Uncovering receptor-ligand interactions using a high-avidity CRISPR activation screening platform

The majority of clinically approved drugs target proteins that are secreted or cell surface bound. However, further advances in this area have been hindered by the challenging nature of receptor deorphanization, as there are still many secreted and cell-bound proteins with unknown binding partners. Here, we developed an advanced screening platform that combines CRISPR-CAS9 guide-mediated gene activation (CRISPRa) and high-avidity bead-based selection. The CRISPRa platform incorporates serial enrichment and flow cytometry-based monitoring, resulting in substantially improved screening sensitivity for well-known yet weak interactions of the checkpoint inhibitor family. Our approach has successfully revealed that siglec-4 exerts regulatory control over T cell activation through a low affinity trans-interaction with the costimulatory receptor 4-1BB. Our highly efficient screening platform holds great promise for identifying extracellular interactions of uncharacterized receptor-ligand partners, which is essential to develop next-generation therapeutics, including additional immune checkpoint inhibitors.

Engineering CD276/B7-H3-targeted antibody-drug conjugates with enhanced cancer-eradicating capability

CD276/B7-H3 represents a promising target for cancer therapy based on widespread overexpression in both cancer cells and tumor-associated stroma. In previous preclinical studies, CD276 antibody-drug conjugates (ADCs) exploiting a talirine-type pyrrolobenzodiazepine (PBD) payload showed potent activity against various solid tumors but with a narrow therapeutic index and dosing regimen higher than that tolerated in clinical trials using other antibody-talirine conjugates. Here, we describe the development of a modified talirine PBD-based fully human CD276 ADC, called m276-SL-PBD, that is cross-species (human/mouse) reactive and can eradicate large 500-1,000-mm3 triple-negative breast cancer xenografts at doses 10- to 40-fold lower than the maximum tolerated dose. By combining CD276 targeting with judicious genetic and chemical ADC engineering, improved ADC purification, and payload sensitivity screening, these studies demonstrate that the therapeutic index of ADCs can be substantially increased, providing an advanced ADC development platform for potent and selective targeting of multiple solid tumor types.

Ten-year territory-wide trends in the utilisation and clinical outcomes of extracorporeal membrane oxygenation in Hong Kong

INTRODUCTION

The utilisation of extracorporeal membrane oxygenation (ECMO) has been rapidly increasing in Hong Kong. This study examined 10-year trends in the utilisation and clinical outcomes of ECMO in Hong Kong.

METHODS

We retrospectively reviewed the records of all adult patients receiving ECMO who were admitted to the intensive care units (ICUs) of public hospitals in Hong Kong between 2010 and 2019. Temporal trends across years were assessed using the Mann-Kendall test. Observed hospital mortality was compared with the Acute Physiology and Chronic Health Evaluation (APACHE) IV-predicted mortality.

RESULTS

The annual number of patients receiving ECMO increased from 18 to 171 over 10 years. In total, 911 patients received ECMO during the study period: 297 (32.6%) received veno-arterial ECMO, 450 (49.4%) received veno-venous ECMO, and 164 (18.0%) received extracorporeal cardiopulmonary resuscitation. The annual number of patients aged ≥65 years increased from 0 to 47 (27.5%) [P for trend=0.001]. The median (interquartile range) Charlson Comorbidity Index increased from 1 (0-1) to 2 (1-3) [P for trend<0.001] while the median (interquartile range) APACHE IV score increased from 90 (57-112) to 105 (77-137) [P for trend=0.003]. The overall standardised mortality ratio comparing hospital mortality with APACHE IV-predicted mortality was 1.11 (95% confidence interval=1.01-1.22). Hospital and ICU length of stay both significantly decreased (P for trend=0.011 and <0.001, respectively).

CONCLUSION

As ECMO utilisation increased in Hong Kong, patients put on ECMO were older, more critically ill, and had more co-morbidities. It is important to combine service expansion with adequate resource allocation and training to maintain quality of care.

