Top-Down Characterization of Bacterial Lipopolysaccharides and Lipooligosaccharides Using Activated-Electron Photodetachment Mass Spectrometry

Lipopolysaccharides (LPS) and lipooligosaccharides (LOS) are located in the outer membrane of Gram-negative bacteria and are comprised of three distinctive parts: lipid A, core oligosaccharide (OS), and O-antigen. The structure of each region influences bacterial stability, toxicity, and pathogenesis. Here, we highlight the use of targeted activated-electron photodetachment (a-EPD) tandem mass spectrometry to characterize LPS and LOS from two crucial players in the human gut microbiota, Escherichia coli Nissle and Bacteroides fragilis. a-EPD is a hybrid activation method that uses ultraviolet photoirradiation to generate charge-reduced radical ions followed by collisional activation to produce informative fragmentation patterns. We benchmark the a-EPD method for top-down characterization of triacyl LOS from E. coli R2, then focus on characterization of LPS from E. coli Nissle and B. fragilis. Notably, a-EPD affords extensive fragmentation throughout the backbone of the core OS and O-antigen regions of LPS from E. coli Nissle. This hybrid approach facilitated the elucidation of structural details for LPS from B. fragilis, revealing a putative hexuronic acid (HexA) conjugated to lipid A.

ROS-dependent S-palmitoylation activates cleaved and intact gasdermin D

Gasdermin D (GSDMD) is the common effector for cytokine secretion and pyroptosis downstream of inflammasome activation and was previously shown to form large transmembrane pores after cleavage by inflammatory caspases to generate the GSDMD N-terminal domain (GSDMD-NT)1-10. Here we report that GSDMD Cys191 is S-palmitoylated and that palmitoylation is required for pore formation. S-palmitoylation, which does not affect GSDMD cleavage, is augmented by mitochondria-generated reactive oxygen species (ROS). Cleavage-deficient GSDMD (D275A) is also palmitoylated after inflammasome stimulation or treatment with ROS activators and causes pyroptosis, although less efficiently than palmitoylated GSDMD-NT. Palmitoylated, but not unpalmitoylated, full-length GSDMD induces liposome leakage and forms a pore similar in structure to GSDMD-NT pores shown by cryogenic electron microscopy. ZDHHC5 and ZDHHC9 are the major palmitoyltransferases that mediate GSDMD palmitoylation, and their expression is upregulated by inflammasome activation and ROS. The other human gasdermins are also palmitoylated at their N termini. These data challenge the concept that cleavage is the only trigger for GSDMD activation. They suggest that reversible palmitoylation is a checkpoint for pore formation by both GSDMD-NT and intact GSDMD that functions as a general switch for the activation of this pore-forming family.

Gut microbial fatty acid isomerization modulates intraepithelial T cells

The human gut microbiome constantly converts natural products derived from the host and diet into numerous bioactive metabolites1-3. Dietary fats are essential micronutrients that undergo lipolysis to release free fatty acids (FAs) for absorption in the small intestine4. Gut commensal bacteria modify some unsaturated FAs-for example, linoleic acid (LA)-into various intestinal FA isomers that regulate host metabolism and have anticarcinogenic properties5. However, little is known about how this diet-microorganism FA isomerization network affects the mucosal immune system of the host. Here we report that both dietary factors and microbial factors influence the level of gut LA isomers (conjugated LAs (CLAs)) and that CLAs in turn modulate a distinct population of CD4+ intraepithelial lymphocytes (IELs) that express CD8αα in the small intestine. Genetic abolition of FA isomerization pathways in individual gut symbionts significantly decreases the number of CD4+CD8αα+ IELs in gnotobiotic mice. Restoration of CLAs increases CD4+CD8αα+ IEL levels in the presence of the transcription factor hepatocyte nuclear factor 4γ (HNF4γ). Mechanistically, HNF4γ facilitates CD4+CD8αα+ IEL development by modulating interleukin-18 signalling. In mice, specific deletion of HNF4γ in T cells leads to early mortality from infection by intestinal pathogens. Our data reveal a new role for bacterial FA metabolic pathways in the control of host intraepithelial immunological homeostasis by modulating the relative number of CD4+ T cells that were CD4+CD8αα+.

