C/EBPα Confers Dependence to Fatty Acid Anabolic Pathways and Vulnerability to Lipid Oxidative Stress-Induced Ferroptosis in FLT3-Mutant Leukemia

Although transcription factor CCAAT-enhancer binding protein α (C/EBPα) is critical for normal and leukemic differentiation, its role in cell and metabolic homeostasis is largely unknown in cancer. Here, multiomics analyses uncovered a coordinated activation of C/EBPα and Fms-like tyrosine kinase 3 (FLT3) that increased lipid anabolism in vivo and in patients with FLT3-mutant acute myeloid leukemia (AML). Mechanistically, C/EBPα regulated the fatty acid synthase (FASN)-stearoyl-CoA desaturase (SCD) axis to promote fatty acid (FA) biosynthesis and desaturation. We further demonstrated that FLT3 or C/EBPα inactivation decreased monounsaturated FA incorporation to membrane phospholipids through SCD downregulation. Consequently, SCD inhibition enhanced susceptibility to lipid redox stress that was exploited by combining FLT3 and glutathione peroxidase 4 inhibition to trigger lipid oxidative stress, enhancing ferroptotic death of FLT3-mutant AML cells. Altogether, our study reveals a C/EBPα function in lipid homeostasis and adaptation to redox stress, and a previously unreported vulnerability of FLT3-mutant AML to ferroptosis with promising therapeutic application.

SIGNIFICANCE

FLT3 mutations are found in 30% of AML cases and are actionable by tyrosine kinase inhibitors. Here, we discovered that C/EBPα regulates FA biosynthesis and protection from lipid redox stress downstream mutant-FLT3 signaling, which confers a vulnerability to ferroptosis upon FLT3 inhibition with therapeutic potential in AML. This article is highlighted in the In This Issue feature, p. 1501.

G protein-coupled receptor 183 mediates the sensitization of Burkitt lymphoma tumors to CD47 immune checkpoint blockade by anti-CD20/PI3Kδi dual therapy

Background

Immunotherapy-based regimens have considerably improved the survival rate of B-cell non-Hodgkin lymphoma (B-NHL) patients in the last decades; however, most disease subtypes remain almost incurable. TG-1801, a bispecific antibody that targets CD47 selectively on CD19+ B-cells, is under clinical evaluation in relapsed/refractory (R/R) B-NHL patients either as a single-agent or in combination with ublituximab, a new generation CD20 antibody.

Methods

A set of eight B-NHL cell lines and primary samples were cultured in vitro in the presence of bone marrow-derived stromal cells, M2-polarized primary macrophages, and primary circulating PBMCs as a source of effector cells. Cell response to TG-1801 alone or combined with the U2 regimen associating ublituximab to the PI3Kδ inhibitor umbralisib, was analyzed by proliferation assay, western blot, transcriptomic analysis (qPCR array and RNA sequencing followed by gene set enrichment analysis) and/or quantification of antibody-dependent cell death (ADCC) and antibody-dependent cell phagocytosis (ADCP). CRISPR-Cas9 gene edition was used to selectively abrogate GPR183 gene expression in B-NHL cells. In vivo, drug efficacy was determined in immunodeficient (NSG mice) or immune-competent (chicken embryo chorioallantoic membrane (CAM)) B-NHL xenograft models.

Results

Using a panel of B-NHL co-cultures, we show that TG-1801, by disrupting the CD47-SIRPα axis, potentiates anti-CD20-mediated ADCC and ADCP. This led to a remarkable and durable antitumor effect of the triplet therapy composed by TG-1801 and U2 regimen, in vitro, as well as in mice and CAM xenograft models of B-NHL. Transcriptomic analysis also uncovered the upregulation of the G protein-coupled and inflammatory receptor, GPR183, as a crucial event associated with the efficacy of the triplet combination. Genetic depletion and pharmacological inhibition of GPR183 impaired ADCP initiation, cytoskeleton remodeling and cell migration in 2D and 3D spheroid B-NHL co-cultures, and disrupted macrophage-mediated control of tumor growth in B-NHL CAM xenografts.

Conclusions

Altogether, our results support a crucial role for GPR183 in the recognition and elimination of malignant B cells upon concomitant targeting of CD20, CD47 and PI3Kδ, and warrant further clinical evaluation of this triplet regimen in B-NHL.

Antitumor Activity of the Novel BTK Inhibitor TG-1701 Is Associated with Disruption of Ikaros Signaling in Patients with B-cell Non-Hodgkin Lymphoma

PURPOSE

Despite the remarkable activity of BTK inhibitors (BTKi) in relapsed B-cell non-Hodgkin lymphoma (B-NHL), no clinically-relevant biomarker has been associated to these agents so far. The relevance of phosphoproteomic profiling for the early identification of BTKi responders remains underexplored.

EXPERIMENTAL DESIGN

A set of six clinical samples from an ongoing phase I trial dosing patients with chronic lymphocytic leukemia (CLL) with TG-1701, a novel irreversible and highly specific BTKi, were characterized by phosphoproteomic and RNA sequencing (RNA-seq) analysis. The activity of TG-1701 was evaluated in a panel of 11 B-NHL cell lines and mouse xenografts, including two NF-κB- and BTK^C481S-driven BTKi-resistant models. Biomarker validation and signal transduction analysis were conducted through real-time PCR, Western blot analysis, immunostaining, and gene knockout (KO) experiments.