Polyethyleneimine/polyethylene glycol-conjugated gold nanoparticles as nanoscale positive/negative controls in nanotoxicology: testing in frog embryo teratogenesis assay-Xenopus and mammalian tissue culture system

Despite the great potential of using positively charged gold nanoparticles (AuNPs) in nanomedicine, no systematic studies have been reported on their synthesis optimization or colloidal stability under physiological conditions until a group at the National Institute of Standards and Technology recently succeeded in producing remarkably stable polyethyleneimine (PEI)-coated AuNPs (Au-PEI). This improved version of Au-PEI (Au-PEI25kB) has increased the demand for toxicity and teratogenicity information for applications in nanomedicine and nanotoxicology. In vitro assays for Au-PEI25kB in various cell lines showed substantial active cytotoxicity. For advanced toxicity research, the frog embryo teratogenesis assay-Xenopus (FETAX) method was employed in this study. We observed that positively-charged Au-PEI25kB exhibited significant toxicity and teratogenicity, whereas polyethylene glycol conjugated AuNPs (Au-PEG) used as comparable negative controls did not. There is a characteristic avidity of Au-PEI25kB for the jelly coat, the chorionic envelope (also known as vitelline membrane) and the cytoplasmic membrane, as well as a barrier effect of the chorionic envelope observed with Au-PEG. To circumvent these characteristics, an injection-mediated FETAX approach was utilized. Like treatment with the FETAX method, the injection of Au-PEI25kB severely impaired embryo development. Notably, the survival/concentration curve that was steep when the standard FETAX approach was employed became gradual in the injection-mediated FETAX. These results suggest that Au-PEI25kB may be a good candidate as a nanoscale positive control material for nanoparticle analysis in toxicology and teratology.

Outcomes of patients with high bleeding risks characteristics presenting with acute coronary syndrome undergoing percutaneous coronary intervention

Background

Patients with high bleeding risk characteristics (HBR) presenting with acute coronary syndrome (ACS) pose a clinical challenge to balance risk for recurrent ischemic events versus incurring bleeding with dual antiplatelet therapy.

Purpose

We seek to determine the incidence and predictors of short and long term ischemic and bleeding outcomes in patients with HBR factors presenting with ACS after percutaneous coronary intervention (PCI).

Method

Consecutive patients over a 1-year period, who underwent PCI for ACS were categorized as having HBR based on: age ≥75, anemia (hemoglobin&lt;110g/L), thrombocytopenia (platelet&lt;100x109/L), renal failure (eGFR&lt;30umol/L) or concurrent use of oral anticoagulation. Primary outcome was major adverse cardiovascular event (MACE) defined as composite of cardiovascular death, myocardial infarction, and stroke at 1 year. Key secondary outcomes include significant bleeding defined as Bleeding Academic Research Consortium (BARC) type 3 or 5, and net adverse cardiovascular event (NACE), as a composite of MACE and significant bleeding.

Results

Of 1351 patients presented with ACS, 389 (28.8%) had at least one HBR criteria. At 1 year, patients with HBR, compared to those without, had increased MACE (11.1% vs 4.2%, p&lt;0.001) and cardiovascular death (5.7% vs 1.7%, p&lt;0.001). Patients with HBR had increased significant bleeding (3.6% vs 2.3%, p=0.011) and NACE (14.4% vs 5.4%, p&lt;0.001). Multivariate analysis showed the presence of HBR and prior history of myocardial infarction were predictors for 1-year MACE (OR 2.67, CI [1.62–4.42], p&lt;0.001 and OR 2.18, CI [1.29–3.70], p=0.004, respectively), whereas the use of second-generation antiplatelet agent was not. Increased MACE and NACE were observed in HBR patients beyond 1 month of DAPT.

Conclusion

Among patients with ACS undergoing PCI, those with HBR had higher risk for both ischemic and bleeding complications. Novel strategies need to be considered for this high-risk group. Current guidelines, recommending 1 year of DAPT for patients with ACS, should be re-evaluated among patients with HBR.

Funding Acknowledgement

Type of funding sources: None. Kaplan-Meier curve for 1 year MACEKaplan-Meier curve for 1 year death

Admission triage tool for adult intensive care unit admission in Hong Kong during the COVID-19 outbreak

Intensive care is expensive, and the numbers of intensive care unit (ICU) beds and trained specialist medical staff able to provide services in Hong Kong are limited. The most recent increase in coronavirus disease 2019 (COVID-19) infections over July to August 2020 resulted in more than 100 new cases per day for a prolonged period. The increased numbers of critically ill patients requiring ICU admission posed a capacity challenge to ICUs across the territory, and it may be reasonably anticipated that should a substantially larger outbreak occur, ICU services will be overwhelmed. Therefore, a transparent and fair prioritisation process for decisions regarding patient ICU admission is urgently required. This triage tool is built on the foundation of the existing guidelines and framework for admission, discharge, and triage that inform routine clinical practice in Hospital Authority ICUs, with the aim of achieving the greatest benefit for the greatest number of patients from the available ICU resources. This COVID-19 Crisis Triage Tool is expected to provide structured guidance to frontline doctors on how to make triage decisions should ICU resources become overwhelmed by patients requiring ICU care, particularly during the current COVID-19 pandemic. The triage tool takes the form of a detailed decision aid algorithm based on a combination of established prognostic scores, and it should increase objectivity and transparency in triage decision making and enhance decision-making consistency between doctors within and across ICUs in Hong Kong. However, it remains an aid rather than a complete substitute for the carefully considered judgement of an experienced intensive care clinician.

