ITPA polymorphisms do not predict additional risk beyond TPMT and NUDT15 for thiopurine-induced cytopenia in inflammatory bowel disease

INTRODUCTION AND AIM

Thiopurine-related leukopenia is associated with polymorphisms in the thiopurine methyltransferase (TPMT) and nucleoside diphosphate-linked moiety X type motif 15 (NUDT15) genes. However, those polymorphisms explain only a fraction of thiopurine-related leukopenia. Our aim was to study the role of an inosine triphosphate pyrophosphatase (ITPA) polymorphism in patients with inflammatory bowel disease (IBD) and thiopurine-related leukopenia that was unexplained by the TPMT and NUDT15 polymorphisms.

MATERIAL AND METHODS

We enrolled consecutive IBD patients on thiopurines (azathioprine or 6-mercaptopurine) from January 2019-March 2020, at a tertiary care center in North India. The presence of the ITPA (C.94C > A) polymorphism was evaluated in all patients, along with its association with thiopurine-related leukopenia.

RESULTS

Of the 33 patients (from a total of 119 patients) that developed leukopenia, 8 had the TPMT (n = 1) or NUDT15 (n = 7) polymorphism. Of the remaining 111 patients, their mean age was 36.36 ± 13.54 years and 57 (51.3%) were males. Twenty-five (21.01%) had unexplained leukopenia. The ITPA polymorphism was detected in 4 (16%) patients in the unexplained leukopenia group and 24 (27.9%) patients in the non-leukopenia group (p = 0.228). The odds ratio for predicting leukopenia with the ITPA polymorphism was 0.4921 (95% CI 0.1520-1.5830, p = 0.234).

CONCLUSION

The ITPA (C.94C > A) polymorphism was frequently detected in the study population but was not predictive for leukopenia in patients with IBD on thiopurine therapy.

Increased fracture risk in Parkinson's disease - An exploration of mechanisms and consequences for fracture prediction with FRAX

The relative contributions of factors such as muscle strength, falls risk and low bone mineral density (BMD) to increased fracture risk in Parkinson's Disease (PD) were examined in an analysis of 5212 community-dwelling women age 75 years or more recruited to a randomised, double-blind, placebo-controlled study of the oral bisphosphonate, clodronate. Similar number of PD and non-PD subjects received treatment. Each participant had measurements of hip and forearm BMD, muscle strength (hand grip strength and maximum isometric quadriceps strength), ability in the sit-to-stand test, and postural stability. Incident radiographic and/or surgically verified fractures, and deaths, were recorded over an average follow-up of 3.8 years. A diagnosis of PD was made if it was self-reported and appropriate medication was recorded at the study entry. 47 of the women (0.9 %) had a diagnosis of PD at baseline. They were of similar age to those without PD, but reported higher disability scores and lower quality of life. While BMD at the forearm and hip regions was lower in PD, this only reached statistical significance at the femoral neck (0.61 ± 0.12 vs 0.65 ± 0.12 g/cm², p = 0.037). Right hand grip strength was non-significantly lower in PD, but maximum right quadriceps strength was much reduced (96.9 ± 49.3 vs 126.3 ± 59.2 N, p = 0.003). Eleven (23.4 %) of the women with PD sustained 12 fractures, while 609 women (11.8 %) without PD sustained 742 osteoporotic fractures. The risk of osteoporotic fracture associated with PD was 2.24-fold higher in women with PD (Cox-regression HR 2.24, 95 % CI 1.23-4.06) and this remained high when adjusted for death as a competing risk (2.17, 95 % CI 1.17-4.01, p = 0.013). Following adjustment for femoral neck BMD, PD remained a significant predictor of fracture (HR 2.04, 1.12-3.70, p = 0.020). Entering PD as a risk variable using the rheumatoid arthritis input as a surrogate resulted in a reduction in PD as a FRAX-independent risk factor, particularly when BMD was included in FRAX (1.65, 95 % CI), but the relationship between PD and fracture risk appears to remain of clinical significance. The study suggests that PD may be an independent input in future iterations of FRAX, possibly due to non-skeletal components of risk such as reduced lower limb muscle strength. Introducing measures of muscle strength and performance in FRAX could also be considered.