RESULTS

A nonsupervised, phosphoproteomic-based clustering did match the early clinical outcomes of patients with CLL and separated a group of "early-responders" from a group of "late-responders." This clustering was based on a selected list of 96 phosphosites with Ikaros-pSer442/445 as a potential biomarker for TG-1701 efficacy. TG-1701 treatment was further shown to blunt Ikaros gene signature, including YES1 and MYC, in early-responder patients as well as in BTKi-sensitive B-NHL cell lines and xenografts. In contrast, Ikaros nuclear activity and signaling remained unaffected by the drug in vitro and in vivo in late-responder patients and in BTK^C481S, BTK^KO, and noncanonical NF-κB models.

CONCLUSIONS

These data validate phosphoproteomic as a valuable tool for the early detection of response to BTK inhibition in the clinic, and for the determination of drug mechanism of action.

The analysis of GSTA1 promoter genetic and functional diversity of human populations

GSTA1 encodes a member of a family of enzymes that function to add glutathione to target electrophilic compounds, including carcinogens, therapeutic drugs, environmental toxins, and products of oxidative stress. GSTA1 has several functional SNPs within its promoter region that are responsible for a change in its expression by altering promoter function. This study aims to investigate distributions of GSTA1 promoter haplotypes across different human populations and to assess their impact on the expression of GSTA1. PHASE 2.1.1 was used to infer haplotypes and diplotypes of six GSTA1 promoter SNPs on 2501 individuals from 26 populations classified by the 1000 Genomes Project into five super-populations that included Africa (N = 660), America (N = 347), East Asia (N = 504), Europe (N = 502), and South Asia (N = 488). We used pairwise FST analysis to compare sub-populations and luciferase reporter assay (LRA) to evaluate the impact of each SNP on activation of transcription and interaction with other SNPs. The distributions of GSTA1 promoter haplotypes and diplotypes were significantly different among the different human populations. Three new promoter haplotypes were found in the African super-population. LRA demonstrated that SNPs at -52 and -69 has the most impact on GSTA1 expression, however other SNPs have a significant impact on transcriptional activity. Based on LRA, a new model of cis-elements interaction is presented. Due to the significant differences in GSTA1 diplotype population frequencies, future pharmacogenomics or disease-related studies would benefit from the inclusion of the complete GSTA1 promoter haplotype based on the newly proposed metabolic grouping derived from the LRA results.

Abstract 2205: TG-1701, a novel irreversible Bruton's kinase (BTK) inhibitor, cooperates with ublituximab-driven ADCC and ADCP in in vitro and in vivo models of ibrutinib-resistant mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare subtype of aggressive B-cell non-Hodgkin lymphoma (NHL) that remains incurable with standard therapy. The first-in-class Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has proven to be an effective agent for patients with relapsed/refractory MCL, although development of a cysteine to serine mutation at the BTK catalytic site (BTKC481S) or over-activation of the NF-kB pathway can impair MCL response to most BTK inhibitors (BTKis). TG-1701 is a novel irreversible inhibitor highly specific to BTK, with improved selectivity when compared to ibrutinib, currently being evaluated in a phase 1 clinical trial in non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) patients. Here we show that, when compared to irreversible and reversible BTKis including ibrutinib, acalabrutinib, and ARQ-531, TG-1701 showed similar cytotoxic activity either in ibrutinib-sensitive or in ibrutinib-resistant MCL cells. We then evaluated the activity of TG-1701 and ibrutinib on anti-CD20 antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP), as ibrutinib has previously been show to block rituximab-mediated ADCC due to off-target inhibition of ITK (Kohrt et al., Blood 2014). In sharp contrast with ibrutinib, which partially antagonized rituximab activity, we found that TG-1701 did not impair the anti-CD20-mediated ADCC and ADCP in a multicellular co-culture system that associated MCL to effector cells. In another set of cell-based assays, we showed that the treatment with TG-1701 led to a strong decrease in IL-10 expression, together with a significant increase in IL-2, IL-6 and IL1RN gene transcription, thus associating TG-1701 exposure with the promotion of an immune response within the tumor microenvironment (TME). Accordingly, TG-1701 cooperated with the novel anti-CD20 antibody ublituximab and the novel PI3Kδ-CK1ϵ dual inhibitor umbralisib in reducing the tumor growth in both ibrutinib-sensitive (REC1) and ibrutinib-resistant (UPN-1res) mouse models of MCL. In accordance with in vitro data, the antitumor activity of the drug combination was associated with increased production of IL-2, IL-6 and TNFα, and with an increased infiltration of mouse macrophages and NK cells. Altogether, these data warrant further clinical investigation of TG-1701-mediated engagement of TME-related anti-tumor effect, and clinical evaluation of the triple combination of TG-1701, ublituximab, and umbralisib, is ongoing.

Citation Format: Marcelo L. Ribeiro, Diana Reyes-Garau, Meritxell Vinyoles, Marc Armengol, Hari Miskin, Francesc Bosch, Pablo Menendez, Emmanuel Normant, Gael Roue. TG-1701, a novel irreversible Bruton's kinase (BTK) inhibitor, cooperates with ublituximab-driven ADCC and ADCP in in vitro and in vivo models of ibrutinib-resistant mantle cell lymphoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2205.

