Translational process Boccardi, Marina
Journal of translational medicine,
09/2023, Letnik:
21, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Requirements and constraints set by regulators, health technology assessment experts and policy makers seldom affect research priorities and study designs. Clinical guidelines must be defined by ...expert consensus despite extensive literature, failing to demonstrate clinical validity 2, 9. Besides delaying benefits to patients, such inconsistent proceeding results in high costs to society, investing in translational research that may be more efficient. Whiting P, Rutjes AWS, Reitsma JB, Glas AS, Bossuyt PMM, Kleijnen J. Sources of variation and bias in studies of diagnostic accuracy: a systematic review.
Purpose
In 2017, the Geneva Alzheimer’s disease (AD) strategic biomarker roadmap initiative proposed a framework of the systematic validation AD biomarkers to harmonize and accelerate their ...development and implementation in clinical practice. Here, we use this framework to examine the translatability of the second-generation tau PET tracers into the clinical context.
Methods
All available literature was systematically searched based on a set of search terms that related independently to analytic validity (phases 1–2), clinical validity (phase 3–4), and clinical utility (phase 5). The progress on each of the phases was determined based on scientific criteria applied for each phase and coded as fully, partially, preliminary achieved or not achieved at all.
Results
The validation of the second-generation tau PET tracers has successfully passed the analytical phase 1 of the strategic biomarker roadmap. Assay definition studies showed evidence on the superiority over first-generation tau PET tracers in terms of off-target binding. Studies have partially achieved the primary aim of the analytical validity stage (phase 2), and preliminary evidence has been provided for the assessment of covariates on PET signal retention. Studies investigating of the clinical validity in phases 3, 4, and 5 are still underway.
Conclusion
The current literature provides overall preliminary evidence on the establishment of the second-generation tau PET tracers into the clinical context, thereby successfully addressing some methodological issues from the tau PET tracer of the first generation. Nevertheless, bigger cohort studies, longitudinal follow-up, and examination of diverse disease population are still needed to gauge their clinical validity.
Abstract The pathway leading from beta-amyloid deposition to cognitive impairment is believed to be a cornerstone of the pathogenesis of Alzheimer’s disease (AD). However, what drives amyloid ...build-up in sporadic non-genetic cases of AD is still unknown. AD brains feature an inflammatory reaction around amyloid plaques, and a specific subset of the gut microbiota (GMB) may promote brain inflammation. We investigated the possible role of the GMB in AD pathogenesis by studying the association of brain amyloidosis with (i) GMB taxa with pro- and anti-inflammatory activity, and (ii) peripheral inflammation in cognitively impaired patients. We measured the stool abundance of selected bacterial GMB taxa ( Escherichia/Shigella, Pseudomonas aeruginosa , Eubacterium rectale, Eubacterium hallii, Faecalibacterium prausnitzii and Bacteroides fragilis ) and the blood expression levels of cytokines (pro-inflammatory cytokines: CXCL2, CXCL10, IL-1β, IL-6, IL-18, IL-8, NLRP3, TNF-α; anti-inflammatory cytokines: IL-4, IL-10, IL-13) in cognitively impaired patients with (n=40, Amy+) and with no brain amyloidosis (n=33, Amy-), and also in a group of controls (n=10, no brain amyloidosis and no cognitive impairment, HC). Amy+ patients showed higher levels of pro-inflammatory cytokines (IL-6, CXCL2, NLRP3 and IL-1β) compared to both controls and to Amy- patients. A reduction of the anti-inflammatory cytokine IL-10 was observed in Amy+ versus Amy-. Amy+ showed lower abundance of Eubacterium rectale and higher abundance of Escherichia/Shigella as compared to both HC (Fold Change, FC=-9.6, p<0.001 and FC=+12.8, p<0.001, respectively ) and to Amy- (FC=-7.7, p<0.001 and FC=+7.4, p=0.003 ). A positive correlation was observed between pro-inflammatory cytokines IL-1β, NLRP3 and CXCL2 with abundance of the inflammatory bacteria taxon Escherichia/Shigella (rho=0.60, p<0.001; rho=0.57, p<0.001; and rho=0.30, p=0.007, respectively) and a negative correlation with the anti-inflammatory Eubacterium rectale ( rho=-0.48, p<0.001; rho=-0.25, p=0.024; rho=-0.49, p<0.001). Our data indicate that an increase in the abundance of a pro-inflammatory GMB taxon, Escherichia/Shigella , and a reduction in the abundance of an anti-inflammatory taxon, Eubacterium rectale , are possibly associated with a peripheral inflammatory state in patients with cognitive impairment and brain amyloidosis. A possible causal relation between GMB-related inflammation and amyloidosis deserves further investigation.