Evaluation of ultrasound airway assessment parameters in pregnant patients and their comparison with that of non-pregnant women: a prospective cohort study

BACKGROUND

Clinical airway assessment parameters differ significantly between pregnant and non-pregnant patients, however literature comparing their ultrasound (US) airway parameters is limited. We planned a prospective cohort study to compare US-assessed airway parameters between pregnant and non-pregnant women.

METHODS

We enrolled 82 pregnant females scheduled for elective cesarean section under neuraxial anesthesia and 80 age-matched non-pregnant females scheduled for elective surgery. Pre-operative clinical airway assessment was performed in both groups. The US airway assessment was done pre-operatively in non-pregnant and postoperatively in pregnant patients. Our primary objective was to compare US-assessed parameters, and secondary objectives included a comparison of clinical airway assessment parameters and investigating a relationship between a difficult airway (defined as a modified Mallampati grade (MMG) ≥ 3) and other airway assessment parameters.

RESULTS

Among several US airway parameters, pregnant patients had significantly higher hyomental distance, anterior neck soft tissue thickness at the hyoid and vocal cord level, and oral cavity height, while the tongue thickness and mandibular condylar movements were significantly lower than in non-pregnant patients. Similarly, for the clinical airway assessment, pregnant patients had significantly higher MMG and upper lip bite test scores, mentohyoid distance, and neck circumference. Pregnancy, the ratio of pre-epiglottic space and epiglottis-to-vocal cords distance (Pre-E/E-VC), and hyoid bone visibility were independent predictors of a difficult airway.

CONCLUSION

The US airway assessment parameters differ significantly between pregnant and non-pregnant patients. Pregnancy, hyoid bone visibility, and Pre-E/E-VC ratio were independent predictors of the difficult airway in female patients.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Azathioprine induced pancreatitis, polyarthritis and panniculitis (PPP) syndrome in a patient with Crohn's disease

Azathioprine and 6-mercaptopurine have been widely used for maintenance of remission in patients with inflammatory bowel disease. The use of thiopurines is associated with multiple adverse effects including dose dependent cytopenias or idiosyncratic reaction. We report about a case of azathioprine related pancreatitis associated with polyarthralgia and panniculitis. Pancreatitis, polyarthritis and panniculitis (PPP) syndrome is an uncommon phenomenon which may accompany a number of pancreatic diseases including acute or chronic pancreatitis or pancreatic malignancy. To the best of our knowledge, this is the first report of Azathioprine related PPP syndrome.

Audit of Quality and Quantity of Nucleic Acid Yield from Pediatric Acute Leukemia Cases Following a Bio-banking Initiative

Information which can be harvested from a biological sample has greatly improved with advancements in diagnostic technologies. However, in developing countries, the awareness about usefulness of bio-banking concept is lacking and centres which do offer it, depend mainly on - 20 or - 80 °C for sample storage due to lack of sophisticated infrastructure like vapour phase nitrogen storage preservation. Hence in these resource constraint settings, timely audit of quality of nucleic acids extractable from samples stored is of utmost importance. In this study, we explore the effect of - 20 °C storage over nucleic acids (DNA/RNA) isolated from blood samples of 180 patients with various leukaemia's following a bio-banking initiative. We observed that the integrity and quality of both DNA and RNA were maintained in 70 and 80% samples respectively over time as reflected by their concentration measurements and inherent uniform expression of housekeeping gene GAPDH. Only 3.7% of the RNA samples and 4.2% of the DNA samples yielded very low concentrations despite minimizing processing and technical loss. In nutshell, audit of our biobank sample yield highlights that storage of blood samples at - 20 °C does not compromise the fidelity of nucleic acids for future diagnostic and research work in a resource constraint setting.

