Preclinical radiolabeling, in vivo biodistribution and positron emission tomography of a novel pyrrolobenzodiazepine (PBD)-based antibody drug conjugate targeting ASCT2.

INTRODUCTION: Anti-ASCT2 antibody drug conjugate (ADC) MEDI7247 has been under development as a potential anti-cancer therapy for patients with selected relapsed/refractory hematological malignancies and advanced solid tumors by MedImmune. Although promising efficacy was observed in the clinic, pharmacokinetic (PK) analyses observed low exposure of MEDI7247 in phase I hematological patients. To investigate the biodistribution properties of MEDI7247, MEDI7247 and control antibodies were radiolabeled with zirconium-89 and in vitro and in vivo properties characterized. METHODS: MEDI7247 (human anti-ASCT2 antibody conjugated with pyrrolobenzodiazepine (PBD)) and MEDI7519 (MEDI7247 without PBD drug conjugate) and an isotype control antibody drug conjugate construct were conjugated with p-isothiocyanatobenzyl-deferoxamine (Df) and radiolabeled with zirconium-89. In vitro studies included determining the radiochemical purity, protein integrity, immunoreactivity (Lindmo analysis), apparent antigen binding affinity for ASCT2-positive cells by Scatchard analysis and serum stability of the radiolabeled immunoconjugates. In vivo studies included biodistribution and PET/MRI imaging studies of the radiolabeled immunoconjugates in an ASCT2-positive tumor model, HT-29 colorectal carcinoma xenografts. RESULTS: Conditions for the Df-conjugation and radiolabeling of antibody constructs were determined to produce active radioimmunoconjugates. In vivo biodistribution and whole body PET/MRI imaging studies of [89Zr]Zr-Df-MEDI7519 and [89Zr]Zr-Df-MEDI7247 radioimmunoconjugates in HT-29 colon carcinoma xenografts in BALB/c nude mice demonstrated specific tumor localization. However, more rapid blood clearance and non-specific localization in liver was observed for [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 compared to isotype control ADC. Except for liver and bone, other normal tissues demonstrated clearance reflecting the blood clearance for all three constructs and no other abnormal tissue uptake. CONCLUSIONS AND ADVANCES IN KNOWLEDGE: Preclinical biodistribution analyses of [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 showed the biodistribution pattern of anti-ASCT2 ADC MEDI7247 was similar to parental MEDI7519, and both antibodies showed specific tumor uptake compared to an isotype control ADC. This study highlights an important role nuclear medicine imaging techniques can play in early preclinical assessment of drug specificity as part of the drug development pipeline.

Effectiveness of telepharmacy diabetes services: A systematic review and meta-analysis.

PURPOSE: Although pharmacist-provided diabetes services have been shown to be effective, the effectiveness of telepharmacy (TP) in diabetes management has not been clearly established. This systematic review and meta-analysis aims to evaluate the effectiveness of diabetes TP services. METHODS: PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched (from inception through September 2021) to identify published studies that evaluated the effect of TP services in patients with diabetes mellitus and reported either glycosylated hemoglobin (HbA1c) or fasting blood glucose (FBG) outcomes. Mean difference (MD), weighted mean difference (WMD), relative risk (RR), and 95% confidence intervals were calculated using the DerSimonian and Laird random-effects model. RESULTS: 36 studies involving 13,773 patients were included in the systematic review, and 23 studies were included in the meta-analysis. TP was associated with a statistically significant decrease in HbA1c (MD, -1.26%; 95% CI, -1.69 to -0.84) from baseline. FBG was not significantly affected (MD, -25.32 mg/dL; 95% CI, -57.62 to 6.98). Compared to non-TP service, TP was associated with a lower risk of hypoglycemia (RR, 0.48; 95% CI, 0.30-0.76). In a subset of studies that compared TP to face-to-face (FTF) pharmacy services, no significant difference in HbA1c lowering was seen between the 2 groups (WMD, -0.09%; 95% CI, -1.07 to 0.90). CONCLUSION: Use of TP was associated with reduction of HbA1c and the risk of hypoglycemia in patients with diabetes mellitus. High-quality randomized controlled trials are needed to validate the effectiveness of diabetes TP services relative to FTF services.