Abstract 2925: Safety and efficacy of EZH2 and BRD4 dual targeting in EZH2Y641mut germinal centre-derived lymphoma

A significant proportion of diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL) patients harbor a gain-of-function, heterozygous somatic mutations of the methyltransferase gene EZH2. Despite acceptable safety profile and early signs of activity in clinical trials, single agent treatment with EZH2 inhibitors is unlikely to be curative in aggressive lymphomas. In an effort to established novel rational combinations, we have evaluated the activity and mechanism of action of the EZH2 small molecule inhibitor CPI169 as single agent and in combination with BET bromodomain inhibition, using preclinical models of DLBCL and FL with distinct EZH2 mutational status. CPI169 anti-tumor activity and specificity was assessed in vitro in 10 DLBCL and FL cell lines, including cells expressing basal or ectopic EZH2mut. Molecular bases of its activity were determined by gene expression profiling (GEP), qPCR and western blot, followed by automated exploratory data analysis. Biomarkers validation was made in vitro and in vivo, using a mouse xenotransplant model of EZH2mut DLBCL, considering both exposure to CPI169 single agent and/or combination treatment with a BRD4 inhibitor, CPI203. CPI169 induced dose-dependent proliferation blockade in EZH2mut, but not EZH2wt DLBCL and FL cell lines, independently of EZH2 expression level or basal methyltransferase activity. Loss of H3K27me3 mark upon CPI169 treatment was associated with upregulation of gene sets related to G1 cell cycle blockade, mTOR and P53 pathways, and MYC signaling. Accordingly, combination with the MYC-interfering drug, BET inhibitor CPI203, achieved a synergistic anti-proliferating activity in EZH2 mutated cases and in mice bearing EZH2mut DLBCL tumors. Activity of EZHi/BRD4i combo was characterized by lower mitotic index, increased loss of H3K27me3 mark, in association with MYC downregulation. GEP analysis, followed by automated exploratory data analysis and validation by a siRNA screening, further identified the PI3K/AKT-regulated gene and mitosis regulator, YPEL2, and the regulator of innate-like B lymphocyte maturation, KLHL14, as crucial factors involved in the efficacy of MYC/EZH2 dual targeting. In conclusion, CPI169 shows significant activity and safety as single agent in EZH2 mutated-DLBCL and FL cases and displays synergistic interaction in vitro and in vivo with BRD4 inhibition, mediated by the modulation of a limited set of EZH2-regulated genes.

Citation Format: Aranzazu Chamorro-Jorganes, Marcelo L. Ribeiro, Nuria Profitos-Peleja, Diana Reyes-Garau, Clara Recasens-Zorzo, Juan G. Valero, Marc Armengol, Patricia Perez-Galan, Ray Butler, Antonio Postigo, Francesc Bosch, Gael Roue. Safety and efficacy of EZH2 and BRD4 dual targeting in EZH2Y641mut germinal centre-derived lymphoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2925.

Recent Advances in the Targeting of Epigenetic Regulators in B-Cell Non-Hodgkin Lymphoma

In the last 10 years, major advances have been made in the diagnosis and development of selective therapies for several blood cancers, including B-cell non-Hodgkin lymphoma (B-NHL), a heterogeneous group of malignancies arising from the mature B lymphocyte compartment. However, most of these entities remain incurable and current treatments are associated with variable efficacy, several adverse events, and frequent relapses. Thus, new diagnostic paradigms and novel therapeutic options are required to improve the prognosis of patients with B-NHL. With the recent deciphering of the mutational landscapes of B-cell disorders by high-throughput sequencing, it came out that different epigenetic deregulations might drive and/or promote B lymphomagenesis. Consistently, over the last decade, numerous epigenetic drugs (or epidrugs) have emerged in the clinical management of B-NHL patients. In this review, we will present an overview of the most relevant epidrugs tested and/or used so far for the treatment of different subtypes of B-NHL, from first-generation epigenetic therapies like histone acetyl transferases (HDACs) or DNA-methyl transferases (DNMTs) inhibitors to new agents showing selectivity for proteins that are mutated, translocated, and/or overexpressed in these diseases, including EZH2, BET, and PRMT. We will dissect the mechanisms of action of these epigenetic inhibitors, as well as the molecular processes underlying their lack of efficacy in refractory patients. This review will also provide a summary of the latest strategies being employed in preclinical and clinical settings, and will point out the most promising lines of investigation in the field.

Morbidity after laparoscopic and open rectal cancer surgery: a comparative analysis of morbidity in octogenarians and younger patients

AIM

Although the oncological adequacy of laparoscopic rectal resection (LR) appears equivalent to open resection (OR), its benefit is controversial in the elderly. The aim of this study was to investigate the influence of LR on morbidity and mortality in octogenarians.

METHOD

This was a retrospective analysis of all patients who underwent rectal surgery for cancer between 2003 and 2013 in a teaching hospital. The primary aim of the study was to assess the influence of surgical approach on mortality and morbidity of rectal resection in patients ≥ 80 years old. Regression analysis was performed to control the effect of covariables on the clinical outcome.

RESULTS

Of 408 patients 203 were in the LR group and 205 in the OR group including 303 (74.3%) less than 80 years and 105 (25.7%) over 80 years. The mortality was lower in the LR group compared with the OR group for patients under 80 years (0% vs 4.6%; P = 0.049) and no different in the over 80 group (11.5% vs 9.4%; P = 0.859). In younger patients, the OR group showed longer hospital stay (9 vs 7 days; P < 0.001) and more complications (44.1% vs 29.8%; P = 0.042). Medical complications were more frequent in LR group than OR group octogenarians (40.4% vs 20.8%; P = 0.009) as well as grade C anastomotic leakage (13.8 vs 10.7; P = 0.041).