Favourable improvement in haematological parameters in response to oral iron and vitamin C combination in children with Iron Refractory Iron Deficiency Anemia (IRIDA) phenotype

Treatment in IRIDA focuses on use of intravenous iron preparations to circumvent oral absorptive defect resulting from high levels of hepcidin due to TMPRSS6 gene variations. However, recent case reports and recommendations on atypical microcytic hypochromic anemias advocate use of oral iron and vitamin c trial before parenteral iron, as the same results in comparable improvement in haemoglobin. We prospectively evaluated our IRIDA cohort (n = 7) with oral iron and vitamin c dose over a period of 10 weeks and noted complete response in majority (6/7 = 86%) with >2 g/dL rise in Hb along with significant improvement of other iron related indices.

Hypoferremic State in Overweight and Obese Children

Children with high body mass index (BMI) are at risk of iron deficiency. In present study, 71 children with overweight or obesity were screened for iron deficiency. Mean BMI, ferritin and plasma soluble transferrin receptor (sTrfR) levels were 26.1 kg/m2, 41.9 µg/L and 0.375 mg/L, respectively. Twenty (28%) children had anemia, and 44 (62%) had an underlying hypoferraemic state.

Liver failure determines the outcome in patients of acute-on-chronic liver failure (ACLF): comparison of APASL ACLF research consortium (AARC) and CLIF-SOFA models

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a progressive disease associated with rapid clinical worsening and high mortality. Early prediction of mortality and intervention can improve patient outcomes. We aimed to develop a dynamic prognostic model and compare it with the existing models.

METHODS

A total of 1402 ACLF patients, enrolled in the APASL-ACLF Research Consortium (AARC) with 90-day follow-up, were analyzed. An ACLF score was developed in a derivation cohort (n = 480) and was validated (n = 922).

RESULTS

The overall survival of ACLF patients at 28 days was 51.7%, with a median of 26.3 days. Five baseline variables, total bilirubin, creatinine, serum lactate, INR and hepatic encephalopathy, were found to be independent predictors of mortality, with AUROC in derivation and validation cohorts being 0.80 and 0.78, respectively. AARC-ACLF score (range 5-15) was found to be superior to MELD and CLIF SOFA scores in predicting mortality with an AUROC of 0.80. The point scores were categorized into grades of liver failure (Gr I: 5-7; II: 8-10; and III: 11-15 points) with 28-day cumulative mortalities of 12.7, 44.5 and 85.9%, respectively. The mortality risk could be dynamically calculated as, with each unit increase in AARC-ACLF score above 10, the risk increased by 20%. A score of ≥11 at baseline or persisting in the first week was often seen among nonsurvivors (p = 0.001).

CONCLUSIONS

The AARC-ACLF score is easy to use, dynamic and reliable, and superior to the existing prediction models. It can reliably predict the need for interventions, such as liver transplant, within the first week.

Lower Plasma Soluble Transferrin Receptor Range in Healthy Indian Pediatric Cohort as Compared to Asian and Western Data

Soluble serum transferrin receptor is derived from erythroid transferrin receptor expressed on surface of developing erythroid cells. It can be detected in blood using sensitive ELISA methodology and blood levels reflect physiological iron dependent erythropoiesis state in bone marrow. Normal adult levels vary from 2 to 5 mg/l. However, pediatric studies are few and describe normal ranges to the tune of 1.0-3.0 mg/l, which are relatively lower than that of adults. In present study 40 healthy children (2-12 years) were evaluated to establish normal soluble transferrin receptor range. The mean transferrin receptor levels were 0.39 mg/l with a range of 0.17-2.1 mg/l. The levels were low as compared to mean levels described in other studies from West and our country (4.39 and 2.0 mg/l respectively). Since, no internationally standard method for reporting and testing for transferrin receptor levels are yet available, hence it is imperative to establish normal control ranges in different population cohorts, especially in pediatric age group, to better interpret their levels in diagnostic context.