Functional and metagenomic level diversities of human gut symbiont-derived glycolipids

Bioactive metabolites produced by symbiotic microbiota causally impact host health and disease, nonetheless, incomplete functional annotation of genes as well as complexities and dynamic nature of microbiota make understanding species-level contribution in production and actions difficult. Alpha-galactosylceramides produced by Bacteroides fragilis (BfaGC) are one of the first modulators of colonic immune development, but biosynthetic pathways and the significance of the single species in the symbiont community still remained elusive. To address these questions at the microbiota level, we have investigated the lipidomic profiles of prominent gut symbionts and the metagenome-level landscape of responsible gene signatures in the human gut. We first elucidated the chemical diversity of sphingolipid biosynthesis pathways of major bacterial species. In addition to commonly shared ceramide backbone synthases showing two distinct intermediates, alpha-galactosyltransferase (agcT), the necessary and sufficient component for BfaGC production and host colonic type I natural killer T (NKT) cell regulation by B. fragilis, was characterized by forward-genetics based targeted metabolomic screenings. Phylogenetic analysis of agcT in human gut symbionts revealed that only a few ceramide producers have agcT and hence can produce aGCs, on the other hand, structurally conserved homologues of agcT are widely distributed among species lacking ceramides. Among them, alpha-glucosyl-diacylglycerol(aGlcDAG)-producing glycosyltransferases with conserved GT4-GT1 domains are one of the most prominent homologs in gut microbiota, represented by Enterococcus bgsB . Of interest, aGlcDAGs produced by bgsB can antagonize BfaGC-mediated activation of NKT cells, showing the opposite, lipid structure-specific actions to regulate host immune responses. Further metagenomic analysis of multiple human cohorts uncovered that the agcT gene signature is almost exclusively contributed by B. fragilis , regardless of age, geographical and health status, where the bgsB signature is contributed by >100 species, of which abundance of individual microbes is highly variable. Our results collectively showcase the diversities of gut microbiota producing biologically relevant metabolites in multiple layers-biosynthetic pathways, host immunomodulatory functions and microbiome-level landscapes in the host.

Kinetic and mechanistic diversity of intestinal immune homeostasis characterized by rapid removal of gut bacteria

Symbiotic microbiota critically contribute to host immune homeostasis in effector cell-specific manner. For exclusion of microbial component, germ-free animals have been the gold standard method. However, total removal of the entire gut microbiota of an animal from birth significantly skews physiological development. On the other hand, removal of gut microbiota from conventional mice using oral antibiotics has its own limitations, especially lack of consistency and the requirement for long-term treatment period. Here, we introduce an improved regimen to quickly remove gut microbiota and to maintain sterility, that is well received by animals without refusal. Rapid and consistent exclusion of resident bacteria in the gut lumen revealed kinetic differences among colonic lymphocyte subsets, which cannot be observed with typical germ-free animal models. Furthermore, the proposed method distinguished the mechanism of microbiota contribution as a direct stimulus to capable effector cells and a homeostatic cue to maintain such cell types.

Mouse phospholipid phosphatase 6 regulates dendritic cell cholesterol, macropinocytosis, and allergen sensitization

Lipid phosphate phosphatases are a family of enzymes with diverse cellular metabolic functions. Phospholipid phosphatase 6 (PLPP6) is a regulator of cellular polyisoprenyl phosphates; however, its in vivo functions remain to be determined. Here, mouse PLPP6 was characterized to possess similar catalytic properties as the human enzyme. Plpp6 knockout mice (Plpp6 ^-/- ) were generated and displayed decreased airway allergen sensitization, pointing to a role for PLPP6 in the early events of lung allergic responses. Dendritic cell (DC) responses were investigated and endocytosis of allergen via macropinocytosis was decreased in Plpp6 ^-/- DCs that had lower cholesterol content. When reversed by cholesterol loading, the DC macropinocytosis defect is corrected. Adoptive transfer of Plpp6 ^-/- DCs to wild-type mice during sensitization was sufficient to decrease allergen-induced responses. Together, our findings have identified PLPP6 as a pivotal regulator of DC cholesterol content and macropinocytosis, cellular mechanisms that are important for pathologic responses in allergen-induced lung inflammation.