CONCLUSION

LR for rectal cancer showed clinical advantages in patients under 80 years and was as safe as OR in patients over 80 years, although the advantages of laparoscopic surgery were lost in the elderly group due to a higher rate of medical complications. OR may be an option in elderly patients with important comorbidities.

Jejunal diverticula causing massive intestinal bleeding

Small bowel diverticula are rare formations and some are prone to complications such as lower gastrointestinal bleeding. We report the case of a patient with hemorrhagic shock following upper gastrointestinal bleeding. A 39-year-old patient was admitted to the unit for recurrent bleeding. The patient received transfusions and selective arteriography was performed which reported bleeding at the level of the ileocolic artery. Laparatomy was performed and blood was found at the entire colon and small intestine up to 40 cm of Treitz angle where multiple diverticula were visualized. Bowel resection was performed. Although duodeno-jejunal diverticula are rare, a special attention should be paid to this clinical entity as it can be a cause of recurrent upper gastrointestinal bleeding.

Use of images in a surgery consultation. Will it improve the communication?

INTRODUCTION

The interviews and interactions with patients are part of everyday health care provider. However, there is sometimes a difficulty in communication, linked to several factors. For this reason, the use of images to illustrate the medical conditions in the outpatient clinic can improve patient communication. We report our initial experience with the use of images to manage the quality of care to surigcal patients.

METHODOLOGY

He used a computer to show pictures of the following conditions: surgery for an inguinal hernia, cholelithiasis, cholecystitis and the choledocholithiasis and finally thyroid pathology. Were randomized two groups of patients. Each of the affected patients in any stage of the disease, they explained their problems. In one of the groups also showed the patient was using the current image and continued to give appropriate explanations related to pathology. Thereafter, patients in both groups filled in an anonymous questionnaire in which they responded to what degree it was considered useful this methodology, and degree of satisfaction received outpatient treatment with or without the deployment of images by computer. We have analyzed the average time expected and made a visit.

RESULTS

187 patients will be visited in the consultations over a period of 8 months. In 83 patients have been using images to give the explanations in external consultations. Of these, 24 patients suffering from thyroid, 24 hernias or incisional hernias and 35 patients with biliary tract pathology. Patients in the group were shown images of conditions have responded mostly be very satisfied with the use of images while the explanations are given on the patient's illness. Also, over 80% of patients report being satisfied with this system. The visiting time was not lengthened.

DISCUSSION

Despite the existence of different variables that can influence patient satisfaction, use of images to illustrate surgical diseases to patients improves communication and flow of the explanations of the physician.

CONCLUSIONS

The relationship doctor-patient communication is the key event in an outpatient setting. It determines a good overall result of the clinical interview. The use of images in an outpatient improves communication between patients and doctors. Moreover, the degree of satisfaction is high and the degree of understanding of the disease. It seems useful to incorporate in our outpatient clinic.

Single incision laparoscopic surgery (SILS) cholecystectomy. A novel technique

INTRODUCTION

Since early nineties, laparoscopic cholecystectomy has become gold standard for cholecystectomy. Also, a high tendency of minimizing surgical trauma encourages the use of new approaches in laparoscopic surgery. A novel approach such as Single incision laparoscopic surgery (SILS) cholecystectomy has been describes.

CASE REPORT

We report on a case of a 33-year-old female patient scheduled for elective laparoscopic cholecystectomy due to symptomatic ultrasonography verified cholelithiasis. A single 2.5-cm long semicircular infraumbilical skin incision was used. Pneumoperitoneum was established alter introduction of the predesigned trocar. Antegrade cholecystectomy was performed without stay suture placement. Postoperative course was uneventful.

DISCUSSION

This article reports the authors' method of performing SILS cholecystectomy. SILS approach is feasible with new standard devices from the industry that offers slightly modified instruments for standard laparoscopic cholecystectomy.

CONCLUSION

Single-incision laparoscopic surgery is a feasible way to perform cholecystectomy. A learning-curve is required and further work in the form of randomized controlled trials is needed to investigate the advantages of this new technique.

Short postal questionnaire and selective clinical examination combined with repeat mailing and telephone reminders as a method of follow-up in hernia surgery

BACKGROUND

We assessed the usefulness of a short postal questionnaire and selective clinical examination combined with repeat mailing and telephone reminders for quality assessment in hernia surgery.

METHODS

All patients (n = 1153) who underwent tension-free hernioplasty through an open preperitoneal approach between 1999 and 2003 received a six-item questionnaire with a covering letter and a stamped addressed envelope. Nonresponders received two successive new questionnaires and a telephone call.

RESULTS

A total of 841 (72.9%) patients returned questionnaires after three reminders (512 after the first mailing, 205 after the second, and 124 after the third). Positive questionnaire answers were documented for 152 (18.1%) of repairs and negative answers for 689 (81.9%). Of the 152 patients who answered "yes" to either of the questions regarding recurrence and/or current pain, 91 declined clinical appointments, 24 could not be contacted by phone, and 37 underwent physical examination. Of the 312 patients who did not return the questionnaire, eight had died, 124 did not want to be visited, and 180 could not be located. The recurrence rate was 2.7% and the chronic pain rate 5.9%.