Effect of Probiotic Supplementation on Glycemic Outcomes in Patients with Abnormal Glucose Metabolism: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

INTRODUCTION: The effectiveness of probiotics in patients with abnormal glucose metabolism has not been clearly demonstrated. It is also unclear if outcomes are consistent across different probiotic formulations. METHODS: A literature search was conducted using PubMed, EMBASE, and Cochrane CENTRAL database from inception through May 2020. Randomized controlled trials that evaluated the effect of probiotics on fasting blood glucose (FBG) or hemoglobin A1c (HbA1c) in patients with prediabetes, type 2 diabetes mellitus, or gestational diabetes were included. Outcomes of interest included FBG, HbA1c, fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of ß-cell function (HOMA-B), and quantitative insulin sensitivity check index (QUICKI). Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated using the DerSimonian and Laird random-effects model. RESULTS: 31 studies involving 1,948 participants were included in this analysis. Compared to control, probiotics had a significant favorable effect on FBG (WMD -5.77 mg/dL, 95% CI -8.48 to -3.06), HbA1c (WMD -0.32%, 95% CI -0.47 to -0.18), fasting insulin (WMD -2.95 µIU/mL, 95% CI -3.76 to -2.14), HOMA-IR (WMD -0.82, 95% CI -1.05 to -0.59), HOMA-B (WMD -14.86, 95% CI -24.57 to -5.16), and QUICKI (WMD 0.015, 95% CI 0.011-0.019). Further, probiotics were associated with favorable outcomes on all parameters at doses between 1 and 10 × 109 colony-forming unit per day (p < 0.004 for all) and formulations containing 2-4 strains (p < 0.05 for all). DISCUSSION/CONCLUSION: Probiotics appear to have a modest effect on glycemic parameters in patients with abnormal glucose metabolism. Due to the limited number of trials conducted in patients with prediabetes, more studies are warranted in this population.

Tumor volumes as a predictor of response to the anti-EGFR antibody drug conjugate depatuxizumab mafadotin.

BACKGROUND: The adverse impact of increasing brain tumor size on the efficacy of antibody-drug conjugates (ADCs) was investigated preclinically then validated with clinical data. METHODS­PRECLINICAL STUDY: The impact of tumor size on ADC tumor delivery and treatment response was evaluated in an EGFR-amplified patient-derived glioblastoma (GBM) model following treatment with Depatuxizumab mafadotin (Depatux-M). Biodistribution and imaging studies correlated drug distribution with starting treatment volume and anti-tumor activity. METHODS­CLINICAL STUDY: M12-356 was a Phase I study of Depatux-M in patients with GBM. Blinded volumetric analysis of baseline tumor volumes of M12-356 patients was undertaken by two reviewers and results correlated with response and survival. RESULTS: Preclinically, imaging and biodistribution studies showed specific and significantly higher tumor uptake of zirconium-89 labeled Depatux-M (89Zr-Depatux-M) in mice with smaller tumor volume (~98 mm3) versus those with larger volumes (~365 mm3); concordantly, mice with tumor volumes ≤100 mm3 at treatment commencement had significantly better growth inhibition by Depatux-M (93% vs 27%, P < .001) and significantly longer overall survival (P < .0001) compared to tumors ≥400 mm3. Clinically, patients with tumor volumes <25 cm3 had significantly higher response rates (17% vs. 0%, P = .009) and longer overall survival (0.5 vs 0.89 years, P = .001) than tumors above 25 cm3. CONCLUSION: Both preclinical and clinical data showed intra-tumoral concentration and efficacy of Depatux-m inversely correlated with tumor size. This finding merit further investigation with pretreatment tumor volume as a predictor for response to ADCs, in both gliomas and other solid tumors.

Energy Drink-Associated Electrophysiological and Ischemic Abnormalities: A Narrative Review.

An increasing number of cardiovascular adverse effects, emergency room visits, and deaths have been linked to energy drinks. In this review, we summarized available published literature assessing electrophysiological and ischemic adverse effects associated with energy drink consumption. Overall, 32 case reports and 19 clinical trials are included in this review. Ventricular arrhythmia, supraventricular arrhythmia, and myocardial ischemia were amongst the most commonly reported in case reports with 3 having a fatal outcome. Although serious ischemic changes, arrhythmias, or death were not observed in clinical trials, significant electrophysiological changes, such as PR/PQ interval shortening/prolongation, QT/QTc shortening/prolongation, and ST-T changes, were noted. QT/QTc interval prolongation appears to be the most significant finding in clinical trials, and there appears to be a dose-response relationship between energy drink consumption and QTc prolongation. The exact mechanisms and the particular combination of ingredients behind energy drink-induced cardiac abnormalities require further evaluation. Until more information is available, energy drink use should be considered as part of the differential diagnosis in appropriate patients presenting with electrocardiographic changes. Further, certain patient populations should exercise caution and limit their energy drink consumption.