Functional assessment of military aircrew applicants in a hypobaric chamber

Background

Aircrew are exposed to environmental pressure changes. In the Republic of Singapore Air Force (RSAF), applicants assessed to be at intermediate risk of otic barotrauma undergo a hypobaric chamber assessment [“trial of chamber” (TOC)] to functionally evaluate their suitability for military aircrew vocations.

Aims

To identify factors associated with TOC failure among applicants with otorhinolaryngological conditions.

Methods

All applicants to RSAF aircrew vocations who were assessed to be at intermediate risk of otic barotrauma over a 3-yr period were identified using the RSAF Aeromedical Centre’s electronic database. Their medical records, as well as the TOC assessment records of the subset of applicants who underwent TOC, were reviewed for demographic data, clinical findings, and TOC outcomes.

Results

Of the 483 identified applicants, 374 (77%) had abnormal otoscopic findings, 103 (21%) had rhinitis symptoms, and 6 (1%) had previous ENT surgery. 123 (25%) underwent TOC, of which 20 (16%) failed. Holding other predictor variables constant, the odds of TOC failure increased by 0.79 per unit decrease in BMI (95% CI 0.63–0.99), and the odds of TOC failure increased by 0.93 per kg decrease in body weight (95% CI 0.87–1.00). An abnormal tympanogram was not a statistically significant predictor of TOC failure (OR 1.96, 95% CI 0.59–6.42). Of the 47 applicants who passed TOC and were eventually recruited, none subsequently developed otic barotrauma (mean follow-up, 3.3 yr ± 1.5 yr).

Conclusions

Applicants with lower weight and BMI are more likely to develop otic barotrauma with environmental pressure change. Tympanometry cannot be reliably used to identify applicants who would more likely pass TOC.

Long-term outcomes of ruptured hepatocellular carcinoma: An international multicentric propensity score-matched study

Objective

Long-term outcomes of patients with ruptured hepatocellular carcinoma (rHCC) remain scant. This study aimed to assess disease-free survival (DFS) and overall survival (OS) after surgical resection of rHCC compared to non-ruptured HCC (nrHCC).

Methods

Patients with rHCC and nrHCC were collected from 8 centers in Europe, Asia, and North America. Resected rHCC patients were matched 1:1 to patients undergoing surgery for nrHCC using propensity score and nearest-neighbor method (matching criteria: age, tumor size, cirrhosis, Child-Pugh score, Barcelona Clinic Liver Cancer stage, resection status, grade, and microvascular invasion). Survival rates were calculated using Kaplan-Meier method.

Results

A total of 2033 patients were included: 226 rHCC patients (172 operated: 68 with upfront surgery and 104 after embolization) and 1807 nrHCC patients. Median DFS and OS of rHCC patients (all treatments confounded) were 10 months (95% CI 7–13) and 22 months (95% CI 13–31). Prognostic factors for worse OS among rHCC patients were absence of preoperative arterial embolization (HR 2.3, 95% CI 1.2–4.6, p=0.016), cirrhosis Child B/C (HR 2.4, 95% CI 1.1–5.4, p=0.040), and R1/R2 margins (HR 2, 95% CI 1–5, p=0.049). Survivals were similar between Western and Eastern rHCC patients.

After propensity score matching, 106 rHCC patients and 106 nrHCC patients displayed similar characteristics. Patients with rHCC had shorter median DFS (12 months, 95% CI 7–17 vs. 22 months, 95% CI 12–32, p=0.011), but similar median OS compared to nrHCC patients (43 months, 95% CI 21–65 vs. 63 months, 95% CI 21–105, p=0.060).

Conclusion

In this large dataset including Eastern and Western patients, rHCC was associated with shorter DFS compared to nrHCC, while OS was similar.