CONCLUSIONS

Repeat mailing was a useful strategy to improve response to self-administered postal questionnaires on hernia surgery quality assessment. However, contacting the group that responded with positive questionnaire answers was a poorly effective way to encourage subjects to come for a physical examination.

High EPHB2 mutation rate in gastric but not endometrial tumors with microsatellite instability

The EPH/EFN family of receptor tyrosine kinases regulates cell adhesion and migration and has an important role in controlling cell positioning in the normal intestinal epithelium. Inactivation of EPHB2 has recently been shown to accelerate tumorigenesis in the colon and rectum, and we have previously demonstrated frequent frameshift mutations (41%) in an A9 coding microsatellite repeat in exon 17 of EPHB2 in colorectal tumors with microsatellite instability (MSI). In this study, we extended these analyses to extracolonic MSI cancers, and found frameshift EPHB2 mutations in 39% (25/64) of gastric tumors and 14% (8/56) of endometrial tumors. Regression analysis of these EPHB2 mutation data on the basis of our previously proposed statistical model identified EPHB2 as a selective target of frameshift mutations in MSI gastric cancers but not in MSI endometrial carcinomas. These results suggest a functional role for EPHB2 in gastric tumor progression, and emphasize the differences between the tumorigenic processes in MSI gastrointestinal and endometrial cancer.

Improved surgical mesh integration into the rat abdominal wall with arginine administration

Prosthetic meshes are used as the standard of care in abdominal wall hernia repair. However, hernia recurrences and side effects remain unsolved problems. The demand by health care providers for increasingly efficient and cost-effective surgery encourages the development of newer strategies to improve devices and outcomes. Here, we evaluated whether l-arginine administration was able to ameliorate long-term polypropylene prostheses incorporation into the abdominal wall of Sprague-Dawley rats. Meshes were placed on-lay and continuous l-arginine was administered. In vivo biocompatibility was studied at 7, 25 and 30 days post-implantation. Effectively, l-arginine administration in combination with mesh triggered subtle changes in ECM composition that impinged on critical biochemical and structural features. Lastly, tensile strength augmented and stiffness decreased over the control condition. This could help to restructure the mechanical load transfer from the implant to the brittle surrounding tissues, i.e., impact load and fatigue load associated with mechanical tensions could be distributed between the mesh and the restored tissue in a more balanced manner, and ultimately help to reduce the incidence of loosening, recurrences, and local wound complications. Since the newly formed tissue is more mechanically stable, this approach could eventually be introduced to human hernia repair.

Long-term results of tacrolimus in cyclosporine- and prednisone-dependent myasthenia gravis

Seventy-nine patients with cyclosporine- and prednisone-dependent myasthenia gravis (MG) after thymectomy received tacrolimus for a mean of 2.5 +/- 0.8 years. Prednisone was withdrawn in all but two patients. Anti-acetylcholine antibodies and MG score for disease severity decreased significantly and muscular strength increased by 39%. Complete stable remission was achieved in 5% of patients and pharmacologic remission in 87.3%. All patients resumed full activities of daily living.

BRAF screening as a low-cost effective strategy for simplifying HNPCC genetic testing

BACKGROUND

According to the international criteria for hereditary non-polyposis colorectal cancer (HNPCC) diagnostics, cancer patients with a family history or early onset of colorectal tumours showing high microsatellite instability (MSI-H) should receive genetic counselling and be offered testing for germline mutations in DNA repair genes, mainly MLH1 and MSH2. Recently, an oncogenic V600E hotspot mutation within BRAF, a kinase encoding gene from the RAS/RAF/MAPK pathway, has been found to be associated with sporadic MSI-H colon cancer, but its association with HNPCC remains to be further clarified.

METHODS

BRAF-V600E mutations were analysed by automatic sequencing in colorectal cancers from 206 sporadic cases with MSI-H and 111 HNPCC cases with known germline mutations in MLH1 and MSH2. In addition, 45 HNPCC cases showing abnormal immunostaining for MSH2 were also analysed.

RESULTS

The BRAF-V600E hotspot mutation was found in 40% (82/206) of the sporadic MSI-H tumours analysed but in none of the 111 tested HNPCC tumours or in the 45 cases showing abnormal MSH2 immunostaining.

CONCLUSIONS

Detection of the V600E mutation in a colorectal MSI-H tumour argues against the presence of a germline mutation in either the MLH1 or MSH2 gene. Therefore, screening of these mismatch repair (MMR) genes can be avoided in cases positive for V600E if no other significant evidence, such as fulfilment of the strict Amsterdam criteria, suggests MMR associated HNPCC. In this context, mutation analysis of the BRAF hotspot is a reliable, fast, and low cost strategy which simplifies genetic testing for HNPCC.

Stress relaxation tests in polypropylene monofilament meshes used in the repair of abdominal walls

The objective of this work has been to characterize stress relaxation in the polymer material on applying different levels of constant strain. The meshes were strained at values of 5.2%, 5.4% and 5.6% which are the values at which the mesh is strained in clinical use for the repair of abdominal walls. Laws have been obtained to model the viscoelastic behavior at different strains for this material. Finally, fracture studies were carried out by environmental scanning electron microscopy to determine the fracture mechanisms of these meshes. Besides, the implantation of the meshes was practised in two different layers of abdominal wall: the superficial or preaponeurotic layer and deep or preperitoneal layer, showing the neoformation of connective tissue on the mesh, which tended to be organized differently in each layer studied; more roughly and densely in the superficial layer than in the deep one.