Abstract The use of Alzheimer's disease (AD) biomarkers is supported in diagnostic criteria, but their maturity for clinical routine is still debated. Here, we evaluate brain fluorodeoxyglucose ...positron emission tomography (FDG PET), a measure of cerebral glucose metabolism, as a biomarker to identify clinical and prodromal AD according to the framework suggested for biomarkers in oncology, using homogenous criteria with other biomarkers addressed in parallel reviews. FDG PET has fully achieved phase 1 (rational for use) and most of phase 2 (ability to discriminate AD subjects from healthy controls or other forms of dementia) aims. Phase 3 aims (early detection ability) are partly achieved. Phase 4 studies (routine use in prodromal patients) are ongoing, and only preliminary results can be extrapolated from retrospective observations. Phase 5 studies (quantify impact and costs) have not been performed. The results of this study show that specific efforts are needed to complete phase 3 evidence, in particular comparing and combining FDG PET with other biomarkers, and to properly design phase 4 prospective studies as a basis for phase 5 evaluations.
Abstract The use of biomarkers has been proposed for diagnosing Alzheimer's disease in recent criteria, but some biomarkers have not been sufficiently investigated to justify their routine clinical ...use. Here, we evaluate in a literature review the clinical validity of amyloid positron emission tomography (PET) imaging using a structured framework developed for the assessment of oncological biomarkers. Homogenous criteria have been addressed in reviews of other Alzheimer's disease biomarkers. There is adequate evidence that the main aims of phases 1 (rationale for use) and 2 (discriminative ability) have been achieved. The aims of phase 3 (early detection ability) have been partly achieved, while phase 4 studies (performance in representative mild cognitive impairment patients) are currently ongoing. Phase 5 studies (quantification of impact and costs) are still to come. This review highlights the priorities to be pursued to enable the proper use of amyloid PET imaging in a clinical setting. Future investigations will primarily be large, phase 4 studies that will assess the utility of amyloid PET imaging in routine clinical practice.
Purpose
We aim to report the quality of accuracy studies investigating the utility of
18
Ffluorodeoxyglucose (FDG)-PET in supporting the diagnosis of prodromal Alzheimer’s Disease (AD), ...frontotemporal lobar degeneration (FTLD) and prodromal dementia with Lewy bodies (DLB) in mild cognitive impairment (MCI) subjects, and the corresponding recommendations made by a panel of experts.
Methods
Seven panellist, four from the European Association of Nuclear Medicine, and three from the European Academy of Neurology, produced recommendations taking into consideration the incremental value of FDG-PET, as added on clinical-neuropsychological examination, to ascertain the aetiology of MCI (AD, FTLD or DLB). A literature search using harmonized population, intervention, comparison, and outcome (PICO) strings was performed, and an evidence assessment consistent with the European Federation of Neurological Societies guidance was provided. The consensual recommendation was achieved based on Delphi rounds.
Results
Fifty-four papers reported the comparison of interest. The selected papers allowed the identification of FDG patterns that characterized MCI due to AD, FTLD and DLB. While clinical outcome studies supporting the diagnosis of MCI due to AD showed varying accuracies (ranging from 58 to 100%) and varying areas under the receiver-operator characteristic curves (0.66 to 0.97), no respective data were identified for MCI due to FTLD or for MCI due to DLB. However, the high negative predictive value of FDG-PET and the existence of different disease-specific patterns of hypometabolism support the consensus recommendations for the clinical use of this imaging technique in MCI subjects.