Transitioning a randomized controlled trial to a digital registry – experience from the TAILOR-PCI digital follow-up study on onboarding, engagement and geofencing consent rate

Background/Introduction

TAILOR-PCI is the largest cardiovascular genotype-based randomized trial (NCT#01742117) investigating whether genotype-guided selection of oral P2Y12 inhibitor therapy improves ischemic outcomes after percutaneous coronary intervention (PCI). The TAILOR-PCI Digital Sub-Study tests the feasibility of extending original follow-up of 1 year to 2 years using state-of-the-art digital solutions. Deep phenotyping acquired during a clinical trial can be leveraged by extending follow-up in an efficient and cost-effective manner using digital technology.

Purpose

Our objective is to describe onboarding and engagement of participants initially recruited in a large, pragmatic, international, multi-center clinical trial to a digital registry.

Methods

TAILOR-PCI participants, within 23 months of their index PCI, were invited by letters containing a URL to the Digital Sub-Study website (http://tailorpci.eurekaplatform.org). These invitations were followed by phone calls, if no response to the letter, to determine reason for non-participation. A NIH-funded direct-to-participant digital research platform (the Eureka Research Platform) was used to onboard, consent and enroll participants for the digital follow-up. Participants were asked to answer health-related surveys at fixed intervals using the Eureka mobile app and desktop platform. To capture hospitalizations, participants could enable geofencing to allow background location tracking, which triggered surveys if a hospitalization was detected.

Result(s)

Letters were mailed to 893 of 929 eligible participants across 22 sites in the United States and Canada leading to 226 homepage visits and 118 registrations. There were 107 consents (12.0% of invited; mean age: 66.4±9.0; 19 females [18%]): 47 (44%) participants consented after the letter, 36 (34%) consented after the 1st call and 24 (22%) consented after a 2nd call. Among those who consented, 100 were eligible (7 did not have a smartphone) 81 downloaded the study mobile app and 73 agreed for geofencing (Figure 1). Among the 722 invited participants who were surveyed, 354 declined participation: due to lack of time (146; 20.2%), lack of smartphone (125; 17.3%), difficulty understanding (41; 5.7%), concern about using smartphone (34; 4.7%), concern of data privacy (14; 1.9%), concerns of location tracking (6; 0.8%) and other reasons (57; 7.9%).

Conclusion

Extended follow-up of a clinical trial using a digital platform is feasible but uptake in this study population was limited largely due to lack of time or a smartphone among participants. Based on data from other digital studies, uptake may also have been limited since digital follow-up consent was not incorporated at the time of consent for the main trial.

Figure 1. Onboarding of the digital substudy

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Institute of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI)

Comparing clinical outcomes following 1 year of dual antiplatelet therapy in patients risk stratified by the PRECISE-DAPT and DAPT scores

Background

Dual antiplatelet therapy (DAPT) is the standard of care following PCI. DAPT reduces ischemic events but increases bleeding risk. Duration of DAPT following PCI remains controversial. Current guidelines recommend duration be individualized based on risk of ischemia and bleeding. Although multiple strategies exist to risk stratify patients, including application of the PRECISE-DAPT and DAPT scores, there is currently no standardized risk assessment protocol.

Purpose

To determine if the PRECISE-DAPT and DAPT scores can identify patients at increased risk of ischemia or bleeding in a cohort prescribed 12 months of DAPT following PCI.

Methods

We calculated the PRECISE-DAPT and DAPT scores for 469 consecutive patients at baseline after PCI. Patients were grouped based on score treatment recommendation; PRECISE-DAPT prolonged or shortened (PRECISE DAPT &lt;25 vs. ≥25) and DAPT prolonged or shortened (DAPT ≥2 vs &lt;2). End points included 1-year rates of major adverse cardiovascular events (MACE) and TIMI major or minor bleeding.