Somatic mutations in the DNA damage-response genes ATR and CHK1 in sporadic stomach tumors with microsatellite instability

Maintenance of genomic stability depends on the appropriate cellular responses to DNA damage and the integrity of the DNA repair systems. We analyzed stomach tumors with microsatellite instability (MSI) for frameshift mutations in several potential targets of the mutator phenotype involved in DNA damage-response pathways, such as the ataxia telangiectasia mutated protein-related protein (ATR)-CHK1-Cdc25c pathway, and DNA repair. High frequency of mutations was found within ATR [5 (21%) of 23], MED1 [10 (43%) of 23], hMSH3 [13 (56%) of 23], and hMSH6 [10 (43%) of 23] genes. Also, a low frequency of mutations within the CHK1 gene was detected in 9% (2 of 23) of tumors. No mutations of hMLH3, ATM, BRCA1, or NBS1 genes were detected. These results confirm ATR, MED1, and CHK1 as targets of the mutator pathway in stomach tumorigenesis, and also suggest a potential role of MED1 increasing, together with hMSH3 and hMSH6, the genomic instability in the mutator pathway as a secondary mutator. Furthermore, these results suggest that the inhibition of the ATR-CHK1 DNA damage-response pathway might be involved in the tumorigenesis of gastric cancer with microsatellite instability.

Early imaging of integration response to polypropylene mesh in abdominal wall by environmental scanning electron microscopy: comparison of two placement techniques and correlation with tensiometric studies

The repair of incisional hernias has taken advantage of the strength provided by prosthetic mesh grafts, but the best position for inserting the materials has not been conclusively established. Environmental scanning electron microscopy (ESEM) provides imaging of biologic samples with minimal manipulation. We used ESEM for early imaging of the integration response to polypropylene meshes placed in two anatomic positions in the abdominal wall and correlated results with tensiometric studies. Two macroporous polypropylene prostheses were implanted in a rat model--one on the abdominal aponeurotic layer and one on the peritoneal surface--without creating a wall defect. Studies were performed over implantation intervals of 7, 15, and 30 days in strips obtained from the polypropylene fiber-receptor repair tissue interface. Microscopic appearance, tensile strength, percent elongation, and stiffness were evaluated. Meshes implanted on the abdominal aponeurotic layer showed better early tissue incorporation (higher collagen deposition, capillary density, cell accumulation) and increased tensile strength, reflecting tighter anchorage to the abdominal wall. The percent elongation increased from day 7 to day 30 after implantation, mainly in the deep stratum. The ESEM images correlated well with biomechanical results, indicating the potential of this technique as a powerful, effective tool for use in wound-healing studies.

Early effects of exogenous arginine after the implantation of prosthetic material into the rat abdominal wall

We have investigated the effects of high arginine (Arg) levels (7.5 mg/100 g body weight per hour) on the early integration of biocompatible mesh grafts into the rat abdominal wall. Studies were performed over implantation intervals of 6, 12, 24 or 48 hours (n=12, each). Arginine and related compounds were quantified in plasma, wound fluids and multiple tissues. Plasma nitric oxide (NO) production was studied. Strips were taken from the polypropylene fiber-host tissue interfaces (PTIs) for optical microscopic analysis and for immunohistochemical analysis using rat-specific antibodies against type I and type III collagens. Exogenous Arg was metabolized at the peripheral tissues but reliably reached the wound space. High amounts of Arg and ornithine (Orn) were detected in the specimens considered. No changes on citrulline (Ctr) or NO concentrations were observed, overall suggesting that, during the period studied, the arginase pathway predominated. The acute scarring response differed significantly in the two placements considered. The P-SS interface evidenced more extensive new tissue growth than the P-DS interface. Forty-eight hours after mesh implantation cellular infiltration, fibroblast proliferation, and mesh-surrounding angiogenesis were higher in the arginine-treated rats. Type III collagen staining was related to arginine treatment, being higher (++) in the study group. In conclusion, and independently of the site of mesh placement, supplemental Arg seemed to favorably affect early local collagen deposition. This could be potentially helpful to ameliorate the integration of biomaterials into the tissues and, consequently, to allow for the design of more selective therapeutic strategies to prevent hernia recurrence rates.

Portomesenteric vein gas: pathologic mechanisms, CT findings, and prognosis

Portomesenteric vein gas is a rare condition whose pathogenesis is not fully understood. Portomesenteric vein gas is most commonly caused by mesenteric ischemia but may have a variety of other causes. The primary factors that favor the development of this pathologic entity are intestinal wall alterations, bowel distention, and sepsis. Portomesenteric vein gas is idiopathic in approximately 15% of cases. Advanced imaging techniques such as computed tomography (CT) have increased the sensitivity for detection of portomesenteric vein gas. At CT, portal vein gas appears as tubular areas of decreased attenuation in the liver, predominantly in the left lobe. Gas in the great mesenteric veins can easily be demonstrated with contrast material-enhanced CT, whereas gas in the small mesenteric veins appears as tubular or branched areas of decreased attenuation in the mesenteric border of the bowel. Findings of portomesenteric vein gas at CT should be carefully evaluated in the context of clinical findings. In the majority of cases, the prognosis is favorable and surgery is not required. However, when CT demonstrates portomesenteric vein gas and clinical findings suggest the presence of mesenteric ischemia, surgery is mandatory.