Do traumatic lumbar punctures lead to greater relapses in acute lymphoblastic leukemia? Experience at a university hospital in India

OBJECTIVE

The aim of the study was to evaluate the impact of traumatic lumbar puncture (TLP) at diagnosis of relapse in childhood acute lymphoblastic leukemia (ALL). Risk factors associated with TLP were assessed.

MATERIALS AND METHODS

A retrospective analysis was performed from the records of children with ALL who were treated from January 2010 to December 2012.

RESULTS

A total of 311 patients with median age of 5 years (range: 1-13) were treated for ALL. The cerebrospinal fluid analysis obtained from first LP revealed 275: Central nervous system 1 (CNS 1) (no blasts); 8: CNS 3 (blasts positive); and 28: TLP. Twenty-eight (9%) patients relapsed. Twelve (3.9%) had a CNS relapse. A TLP at diagnosis was not associated with an increased risk of systemic or CNS relapse (P = 0.298, 0.295). Three years event-free survival of patients with TLP and without atraumatic LP (ATLP) at diagnosis was 56 ± 5.2% and 51.8 ± 12.4%, (P = 0.520). Three years overall survival with TLP and ATLP was 73.3 ± 3.5% and 70.4 ± 12.5%, respectively, (P = 0.963). Median platelet count in patients with TLP was significantly lower than those without TLP (10,000/μL and 28,000/μL, P < 0.001). A receiver operating characteristic curve was constructed for predicting the risk of TLP based on platelet count. Area under the curve was 0.74 ± 0.05 (95% confidence interval 0.64-0.84). Platelet count < 23.5 × 109/L at the time of LP had 75% sensitivity and 64.4% specificity in predicting a TLP.

CONCLUSIONS

Low platelet counts are significantly associated with risk of TLP. Traumatic LP at diagnosis was not associated with an increased risk of relapse.

Prevalence and correlates of Herpes Simplex Virus-2 and syphilis infections in the general population in India

OBJECTIVES

To determine the prevalence and correlates of Herpes Simplex Virus-2 (HSV-2) and syphilis infections in the general population in India.

METHODS

2456 adults were surveyed in Hyderabad, Bangalore and Chandigarh in India. Socio-demographic and lifestyle characteristics were obtained through a questionnaire, and a dried blood spot (DBS) was collected from all individuals aged 18 years and over; sexual behaviour was collected from those aged 18-49 years. DBS samples were tested for HSV-2 and syphilis serology. The association between HSV-2 and syphilis infections with socio-demographic and behavioural variables was analysed using multivariable logistic regression.

RESULTS

The prevalence of HSV-2 and syphilis was 10.1% and 1.7%, respectively. Geographic differences in HSV-2 prevalence were significant, while for syphilis it was comparable. Urban-rural differences in prevalence were only seen for syphilis. For both infections, the prevalence between males and females was not significantly different. In males and females, HSV-2 prevalence increased significantly with increasing age; for syphilis, a slight trend was seen only in females. In a multivariable analysis, HSV-2 infection in males and females was associated with site, religion and testing positive for syphilis, in addition to reporting ≥ 2 lifetime partners in the previous year among males and being ever married or having had sex with a non-regular partner in the last year among females.

CONCLUSIONS

The burden and geographic heterogeneity of HSV-2 and syphilis infections in India are significant. A national household and DBS-based sexually transmitted infection (STI) surveillance system would enable monitoring, especially in relation to the HIV epidemic, and planning of evidence-based prevention and treatment programmes.

Screening for hepatitis B, C and non-alcoholic fatty liver disease: a survey of community-based physicians

BACKGROUND

Screening guidelines for hepatitis B (HBV) and hepatitis C viruses (HCV) as well as a position statement for non-alcoholic fatty liver disease (NAFLD) have been put forth by different sources, but awareness of these guidelines and their impact on the physician practices have not been assessed.