Development of a mass spectrometric screening assay for hepatitis B virus entry inhibitors

Sodium taurocholate cotransporting polypeptide (NTCP) involved in bile acid transport in the liver is an entry receptor of hepatitis B virus (HBV). In the present study, we introduce a mass spectrometric screening assay for targeting HBV entry inhibitors that can reduce NTCP transporter activity by employing taurocholic acid (TCA) labeled with stable isotope (2,2,4,4-d₄-TCA, d₄-TCA) and NTCP-overexpressing human liver cancer cell lines such as HepG2 and Huh-7. The accuracy and reliability of the proposed mass spectrometric NTCP activity assay have been validated with known HBV inhibitors including cyclosporine A (CsA) and pre-S1 peptide (PreS/2-48^Myr or myrcludex B analog) that suppress the entry of HBV into hepatocytes by targeting NTCP. For the inhibitor screening assay, NTCP-overexpressing HepG2 or Huh-7 cells are treated with either a combination of TCA and an inhibitor (CsA or PreS/2-48^Myr) or d₄-TCA alone to serve as a reference. The activity of an HBV inhibitor is determined by relative quantification between TCA and d₄-TCA in a 1:1 mixture of inhibitor-treated cells and untreated control cells using liquid chromatography-mass spectrometry. With our new approach, the half maximal inhibitory concentration (IC₅₀) values for CsA and PreS/2-48^Myr have been determined at micromolar and nanomolar concentrations, respectively, which is consistent with the previous results obtained with other conventional HBV entry inhibitor assay methods. Our assay method does not require HBV infection or radioactive ³H-TCA and provides a facile way to identify viral entry inhibitors via measuring bile acid transport activity of NTCP.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Precisely tuneable energy transfer system using peptoid helix-based molecular scaffold

The energy flow during natural photosynthesis is controlled by maintaining the spatial arrangement of pigments, employing helices as scaffolds. In this study, we have developed porphyrin-peptoid (pigment-helix) conjugates (PPCs) that can modulate the donor-acceptor energy transfer efficiency with exceptional precision by controlling the relative distance and orientation of the two pigments. Five donor-acceptor molecular dyads were constructed using zinc porphyrin and free base porphyrin (Zn(i + 2)–Zn(i + 6)), and highly efficient energy transfer was demonstrated with estimated efficiencies ranging from 92% to 96% measured by static fluorescence emission in CH₂Cl₂ and from 96.3% to 97.6% using femtosecond transient absorption measurements in toluene, depending on the relative spatial arrangement of the donor-acceptor pairs. Our results suggest that the remarkable precision and tunability exhibited by nature can be achieved by mimicking the design principles of natural photosynthetic proteins.

Syphilis masquerading as focal segmental glomerulosclerosis

A patient referred to the genitourinary clinic for positive syphilis serology was found to have symptoms and signs of nephrotic syndrome. A renal biopsy showed focal segmental glomerulosclerosis (FSGS). Doxycycline 200 mg twice daily for 28 days coincided with considerable decrease in proteinuria and rise in serum albumin, suggesting a causal relationship.

Feasibility and Accuracy of Sentinel Lymph Node Biopsy in Clinically Node Negative Patients after Neoadjuvant Chemotherapy for Breast Cancer – A Systematic Review and Metaanalysis

BackgroundThe sentinel lymph node biopsy (SLNB) has become an accepted alternative to the axillary lymph node dissection (ALND) for pathologic evaluation of the axillary lymph node status in patients with early breast cancer and a clinically negative axilla. Patients with a negative sentinel lymph node are spared the ALND and its associated morbidities.Currently, there is insufficient evidence to recommend the use of SLNB in patients who have received neoadjuvant chemotherapy (NAC), and treatment of the axilla after neoadjuvant chemotherapy is an ALND.The use of neoadjuvant chemotherapy is increasing, and NAC has been shown to downstage both the primary tumour and axillary lymph nodes. Potentially, an additional proportion of patients who are node negative after NAC may be spared a full ALND and its attendant morbidities.AimsTo determine the feasibility and accuracy of SLNB in patients who have a clinically negative axilla after neoadjuvant chemotherapy for breast cancer.MethodsA systematic review of the English literature of SLNB in patients who have had neoadjuvant chemotherapy (NAC) was conducted and meta analyses performed. Studies selected had an identifiable group of patients with breast cancer who received neoadjuvant chemotherapy and were clinically node negative. These patients had a SLNB prior to the standard ALND regardless of outcome of the SLNB.ResultsTen studies that met the eligibility criteria were identified. A total of 449 patients were studied. Pooled analysis using the fixed effects model was used to calculate successful identification rate and accuracy parameters. The summary rate of identification of SLN was 94% [95% CI: 91.6% – 96.7%]. The pooled sensitivity of SLNB after NAC was 93% [95% CI: 88.5% – 96.8%] and the false negative rate 7.0% [95% CI: 3.2% – 11.5%].ConclusionSLNB in patients with a clinically node negative axilla after neoadjuvant chemotherapy is feasible and accurate.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1013.

