A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Whole-genome sequencing of clinical Clostridioides difficile isolates reveals molecular epidemiology and discrepancies with conventional laboratory diagnostic testing

BACKGROUND

The high clinical burden of Clostridioides difficile infections merits rapid and sensitive identification of affected individuals. However, effective diagnosis remains challenging. Current best practice guidelines recommend molecular and/or direct toxin detection-based screening for symptomatic individuals, but previous work has called into question the concordance and performance of extant clinical assays.

AIM

To better correlate the genomic and phenotypic properties of clinical C. difficile isolates with laboratory testing outcomes in both C. difficile-infected patients and asymptomatic carriers.

METHODS

Whole-genome sequencing of clinical C. difficile isolates collected from an inpatient population at a single healthcare institution was performed, enabling examination of their molecular epidemiology and toxigenic gene content. Genomic findings were compared with clinical testing outcomes, identifying multiple diagnostic discrepancies.

FINDINGS

Toxigenic culture, considered a 'reference standard', provided perfect sensitivity and specificity in predicting toxigenic gene content, whereas reduced performance was observed for Simplexa C. difficile Direct Assay (100% specificity, 88% sensitivity), Gene Xpert CD/Epi Assay (86% specificity, 83% sensitivity), and Quick Check Complete Tox A/B (100% specificity, 30% sensitivity). Genomic analysis additionally revealed variability in toxin gene sequences among C. difficile strains, phylogenomic equivalency between isolates from affected patients and carriers, and patient carriage with uncommon environmentally derived C. difficile lineages, as well as presenting opportunities for tracing pathogen transmission events.

CONCLUSION

These results highlight the variable performance of clinical stool-based testing approaches as well as the potential diagnostic utility of whole-genome sequencing as an alternative to conventional testing algorithms.

Targeted inhibition of activated protein C by a non-active-site inhibitory antibody to treat hemophilia

Activated protein C (APC) is a plasma serine protease with antithrombotic and cytoprotective functions. Based on the hypothesis that specific inhibition of APC’s anticoagulant but not its cytoprotective activity can be beneficial for hemophilia therapy, 2 types of inhibitory monoclonal antibodies (mAbs) are tested: A type I active-site binding mAb and a type II mAb binding to an exosite on APC (required for anticoagulant activity) as shown by X-ray crystallography. Both mAbs increase thrombin generation and promote plasma clotting. Type I blocks all APC activities, whereas type II preserves APC’s cytoprotective function. In normal monkeys, type I causes many adverse effects including animal death. In contrast, type II is well-tolerated in normal monkeys and shows both acute and prophylactic dose-dependent efficacy in hemophilic monkeys. Our data show that the type II mAb can specifically inhibit APC’s anticoagulant function without compromising its cytoprotective function and offers superior therapeutic opportunities for hemophilia.

Activated protein C (APC) is a plasma serine protease with antithrombotic and cytoprotective functions. Here, the authors develop a monoclonal antibody that specifically inhibits APC’s anticoagulant function without compromising its cytoprotective function, and shows efficacy in animal models.

Efficacy and Toxicity of Stereotactic Body Radiotherapy for Early to Advanced Stage Hepatocellular Carcinoma - Initial Experience From an Australian Liver Cancer Service

AIMS

Intrahepatic progression remains the predominant mode of cancer-related death in hepatocellular carcinoma (HCC) underscoring the need for effective local therapies. We report our initial experience with liver stereotactic body radiotherapy (SBRT) in the management of early to advanced stage HCC at an Australian tertiary liver cancer service.

MATERIALS AND METHODS

Patients with liver-confined HCC unsuitable for surgical resection or thermal ablation treated with SBRT between October 2013 and December 2018 were retrospectively evaluated. The primary end point was freedom from local progression. Secondary end points were progression-free survival, disease-specific survival, overall survival and toxicity.