AIM

To assess the attitudes of primary care physicians (PCPs), gastroenterologists (GEs) and hepatologists (HEPs) regarding screening for HBV, HCV and NAFLD.

DESIGN

A survey questionnaire was sent to community-based PCPs and GEs to assess issues related to HBV, HCV and NAFLD. The same questionnaire was sent to hepatologists (HEPs). The questionnaire contained 10 items related to demographic and practice patterns of these physicians, 35 items related to HBV, 35 items related to HCV and 29 items related to NAFLD.

RESULTS

A total of 214 physicians (103 PCPs, 59 GEs and 52 HEPs) completed the survey. A majority of PCPs, GEs and HEPs agreed on most screening issues for these causes of liver disease. Nevertheless, within group comparison of physicians (guideline aware versus guideline unaware) showed significant differences in accurate response between those who were aware of guidelines and those who were not aware.

CONCLUSIONS

A large percentage of PCPs and GEs were unaware of official guidelines for viral hepatitis B and hepatitis C. Those aware of guidelines were more likely to screen appropriately and avoid unnecessary testing. More needs to be done to assess awareness and the impact implementation of guidelines in hepatology.

Determination and modelling of stereoselective interactions of ligands with drug transporters: a key dimension in the understanding of drug disposition

1. Stereochemistry is an important dimension in pharmacology and plays a role in every aspect of the pharmacological fate of chiral xenobiotics. This includes small molecule-drug transporter binding. 2. This paper reviews the reported stereoselectivities of substrate and inhibitor interactions with P-glycoprotein and the organic cation transporter obtained using standard functional and binding studies, as well as data obtained from online cellular membrane affinity chromatography studies. 3. The use of stereochemical data in quantitative structure-activity relationship (QSAR) and pharmacophore modelling is also addressed as is the effect of ignoring the fact that small molecule-drug transporter interactions take place in three-dimensional and asymmetric space.

Blockade of mGluR1 receptor results in analgesia and disruption of motor and cognitive performances: effects of A-841720, a novel non-competitive mGluR1 receptor antagonist

BACKGROUND AND PURPOSE

To further assess the clinical potential of the blockade of metabotropic glutamate receptors (mGluR1) for the treatment of pain.

EXPERIMENTAL APPROACH

We characterized the effects of A-841720, a novel, potent and non-competitive mGluR1 antagonist in models of pain and of motor and cognitive function.

KEY RESULTS

At recombinant human and native rat mGluR1 receptors, A-841720 inhibited agonist-induced calcium mobilization, with IC50 values of 10.7+/-3.9 and 1.0 +/- 0.2 nM, respectively, while showing selectivity over other mGluR receptors, in addition to other neurotransmitter receptors, ion channels, and transporters. Intraperitoneal injection of A-841720 potently reduced complete Freund's adjuvant-induced inflammatory pain (ED50 = 23 micromol kg(-1)) and monoiodoacetate-induced joint pain (ED50 = 43 micromol kg(-1)). A-841720 also decreased mechanical allodynia observed in both the sciatic nerve chronic constriction injury and L5-L6 spinal nerve ligation (SNL) models of neuropathic pain (ED50 = 28 and 27 micromol kg(-1), respectively). Electrophysiological studies demonstrated that systemic administration of A-841720 in SNL animals significantly reduced evoked firing in spinal wide dynamic range neurons. Significant motor side effects were observed at analgesic doses and A-841720 also impaired cognitive function in the Y-maze and the Water Maze tests.

CONCLUSIONS AND IMPLICATIONS

The analgesic effects of a selective mGluR1 receptor antagonist are associated with motor and cognitive side effects. The lack of separation between efficacy and side effects in pre-clinical models indicates that mGluR1 antagonism may not provide an adequate therapeutic window for the development of such antagonists as novel analgesic agents in humans.