Interethnic differences in Cyp3A4 inhibition by ketoconazole on docetaxel pharmacokinetics (PK) and pharmacodynamics (PD)

2526

Background: Use of concomitant medications that inhibit drug metabolizing enzymes such as Cyp3A4 is common and may affect chemotherapy PK/PD. We studied the effects of Cyp3A4 inhibition with ketoconazole on docetaxel PK/PD in 3 Asian ethnic groups. Methods: Two cohorts of chemonaive breast cancer patients were compared. The first cohort comprised of 95 patients (62 Chinese, 26 Malay, 7 Indian) treated with 75mg/m2 docetaxel unmodulated by ketoconazole, while the second cohort comprised of 31 patients (14 Chinese, 14 Malay, 3 Indian) treated with docetaxel 70mg flat dose modulated by oral ketoconazole, a regimen we previously reported to result in comparable docetaxel AUC as 75mg/m2 docetaxel. Plasma docetaxel concentrations were obtained at 0, 0.5, 1, 2, 5, 7 and 24 hours, and blood counts monitored on days 8 and 15 of cycle 1. Results: No significant differences in docetaxel PK or neutropenia between the races were observed in response to 75mg/m2 docetaxel unmodulated by ketoconazole (docetaxel clearance 36.4±16.9, 34.3±12.5, 44.2±27.7L/h, p=0.702; docetaxel AUC 3.6±2.7, 3.5±1.2, 2.9±1.3mg/L h, p=0.418; day 8 neutrophil count 0.5±0.6, 0.8±0.8, 0.4±0.3x109/L, p=0.138; grade 4 neutropenia 66%, 50%, 86%, p=0.157). In contrast, when docetaxel was administered with ketoconazole to inhibit Cyp3A4, inter-ethnic differences in docetaxel PK/PD were observed, with Chinese having the lowest docetaxel clearance and highest docetaxel AUC, followed by Malays and Indians (docetaxel clearance 18.6±5.7, 23.7±9.3, 30.6±6.7L/h, p=0.048; p=0.017 trend test; docetaxel AUC 4.2±1.4, 4.1±3.9, 2.4±0.5 mg/L h, p=0.048, p=0.017 trend test), although there were no statistically significant differences in body weight or surface area between the races. In concordance, Chinese patients experienced greatest degree of myelosuppression, followed by Malays and Indians (day 8 neutrophil count 0.8±0.8, 1.5±1.1, 1.7±1.1x109/L, p=0.046, p=0.013 trend test), and were more likely to develop grade 4 neutropenia (57%, 14%, 0%, p=0.024) from docetaxel + ketoconazole. Conclusions: Inter-ethnic differences in CYP3A inhibition by ketoconazole exist, and are important when evaluating the impact of concomitant medications with chemotherapy that may inhibit Cyp3A4.

No significant financial relationships to disclose.