Radiolabelling and preclinical characterization of 89Zr-Df-radiolabelled bispecific anti-PD-L1/TGF-ßRII fusion protein bintrafusp alfa.

PURPOSE: Τhis study aimed to optimize the 89Zr-radiolabelling of bintrafusp alfa investigational drug product and controls, and perform the in vitro and in vivo characterization of 89Zr-Df-bintrafusp alfa and 89Zr-Df-control radioconjugates. METHODS: Bintrafusp alfa (anti-PD-L1 human IgG1 antibody fused to TGF-ß receptor II (TGF-ßRII), avelumab (anti-PD-L1 human IgG1 control antibody), isotype control (mutated inactive anti-PD-L1 IgG1 control antibody), and trap control (mutated inactive anti-PD-L1 human IgG1 fused to active TGF-ßRII) were chelated with p-isothiocyanatobenzyl-desferrioxamine (Df). After radiolabelling with zirconium-89 (89Zr), radioconjugates were assessed for radiochemical purity, immunoreactivity, antigen binding affinity, and serum stability in vitro. In vivo biodistribution and imaging studies were performed with PET/CT to identify and quantitate 89Zr-Df-bintrafusp alfa tumour uptake in a PD-L1/TGF-ß-positive murine breast cancer model (EMT-6). Specificity of 89Zr-Df-bintrafusp alfa was assessed via a combined biodistribution and imaging experiment in the presence of competing cold bintrafusp alfa (1 mg/kg). RESULTS: Nanomolar affinities for PD-L1 were achieved with 89Zr-Df-bintrafusp alfa and 89Zr-avelumab. Biodistribution and imaging studies in PD-L1- and TGF-ß-positive EMT-6 tumour-bearing BALB/c mice demonstrated the biologic similarity of 89Zr-Df-bintrafusp alfa and 89Zr-avelumab indicating the in vivo distribution pattern of bintrafusp alfa is driven by its PD-L1 binding arm. Competition study with 1 mg of unlabelled bintrafusp alfa or avelumab co-administered with trace dose of 89Zr-labelled bintrafusp alfa demonstrated the impact of dose and specificity of PD-L1 targeting in vivo. CONCLUSION: Molecular imaging of 89Zr-Df-bintrafusp alfa biodistribution was achievable and allows non-invasive quantitation of tumour uptake of 89Zr-Df-bintrafusp alfa, suitable for use in bioimaging clinical trials in cancer patients.

Effectiveness of Telepharmacy Versus Face-to-Face Anticoagulation Services in the Ambulatory Care Setting: A Systematic Review and Meta-analysis.

BACKGROUND: Effectiveness of anticoagulation services managed via telepharmacy (TP) has not been clearly demonstrated. OBJECTIVE: This systematic review and meta-analysis compares the effectiveness of TP anticoagulation services to face-to-face (FTF) anticoagulation services in the ambulatory care setting. METHODS: A literature search for studies assessing the effectiveness of TP services was conducted using PubMed, EMBASE, and Cochrane Central databases, from inception through November 18, 2020. Studies that compared TP with FTF anticoagulation services in the ambulatory care setting were included. Outcomes of interest included thromboembolic events, major bleeding, minor bleeding, any bleeding, warfarin international normalized ratio (INR) time in therapeutic range (TTR), frequency of extreme INR, anticoagulation-related emergency department visits, anticoagulation-related hospitalization, any hospitalization, and mortality. Relative risk (RR) and weighted mean difference were calculated using the DerSimonian and Laird random-effects model. RESULTS: Overall, 11 studies involving 8395 patients were included in the systematic review, and 9 studies were included in the pooled meta-analysis. Compared with FTF service, TP was associated with a lower risk of any bleeding and any hospitalization, with RRs of 0.65 (95% CI = 0.47 to 0.90; P = 0.01) and 0.59 (95% CI = 0.39 to 0.87; P = 0.01), respectively. There was no statistically significant difference in TTR or the risk of extreme supratherapeutic INR, major bleeding, minor bleeding, or thromboembolic events between the 2 groups. CONCLUSIONS: TP appears to be at least as effective as FTF anticoagulation services. Findings from this study support the utilization of TP practice models in ambulatory care anticoagulation management.