Fluorouracil and high-dose leucovorin with radiotherapy as adjuvant therapy for rectal cancer. Results of a phase II study

The purpose of this phase II study was to evaluate the efficacy and toxicity of fluorouracil and high-dose leucovorin (5-FU/LV) with pelvic irradiation as adjuvant therapy for patients with macroscopical resected rectal or recto-sigmoid cancer. Following surgery for stages II-III primary (52) or recurrent rectal cancer (4), 56 patients received 8 cycles of 5-FU/LV and pelvic irradiation. 5-FU doses were 200 mgr/m2 for cycles 2-3 and 300 mgr/m2 for cycles 1 and 4-8. LV doses remained fixed at 200 mgr/m2. Pelvic radiation was started in the third week, between the first and second cycle. The total dose was 50.4 Gy. No severe complications had been recorded. The incidence of grade 3 diarrhea was 19%. Three patients presented leukopenia grade 3 (5%). In 44 patients (78%) the planned treatment could be administered. The median follow-up was 40 months (range 22-66). Seven patients had a local relapse (13%) and 6 developed distant metastasis (10%). The 3-year disease-free survival was 72% and the overall survival was 76%. These preliminary results show that combined post-operative 5-FU/LV and pelvic radiotherapy are well tolerated and present a reasonable local control and survival rates. This adjuvant treatment should be evaluated in randomized trials.

[Pseudotumorous hyperplasia of the caudate lobe of the liver in a patient with Alagille syndrome]

The Alagille's syndrome consists in hypoplasia of the intrahepatic biliary ducts associated to congenital abnormalities of different organs. It is usually diagnosed in infancy due to cholestasis with good prognosis. The case of a 31-year old women who presented prominent chin, micrognathia, flattening of the nasal bone, infundibular stenosis of the pulmonary artery and cholestasis is reported. Ultrasonography demonstrated a lesion in the space of the hepatic caudate lobe with punction showing sinusoidal dilatation and infiltration of some portal spaces by lymphocytes, eosinophils and neutrophils. Samples of liver tissue obtained during laparotomy showed an absence of intrahepatic biliary ducts in the right and left lobes and preservation of those of the caudate lobe, which was also increased in size with a pseudotumoral appearance. The patients was asymptomatic with slight anicteric cholestasis at 16 months of diagnosis. The rarity of these forms of Alagille's syndrome with areas free of hypoplasia of the intrahepatic biliary ducts are of note.

[Application of extracorporeal lithotripsy in intestinal subocclusion caused by a clam shell]

A patient with intestinal obstruction secondary to a foreign body (clam shell) impacted in the ileocecal valve was treated by extracorporeal shock wave lithotripsy. The resolution of ileus without complications was obtained.

A prospective randomized trial comparing somatostatin and sclerotherapy in the treatment of acute variceal bleeding

Somatostatin and endoscopic sclerotherapy are widely used in the treatment of acute variceal bleeding. Although objective evidence does exist about the advantages of either treatment, data comparing both procedures are scarce. In order to compare the effectiveness and safety of somatostatin and sclerotherapy in the treatment of acute variceal bleeding, 70 consecutive cirrhotic patients suffering from esophageal variceal hemorrhage and meeting the inclusion criteria were randomly assigned to treatment with somatostatin (35 patients) or sclerotherapy (35 patients). No differences in age, sex, alcohol intake, etiology of cirrhosis and severity of liver failure were found between groups. Failure of treatment (defined as persistence of bleeding despite therapy or subsequent rebleeding within the 48-hr trial period) occurred in seven patients (20%) in the somatostatin group and in six (17.1%) in the sclerotherapy group (NS). Early rebleeding occurred in seven of 28 patients (25%) in the somatostatin group and in five of 29 (17.2%) in the sclerotherapy group (NS). Mortality within the first 6 wk was no different between both groups: 10 (28.5%) and eight (22.8%) in the somatostatin and sclerotherapy groups, respectively. Sclerotherapy, but not somatostatin, was associated with major complications in five cases (14.2%) (p = 0.026), two of which resulted in patient's death. These results suggest that somatostatin is safer, and as effective as sclerotherapy, in controlling acute variceal bleeding until an elective treatment can be established.

Prognostic factors of hepatic encephalopathy after portacaval anastomosis: a multivariate analysis in 50 patients

Portacaval anastomosis has proved to be effective in avoiding active and recurrent hemorrhage from gastroesophageal varices in liver cirrhosis. However, hepatic encephalopathy is the most common and serious complication of this procedure. The aim of this study was to investigate by multivariate analysis the predictive factors of development of hepatic encephalopathy in 50 Child's A and B cirrhotic patients whose variceal bleeding was treated with emergency (n = 17) or elective (n = 33) portacaval anastomosis. The etiology of the cirrhosis was alcoholic in 74% of cases. The mean follow-up was 22.7 +/- 16.6 months (range 1-60 months). The 2-yr probability of suffering from at least one episode of hepatic encephalopathy in the overall group was 43%. The multivariate analyses (Cox's regression method) of 37 variables based upon clinical history, physical examination, and laboratory data disclosed that only five of these variables had independent predictive value: need for diuretic treatment in the days prior to surgery, absence of hepatomegaly, and serum levels of total bilirubin, gamma-globulin, and hemoglobin. According to the contribution of each one of these factors to the final model, a prognostic index was obtained which allowed the division of patients in two different groups of risk for developing hepatic encephalopathy (20% and 74%, respectively, after 2 yr of surgery; p = 0.0002). This index may help to better choose those candidates for portacaval anastomosis.