Results

Among 469 patients, mean age was 64.4 (SD 12.2); 102 (21.7%) were women. Index presentation consisted of a STEMI in 207 (44.1%), NSTEMI in 99 (21.1%), and UA in 60 (12.8%). At presentation, 174 (37.1%) were current smokers, 115 (24.5%) had a prior MI, 118 (25.2%) had diabetes, 249 (53.1%) had dyslipidemia and 281 (60.0%) were previously diagnosed as hypertensive. Overall, there was an increase in bleeding and no difference in MACE for patients with a PRECISE-DAPT score ≥25 (13.3% vs. 4.1% P&lt;0.001). No difference in bleeding or MACE was present in patients stratified by the DAPT score.

Conclusion

A PRECISE-DAPT score ≥25 was associated with an increased rate of bleeding and no difference in MACE in patients prescribed 12 months of DAPT. This supports the use of the PRECISE-DAPT as a prospective tool in clinical practice.

Funding Acknowledgement

Type of funding source: None

P1933Comparing treatment recommendations for the DAPT and PRECISE-DAPT scores after percutaneous coronary intervention

Background

Dual antiplatelet therapy (DAPT), with aspirin and a P2Y12 inhibitor, is the standard therapy for patients following PCI. Duration of treatment with DAPT has been controversial despite large studies. Current guidelines recommend treatment duration be individualized based on risk of ischemia and bleeding. To facilitate treatment decisions, risk assessment tools, including the DAPT and PRECISE-DAPT scores, have been developed.

Purpose

As components of these scores differ, the variability of recommendation remains unknown. We set to evaluate inter-tool concordance in treatment recommendation in a cohort of patients after PCI.

Methods

Using data from our local PCI registry, we calculated the PRECISE-DAPT at baseline following PCI and the DAPT after 1 year of treatment for 311 consecutive patients with complete data for both scores to be calculated. Based on their DAPT and PRECISE-DAPT scores, patients were grouped into concordant for long-term treatment (DAPT ≥2 and PRECISE-DAPT <25) or concordant for shortened treatment (DAPT <2 and PRECISE- DAPT ≥25). All other patients were considered discordant. We then performed a concordance analysis using Cohen's kappa to measure degree of agreement.

Results

Among the 311 patients, mean age was 63.4 (SD 11.6); 245 (79%) were men, 93 (29.9%) had history of a prior MI, 130 (41.8%) were current smokers, 32 (10.3%) had a history of CHF or LVEF <30%, 82 (26.3%) had diabetes and 196 (63.0%) were previously diagnosed with hypertension. Index event consisted of a STEMI in 101 (32.4%), NSTEMI in 93 (29.9%), unstable angina in 27 (8.7%), stable angina in 67 (21.5%) and the remaining 23 (7.4%) had other indications for PCI. Mean DAPT score was 1.52 (SD 1.37). Mean PRECISE-DAPT was 17.65 (SD 12.73). The DAPT recommended long-term treatment for 162 (52.1%) and shortened treatment for 149 (47.9%). The PRECISE-DAPT recommended long-term treatment for 245 (78.9%) and shortened treatment for 66 (21.2%). The overall proportion of agreement between the two risk scores was 56.6% with a Cohen's kappa index of 0.110 (95% CI, 0.017 to 0.204). See Table.

Concordance Analysis PRECISE-DAPT Score Recommendation Long Term (N=245) Shortened (N=66) DAPT Score Recommendation Long Term (N=162) 136 (43.7%) 26 (8.4%) Concordant for Long Term Treatment Shortened (N=149) 109 (35%) 40 (12.8%) Concordant for Shortened Treatment

Conclusion

Comparison of the DAPT score and the PRECISE-DAPT score showed concordance in treatment recommendation in only 56.6% of patients. Given the poor agreement between these tools, prospective concurrent evaluations and correlation to outcomes will be required in future studies.