A phase II randomized study of oral seliciclib in patients with previously treated nasopharyngeal carcinoma

6026

Background: Seliciclib is a selective inhibitor of cyclin dependent kinases (CDKs) 2, 7 and 9. In a phase I study of 2 weeks of oral administration, clinical antitumor activity was observed in patients with treatment-naive nasopharyngeal carcinoma (NPC) and biological effects consistent with CDK inhibition were detected in tumor biopsy samples. We are conducting a multicenter, randomized phase 2 study to evaluate the safety and efficacy of prolonged administration of seliciclib in patients with previously treated NPC. The study has a lead-in phase where the safety and tolerability of 2 dosing schedules of seliciclib are to be confirmed in patients with advanced solid tumors (including NPC) before being used in the randomized phase of the study where only NPC patients are eligible to participate. The primary efficacy endpoint is 6-month progression free survival. Here we report interim findings from the lead-in phase. Methods: Eligible patients must be ≥18 years with previously treated NPC or other incurable solid tumors; must have measurable disease according to RECIST, ECOG 0–1, and adequate bone marrow, hepatic and renal function. The planned sample size is 6 to 12 patients per dosing schedule. A dosing schedule is considered tolerable for proceeding to the randomized phase if <33% patients experienced dose-limiting toxicities (DLT) during the first treatment cycle. Results: Twenty-three patients (age 38 - 74) were enrolled and treated. DLTs were observed in 4 patients: grade 3 increase in ALT or AST (n=3), and treatment delay > 2 weeks for grade 1 creatinine (n=1). Common adverse events (all grades, regardless of causality) included fatigue, nausea/vomiting, constipation, cough, fever, hypokalemia, hyponatremia, and elevation in ALT/AST, most of which were mild to moderate in intensity. Conclusions: These interim data confirm that both dosing schedules are tolerable for proceeding to the randomized phase. Majority of stable disease occurred in NPC patients. Updated data will be presented at the meeting.

[Table: see text]

No significant financial relationships to disclose.

Phase I study of SB939 three times weekly for 3 weeks every 4 weeks in patients with advanced solid malignancies

2560

Background: SB939 is a novel orally bioavailable inhibitor of class 1 and 2 histone deacetylases. We conducted a phase I study to assess the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics and preliminary efficacy of SB939 in patients with advanced solid malignancies. Methods: SB939 was administered orally every other day 3 times a week for 3 consecutive weeks, in a 4-week cycle. Cohorts of patient were treated with escalating doses of SB939 starting from 10 mg. PK and PD (Acetylated Histone 3 in PBMCs) samples were collected in the first cycle. Results: 31 patients were enrolled at 10 mg (n=3), 20 mg (4), 40 mg (8), 60 mg (10) and 80 mg (6). The median number of treatment cycles received was 3.6. Fatigue, elevation of troponin T and QTc prolongation were the observed dose-limiting toxicities (DLT). At 80mg, one patient each (3/6) experienced a DLT of grade 3 fatigue, grade 3 asymptomatic elevation of troponin T and grade 3 QTc prolongation respectively. All DLTs were reversible and no treatment mortality was observed. Grade 1–2 fatigue occurred in 56% of patients occurring mainly at the 4th week, and 37% of pts had G1–2 anorexia. Grade 3–4 thrombocytopenia was observed in 2 patients at 60 mg at cycles 1 and 6 of treatment. SB939 was rapidly absorbed reaching Tmax between 1–3 h after ingestion, and mean elimination half-life and oral clearance of SB939 were 7.2 + 0.6 hrs and 53 + 8.5 L/h respectively. Cmax and AUC (0-∞) were dose-proportionally increased at this dose range. There was no substantial accumulation of SB939 on day 15 following repeated dosing. Concentrations above IC50 of SB939 for HDAC I was reached at all doses. Acetylation of H3 was dose dependent and consistent at 60mg. Of the 13 patients evaluable for response, stable disease was seen in 1 patient with follicular thyroid carcinoma and 1 with hepatocellular carcinoma for 51 and 164 days respectively. Conclusions: SB939 has similar toxicity profiles as that of other HDAC inhibitors and a favorable PK/PD profile. The MTD of SB939 in this regimen was 80 mg and 60mg is the recommended dose, at which acetylation of H3 is consistently observed. Further phase 2 studies with SB939 in specific indications are being planned.

No significant financial relationships to disclose.

