Clinical and Translational Gastroenterology

Primer on Precision Medicine for Complex Chronic Disorders Precision medicine promises patients with complex disorders the right treatment for the right patient at the right dose at the right time with expectation of better health at a lower cost. The demand for precision medicine highlights the limitations of modern Western medicine. Modern Western medicine is a population-based, top-down approach that uses pathology to define disease. Precision medicine is a bottom-up approach that identifies predisease disorders using genetics, biomarkers, and modeling to prevent disease. This primer demonstrates the contrasting strengths and limitations of each paradigm and why precision medicine will eventually deliver on the promises.

Blunted Evoked Prouroguanylin Endocrine Secretion in Chronic Constipation OBJECTIVES: Prouroguanylin (ProUGN) in the intestine is cleaved to form uroguanylin (UGN), which stimulates guanylate cyclase C (GUCY2C), inducing cyclic guanosine monophosphate signaling. Paracrine release regulates fluid secretion, contributing to bowel function, whereas endocrine secretion evoked by eating forms a gut-brain axis, controlling appetite. Whereas hormone insufficiency contributes to hyperphagia in obesity, its contribution to the pathophysiology of constipation syndromes remains unexplored. Here, we compared circulating ProUGN and UGN in healthy subjects and in patients with chronic idiopathic constipation (CIC) and patients with irritable bowel syndrome with constipation (IBS-C). METHODS: Circulating ProUGN and UGN levels were measured in 60 healthy subjects, 53 patients with CIC, and 54 patients with IBS-C. After an overnight fast, the participants ingested a standardized meal; blood samples were drawn at fasting and at 30, 60, and 90 minutes thereafter, and hormone levels were quantified by enzyme-linked immunosorbent assay. RESULTS: Fasting ProUGN levels were >30% lower in patients with CIC and those with IBS-C compared with healthy subjects regardless of age, sex, or disease state. After eating, ProUGN levels increased compared with fasting levels, although the rate of change was slower and maximum levels were lower in patients with CIC and those with IBS-C. Similarly, fasting UGN levels were lower in patients with CIC and those with IBS-C compared with healthy subjects. However, unlike ProUGN levels, UGN levels did not increase after eating. DISCUSSION: These observations support a novel pathophysiologic model in which CIC and IBS-C reflect a contribution of ProUGN insufficiency dysregulating intestinal fluid and electrolyte secretion. TRANSLATIONAL IMPACT: This study suggests that CIC and IBS-C can be treated by oral GUCY2C hormone replacement. Indeed, these observations provide a mechanistic framework for the clinical utility of oral GUCY2C ligands like plecanatide (Trulance) and linaclotide (Linzess) to treat CIC and IBS-C.

Immunologic Features of Patients With Advanced Hepatocellular Carcinoma Before and During Sorafenib or Anti-programmed Death-1/Programmed Death-L1 Treatment INTRODUCTION: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Today, a promising treatment strategy is focused on the enhancement of antitumor immune responses by immune checkpoint modification. However, as only 20% of patients with HCC are responders, identification of predictive factors is urgently required. Therefore, for the first time, the features of the intrahepatic and circulating immune system in patients with advanced-stage HCC, before and during the treatment, were analyzed. METHODS: We collected fresh HCC biopsies, along with adjacent tumor-free liver tissues and peripheral blood samples, from 21 patients with advanced HCC. Furthermore, we performed an extensive immunomonitoring of patients with HCC treated with sorafenib or programmed death (PD)-1/PD-L1 pathway blockade using multiparametric flow cytometry. RESULTS: We observed that regardless of the treatment, low baseline intratumoral CD4+/CD8+ T-cell ratio was associated with better overall survival (P = 0.0002). The baseline frequency of intratumoral PD-1high CD8+ T cells was significantly lower in patients responding to sorafenib treatment than in the nonresponders (P = 0.0117), and the frequency of circulating PD-1high T cells increased with tumor progression (P = 0.0329). By contrast, responders to PD-1/PD-L1 pathway blockade showed a trend of high baseline frequency of intratumoral PD-1high CD8+ T cells. Moreover, we observed a trend of LAG3 and TIM3 upregulation on circulating T cells in nonresponding patients to PD-1/PD-L1 pathway blockade. DISCUSSION: Immunosuppressive state, characterized by an enhanced intratumoral CD4+/CD8+ T-cell ratio, was associated with poor prognosis. Additionally, our results suggest that the frequency of intratumoral PD-1high CD8+ T cells may serve as a biomarker to identify which individuals will benefit from which treatment and support the use of combination strategies.