A Survey of Energy Drink Consumption and Associated Adverse Effects in Air Force Personnel.

INTRODUCTION: Energy drinks are an increasingly utilized beverage and are gaining popularity in recent years. The U.S. Air Force (USAF) represents a unique population where energy drink consumption may be higher than the general population. To better understand the safety and health impact of energy drinks, this large-scale comprehensive survey was conducted to study energy drink consumption patterns and its associated adverse effects. MATERIALS AND METHODS: A survey was conducted across 12 USAF installations to assess self-reported energy drink consumption and adverse effects in the military population. This study was approved by the David Grant USAF Medical Center Institutional Review Board. RESULTS: A total of 9,655 participants participated in the survey. Energy drink consumption was reported in 76.7% of the participants, with 12.0% consuming ≥1 energy drink per day. Male gender, younger age, and enlisted military members are more likely to be high consumers; 58.6% of participants reported having at least once tried a premixed beverage that combines alcohol, caffeine, and other stimulants. Among energy drink users, 60.0% reported experiencing ≥1 adverse effect, and 0.92% reported needing to see a physician or going to the emergency department because of adverse effects from energy drinks. Higher energy drink or premixed combination beverage consumption frequency was associated with increased likelihood of physician or emergency department visits (P ≤ 0.002 for both). CONCLUSION: Approximately three in four USAF members reported ever consuming an energy drink. Caution should be exercised on the amount of energy drink consumed to limit the risk of serious adverse effects. Future studies should identify populations at greatest risk for adverse effects and alternative sources of energy maintenance to attain optimal mission readiness.

Targeting and Efficacy of Novel mAb806-Antibody-Drug Conjugates in Malignant Mesothelioma.

Epidermal growth factor receptor (EGFR) is highly overexpressed in malignant mesothelioma (MM). MAb806 is a novel anti-EGFR antibody that selectively targets a tumor-selective epitope. MAb806-derived antibody drug conjugates (ADCs), ABT-414, ABBV-221 and ABBV-322, may represent a novel therapeutic strategy in MM. EGFR and mAb806 epitope expressions in mesothelioma cell lines were evaluated using an array of binding assays, and the in vitro cell effects of ABT-414 and ABBV-322 were determined. In vivo therapy studies were conducted in mesothelioma xenograft and patient-derived xenograft (PDX) tumor models. We also performed biodistribution and imaging studies to allow the quantitative targeting of MM by mAb806 using a 89Zr-labeled immunoconjugate-ch806. A high EGFR expression was present in all mesothelioma cell lines evaluated and mAb806 binding present in all cell lines, except NCIH-2452. ABT-414 and ABBV-322 resulted in significant tumor growth inhibition in MM models with high EGFR and mAb806 epitope expressions. In contrast, in an EGFR-expressing PDX model that was negative for the mAb806 epitope, no growth inhibition was observed. We demonstrated the specific targeting of the mAb806 epitope expressing MM tumors using 89Zr-based PET imaging. Our data suggest that targeting EGFR in MM using specific ADCs is a valid therapeutic strategy and supports further investigation of the mAb806 epitope expression as a predictive biomarker.

Targeting Multiple EGFR-expressing Tumors with a Highly Potent Tumor-selective Antibody-Drug Conjugate.