Conclusions
FDG-PET has clinical utility on a fair level of evidence in detecting MCI due to AD. Although promising also in detecting MCI due to FTLD and MCI due to DLB, more research is needed to ultimately judge the clinical utility of FDG-PET in these entities.
Abstract Background The Target Product Profile (TPP) is a tool used in industry to guide development strategies by addressing user needs and fostering effective communication among stakeholders. ...However, they are not frequently used in academic research, where they may be equally useful. This systematic review aims to extract the features of accessible TPPs, to identify commonalities and facilitate their integration in academic research methodology. Methods We searched peer-reviewed papers published in English developing TPPs for different products and health conditions in four biomedical databases. Interrater agreement, computed on random abstract and paper sets (Cohen’s Kappa; percentage agreement with zero tolerance) was > 0.91. We interviewed experts from industry contexts to gain insight on the process of TPP development, and extracted general and specific features on TPP use and structure. Results 138 papers were eligible for data extraction. Of them, 92% ( n = 128) developed a new TPP, with 41.3% ( n = 57) focusing on therapeutics. The addressed disease categories were diverse; the largest (47.1%, n = 65) was infectious diseases. Only one TPP was identified for several fields, including global priorities like dementia. Our analyses found that 56.5% of papers ( n = 78) was authored by academics, and 57.8% of TPPs ( n = 80) featured one threshold level of product performance. The number of TPP features varied widely across and within product types ( n = 3–44). Common features included purpose/context of use, shelf life for drug stability and validation aspects. Most papers did not describe the methods used to develop the TPP. We identified aspects to be taken into account to build and report TPPs, as a starting point for more focused initiatives guiding use by academics. Discussion TPPs are used in academic research mostly for infectious diseases and have heterogeneous features. Our extraction of key features and common structures helps to understand the tool and widen its use in academia. This is of particular relevance for areas of notable unmet needs, like dementia. Collaboration between stakeholders is key for innovation. Tools to streamline communication such as TPPs would support the development of products and services in academia as well as industry.
Purpose
Assess the individual and combined diagnostic value of amyloid-PET and tau-PET in a memory clinic population.
Methods
Clinical reports of 136 patients were randomly assigned to two diagnostic ...pathways: AMY-TAU, amyloid-PET is presented before tau-PET; and TAU-AMY, tau-PET is presented before amyloid-PET. Two neurologists independently assessed all reports with a balanced randomized design, and expressed etiological diagnosis and diagnostic confidence (50–100%) three times: (i) at baseline based on the routine diagnostic workup, (ii) after the first exam (amyloid-PET for the AMY-TAU pathway, and tau-PET for the TAU-AMY pathway), and (iii) after the remaining exam. The main outcomes were changes in diagnosis (from AD to non-AD or vice versa) and in diagnostic confidence.
Results
Amyloid-PET and tau-PET, when presented as the first exam, resulted in a change of etiological diagnosis in 28% (
p
= 0.006) and 28% (
p
< 0.001) of cases, and diagnostic confidence increased by 18% (
p
< 0.001) and 19% (
p
< 0.001) respectively, with no differences between exams (
p
> 0.05). We observed a stronger impact of a negative amyloid-PET versus a negative tau-PET (
p
= 0.014). When added as the second exam, amyloid-PET and tau-PET resulted in a further change in etiological diagnosis in 6% (
p
= 0.077) and 9% (
p
= 0.149) of cases, and diagnostic confidence increased by 4% (
p
< 0.001) and 5% (
p
< 0.001) respectively, with no differences between exams (
p
> 0.05).
Conclusion
Amyloid-PET and tau-PET significantly impacted diagnosis and diagnostic confidence in a similar way, although a negative amyloid-PET has a stronger impact on diagnosis than a negative tau-PET. Adding either of the two as second exam further improved diagnostic confidence.
Trial number
PB 2016-01346.
PDF