Accelerated tumor growth under intermittent hypoxia is associated with hypoxia-inducible factor-1-dependent adaptive responses to hypoxia

Mounting evidence has revealed a causative role of intermittent hypoxia (IH) in cancer progression in mouse models of obstructive sleep apnea (OSA), but most studies have focused on the effects of IH following tumor implantation using an exposure to single IH frequency. Thus, we aimed to investigate 1) the potential effect of IH on the initial tumor growth in patients with OSA without an interaction with other mechanisms induced by IH in mice and 2) the influence of the IH frequency on tumor growth, which were tested using pre-conditioning with IH (Pre-IH) and 2 different IH frequencies, respectively. Pre-IH was achieved by alternatively maintaining melanoma cells between normoxia (10 min, 21% O₂) and hypoxia (50 min, 1% O₂) for 7 days (12 cycles per day) before administering them to mice. The conditions for IH-1 and IH-2 were 90 s of 12% FiO₂ followed by 270s of 21% FiO₂ (10 cycles/h), and 90 s of 12% FiO₂ and 90 s of 21% FiO₂ (20 cycles/h), respectively, for 8 h per day. Tumor growth was significantly higher in the Pre-IH group than in the normoxia group. In addition, the IH-2 group showed more accelerated tumor growth compared to the normoxia and IH-1 groups. Immunohistochemistry and gene-expression results consistently showed the up-regulation of molecules associated with HIF-1α-dependent hypoxic adaptation in tumors of the Pre-IH and IH-2 groups. Our findings reveal that IH increased tumor progression in a frequency-dependent manner, regardless of whether it was introduced before or after in vivo tumor cell implantation.

Solid-state colloidal CuInS2 quantum dot solar cells enabled by bulk heterojunctions

Colloidal copper indium sulfide (CIS) nanocrystals (NCs) are Pb- and Cd-free alternatives for use as absorbers in quantum dot solar cells. In a heterojunction with TiO₂, non-annealed ligand-exchanged CIS NCs form solar cells yielding a meager power conversion efficiency (PCE) of 0.15%, with photocurrents plummeting far below predicted values from absorption. Decreasing the amount of zinc during post-treatment leads to improved mobility but marginal improvement in device performance (PCE = 0.30%). By incorporating CIS into a porous TiO₂ network, we saw an overall drastic improvement in device performance, reaching a PCE of 1.16%, mainly from an increase in short circuit current density (J_sc) and fill factor (FF) and a 10-fold increase in internal quantum efficiency (IQE). We have determined that by moving from a bilayer to a bulk heterojunction architecture, we have reduced the trap-assisted recombination as seen in changes in the ideality factor, the intensity dependence of the photocurrent and transient photocurrent (TPC) and photovoltage (TPV) characteristics.

The PR status of the originating cell of ER/PR-negative mouse mammary tumors

Progesterone receptor (PR) is usually co-localized with estrogen receptor (ER) in normal mammary cells. It is not known whether ER/PR-negative human breast cancer arises from an ER/PR-negative cell or from an ER/PR-positive cell that later lost ER/PR. Using intraductal injection of a lentivirus to deliver both an oncogene (ErbB2) and a floxed green fluorescent protein (GFP) in PR(Cre/+)mice, whose Cre gene is under the control of the PR promoter, we were able to trace the PR status of the infected cells as they progressed to cancer. We found that the resulting early lesions stained negative for PR in most of the cells and usually retained GFP. The resulting tumors lacked ER and PR, and 75% (15/20) of them retained the GFP signal in all tumor cells, suggesting PR was never expressed throughout the evolution of a majority of these tumors. In conclusion, our data demonstrate that ErbB2-initiated ER/PR-negative mammary tumors primarily originate from the subset of the mammary epithelium that is negative for PR and probably ER as well. These findings also provide an explanation for why antihormonal therapy fails to prevent ER-negative breast cancers.

HIF-1α Upregulation due to Depletion of the Free Ubiquitin Pool

Hypoxia-inducible factor 1alpha (HIF-1α), which transactivates a variety of hypoxia-induced genes, is rapidly degraded under nomoxia through the hydroxylation-ubiquitination-proteasome pathway. In this study, we addressed how HIF-1α is stabilized by proteasome inhibitors. The ubiquitin pool was rapidly reduced after proteasome inhibition, followed by the accumulation of non-ubiquitinated HIF-1α. The poly-ubiquitination of HIF-1α was resumed by restoration of free ubiquitin, which suggests that the HIF-1α stabilization under proteasome inhibition is attributed to depletion of the free ubiquitin pool. Ni(2+) and Zn(2+) also stabilized HIF-1α with depletion of the free ubiquitin pool and these effects of metal ions were attenuated by restoration of free ubiquitin. Ni(2+) and Zn(2+) may disturb the recycling of free ubiquitin, as MG132 does. Based on these results, the state of the ubiquitin pool seems to be another critical factor determining the cellular level of HIF-1α.