Use of peripheral blood genomic markers whose expression levels reflect that of breast tumor genomic markers to predict drug treatment and sensitivity

3588

Background: Tumor gene expression signatures have been used to predict drug response, and we have previously reported drug-induced signatures to be more informative than the untreated baseline signatures. However, repeated tumor sampling during treatment is not feasible for most patients. We studied peripheral mononuclear cell (PBMC) gene expression levels in association with tumor gene expression levels in an attempt to identify peripheral blood markers that may serve as more accessible surrogates to predict drug treatment and response. Methods: Chemonaive breast cancer patients were treated with an alternating sequential regimen of doxorubicin and docetaxel and randomized to start with either drug. RNA from primary tumor before and 3 weeks, and from PBMC before and 24 hours after the first cycle of each drug was hybridized on the Affymetrix HG-U133+2 array containing 54,675 probe sets. Results: Pre- and post-treatment tumors from 47 patients were studied, including 35 with paired PBMC samples. 230 pre- and 85 posttreatment PBMC probe sets showed strong correlation in expression level (Pearson correlation coefficient >0.9) with the corresponding pre- and posttreatment tumor probe set, and included genes involved in transcription regulation and binding. Of the 975 tumor probe sets whose changes distinguished doxorubicin from docetaxel treatment, 12 corresponding PBMC probe sets were identified (p < 0.001) whose changes at 24 hours distinguished the two treatments with 77% accuracy. Of the 1,081 and 1,526 tumor probe sets whose changes predicted treatment response to doxorubicin and docetaxel, 19 and 15 informative PBMC probe sets predicted response to each drug with 100% and 80% accuracy, and included TNF receptor associated protein 1 and trefoil factor 1 for doxorubicin-, and folliculin and dynein for docetaxel-response. When the PBMC probe sets were validated in an independent test set treated with docetaxel (n = 23), 87% was correctly classified as docetaxel-treated, while 89% of non-responders clustered together. Conclusions: Peripheral blood contains genomic markers whose expression levels closely reflect that of breast tumor markers, and may be promising as surrogates to predict drug treatment and sensitivity.

No significant financial relationships to disclose.

A phase I/II study of belinostat (PXD101) in patients with unresectable hepatocellular carcinoma

15081

Background: Hepatocellular carcinoma (HCC) is a common cause of cancer morbidity and mortality. It is a highly aggressive tumor with 90% presenting with unresectable disease, resulting in a median survival of 3–6 months. Inhibitors of histone deacetylase (HDAC) have been demonstrated in HCC cell lines and xenografts to induce apoptosis and tumor regression, and have anti-proliferative, anti-metastatic and anti-invasive effects. Belinostat (N-hydroxy-3-[phenylsulphamoylphenyl] acryl amide) is a novel, low molecular weight, HDAC inhibitor. The Cancer Therapeutic Research Group (CTRG) is conducting a phase I/II study of belinostat as the first line therapy for pts with unresectable HCC. The phase I study aims to determine dose limiting toxicity (DLT) and maximum tolerated dose (MTD). Methods: Patient eligibilities include histologically or cytologically confirmed unresectable HCC, ECOG = 2, adequate hematologic, renal and hepatic functions. The dose of belinostat was started at 600 mg/m2/day i.v. on day 1–5 every 3 weeks; with increment of 300 mg/m2/day up to 1200 mg/m2/day. Dose limiting toxicities (DLT) are defined as grade 4 hematological toxicity or grade 3 or 4 nonhematological toxicity during cycle 1 (according to NCI CTC v3), or treatment delay >2 weeks. The MTD is defined as the dose below which ≥ 2 of 3 or ≥ 2 of 6 patients experiencing DLT. After determination of the MTD, 3 additional patients will be treated at this dose to further define toxicity. Results: From June-December 2006, 12 pts were entered; 3 were treated at level I (600 mg/m2/day), 3 at level 2 (900 mg/m2/day), and 6 at level 3 (1200 mg/m2/day). There were no DLTs on level 1, 2 or 3. Therefore, the MTD of belinostat was not reached. Overall toxicities were WBC gr. 0/1/2/3/4: 12/0/0/0/0, ANC gr. 0/1/2/3/4: 12/0/0/0/0; Hb gr. 0/1/2/3/4: 4/7/0/1/0; platelet gr. 0/1/2/3/4: 8/4/0/0/0; lethargy gr. 0/1/2/3: 12/0/0/0/0, phlebitis gr. 0/1/2/3: 10/0/2/0; Cough gr. 0/1/2/3: 9/0/3/0; Nausea gr. 0/1/2/3: 7/3/2/0 and vomiting gr. 0/1/2/3: 9/3/0/0. Conclusions: At the maximum dose of 1200 mg/m2/day (level 3), MTD has not been reached. Belinostat is very well tolerated. Phase II study will be started at dose level 1200 mg/m2/day. Sponsor: The Division of Cancer Treatment and Diagnosis, National Cancer Institute, USA.