Sequential combination of methotrexate (MTX), 5-fluorouracil (FU), and high-dose folinic acid (FA) in advanced colorectal cancer: double biochemical modulation?

Thirty evaluable patients were treated with methotrexate (MTX) 200 mg/m2, i.v. infusion over 60 minutes, 24 hours prior to the administration of 5-fluorouracil 600 mg/m2, and folinic acid 200 mg/m2, i.v. infusion over 60 minutes, every 2 weeks. A partial or complete response was achieved in 12 patients (40%), and disease stable in 10 patients (33%). Median actuarial survival was 18 months. Side effects, which were within acceptable limits, included 11 cases of stomatitis (5 Grade 3), 3 cases of leukopenia (Grade 2) and 12 cases of mild nausea and vomiting. We conclude that the present combination is active in metastatic colorectal cancer with mild toxicity. These results are being confirmed and a randomized trial is being carried out to prove that this combination holds therapeutic advantage.

Nonoperative management of splenic injuries

The traditional management of splenic trauma has undergone major revision in recent years. Given the physiological importance of the spleen, certain controversy has arisen regarding the most appropriate method of managing this type of trauma. Nonoperative therapy in children has proven to be successful not only in the case of kidney lesions but also for splenic lesions. Nonoperative management carried out in the authors' hospital on a group of 56 patients (49 adults and seven children over the age of 7 years) has proved successful in 37 cases. The success of this technique requires a well-formulated protocol, diagnostic methods (ultrasound and computed tomography), rigorous patient control in the emergency room during the initial phase (first 48 hours), the availability of a medical team if surgical intervention becomes necessary (persistent or recurrent hemorrhage), and complementary measures which facilitate the cicatrization of the splenic injury (bed rest, antibiotic therapy).

Portacaval shunt versus endoscopic sclerotherapy in the elective treatment of variceal hemorrhage

Eighty-two consecutive Child-Campbell class A and B cirrhotic patients were included in a prospective controlled trial to assess the efficacy and safety of portacaval anastomosis vs. endoscopic sclerotherapy as elective treatment of variceal hemorrhage. Forty-one patients were randomized to portacaval anastomosis and 41 to sclerotherapy. After excluding dropouts, 34 patients were treated with portacaval anastomosis and 35 with sclerotherapy. The incidence of variceal rebleeding during follow-up (mean +/- SD, 20.6 +/- 14.2 months) was significantly higher in the sclerotherapy than in the portacaval groups, either considering the overall treated group or only patients completing sclerotherapy (40% and 25% vs. 2.9%; P = 0.0002 and P = 0.01, respectively). The 2-year probability of suffering from at least one episode of hepatic encephalopathy was significantly higher in patients submitted to portacaval anastomosis than in those treated with endoscopic sclerotherapy (40% vs. 12%; P = 0.04). However, disabling encephalopathy only appeared in 3 of 34 patients who underwent surgery (8.8%). Early and long-term mortality did not differ between the therapeutic groups; 2-year survival rates were 83% for portacaval anastomosis and 79% for sclerotherapy. It is concluded that portacaval anastomosis is more effective than endoscopic sclerotherapy in preventing variceal rebleeding in spite of the greater incidence of hepatic encephalopathy. The role of portacaval anastomosis in the elective treatment of variceal rebleeding should be reassessed.

[Correlation of etiology and severity in a series of 506 cases of acute pancreatitis]

We present a retrospective study on 506 patients with acute pancreatitis (AP), admitted in our hospital in the last five years (1984-1988). The goal of the paper is to establish a possible correlation between the severity and the etiology of the AP. Depending on the severity of the acute attack, and according to the Ranson's prognostic signs and the findings of the abdominal CAT, we have classified AP in three grades: mild, moderate and severe. 52% of AP were of biliary etiology, 25.7% alcoholic, and in 17.0% of the cases the responsible agent was not demonstrated. In relation with severity, the distribution was as follows: mild, 184 (36.4%), moderate, 254 (50.2%) and severe, 68 (13.4%). Among the cases of biliary and alcoholic etiology, 14.7% and 9.2%, respectively, were severe. Postoperative AP were severe in 71.4% of the cases. Systemic complications were more frequent in the severe forms, particularly of biliary etiology. Pancreatic abscesses and fistulas were also more frequent in biliary pancreatitis; on the other hand, pseudocysts and ascites were more common in alcoholic pancreatitis. Overall mortality was 2.8% (14 patients). Mortality was 19.1% in the severe forms. In relation to etiology the mortality was as follows: 3.7% in biliary AP; 0.8% in alcoholic AP; 14.3% in postoperative AP; and 2.3% in the idiopathic AP.

[Biliary peritonitis after hepatic biopsy: favorable course with conservative medical treatment]

In a 53-year-old woman a percutaneous liver biopsy was performed with tru-cut to study persistent hypertransaminasemia. The patient did not present extrahepatic cholestasis. Immediately after biopsy the patient had a picture of biliary peritonitis that evolved favorably with conservative medical treatment, including hemodynamic resuscitation, antibiotic therapy, analgesic treatment and monitoring by the resuscitation service. A review is made of the literature on this complication of liver biopsy and treatment is discussed.