ITF2 prevents activation of the β-catenin-TCF4 complex in colon cancer cells and levels decrease with tumor progression

BACKGROUND & AIMS

Immunoglobulin transcription factor 2 (ITF2) was believed to promote neoplastic transformation via activation of β-catenin. However, ITF2 recently was reported to suppress colon carcinogenesis. We investigated the roles of ITF2 in colorectal cancer cell lines and tumor formation and growth in mice.

METHODS

Levels of ITF2, β-catenin, and c-Myc were measured in 12 human colorectal tumor samples and by immunohistochemistry. ITF2 regulation of β-catenin and T-cell factor (TCF) were analyzed using luciferase reporter, reverse-transcription quantitative polymerase chain reaction, flow cytometry, and immunoblot analyses. Mice were given subcutaneous injections of human colorectal cancer cell lines that stably express ITF2, small hairpin RNAs to reduce levels of ITF2, or control plasmids; xenograft tumor growth was assessed. Human colorectal carcinoma tissue arrays were used to associate levels of ITF2 expression and clinical outcomes.

RESULTS

Levels of β-catenin, cMyc, and ITF2 were increased in areas of human colon adenomas and carcinomas, compared with nontumor areas of the same tissues. ITF2 levels were reduced and cMyc levels were increased in areas of carcinoma, compared with adenoma. In human colorectal cancer cell lines, activation of the β-catenin-TCF4 complex and expression of its target genes were regulated negatively by ITF2. ITF2 inhibited formation of the β-catenin-TCF4 complex by competing with TCF4 for β-catenin binding. Stable transgenic expression of ITF2 in human colorectal cancer cell lines reduced their proliferation and tumorigenic potential in mice, whereas small hairpin RNA knockdown of ITF2 promoted growth of xenograft tumors in mice. In an analysis of colorectal tumor tissue arrays, loss of ITF2 from colorectal tumor tissues was associated with poor outcomes of patients. A gene set enrichment analysis supported the negative correlation between the level of ITF2 and activity of the β-catenin-TCF4 complex.

CONCLUSIONS

In human colorectal cancer cell lines and tissue samples, ITF2 appears to prevent activation of the β-catenin-TCF4 complex and transcription of its gene targets. Loss of ITF2 promotes the ability of colorectal cancer cells to form xenograft tumors, and is associated with tumor progression and shorter survival times of patients.

Comparison of seven serum thyroglobulin assays in the follow-up of papillary and follicular thyroid cancer patients

BACKGROUND

Serum thyroglobulin (Tg) is the marker of differentiated thyroid cancer after initial treatment and TSH stimulation increases its sensitivity for the diagnosis of recurrent disease.

AIM

The goal of the study is to compare the diagnostic values of seven methods for serum Tg measurement for detecting recurrent disease both during L-T4 treatment and after TSH stimulation.

METHODS

Thyroid cancer patients who had no evidence of persistent disease after initial treatment (total thyroidectomy and radioiodine ablation) were studied at 3 months on L-T4 treatment (Tg1) and then at 9-12 months after withdrawal or recombinant human TSH stimulation (Tg2). Sera with anti-Tg antibodies or with an abnormal recovery test result were excluded from Tg analysis with the corresponding assay. The results of serum Tg determination were compared to the clinical status of the patient at the end of follow-up.

RESULTS

Thirty recurrences were detected among 944 patients. A control 131I total body scan had a low sensitivity, a low specificity, and a low clinical impact. Assuming a common cutoff for all Tg assays at 0.9 ng/ml, sensitivity ranged from 19-40% and 68-76% and specificity ranged from 92-97% and 81-91% for Tg 1 and Tg2, respectively. Using assays with a functional sensitivity at 0.2-0.3 ng/ml, sensitivity was 54-63% and specificity was 89% for Tg1. Using the two methods with a lowest functional sensitivity at 0.02 and 0.11 ng/ml resulted in a higher sensitivity for Tg1 (81% and 78%), but at the expense of a loss of specificity (42% and 63%); finally, for these two methods, using an optimized functional sensitivity according to receiver operating characteristic curves at 0.22 and 0.27 ng/ml resulted in a sensitivity at 65% and specificity at 85-87% for Tg1.

CONCLUSION

Using an assay with a lower functional sensitivity may give an earlier indication of the presence of Tg in the serum on L-T4 treatment and may be used to study the trend in serum Tg without performing any TSH stimulation. Serum Tg determination obtained after TSH stimulation still permits a more reliable assessment of cure and patient's reassurance.