RESULTS

Ninety-six patients were treated for 112 lesions (median size 3.8 cm, range 1.5-17 cm). The median follow-up was 13 months (range 3-65). Forty-six patients had received prior local therapies (median 1, range 1-5), 83 (86%) patients had cirrhosis with baseline Child-Pugh scores of A (88%) and B7-8 (12%). Fifty-nine (61%) patients had Barcelona Clinic Liver Cancer (BCLC) stage 0/A disease and 37 (39%) had stage B/C. Macrovascular invasion was present in 20 (21%). The median biologically effective dose (BED₁₀) was 86 and 60 Gy for the BCLC 0/A and B/C cohorts, respectively. Freedom from local progression at 18 months was 94% for BCLC 0/A and 74% for BCLC B/C. Progression-free survival and overall survival at 12 months were 80 and 95% for BCLC 0/A and 40 and 71% for BCLC B/C, respectively. Five patients (7%) with cirrhosis and without disease progression had an increase in Child-Pugh score >1 within 3 months of SBRT, four of whom had intercurrent infections. Clinical toxicities grade ≥2 were reported in 20% of patients.

CONCLUSION

SBRT is an effective ablative modality for early stage HCC with low rates of significant toxicity. Lower dose SBRT can provide durable local control for advanced stage HCC. However, out-of-field relapse remains common, providing a rationale to investigate SBRT in combination with other therapies.

Protocol for geolocating rural villages of women in Liberia utilizing a maternity waiting home

OBJECTIVE

Geospatial data are used by health systems and researchers to understand disease burdens, trace outbreaks, and allocate resources, however, there are few well-documented protocols for collecting and analyzing geographic information systems data in rural areas of low- and middle-income countries. Even with the proliferation of spatial technologies such as Open Street Map and Google Maps, basic geographic data-such as village locations-are not widely available in many countries in sub-Saharan Africa. The purpose of this paper is to report a step-wise protocol, using geographic information system techniques and tools, developed to collect and analyze the type of spatial data necessary to calculate the distance between rural villages and maternity waiting homes located near rural primary healthcare facilities in Bong County, Liberia.

RESULTS

Using a step-wise approach incorporating local healthcare provider knowledge, intensive field work, and spatial technologies such as Open Street Map and Google Maps for village geospatial data collection and verification, we identified village locations of 93.7% of the women who accessed the five maternity waiting homes in our study from 2012 to 2016.

Obligate Multivalent Recognition of Cell Surface Tomoregulin following Selection from a Multivalent Phage Antibody Library

A therapeutic antibody candidate (AT-19) isolated using multivalent phage display binds native tomoregulin (TR) as a mul-timer not as a monomer. This report raises the importance of screening and selecting phage antibodies on native antigen and reemphasizes the possibility that potentially valuable antibodies are discarded when a monomeric phage display system is used for screening. A detailed live cell panning selection and screening method to isolate multivalently active antibodies is described. AT-19 is a fully human antibody recognizing the cell surface protein TR, a proposed prostate cancer target for therapeutic antibody internalization. AT-19 was isolated from a multivalent single-chain variable fragment (scFv) antibody library rescued with hyperphage. The required multivalency for isolation of AT-19 is supported by fluorescence activated cell sorting data demonstrating binding of the multivalent AT-19 phage particles at high phage concentrations and failure of monovalent particles to bind. Pure monomeric scFv AT-19 does not bind native receptor on cells, whereas dimeric scFv or immunoglobulin G binds with nanomolar affinity. The isolation of AT-19 antibody with obligate bivalent binding activity to native TR is attributed to the use of a multivalent display of scFv on phage and the method for selecting and screening by alternate use of 2 recombinant cell lines.

Screening for asymptomatic lymphogranuloma venereum co-infection in men who have sex with men newly diagnosed with HIV, hepatitis C or syphilis

Patients diagnosed with lymphogranuloma venereum have high rates of co-infection with HIV, syphilis and hepatitis C. The aim of this enhanced surveillance was to screen all men who have sex with men (MSM) newly diagnosed with HIV, syphilis or hepatitis C for co-infection with asymptomatic lymphogranuloma venereum as part of the recommended sexual health screen. Of the 145 patients screened, 21 patients were diagnosed with rectal Chlamydia trachomatis, one with both rectal and urethral chlamydia and six with urethral chlamydia. One rectal chlamydia-positive sample, when tested, was equivocal for lymphogranuloma venereum. Our data suggested that there was not a pool of asymptomatic lymphogranuloma venereum infection in MSM recently diagnosed with HIV, hepatitis C and syphilis. However, there have been recent reports of an increased incidence of asymptomatic lymphogranuloma venereum, raising the question whether lymphogranuloma venereum should be screened for in high risk asymptomatic MSM. The prevalence of asymptomatic rectal chlamydia infections was 19%.