EGFR expression in breast cancer: Association with biologic phenotype, prognosis, and resistance to adjuvant therapy

513

Background: Expression of the epidermal growth factor receptor (EGFR) in preclinical models of breast cancer is associated with increased proliferation and resistance to apoptosis. In clinical studies, EGFR has been inconsistently linked to poor outcome. We hypothesized that EGFR expression, when objectively and uniformly assessed, is associated with an aggressive biologic phenotype and resistance to systemic adjuvant therapy. Methods: In a database of 54,865 patients with breast cancer, EGFR status was known on 2,567. EGFR levels were measured centrally by ligand binding assay performed on frozen tissue. Tumors with ≥10 fmol/mg of cytosol protein were prospectively deemed positive. Clinical and biological features of EGFR positive and negative tumors were compared. Disease-free survival (DFS) and overall survival (OS) were assessed in systemically untreated patients (untreated patients, n=1068) and those who received hormonal and/or chemotherapy (treated patients, n=1256). Results: 475 out of 2,567 tumors (18.5%) were EGFR positive. Compared to EGFR negative tumors, EGFR positive tumors were more common in younger (<50 years, 40% vs 24% p<0.0001), premenopausal (20% vs 10%, p<0.0001), and black women (10% vs 6% p=0.005). EGFR expression was associated with larger tumors (64% vs 46%, p<0.0001), aneuploidy (68% vs 46%, p<0.0001), high S-phase fraction (53% vs 22%, p<0.0001), and nodal involvement (43% vs 37%, p=0.009). Co-expression of other biomarkers was also studied. EGFR positive tumors were more likely to be HER2 positive (26% vs 16%, p<0.0001), but less likely to be ER positive (60% vs 88%, p<0.0001), and PR positive (26% vs 65%, p<0.0001). In a multivariate analysis, EGFR expression independently correlated with worse DFS (HR=1.6, 95%CI=1.2–2.2, p=0.001) and OS (HR=1.7, 95% CI=1.2–2.4, p=0.001) in treated patients, but not in untreated patients. Conclusions: EGFR expression is more common in breast tumors in young and black women. It is associated with lower hormone receptor levels, higher proliferation, genomic instability, nodal involvement, and HER2 over-expression. It is correlated with significant resistance to adjuvant hormonal and chemotherapy. Blocking EGFR activity may help overcome this resistance in selected patients.

No significant financial relationships to disclose.

Successful treatment of narcolepsy and cataplexy: a review

A 25-year-old woman with narcolepsy and cataplexy was treated with well-recognized drugs for these conditions. Because she did not respond, a decision was made to treat her with sodium oxybate.

Enhanced immunogenicity of a contraceptive vaccine using diverse synthetic carriers with permissible adjuvant

A vaccine directed against human chorionic gonadotropin (hCG) has previously undergone clinical testing demonstrating the feasibility of the approach in preventing pregnancy in women. Some individuals, however, did not respond adequately despite employing highly immunogenic bacterial toxoids as carriers. We investigated the potential of three promiscuous pathogen-derived Th peptides as carriers, employing alum as the adjuvant. While conjugation with each peptide improved the antibody response against hCG in mice of different haplotypes, immunisation with a combination of these peptide-conjugates generated anti-hCG responses higher than those achieved with the individual peptides or tetanus toxoid (TT). Antibodies were of high affinity and capable of neutralising the bioactivity of hCG but were devoid of anti-peptide reactivity. These results have implication for the design of hCG vaccine with improved immunogenicity for diverse population.