Clinicopathologic and Racial/Ethnic Differences of Colorectal Cancer Among Adolescents and Young Adults OBJECTIVES: Despite overall reductions in colorectal cancer burden, incidence rates continue to rise among younger patients, and causes remain unknown. We examined differences in clinicopathologic and racial/ethnic characteristics within the adolescent and young adult (AYA) population diagnosed with colorectal cancer in the United States. METHODS: Using the National Cancer Institute's Surveillance, Epidemiology, and End Results program data, we identified individuals diagnosed with first primary colorectal cancer between ages 15 and 39 years from 2010 to 2015. Adjusted multivariable logistic regression models were used to quantify clinicopathologic and racial/ethnic differences across age at onset subgroups (15–19, 20–24, 25–29, 30–34, and 35–39 years). RESULTS: We identified 5,350 AYA patients diagnosed with colorectal cancer. Of note, 28.6% of AYA cases were diagnosed with right-sided tumors (cecum to transverse colon). The proportion of right-sided colorectal cancers differed significantly by age group at diagnosis (38.3% vs 27.3% of AYAs aged 15–19 vs 35–39 years, respectively; P trend = 0.01). Proportions of cases with mucinous adenocarcinoma and signet ring cell carcinoma histopathologic subtypes significantly increased with younger age at onset (P trends = 0.01 and 0.03, respectively). Differences in clinical stage were observed across AYA age groups, with stage II disease increasing with younger age (P trend = 0.01). The proportion of Hispanic AYAs was higher within younger patients, accounting for 21.0% of the AYA population aged 35–39 years up to 28.3% of 15–19-year-old individuals (P trend = 0.003). DISCUSSION: Within the AYA population, colorectal cancers differ by clinicopathologic and racial/ethnic characteristics. Further investigation of the clinical and biologic diversity of colorectal cancers that partially underlie age- and race-related differences in cancer susceptibility and outcomes is warranted.

Variable Features of Juvenile Polyposis Syndrome With Gastric Involvement Among Patients With a Large Genomic Deletion of BMPR1A OBJECTIVES: Loss-of-function mutations of BMPR1A cause juvenile polyposis syndrome (JPS), but large genomic deletions in BMPR1A are rare, reported in few families only, and data regarding the associated phenotype are limited. METHODS: We investigated clinical features and genomic data of 7 extended seemingly unrelated families with a genomic deletion of the entire coding region of BMPR1A. We defined mutation size, mutation prevalence, and tumor pathogenesis using whole-genome sequencing, targeted genotyping, and haplotype analysis. RESULTS: Patients with JPS from 7 families of Bukharin Jewish ancestry carried a deletion of 429 kb, encompassing the BMPR1A coding sequence and 8 downstream genes. Haplotype analysis and testing controls identified this as a common founder mutation occurring in 1/124 individuals of Bukharin origin. Tumor testing did not demonstrate loss of heterozygosity. Among carriers, JPS was almost fully penetrant, but clinical features varied widely, ranging from mild to very severe, including pan-enteric polyps, gastritis, and colorectal, esophageal, and testicular cancer, and carriers with phenotypes, which would not have raised suspicion of JPS. DISCUSSION: The phenotype in this large cohort was extremely variable, although all carriers shared the same variant and the same genetic background. New observations include a preponderance of adenomatous rather than juvenile polyps, possible association with testicular cancer, and unexpected upper gastrointestinal involvement.