Effects of low protein diets on performance of pigs with a lean genotype between 40 and 115 kg liveweight

The aim of the work was to assess the effects of three dietary protein regimes on pig performance and nitrogen (N) excretion, in particular, whether performance can be maintained in lean, fast growing pigs when protein levels are reduced to limit N excretion. Entire male pigs of a lean genotype (Pietrain × Large White × Landrace), 192 in total in four batches, were grown from 40 to 115 kg in pens with four pigs per pen. The diets were: (i) a high-protein control regime; (ii) a low-protein regime in which protein was reduced by ~2 percentage units in each growth stage, but with levels of five essential amino acids the same as in the control (LP1); (iii) an even lower protein regime in which levels of essential amino acids were not maintained beyond 60 kg (LP2). The LP2 regime was designed to promote intramuscular fat deposition rather than efficient growth. Excretion of N was reduced by 17% and 19% in LP1 and LP2, respectively, compared with the control. Average daily gain was lower and feed conversion ratio higher in LP2 than the other regimes, as expected. The control and LP1, which differed in protein but not essential amino acid levels, produced broadly similar results for performance, but pigs in LP1 had poorer feed conversion than control pigs, which could be due to slightly greater fat deposition. The results show the difficulty in maintaining consistently high levels of performance in fast-growing, lean pigs when dietary protein levels are reduced.

Abstract LB-206: Target validation of C4.4a (LYPD3) as a target for antibody-drug conjugates for the treatment of squamous cell carcinoma of different origin

C4.4a (LYPD3) is a GPI-anchored cell surface protein with unknown physiological function, although it has been speculated that it might play a role in tumor invasion and metastasis formation. In addition, over-expression of C4.4a correlates with a malignant phenotype and poor prognosis in several cancer indications.

As a result of comprehensive gene expression profiling, we report that the C4.4a transcript is being significantly up-regulated in human non-small cell lung cancer (NSCLC) as well as in other tumors compared to the respective normal tissue. This finding was confirmed in IHC studies showing strong C4.4a protein expression on the surface of tumor cells particularly in lung squamous cell carcinoma. Interestingly, a high incidence of C4.4a protein expression was found in a number of additional cancers such as stomach, bladder, colorectal, ovarian, prostate, hepatocellular as well as SCC of the head and neck. In marked contrast to tumors, C4.4a expression in normal tissues is restricted to esophagus, cervix and the outer epithelial layer of skin (stratum spinosum and stratum granulosum). Employing FACS and IHC analyses, several model systems were identified expressing C4.4a in vitro and in vivo. Subsequently, Mab-Zap assays were used to demonstrate efficient internalization of C4.4a in endogenously expressing cells as well as in cells transfected to over-express C4.4a.

In summary, the observed strong over-expression of C4.4a in tumors, its very limited expression in normal tissue as well as its ability to rapidly internalize make it a promising target for the generation of antibody-drug conjugates for the treatment of several cancer indications, in particular lung squamous cell carcinoma.

Citation Format: Gabriele Leder, Yong-Jiang Cao, Lars Linden, Sven Golfier, Oliver von Ahsen, Claudia Schneider, Joerg Willuda, Kirk McLean, Hans-Dieter Pohlenz, Bertolt Kreft, Karl Ziegelbauer. Target validation of C4.4a (LYPD3) as a target for antibody-drug conjugates for the treatment of squamous cell carcinoma of different origin. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-206. doi:10.1158/1538-7445.AM2013-LB-206

In vivo biodistribution, PET imaging, and tumor accumulation of 86Y- and 111In-antimindin/RG-1, engineered antibody fragments in LNCaP tumor-bearing nude mice

To optimize in vivo tissue uptake kinetics and clearance of engineered monoclonal antibody (mAb) fragments for radiotherapeutic and radiodiagnostic applications, we compared the biodistribution and tumor localization of four (111)In- and (86)Y-labeled antibody formats, derived from a single antimindin/RG-1 mAb, in a prostate tumor model. The IgG, diabody, single-chain variable domain (scFv), and novel miniantibody formats, composed of the human IgE-C(H)4 and a modified IgG1 hinge linked to scFv domains, were compared.