ABBV-321 (serclutamab talirine), a next-generation EGFR-targeted antibody-drug conjugate (ADC) incorporates a potent pyrrolobenzodiazepine (PBD) dimer toxin conjugated to the EGFR-targeting ABT-806 affinity-matured AM1 antibody. ABBV-321 follows the development of related EGFR-targeted ADCs including depatuxizumab mafodotin (depatux-m, ABT-414), ABT-806 conjugated to monomethyl auristatin F (MMAF), and ABBV-221 (losatuxizumab vedotin), AM1 antibody conjugated to monomethyl auristatin E (MMAE). The distinct tumor selectivity of ABBV-321 differentiates it from many previous highly active antibody PBD conjugates that lack a therapeutic window. Potency of the PBD dimer, combined with increased binding of AM1 to EGFR-positive tumor cells, opens the possibility to target a wide array of tumors beyond those with high levels of EGFR overexpression or amplification, including those insensitive to auristatin-based ADCs. ABBV-321 exhibits potent antitumor activity in cellular and in vivo studies including xenograft cell line and patient-derived xenograft glioblastoma, colorectal, lung, head and neck, and malignant mesothelioma tumor models that are less sensitive to depatux-m or ABBV-221. Combination studies with ABBV-321 and depatux-m suggest a promising treatment option permitting suboptimal, and potentially better tolerated, doses of both ADCs while providing improved potency. Collectively, these data suggest that ABBV-321 may offer an extended breadth of efficacy relative to other EGFR ADCs while extending utility to multiple EGFR-expressing tumor indications. Despite its highly potent PBD dimer payload, the tumor selectivity of ABBV-321, coupled with its pharmacology, toxicology, and pharmacokinetic profiles, support continuation of ongoing phase I clinical trials in patients with advanced EGFR-expressing malignancies.

Characterization of ABBV-221, a Tumor-Selective EGFR-Targeting Antibody Drug Conjugate.

Depatuxizumab mafodotin (depatux-m, ABT-414) is a tumor-selective antibody drug conjugate (ADC) comprised of the anti-EGFR antibody ABT-806 and the monomethyl auristatin F (MMAF) warhead. Depatux-m has demonstrated promising clinical activity in glioblastoma multiforme (GBM) patients and is currently being evaluated in clinical trials in first-line and recurrent GBM disease settings. Depatux-m responses have been restricted to patients with amplified EGFR, highlighting the need for therapies with activity against tumors with nonamplified EGFR overexpression. In addition, depatux-m dosing has been limited by corneal side effects common to MMAF conjugates. We hypothesized that a monomethyl auristatin E (MMAE) ADC utilizing an EGFR-targeting antibody with increased affinity may have broader utility against tumors with more modest EGFR overexpression while mitigating the risk of corneal side effects. We describe here preclinical characterization of ABBV-221, an EGFR-targeting ADC comprised of an affinity-matured ABT-806 conjugated to MMAE. ABBV-221 binds to a similar EGFR epitope as depatux-m and retains tumor selectivity with increased binding to EGFR-positive tumor cells and greater in vitro potency. ABBV-221 displays increased tumor uptake and antitumor activity against wild-type EGFR-positive xenografts with a greatly reduced incidence of corneal side effects relative to depatux-m. ABBV-221 has similar activity as depatux-m against an EGFR-amplified GBM patient derived xenograft (PDX) model and is highly effective alone and in combination with standard-of-care temozolomide in an EGFRvIII-positive GBM xenograft model. Based on these results, ABBV-221 has advanced to a phase I clinical trial in patients with advanced solid tumors associated with elevated levels of EGFR. Mol Cancer Ther; 17(4); 795-805. ©2018 AACR.

Considerations for Optimal Blood Pressure Goals in the Elderly Population: A Review of Emergent Evidence.

Recent hypertension clinical trials and national guideline updates have created a debate on the most appropriate treatment goals in elderly patients with hypertension. In 2014, recommendations by the Eighth Joint National Committee allowed a more lenient goal for patients 60 years and older compared with previous guidelines. Since then, several large clinical trials and meta-analyses have added more information regarding strict versus lenient treatment goals. Most recently, the American College of Cardiology and American Heart Association Task Force published their highly anticipated hypertension guideline developed in conjunction with nine additional interdisciplinary organizations. This review discusses the culmination of emerging data to provide more insight into the treatment of hypertension in the elderly. A literature search was conducted using PubMed, the Cumulative Index of Nursing and Allied Health, the Cochrane database, and by hand-searching references from relevant articles. The following key terms were used: hypertension, blood pressure, systolic, and elderly. Available literature suggests that it is reasonable to target an office systolic blood pressure of less than 130 mm Hg in elderly patients with hypertension. An individualized approach is reasonable for those who are institutionalized, with high comorbidity burden, or have a short life expectancy. A diastolic blood pressure of less than 60 mm Hg should be avoided due to the potential for an increase in cardiovascular risk. The method of blood pressure measurement is extremely important to consider when determining the blood pressure goal, and proper procedures for accurate blood pressure measurement must be followed. Other factors important to consider may include the patient's comorbidities, frailty, as well as the patient's potential for adverse drug reactions.