Transjugular Liver Biopsy: Safe Even in Patients With Severe Coagulopathies and Multiple Biopsies OBJECTIVES: To investigate the safety profile and diagnostic efficacy of transjugular liver biopsy (TJLB), with a focus on patients with severe coagulopathies and with multiple biopsies. METHODS: Clinical, laboratory, and demographic information was collected on 1,321 TJLBs in 932 patients (mean age 43.5 ± 23.2 years) performed between January 2009 and May 2017 to determine the diagnostic success rate and incidence of both major and minor complications in the 3-day and 30-day period post-biopsies. These outcomes were also analyzed for severely coagulopathic patients and a subgroup of patients who underwent multiple biopsies. RESULTS: The overall success rate (diagnostic yield) of the TJLB procedure was 97.7% (1,291/1,321). Overall, the major and minor complication rates were 1.0% (13/1,321) and 9.5% (126/1,321), respectively. In patients with multiple biopsies, the overall complication rate was similar to the entire study cohort, which was 10.4% (57/550). Patients were also stratified according to the platelet counts of 0–50, 51–100, 101–200, 201–300 and >300 × 103 platelets/μL. The overall complication rates were 8.0% (10/124), 11.6% (36/310), 9.9% (54/547), 11.9% (28/235), and 14.3% (11/77), respectively, and these were not statistically significant from each other. Patients were also stratified by international normalized ratio into 0–1, 1.1–2, 2.1–3, and >3. The overall complication rates of these patients were 8.0% (19/237), 11.8% (113/954), 16.3% (7/43), and 0% (0/9), respectively, and were not statistically significant from each other. DISCUSSION: TJLB is a highly efficacious, well-tolerated and safe procedure. It can be safely performed multiple times in the same patient or in critically ill, severely coagulopathic patients with no significant increase in the rate of complication while maintaining an extremely favorable diagnostic yield.

Clinical Potential of Circulating Tumor Cells in Colorectal Cancer: A Prospective Study OBJECTIVES: Circulating tumor cells (CTCs) in the blood have been used as diagnostic markers in patients with colorectal cancer (CRC). In this study, we evaluated a CTC detection system based on cell size to assess CTCs and their potential as early diagnostic and prognostic biomarkers for CRC. METHODS: From 2014 to 2015, 88 patients with newly diagnosed CRC, who were scheduled for surgery, and 31 healthy volunteers were enrolled and followed up in Pusan National University Hospital. CTCs were enriched using a centrifugal microfluidic system with a new fluid-assisted separation technique (FAST) and detected by cytomorphological evaluation using fluorescence microscopy. RESULTS: Two or more CTCs were detected using FAST in 74 patients and 3 healthy volunteers. The number of CTCs in the CRC group was significantly higher than that in the healthy volunteers (P < 0.001). When a receiver operating characteristic curve was created to differentiate patients with CRC from healthy volunteers, the sensitivity and specificity were almost optimized when the critical CTC value was 5/7.5 mL of blood. When this value was used, the sensitivity and specificity in differentiating patients with CRC from the healthy controls were 75% and 100%, respectively. In patients with CRC with ≥5 CTCs, vascular invasion was frequently identified (P = 0.035). All patients with stage IV were positive for CTCs. Patients with ≥5 CTCs showed a trend toward poor overall and progression-free survival. DISCUSSION: Our study demonstrated promising results with the use of FAST-based CTC detection for the early diagnosis and prognosis of CRC.