METHODS

Antibodies were first derivatized with the bifunctional chelator CHX-A''-diethylenetriamine pentaacetic acid and then bound to the radiometal to create radiolabeled immunoconjugates. Human LNCaP xenografts were grown in nude mice, and (111)In- or (86)Y-labeled antibodies were administered intravenously. Tissues were harvested at different times, and the level of antibody deposition was determined by measuring radioactivity. Whole-body small-animal PET of mice receiving (86)Y-labeled antibodies was performed at 6 time points and colocalized with simultaneous micro-CT imaging.

RESULTS

The biodistributions of (111)In and (86)Y antibodies were quite similar. The blood, tumor, kidney, and liver tissues contained varying levels of radioactivity. The antibody accumulation in the tumor correlated with molecular size. The IgG steadily increased with time to 24.1 percentage injected dose per gram (%ID/g) at 48 h. The miniantibody accumulated at a similar rate to reach a lower level (14.2 %ID/g) at 48 h but with a higher tumor-to-blood ratio than the IgG. Tumor accumulation of the diabody peaked at 3 h, reaching a much lower level (3.7 %ID/g). A combination of rapid clearance and lower relative affinity of the scFv precluded deposition in the tumor. Small-animal PET results correlated well with the biodistribution results, with similar tumor localization patterns.

CONCLUSION

The larger antibody formats (IgG and miniantibody) gave higher tumor uptake levels than did the smaller formats (diabody and scFv). These larger formats may be more suitable for radioimmunotherapy applications, evidenced by the preclinical efficacy previously shown by a report on the IgG format. The smaller formats were rapidly cleared from circulation, and the diabody, which accumulated in the tumor, may be more suitable for radiodiagnostic applications.

Amplified anticoagulant activity of tissue factor-targeted thrombomodulin: in-vivo validation of a tissue factor-neutralizing antibody fused to soluble thrombomodulin

Tissue factor (TF) exposure is a potent pro-thrombotic trigger that initiates activation of the coagulation cascade, while thrombomodulin (TM) is a potent anticoagulant protein that limits the extent of activation. Both TF neutralizing antibodies and soluble TM (sTM) are effective anticoagulants. We have developed a novel anticoagulant fusion protein, Ab(TF)-TM, by fusing a TFneutralizing single-chain antibody, Ab(TF), to an active fragment of TM. Ab(TF)-TM is a novel anticoagulant targeting to sites of TF exposure with a dual mechanism of action. The Ab(TF) portion of the molecule inhibitsTF/factorVIIa mediated activation of FIX and FX, and the TM portion of the molecule acts as a cofactor for activation of protein C. In-vitro coagulation assays show that Ab(TF)-TM more potently inhibits TF-initiated coagulation (prothrombin time) than can its individual components, Ab(TF) (20-fold) and sTM (80-fold) alone, or in combination (10-fold). In contrast, the potency of Ab(TF)-TM in the activated partial thromboplastin and thrombin clotting time assays was similar to sTM alone. In a rat model of disseminated intravascular coagulation (DIC), intravenous injection of a human TF-containing thromboplastin reagent (0.5 ml/kg) resulted in an immediate death in approximately 60% of the animals and a clinical score of approximately 2.5. Pre-injection of Ab(TF)-TM or Ab(TF) and sTM, given alone or in combination, showed dose-dependent efficacy. At a dose of 0.7 nmol/kg, Ab(TF)-TM completely prevented death and reduced clinical scores by 79%, while neitherAb(TF) nor sTM, given alone or in combination, showed significant therapeutic effects. Calculated effective doses that reduced mortality by 50% relative to that in the control group (ED(50), nmol/kg) were 0.21 for Ab(TF)-TM, 3.2 for an equimolar mixture of Ab(TF) and sTM, 4.3 for sTM and 20 for Ab(TF). Thus, Ab(TF)-TM presented 10- to 100-fold enhancement of the anticoagulant potency, relative to the ED(50) in Ab(TF) and sTM given either alone or in combination, in a rat DIC model.