No significant financial relationships to disclose.

Management of a syphilis outbreak in street sex workers in east London

OBJECTIVE

To describe the control and management of a syphilis outbreak in female street sex workers (SSWs) in east London.

METHODS

Following the identification of several cases of infectious syphilis in SSWs in east London, a targeted service for screening and treatment of syphilis and other sexually transmitted infections was developed. A multidisciplinary team (MDT) joined an existing outreach service to facilitate this. Once it became apparent that this was not an isolated case, an outbreak control team (OCT) was established.

RESULTS

Between April and December 2004 a total of 14 (58%) women with 15 cases of infectious syphilis were identified in 24 SSWs: 14/15 (93%) received treatment. Epidemiological treatment for syphilis was also given to the rest of SSWs at the initial visit. Several coexistent STIs were identified in this cohort. As part of the enhanced outbreak surveillance in north east London, 21 cases of infectious syphilis were reported in SSWs between April 2004 and December 2005.

CONCLUSION

Outbreak management in this population was challenging: an MDT approach was crucial in identifying and treating syphilis to prevent onward transmission. There was a high prevalence of syphilis and other STIs in this cohort, and we treated the majority of cases. The formation of an OCT enabled us to monitor the outbreak and implement control measures more effectively. The novel intervention we describe has proved valuable in helping to control this syphilis outbreak.

Activation of Akt/protein kinase B in epithelial cells by the Salmonella typhimurium effector sigD

The serine-threonine kinase Akt is a protooncogene involved in the regulation of cell proliferation and survival. Activation of Akt is initiated by binding to the phospholipid products of phosphoinositide 3-kinase at the inner leaflet of the plasma membranes followed by phosphorylation at Ser(473) and Thr(308). We have found that Akt is activated by Salmonella enterica serovar Typhimurium in epithelial cells. A bacterial effector protein, SigD, which is translocated into host cells via the specialized type III secretion system, is essential for Akt activation. In HeLa cells, wild type S. typhimurium induced translocation of Akt to membrane ruffles and phosphorylation at residues Thr(308) and Ser(473) and increased kinase activity. In contrast, infection with a SigD deletion mutant did not induce phosphorylation or activity although Akt was translocated to membrane ruffles. Complementation of the SigD deletion strain with a mutant containing a single Cys to Ser mutation (C462S), did not restore the Akt activation phenotype. This residue has previously been shown to be essential for inositol phosphatase activity of the SigD homologue, SopB. Our data indicate a novel mechanism of Akt activation in which the endogenous cellular pathway does not convert membrane-associated Akt into its active form. SigD is also the first bacterial effector to be identified as an activator of Akt.

Gonorrhoea in HIV seropositive homosexual men attending an East London genitourinary medicine clinic

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Sequence analysis of an HIV-1 isolate which displays unusually high-level AZT resistance in vitro

Multiple mutations in the reverse transcriptase (RT) gene were observed in a drug-resistant isolate of human immunodeficiency virus type 1 (HIV1) from an individual having prolonged (greater than 2 years) zidovudine (AZT) therapy. The virus replicated in PBMC's in the presence of very high concentrations of AZT (125 microM). Drug-sensitive strains were curtailed by 0.01 microM AZT. Eleven defined mutations were observed as compared with published sequences of RT for eight strains of HIV1. Eight of these mutations were found in the domain involved in nucleotide recognition and enzyme function. Only one of the mutations, giving a Thr--Tyr change at amino acid 215, matched those previously ascribed (67, 70, 215, and 219) to the generation of high-level resistance to AZT. Therefore additional amino acid changes may have significance in the emergence of super-resistant viruses.