A Phase 2 Study of Galunisertib (TGF-β1 Receptor Type I Inhibitor) and Sorafenib in Patients With Advanced Hepatocellular Carcinoma INTRODUCTION: Inhibition of tumor growth factor-β (TGF-β) receptor type I potentiated the activity of sorafenib in preclinical models of hepatocellular carcinoma (HCC). Galunisertib is a small-molecule selective inhibitor of TGF-β1 receptor type I, which demonstrated activity in a phase 2 trial as second-line HCC treatment. METHODS: The combination of galunisertib and sorafenib (400 mg BID) was tested in patients with advanced HCC and Child-Pugh A liver function without prior systemic therapy. Galunisertib dose was administered 80 or 150 mg b.i.d. orally for 14 days every 28 days in safety lead-in cohorts; in the expansion cohort, all patients received galunisertib 150 mg b.i.d. Objectives included time-to-tumor progression, changes in circulating alpha fetoprotein and TGF-β1, safety, overall survival (OS), response rate, and pharmacokinetics (PK). RESULTS: Patients (n = 47) were enrolled from 5 non-Asian countries; 3 and 44 patients received the 80 mg and 150 mg b.i.d. doses of galunisertib, respectively. The pharmacokinetics and safety profiles were consistent with monotherapy of each drug. For the 150 mg b.i.d. galunisertib cohort, the median time-to-tumor progression was 4.1 months; the median OS was 18.8 months. A partial response was seen in 2 patients, stable disease in 21, and progressive disease in 13. TGF-β1 responders (decrease of >20% from baseline) vs nonresponders had longer OS (22.8 vs 12.0 months, P = 0.038). DISCUSSION: The combination of galunisertib and sorafenib showed acceptable safety and a prolonged OS outcome.

Genetic Risk Score in Diabetes Associated With Chronic Pancreatitis Versus Type 2 Diabetes Mellitus Introduction: Diabetes mellitus (DM) is a complication of chronic pancreatitis (CP). Whether pancreatogenic diabetes associated with CP-DM represents a discrete pathophysiologic entity from type 2 DM (T2DM) remains uncertain. Addressing this question is needed for development of specific measures to manage CP-DM. We approached this question from a unique standpoint, hypothesizing that if CP-DM and T2DM are separate disorders, they should be genetically distinct. To test this hypothesis, we sought to determine whether a genetic risk score (GRS) based on validated single nucleotide polymorphisms for T2DM could distinguish between groups with CP-DM and T2DM. Methods: We used 60 T2DM single nucleotide polymorphisms to construct a weighted GRS in 1,613 subjects from the North American Pancreatitis Study 2 and 2,685 subjects from the Multi-Ethnic Study of Atherosclerosis, all of European origin. Results: The mean GRS was identical between 321 subjects with CP-DM and 423 subjects with T2DM (66.53 vs 66.42, P = 0.95), and the GRS of both diabetic groups was significantly higher than that of nondiabetic controls (n = 3,554, P < 0.0001). Exploratory analyses attempting to enrich the CP-DM group for pancreatogenic diabetes, such as eliminating diabetes diagnosed before CP, requiring pancreas-specific comorbidities, or removing those with a family history of diabetes, did not improve the ability of the GRS to distinguish between CP-DM and T2DM. Discussion: Recognizing that we lacked a gold standard to define CP-DM, our study suggests that CP-DM may be a subtype of T2DM, a notion that should be tested in future, large prospective studies.

A Low FODMAP Diet May Reduce Symptoms in Patients With Fecal Incontinence INTRODUCTION: Fecal incontinence (FI) is a common complaint and is often associated with diarrhea and urgency. Foods high in fermentable oligo-, di-, and mono-saccharides and polyols (FODMAP) cause symptoms of diarrhea and urgency. Therefore, this study assesses the impact of a low FODMAP diet on the occurrence of FI due to loose stool. METHODS: This study is a retrospective chart review of patients with FI seen in the Michigan Bowel Control Program clinic between August 2012 and December 2017. Patients who had FI with loose stool without red flag signs and who were recommended a low FODMAP diet and underwent formal dietary instruction with a Michigan Medicine dietician were included. RESULTS: Sixty-five patients with FI who underwent formal dietary teaching were included in this study. Eighty-eight percent of the patients were white, and 87% were women with a mean age of 62 years (±14 years). Additionally, the chart review showed that 35% of the patients had FI daily, 21.5% had FI weekly, and 5% had FI monthly. About 64.6% of the patients (42) had reported a reduction in their FI symptoms with the low FODMAP diet. There was no demographic or clinical characteristic that predicted the response to a low FODMAP diet. DISCUSSION: In this case series, dietary manipulation with a low FODMAP diet was a useful tool to treat patients who suffer from FI due to loose stool. Further confirmatory, prospective randomized controlled trials are required to see the true efficacy of a low FODMAP diet in patients who suffer with FI.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com