Cross-species analysis of Fc engineered anti-Lewis-Y human IgG1 variants in human neonatal receptor transgenic mice reveal importance of S254 and Y436 in binding human neonatal Fc receptor.

IgG has a long half-life through engagement of its Fc region with the neonatal Fc receptor (FcRn). The FcRn binding site on IgG1 has been shown to contain I253 and H310 in the CH2 domain and H435 in the CH3 domain. Altering the half-life of IgG has been pursued with the aim to prolong or reduce the half-life of therapeutic IgGs. More recent studies have shown that IgGs bind differently to mouse and human FcRn. In this study we characterize a set of hu3S193 IgG1 variants with mutations in the FcRn binding site. A double mutation in the binding site is necessary to abrogate binding to murine FcRn, whereas a single mutation in the FcRn binding site is sufficient to no longer detect binding to human FcRn and create hu3S193 IgG1 variants with a half-life similar to previously studied hu3S193 F(ab')2 (t1/2ß, I253A, 12.23 h; H310A, 12.94; H435A, 12.57; F(ab')2, 12.6 h). Alanine substitutions in S254 in the CH2 domain and Y436 in the CH3 domain showed reduced binding in vitro to human FcRn and reduced elimination half-lives in huFcRn transgenic mice (t1/2ß, S254A, 37.43 h; Y436A, 39.53 h; wild-type, 83.15 h). These variants had minimal effect on half-life in BALB/c nu/nu mice (t1/2ß, S254A, 119.9 h; Y436A, 162.1 h; wild-type, 163.1 h). These results provide insight into the interaction of human Fc by human FcRn, and are important for antibody-based therapeutics with optimal pharmacokinetics for payload strategies used in the clinic.

Engineering anti-Lewis-Y hu3S193 antibodies with improved therapeutic ratio for radioimmunotherapy of epithelial cancers.

BACKGROUND: The aim of the study was to explore Fc mutations of a humanised anti-Lewis-Y antibody (IgG1) hu3S193 as a strategy to improve therapeutic ratios for therapeutic payload delivery. METHODS: Four hu3S193 variants (I253A, H310A, H435A and I253A/H310A) were generated via site-directed mutagenesis and radiolabelled with diagnostic isotopes iodine-125 or indium-111. Biodistribution studies in Lewis-Y-positive tumour-bearing mice were used to calculate the dose in tumours and organs for therapeutic isotopes (iodine-131, yttrium-90 and lutetium-177). RESULTS: (111)In-labelled I253A and H435A showed similar slow kinetics (t 1/2ß, 63.2 and 62.2 h, respectively) and a maximum tumour uptake of 33.11 ± 4.05 and 33.69 ± 3.77 percentage injected dose per gramme (%ID/g), respectively. (111)In-labelled I253A/H310A cleared fastest (t 1/2ß, 9.1 h) with the lowest maximum tumour uptake (23.72 ± 0.85 %ID/g). The highest increase in tumour-to-blood area under the curve (AUC) ratio was observed with the metal-labelled mutants ((90)Y and (177)Lu). (177)Lu-CHX-A" DTPA-hu3S193 I253A/H310A (6:1) showed the highest tumour-to-blood AUC ratio compared to wild type (3:1) and other variants and doubling of calculated dose to tumour based on red marrow dose constraints. CONCLUSIONS: These results suggest that hu3S193 Fc can be engineered with improved therapeutic ratios for (90)Y- and (177)Lu-based therapy, with the best candidate being hu3S193 I253A/H310A for (177)Lu-based therapy.

Integral membrane protease fibroblast activation protein sensitizes fibrosarcoma to chemotherapy and alters cell death mechanisms.

Fibroblast activation protein (FAP), an integral membrane serine protease, is found on fibro- and osteo-sarcoma and on myofibroblasts in epithelial carcinoma, but rarely on other adult tissue. FAP has been demonstrated to be an excellent target for tumor imaging in clinical trials, and antibodies and other FAP-targeting drugs are in development. Here we have shown that FAP overexpression increased the growth of HT1080 fibrosarcoma cells in vitro and in vivo, and found that the expression of FAP affects response to chemotherapy. When treated with doxorubicin, expression of FAP increased susceptibility to the drug. In spite of this, FAP-HT1080 cells had fewer markers of classical apoptosis than HT1080 cells and neither necrosis nor necroptosis were enhanced. However, levels of early mitochondrial and lysosomal membrane permeability markers were increased, and autophagy switched from a protective function in HT1080 cells to part of the cell death mechanism with FAP expression. Therefore, FAP may affect how the tumor responds to chemotherapeutic drugs overall, which should be considered in targeted drug development. The overexpression of FAP also alters cell signaling and responses to the environment in this cell line. This includes cell death mechanisms, changing the response of HT1080 cells to doxorubicin from classical apoptosis to an organelle membrane permeability-dependent form of cell death.