Symmetrical bis(heteroarylmethoxyphenyl)alkylcarboxylic acids as inhibitors of leukotriene biosynthesis

Symmetrical bis(quinolylmethoxyphenyl)alkylcarboxylic acids were investigated as inhibitors of leukotriene biosynthesis and 4, 4-bis(4-(2-quinolylmethoxy)phenyl)pentanoic acid sodium salt (47.Na) met our design parameters for a drug candidate (ABT-080). This compound was readily synthesized in three steps from commercially available diphenolic acid. Against intact human neutrophils, 47.Na inhibited ionophore-stimulated LTB(4) formation with an IC(50) = 20 nM. In zymosan-stimulated mouse peritoneal macrophages producing both LTC(4) and PGE(2), 47.Na showed 9000-fold selectivity for inhibition of LTC(4) (IC(50) = 0.16 nM) over PGE(2) (IC(50) = 1500 nM). Preliminary pharmacokinetic evaluation in rat and cynomolgus monkey demonstrated good oral bioavailability and elimination half-lives of 9 and 5 h, respectively. Pharmacological evaluation of leukotriene inhibition with oral dosing was demonstrated in a rat pleural inflammation model (ED(50) = 3 mg/kg) and a rat peritoneal passive anaphylaxis model (LTB(4), ED(50) = 2.5 mg/kg; LTE(4), ED(50) = 1.0 mg/kg). In a model of airway constriction induced by antigen challenge in actively sensitized guinea pigs, 47.Na dosed orally blocked bronchoconstriction with an ED(50) = 0.4 mg/kg, the most potent activity we have observed for any leukotriene inhibitor in this model. The mode of inhibitory action of 47.Na occurs at the stage of 5-lipoxygenase biosynthesis as it blocks both leukotriene pathways leading to LTB(4) and LTC(4) but not PGH(2) biosynthesis. However, 47.Na does not inhibit 5-lipoxygenase catalysis in a broken cell enzyme assay; therefore it is likely that 47.Na acts as a FLAP inhibitor.

Heteroarylmethoxyphenylalkoxyiminoalkylcarboxylic acids as leukotriene biosynthesis inhibitors

A novel series of heteroarylmethoxyphenylalkoxyiminoalkylcarboxylic acids was studied as leukotriene biosynthesis inhibitors. A hypothesis of structure-activity optimization by insertion of an oxime moiety was investigated using REV-5901 as a starting point. A systematic structure-activity optimization showed that the spatial arrangement and stereochemistry of the oxime insertion unit proved to be important for inhibitory activity. The promising lead, S-(E)-11, inhibited LTB(4) biosynthesis in the intact human neutrophil with IC(50) of 8 nM and had superior oral activity in vivo, in a rat pleurisy model (ED(50) = 0.14 mg/kg) and rat anaphylaxis model (ED(50) = 0.13 mg/kg). In a model of lung inflammation, S-(E)-11 blocked LTE(4) biosynthesis (ED(50) of 0.1 mg/kg) and eosinophil influx (ED(50) of 0.2 mg/kg). S-(E)-11 (A-93178) was selected for further preclinical evaluation.

Common mechanisms of osteosarcoma and Paget's disease

One of the most serious complications of Paget's disease is a significant increase in the incidence of osteosarcoma. Approximately 1% of Paget's patients develop osteosarcoma, an increase in risk that is several thousand-fold higher than the general population. This risk contributes significantly to the mortality and morbidity of Paget's disease patients. We examined several cases of pagetic and sporadic osteosarcoma for tumor-specific loss of constitutional heterozygosity (LoH) on chromosome 18q. Our analysis found that both pagetic and sporadic osteosarcoma tumors showed LoH for all or part of the distal portion of chromosome 18q. The pattern of LoH in both types of tumors identified a region between loci D18S60 and D18S42 that must contain the putative tumor suppressor locus. This region is tightly linked to familial Paget disease and familial expansile osteolysis (FEO). Our hypothesis is that the predisposition locus for Paget's disease and the tumor suppressor locus for osteosarcoma are either the same gene or that osteosarcoma in Paget's disease represents a deletion affecting two adjacent genes. In either model, localization of the osteosarcoma tumor suppressor gene would be of benefit in the eventual isolation of the predisposition locus for Paget's disease. We have begun to isolate and test candidate genes from within the region defined by both the familial Paget's disease families and the minimal region of LoH in osteosarcomas for evidence that one or more of them is responsible for predisposition to Paget's disease and/or osteosarcoma.