate with accelerated tumor formation in both hereditary and sporadic cancers. A model is proposed whereby SNP309 serves as a rate-limiting event in carcinogenesis.