Association of hyponatremia to diuretic response and incidence of increased serum creatinine levels in hospitalized patients with acute decompensated heart failure.

OBJECTIVES: Although hyponatremia is a prognostic factor in acute heart failure (AHF), its influence on the acute clinical course of heart failure is unknown. Our objective was to evaluate the association of hyponatremia with diuretic response, renal function, and clinical outcomes in AHF. METHODS: A retrospective study included 499 hospitalized AHF patients treated with intravenous loop diuretics for ≥48 h. Patients were grouped by nadir sodium concentrations (normonatremic, NN) ≥135 mEq/l, (mild hyponatremia, MHN) 130-134 mEq/l, and (moderate to severe hyponatremia, MSHN) <130 mEq/l. Association to diuretic response and clinical outcome was assessed. RESULTS: The incidence of hyponatremia was 54% (36% MHN, 18% MSHN). Maximum diuretic dose (furosemide equivalents: NN 84 ± 132 mg/day vs. MHN 114 ± 165 mg/day vs. MSHN 249 ± 450 mg/day, p < 0.001) and incidence of diuretic regimen escalation (NN 11% vs. MHN 16% vs. MSHN 44%, p < 0.001) were significantly higher in patients experiencing hyponatremia. Hyponatremia was also associated with a higher incidence of acute increases in serum creatinine (NN 27% vs. MHN 45% vs. MSHN 63%, p < 0.001), greater increases in blood urea nitrogen, longer hospital stay, and higher mortality. Outcome disparities to NN patients were similar whether hyponatremia was acute or present upon admission. CONCLUSIONS: Acute or admission hyponatremia, especially <130 mEq/l, in AHF patients is associated with greater diuretic requirements, higher incidence of serum creatinine increases, and a poorer outcome. Alternative treatments warrant evaluation in these patients.

Radiolabelling and evaluation of a novel sulfoxide as a PET imaging agent for tumor hypoxia.

[¹8F]FMISO is the most widely validated PET radiotracer for imaging hypoxic tissue. However, as a result of the pharmacokinetics of [¹8F]FMISO a 2h wait between tracer administration and patient scanning is required for optimal image acquisition. In order to develop hypoxia imaging agents with faster kinetics, we have synthesised and evaluated several F-18 labelled anilino sulfoxides. In this manuscript we report on the synthesis, in vitro and in vivo evaluation of a novel fluoroethyltriazolyl propargyl anilino sulfoxide. The radiolabelling of the novel tracer was achieved via 2-[¹8F]fluoroethyl azide click chemistry. Radiochemical yields were 23 ± 4% based on 2-[¹8F]fluoroethyl azide and 7 ± 2% based on K[¹8F]F. The radiotracer did not undergo metabolism or defluorination in an in vitro assay using S9 liver fractions. Imaging studies using SK-RC-52 tumors in BALB/c nude mice have indicated that the tracer may have a higher pO2 threshold than [¹8F]FMISO for uptake in hypoxic tumors. Although clearance from muscle was faster than [¹8F]FMISO, uptake in hypoxic tumors was slower. The average tumor to muscle ratio at 2h post injection in large, hypoxic tumors with a volume greater than 686 mm³ was 1.7, which was similar to the observed ratio of 1.75 for [¹8F]FMISO. Although the new tracer showed improved pharmacokinetics when compared with the previously synthesised sulfoxides, further modifications to the chemical structure need to be made in order to offer significant in vivo imaging advantages over [¹8F]FMISO.

Molecular imaging of death receptor 5 occupancy and saturation kinetics in vivo by humanized monoclonal antibody CS-1008.

PURPOSE: CS-1008 (tigatuzumab; phase I/II), an antihuman death receptor 5 (DR5) agonist, induces apoptosis and has cytotoxic activity against human cancer cell lines. This study reports on the preclinical validation of (111)In-labeled anti-DR5 humanized antibody CS-1008 as a diagnostic tool to study the DR5 occupancy in patients with cancer and establish dose ranges for receptor saturation kinetics in vivo. EXPERIMENTAL DESIGN: CS-1008 was radiolabeled and characterized for DR5 binding and labeling efficiency on TRAIL-sensitive DR5-positive colorectal cancer cells (COLO 205 and WiDr). Pharmacokinetic and biodistribution studies were conducted in BALB/c nu/nu mice bearing COLO 205, WiDr, or DR5-negative CT26 colon tumors. Planar gamma camera imaging and computerized tomography (CT) images were obtained to study receptor occupancy in vivo. RESULTS: Scatchard analysis showed high and specific binding affinity (Kd, 1.05 ± 0.12 nmol/L) of (111)In-labeled CS-1008. (111)In-labeled CS-1008 was specifically taken up in mice bearing COLO 205 and WiDr tumors with prolonged tumor retention (26.25 ± 2.85%ID/g vs. 12.20 ± 2.24 at 168 hours post injection; n = 5, SD), and uptake correlated both with DR5 expression on tumor cells and antitumor activity. DR5 saturation was shown in vivo via both biodistribution studies and planar gamma camera imaging/CT imaging of (111)In-labeled CS-1008. Saturation of DR5 corresponded to maximal in vivo antitumor efficacy. CONCLUSIONS: Imaging of DR5 receptor occupancy in vivo correlates with tumor concentration and in vivo efficacy, and is a novel molecular imaging technique that can be used to determine receptor occupancy and effective dose levels of DR5 agonist antibodies in the clinic.

Radiolabelling and evaluation of novel haloethylsulfoxides as PET imaging agents for tumor hypoxia.

The significance of imaging hypoxia with the PET ligand [(18)F]FMISO has been demonstrated in a variety of cancers. However, the slow kinetics of [(18)F]FMISO require a 2-h delay between tracer administration and patient scanning. Labelled chloroethyl sulfoxides have shown faster kinetics and higher contrast than [(18)F]FMISO in a rat model of ischemic stroke. However, these nitrogen mustard analogues are unsuitable for routine production and use in humans. Here we report on the synthesis and in vitro and in vivo evaluation of two novel sulfoxides which we synthesised from a single precursor molecule via either 2-[(18)F]fluoroethyl azide click chemistry or conventional nucleophilic displacement of a chloride leaving group. The yields of the click chemistry approach were 90±5% of [(18)F]2 based on 2-[(18)F]fluoroethyl azide, and the yields for the S(N) reaction were 15±5% of [(18)F]1 based on K[(18)F]F. Both radiotracers underwent metabolism in an in vitro assay using S9 liver fractions with biological half-lives of 32.39 and 43.32 min, respectively. Imaging studies using an SK-RC-52 tumor model in BALB/c nude mice have revealed that only [(18)F]1 is retained in hypoxic tumors, whereas [(18)F]2 is cleared from those tumors at a rate similar to that of muscle tissue. [(18)F]1 has emerged as a promising new lead structure for further development of sulfoxide-based hypoxia imaging agents. In particular, the mechanism of uptake needs to be elucidated and changes to the chemical structure need to be made in order to reduce metabolism and improve radiotracer kinetics.

18F-THK523: a novel in vivo tau imaging ligand for Alzheimer's disease.

While considerable effort has focused on developing positron emission tomography ß-amyloid imaging radiotracers for the early diagnosis of Alzheimer's disease, no radiotracer is available for the non-invasive quantification of tau. In this study, we detail the characterization of (18)F-THK523 as a novel tau imaging radiotracer. In vitro binding studies demonstrated that (18)F-THK523 binds with higher affinity to a greater number of binding sites on recombinant tau (K18Δ280K) compared with ß-amyloid(1-42) fibrils. Autoradiographic and histofluorescence analysis of human hippocampal serial sections with Alzheimer's disease exhibited positive THK523 binding that co-localized with immunoreactive tau pathology, but failed to highlight ß-amyloid plaques. Micro-positron emission tomography analysis demonstrated significantly higher retention of (18)F-THK523 (48%; P < 0.007) in tau transgenic mice brains compared with their wild-type littermates or APP/PS1 mice. The preclinical examination of THK523 has demonstrated its high affinity and selectivity for tau pathology both in vitro and in vivo, indicating that (18)F-THK523 fulfils ligand criteria for human imaging trials.